Neeves
Well-known member
The induction hob is in Aldi, here - In Australia.
Induction Hob (and air fryer)
- Thread starter Neeves
- Start date
Neeves
Well-known member
One reason for following certain assembly routes is that in the case of an untimely failure and the Lithium circuits switch off (or the Lithium batteries switch off) and this will deny power to Nav, AP etc etc. This is meant to be a serious difference between marine and terrestrial installations.
This is introduced as a dooms day scenario - you can always assume someone will introduce a fear factor in threads.
It is already recommended that a 'T' fuse (?) is installed as close to the battery as possible in the positive lead to the Lithium batteries from the alternator - have not check if my memory is lacking. I wonder how many times these fuses are necessary (ie how often they do what they are meant to do - and blow).
If the 'T' fuse is felt necessary surely it would be equally sensible to have a 1,2 Both (but remove 'both') switch for the Lead and Lithium batteries to allow temporary power to be established in the critical navigational circuits or any other circuits deemed critical. All yachts will have a Lead battery - as Lithium is not used for engine start. Effectively all Lithium 'powered' yachts are hybrid systems. It seems reasonable that if there is a risk of the Lithium shutting down, the battery management systems cannot be 100% reliable, to use the resources available - plan in advance and use the Lead engine start battery - if there is concern at running the battery flat - run the engine and then sort out the Lithium.
I vaguely recall that Geem is building a new, or modifying the old, Lead battery bank - but I forget why. For anyone retrofitting a Lithium house bank most of the kit already on the yacht will be perfectly serviceable except the Lead batteries whose failure is promoting the change. Instead of tossing all the old kit - if Lithium shut off is a real issue - add an extra Lead battery, small, simply for the off chance (and then you do not need to use the engine start battery). The extra solar to keep it charged is minimal.
Jonathan
This is introduced as a dooms day scenario - you can always assume someone will introduce a fear factor in threads.
It is already recommended that a 'T' fuse (?) is installed as close to the battery as possible in the positive lead to the Lithium batteries from the alternator - have not check if my memory is lacking. I wonder how many times these fuses are necessary (ie how often they do what they are meant to do - and blow).
If the 'T' fuse is felt necessary surely it would be equally sensible to have a 1,2 Both (but remove 'both') switch for the Lead and Lithium batteries to allow temporary power to be established in the critical navigational circuits or any other circuits deemed critical. All yachts will have a Lead battery - as Lithium is not used for engine start. Effectively all Lithium 'powered' yachts are hybrid systems. It seems reasonable that if there is a risk of the Lithium shutting down, the battery management systems cannot be 100% reliable, to use the resources available - plan in advance and use the Lead engine start battery - if there is concern at running the battery flat - run the engine and then sort out the Lithium.
I vaguely recall that Geem is building a new, or modifying the old, Lead battery bank - but I forget why. For anyone retrofitting a Lithium house bank most of the kit already on the yacht will be perfectly serviceable except the Lead batteries whose failure is promoting the change. Instead of tossing all the old kit - if Lithium shut off is a real issue - add an extra Lead battery, small, simply for the off chance (and then you do not need to use the engine start battery). The extra solar to keep it charged is minimal.
Jonathan
Neeves
Well-known member
Convenience. Anyone can buy a drop in this afternoon. You have to import the cells, pay well in advance, possibly sort out import paper work, maybe pick up at the docks (this was the option when we bought our Spade (go and get it).
Its an interesting project but the many who employ a mechanic to service their yacht are not going to do it - they will want it all NOW, or at least soon.
Jonathan
noelex
Well-known member
The BMS disconnecting the lithium battery bank is certainly a real issue that needs to be considered.
Combining lead acid batteries with lithium is one common solution to this problem. An advantage of this solution is that it will work with batteries containing a simple internal BMS without any communication.
Kelpie
Well-known member
I'm not sure if it's the point you were making but choice of DIY or drop-in has zero impact on this. Both will shut power off without warning if the BMS trips.
The DIY route does at least let you choose a split load bus, retaining power in *some* trip scenarios. AFAIK no drop in battery offers that.
The class T fuse is there to prevent arcing in case of a very high current short. It's arguable that in small systems it's not really necessary, and ANL or MRBF can be used instead, but it's become the ABYC standard and for larger systems it's definitely what you want to fit.
It doesn't just go between the battery and alternator, it should be the first thing the battery is connected to, before any loads. Slight exception, the solar charge controller will connect directly to the battery, via its which own fuse, otherwise you can end up with the main fuse blowing and the boat's systems running directly off solar.
They'll blow for the same reasons a any fuse blows. Are you getting confused between BMS shut off and a fuse blowing?
We all should have a main fuse in our electrical system regardless of battery type. Hopefully it won't ever blow but we fit these things for a reason. A faulty component, a wire comes adrift and causes a short, human error working on a live system. If it happens, you don't want to start a fire.
This is pretty much what I have, except I couldn't find a 1-2-off switch.
I installed a pair of simple isolators, the type with a key that is removable in the 'off' position. One turns on the lithium supply, the other the lead acid. You have to shut one supply down, remove the key, and then turn on the other one. It's impossible to accidentally turn them both on unless you have a second compatible key.
It's not seamless, you have to reboot the plotter, but it only takes a second to make the switch, and it's idiot proof.
That's pretty much standard practice.
Although, just to correct you, you can easily start an engine from all but the smartest lithium batteries. Some people have chosen to do this but it's a minority decision, because lead acid makes perfect sense. Same goes for bow thrusters and windlass.
Pretty much what I did. Kept the old lead acid system in place. The batteries live in the engine room so I wasn't going to put my new lithium in there anyway. I have 230w of solar feeding 330Ah of lead acid. Most of my loads run from the lithium, but a handful of cabin lights and charging sockets remain on the lead acid, so I can still get around the boat and use one of the heads- and I can still charge a phone.
The instruments can run off either power source, as described above.
Kelpie
Well-known member
Yes that's true, if you don't want to wait two months you're probably going to need to buy drop in. Not many people stock cells on their own
But you will pay for that convenience.
If you are willing to import, then you have the choice of DIY or drop-in, and the best prices.
geem
Well-known member
On the assumption that you have a breaker or isolator on your lithium battery, you only need a simple emergency switch to link the engine batteries to the domestic circuit. This is what I have. The emergency switch is in a steel cabinet in the engine room. Open the door, install the key and turn.
I have just built a second lithium battery and I gave my 4xlead Trojan T105RE batteries away. The weight saving is huge!
With two lithium batteries and seperate class T fuses, BMS, smart shunt and isolator, you have resilience and redundancy should a BMS fail or the bms trip for a HVE, etc
Neeves
Well-known member
Noelex,
You are a significant contributor to Lithium threads but I don't recall your describing your Lithium system. It would be useful to know what you did and now, after some time using it, what you might change if you were to build a new system in the future. For example did you build your own Lithium bank (and where did you get the cells from).
Geem, Pete 7, Kelpie and others have been fulsome in their descriptions - we know nothing of yours (or I missed the posts - which is very likely).
Jonathan
noelex
Well-known member
No lithium system. Our current boat has 600Ahrs @24v of gel batteries.
Neeves
Well-known member
That's a serious battery bank (what solar capacity?) - why not Lithium, or was it too early?
Jonathan
Neeves
Well-known member
Answering my own question on using the BMS, in a Lithium battery with built in BMS, as a solar controller.
We had not charged our 200amp Lithium Battery to 100%, I thought I had but seem to have been out by 1 or 2 amps when setting the battery monitor. We have also been testing various domestic devices to find out how our 'build' performs (especially as our inverter is only 1500amps). We had been cautious and had been using a 1300 watts air fryer and tried a 1500 watt air fryer only yesterday. The Breadmaker works well (as did the air fryers). The next device is the induction hob - but we don't have one yet.
We should have bought a bigger inverter, lesson learnt
We had the chance to charge the battery fully.
When the battery achieved 100% fully charged - nothing happened. Solar charging amps remained high and the battery Mon displayed the charging amps and the battery at 100% - leaving everything as was the capacity did not increase beyond 100% - which might suggest I had not set the Mon accurately.
But within about 2 minutes the charging amps dropped to 000.1 amp. The only other thing I could check was temperature - and the battery had not warmed up (nor cooled down
) - temperature measured by hand (really scientific).
Isolating the charge from the solars, 2 separate cables to 2 x 250 watt folding panels each with an Anderson plug, immediately allowed the Mon to cancel the 000.1 amp and display devices using or taking the stored amps, primarily esky taking 5.5 amps. The 000.1 amp might suggest that battery power was inaccessible. It possibly had isolated itself.
To those that think I'm mad - we do have a solar controller but for some reason it only displays amps being consumed, not amps charging (nor the addition subtraction of the 2). The solar controller has only one connection port, and we have 2 panels (I need to wire up a 'Y' connector) so I'm using 2 separate, spare, Anderson plugs, connected for 'just in case' but not on the solar controller circuit. The amps being produced by the 2 panels, seems, is accurately recorded on the shunt/mon and then reduced when the esky comes on line.
The solar controller charges the battery but only records amps being used. The solar controller only has one input. I can improve the number of devices (solar panels) but cannot alter the display. The cheap as chips battery mon works as it says on the box, reads amps in and out, sums the 2, displays battery state as a little picture, as a % and also as amps remaining. It has a memory function - but I have not had to use it yet. We bought the Mon direct from China, through Aliexpress (and as with much from Aliexpress - no brand name) The off the shelf battery with internal BMS works (though there are no indication on the box how it works, whether volts, amps or when it detects it is full (of amps) - but when the battery is full - it shuts of the input of the solars. It may also shut off access to the battery - I need to check that (the dooms day scenario).
What have I done wrong - what else should I check?
Finally - I'm glad, very glad to be doing this at home and not on a yacht - simply speaking its factorially more convenient. No...we don't have a mast shading the panels, we don't have a yacht swinging at anchor - but we do have mains power and we are not starving through being unable to cook nor needing to take cold showers - because I got it wrong (this is the first electric build I have attempted). As far as I know the terrestrial amps are identical to marine amps - I fail to see the difference. We have yet to test the B2B charging - another exciting aspect.
When we get it right we can take the whole build and re-build on a yacht. It will work 'out of the box' the trial and error will have been completed.
Jonathan
We had not charged our 200amp Lithium Battery to 100%, I thought I had but seem to have been out by 1 or 2 amps when setting the battery monitor. We have also been testing various domestic devices to find out how our 'build' performs (especially as our inverter is only 1500amps). We had been cautious and had been using a 1300 watts air fryer and tried a 1500 watt air fryer only yesterday. The Breadmaker works well (as did the air fryers). The next device is the induction hob - but we don't have one yet.
We should have bought a bigger inverter, lesson learnt
We had the chance to charge the battery fully.
When the battery achieved 100% fully charged - nothing happened. Solar charging amps remained high and the battery Mon displayed the charging amps and the battery at 100% - leaving everything as was the capacity did not increase beyond 100% - which might suggest I had not set the Mon accurately.
But within about 2 minutes the charging amps dropped to 000.1 amp. The only other thing I could check was temperature - and the battery had not warmed up (nor cooled down
) - temperature measured by hand (really scientific).Isolating the charge from the solars, 2 separate cables to 2 x 250 watt folding panels each with an Anderson plug, immediately allowed the Mon to cancel the 000.1 amp and display devices using or taking the stored amps, primarily esky taking 5.5 amps. The 000.1 amp might suggest that battery power was inaccessible. It possibly had isolated itself.
To those that think I'm mad - we do have a solar controller but for some reason it only displays amps being consumed, not amps charging (nor the addition subtraction of the 2). The solar controller has only one connection port, and we have 2 panels (I need to wire up a 'Y' connector) so I'm using 2 separate, spare, Anderson plugs, connected for 'just in case' but not on the solar controller circuit. The amps being produced by the 2 panels, seems, is accurately recorded on the shunt/mon and then reduced when the esky comes on line.
The solar controller charges the battery but only records amps being used. The solar controller only has one input. I can improve the number of devices (solar panels) but cannot alter the display. The cheap as chips battery mon works as it says on the box, reads amps in and out, sums the 2, displays battery state as a little picture, as a % and also as amps remaining. It has a memory function - but I have not had to use it yet. We bought the Mon direct from China, through Aliexpress (and as with much from Aliexpress - no brand name) The off the shelf battery with internal BMS works (though there are no indication on the box how it works, whether volts, amps or when it detects it is full (of amps) - but when the battery is full - it shuts of the input of the solars. It may also shut off access to the battery - I need to check that (the dooms day scenario).
What have I done wrong - what else should I check?
Finally - I'm glad, very glad to be doing this at home and not on a yacht - simply speaking its factorially more convenient. No...we don't have a mast shading the panels, we don't have a yacht swinging at anchor - but we do have mains power and we are not starving through being unable to cook nor needing to take cold showers - because I got it wrong (this is the first electric build I have attempted). As far as I know the terrestrial amps are identical to marine amps - I fail to see the difference. We have yet to test the B2B charging - another exciting aspect.
When we get it right we can take the whole build and re-build on a yacht. It will work 'out of the box' the trial and error will have been completed.
Jonathan
geem
Well-known member
How do you know where 100% charge is? Are you reading the voltage at cell level? Does your battery have a BMS you can interface and adjust settings?Answering my own question on using the BMS, in a Lithium battery with built in BMS, as a solar controller.
We had not charged our 200amp Lithium Battery to 100%, I thought I had but seem to have been out by 1 or 2 amps when setting the battery monitor. We have also been testing various domestic devices to find out how our 'build' performs (especially as our inverter is only 1500amps). We had been cautious and had been using a 1300 watts air fryer and tried a 1500 watt air fryer only yesterday. The Breadmaker works well (as did the air fryers). The next device is the induction hob - but we don't have one yet.
We should have bought a bigger inverter, lesson learnt
We had the chance to charge the battery fully.
When the battery achieved 100% fully charged - nothing happened. Solar charging amps remained high and the battery Mon displayed the charging amps and the battery at 100% - leaving everything as was the capacity did not increase beyond 100% - which might suggest I had not set the Mon accurately.
But within about 2 minutes the charging amps dropped to 000.1 amp. The only other thing I could check was temperature - and the battery had not warmed up (nor cooled down
Isolating the charge from the solars, 2 separate cables to 2 x 250 watt folding panels each with an Anderson plug, immediately allowed the Mon to cancel the 000.1 amp and display devices using or taking the stored amps, primarily esky taking 5.5 amps. The 000.1 amp might suggest that battery power was inaccessible. It possibly had isolated itself.
To those that think I'm mad - we do have a solar controller but for some reason it only displays amps being consumed, not amps charging (nor the addition subtraction of the 2). The solar controller has only one connection port, and we have 2 panels (I need to wire up a 'Y' connector) so I'm using 2 separate, spare, Anderson plugs, connected for 'just in case' but not on the solar controller circuit. The amps being produced by the 2 panels, seems, is accurately recorded on the shunt/mon and then reduced when the esky comes on line.
The solar controller charges the battery but only records amps being used. The solar controller only has one input. I can improve the number of devices (solar panels) but cannot alter the display. The cheap as chips battery mon works as it says on the box, reads amps in and out, sums the 2, displays battery state as a little picture, as a % and also as amps remaining. It has a memory function - but I have not had to use it yet. We bought the Mon direct from China, through Aliexpress (and as with much from Aliexpress - no brand name) The off the shelf battery with internal BMS works (though there are no indication on the box how it works, whether volts, amps or when it detects it is full (of amps) - but when the battery is full - it shuts of the input of the solars. It may also shut off access to the battery - I need to check that (the dooms day scenario).
What have I done wrong - what else should I check?
Finally - I'm glad, very glad to be doing this at home and not on a yacht - simply speaking its factorially more convenient. No...we don't have a mast shading the panels, we don't have a yacht swinging at anchor - but we do have mains power and we are not starving through being unable to cook nor needing to take cold showers - because I got it wrong (this is the first electric build I have attempted). As far as I know the terrestrial amps are identical to marine amps - I fail to see the difference. We have yet to test the B2B charging - another exciting aspect.
When we get it right we can take the whole build and re-build on a yacht. It will work 'out of the box' the trial and error will have been completed.
Jonathan
Is your cheap as chips battery monitor set up for lithium? What value for Peukerts are you using? What about charge efficiency factor? Is this taken care of with a generic lifepo4 setting?
Thr BMS will likely ignore the 100% charged figure and will simply keep accepting charge until there is a HVE (high voltage event). The BMS then shuts down to protect the highest cell from over charge.
I know you are not using this on a yacht so shutting down the battery is no big deal, but since we are on a boating website I would point out thst this is very bad practise.
In my opinion, drop in batteries with a BMS that isn't fully interactive via Bluetooth has no place on a boat. SOC of the battery bank is best monitored with something designed for the job. A Victron Smart shunt does an excellent job. Way more accurate than the built in SOC monitors within a BMS. The voltage can be calibrated to accurately reflect battery voltage.
What is the current handling capacity of your BMS in each battery?
Neeves
Well-known member
In answer to most of your questions:
No.
The BMS is not adjustable, there is no ability to monitor the BMS. I think this is common for many Lithium Batteries with a built in BMS
The cheap of chips Monitor/shunt is specifically for Lithium.
I don't know if the BMS in the battery shuts the charging down when a high voltage is detected or if the battery shuts down when the battery is detected as being full. I can monitor voltage - maybe I need to almost fully charge, or fully charge and then monitor. Either my operator input of 'full' is very accurate or the voltage shot up when the battery was full (and my setting is accurate) but the battery shut down within a couple of minutes, literally - not 5 or 10m but 2 minutes (though this might be coincidental), of the Monitor detecting my 'full' input. The monitor, or rather shunt, is rated at 200 amps, 250 amps max. Our single battery is 200 amps (but that is insufficient).
My take is slightly different.
Historically we would monitor our Lead batteries almost constantly - we were living on the boat and battery state was critical, because we needed the power and we ensured we did not over charge (and have the annoyance of an engine running wasting diesel). We are quite familiar with shutting down the engines at 90% capacity as that last 10% takes an age to input. We had an original Xantrex battery mon and shunt, though the device was built by the company that Xantrex bought about 15/20 years ago (but I forget its name). This was 25 years ago. The technology is hardly new. The new Mon displays the self same data - except the SOC is displayed more usefully in 1% increments (though how accurate this is - don't know).
I see no reason why we would not do something similar with Lithium based on a large solar display and simply disconnect the solar when a charge of, say, 90% had been achieved and/or reduce the number of solars being used to, almost, balance the power needed to run the the systems on the boat, fridge, freezer, AP etc. We are very used to monitoring equipment on a yacht, testing oil, check water flow in engines, checking the batteries etc etc - its part of the facts of life - which we accept.
I think this is what Alan S is doing on a canal boat.
Its only Noelex that mentions this is not for a yacht - but that is a bit of imaginative fiction on Noelex part he just wants to needle me - it brings out the child in him,
The intention is to instal the system in a new cat - unless someone can define why there is a significant difference between a good yacht build and a new terrestrial build that is for a yacht. We are finding out what works and does not work so that we get it right - first time.
In the fullness of time we will take on board - comment. We are currently testing.
Being a realist I don't see uptake of Lithium being very rapid if the Lithium batteries have to be owner built. Looking at Lithium threads and Lithium 'users' you are few and far between on this forum and can be counted on the fingers of 2 hands. Yet Lithium is now common place (in terrestrial applications) in cars, it has undoubted advantages but even Noelex who has a spanking new custom built yacht is not using Lithium. Or to put it another way - I see off the shelf Lithium batteries being the common route and most owners will not have a clue (with no disrespect) and will accept what the local sparky says. We are not willing to test the sparky, we are doing it ourselves, and relying on the few here for correction.
In the fullness of time we will have a decent solar controller - but should it fail - we know what the fall back is. Charge to 95% etc. I think we might be able to better tune the 'charge to 95%' - maybe automate it. Again time will tell.
I am immensely grateful for access to the resource the few of you command - and share.
Jonathan
geem
Well-known member
Jonathan, your thinking is way off here. The BMS disconnected on a HVE. They do not disconnect on full charge. They are not a charge controller. The BMS is there as a mechanism to stop you destroying the cells. It is your last ditch attempt to save the cells when something goes wrong with your charging system or you over discharge.
The way to control your lithium/ solar set up is like this. Buy a decent high quality shunt. Victron smart shunt rated at 500A. But a decent Victron mppt that you programme a set of parameters for lithium. Typically 14v bulk. 13.4v float. You can absorb for say 1/2 hour to help the decent active balancer you would have on a decent quality lithium battery do its job. You programme the smart shunt to provide super accurate voltage information to the MPPT so it charges to exactly the voltage you want not what the MPPT measures at the MPPT. This can be quite different.
The idea is to set the bulk voltage lower than the BMS safety shut down voltage. This way you dont get a black out. You cannot do this yourself. This isn't lead where you can guess the SOC based off voltage. Lithium doesn't work like that. It will sit on charge at the same voltage taking lots of amps. You can stare at the voltage all day and it won't change. Go and make a cup,of tea and come back to staring at you voltage and you find it's just tripped out on a HVE. The voltage will spike really quickly once you hit the knuckle on the voltage curve if the amps going in are high enough.
A high quality programmable shunt will accurately measure your battery SOC. You cannot guess it.
Pete7
Well-known member
Yes, because new ones are chrome plated or something, whilst the old ones are stainless steel. So an hour with a brillo pad and they cleaned up lovely.
Next problem is the gimbal position has to be changed, because I didn't have 14kgs of oven hanging below. I bought a couple of spare gimbal bits and fitted them back to back with the existing ones which lowered the "deck" of the induction stove to the same position that just a gas hob and grill would be. Again you can buy the right ones for just a gas hob and grill, but difficult to find anyone who actually has stock.
Pete
Attachments
Neeves
Well-known member
Geem,
I've taken on board your 2 posts, particularly Post 52 - in which I read your passion. Normally you are not passionate (or not on posts ).
Thank you also for chapter and verse, full of detail, in post 54. All duly noted.
I don't mind critical comment especially when it is supported with options.
We were out today and the simple solution, part of what I suggested yesterday, was to disconnect the solars.
The worry is hundreds of these and similar batteries, maybe thousands, have been sold in Australia and certainly thousands across Europe. Lithium is heavily promoted and the batteries are all similar, internal BMS. The owners will not be sharing how they use them and will not enjoy the attentive support from you and your like, Pete7, Kelpie et al. Lithium fires enjoy high media coverage here (bad news sells) but reports are limited to recharging of small devices, bikes, scooters or the occasional car. No reports of fires on boats, (and for Noelex, none on caravans and motorhomes) - but maybe its too soon.
Going back to our shut down, it was too coincidental that the battery shut down because the battery was fully charged. Your interpretation of an HVE seems very much more likely. I don't commonly and attentively monitor volts the emphasis has been amps and SOC. However it seems that monitoring voltage is not going to be very effective anyway. I now know that a HVE will occur, effectively, as soon as the current setting on battery state reaches 100%. One thing I can do is change the state of full charge to its charge at 85%, so 85% then becomes the new 100%. Its easy to change 85% to become the new 100%. I appreciate this does not meet your advice - but your advice will take some time to enact. Its not automatic but I can easily calculate when 85% SOC will occur so, anticipate new full charge, the new 100% and shut off the solar at that point. This give me a 30 amp buffer before a potential HVE. With the best sun we are currently reaping 25 amps - so again with the best sun I have a 1 hour window - and phones have underused timers
Jonathan
I've taken on board your 2 posts, particularly Post 52 - in which I read your passion. Normally you are not passionate (or not on posts
).Thank you also for chapter and verse, full of detail, in post 54. All duly noted.
I don't mind critical comment especially when it is supported with options.
We were out today and the simple solution, part of what I suggested yesterday, was to disconnect the solars.
The worry is hundreds of these and similar batteries, maybe thousands, have been sold in Australia and certainly thousands across Europe. Lithium is heavily promoted and the batteries are all similar, internal BMS. The owners will not be sharing how they use them and will not enjoy the attentive support from you and your like, Pete7, Kelpie et al. Lithium fires enjoy high media coverage here (bad news sells) but reports are limited to recharging of small devices, bikes, scooters or the occasional car. No reports of fires on boats, (and for Noelex, none on caravans and motorhomes) - but maybe its too soon.
Going back to our shut down, it was too coincidental that the battery shut down because the battery was fully charged. Your interpretation of an HVE seems very much more likely. I don't commonly and attentively monitor volts the emphasis has been amps and SOC. However it seems that monitoring voltage is not going to be very effective anyway. I now know that a HVE will occur, effectively, as soon as the current setting on battery state reaches 100%. One thing I can do is change the state of full charge to its charge at 85%, so 85% then becomes the new 100%. Its easy to change 85% to become the new 100%. I appreciate this does not meet your advice - but your advice will take some time to enact. Its not automatic but I can easily calculate when 85% SOC will occur so, anticipate new full charge, the new 100% and shut off the solar at that point. This give me a 30 amp buffer before a potential HVE. With the best sun we are currently reaping 25 amps - so again with the best sun I have a 1 hour window - and phones have underused timers
Jonathan
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geem
Well-known member
It might work in the short term, but not the long term. Cheap shunts that are not programmable will start to run out of sync. Even BMS SOC readings very quickly show the wrong state of charge. It is possible to have several lithium batteries in parallel and they all show different states of charge at BMS level.Geem,
I've taken on board your 2 posts, particularly Post 52 - in which I read your passion. Normally you are not passionate (or not on posts
Thank you also for chapter and verse, full of detail, in post 54. All duly noted.
I don't mind critical comment especially when it is supported with options.
We were out today and the simple solution, part of what I suggested yesterday, was to disconnect the solars.
The worry is hundreds of these and similar batteries, maybe thousands, have been sold in Australia and certainly thousands across Europe. Lithium is heavily promoted and the batteries are all similar, internal BMS. The owners will not be sharing how they use them and will not enjoy the attentive support from you and your like, Pete7, Kelpie et al. Lithium fires enjoy high media coverage here (bad news sells) but reports are limited to recharging of small devices, bikes, scooters or the occasional car. No reports of fires on boats, (and for Noelex, none on caravans and motorhomes) - but maybe its too soon.
Going back to our shut down, it was too coincidental that the battery shut down because the battery was fully charged. Your interpretation of an HVE seems very much more likely. I don't commonly and attentively monitor volts the emphasis has been amps and SOC. However it seems that monitoring voltage is not going to be very effective anyway. I now know that a HVE will occur, effectively, as soon as the current setting on battery state reaches 100%. One thing I can do is change the state of full charge to its charge at 85%, so 85% then becomes the new 100%. Its easy to change 85% to become the new 100%. I appreciate this does not meet your advice - but your advice will take some time to enact. Its not automatic but I can easily calculate when 85% SOC will occur so, anticipate new full charge, the new 100% and shut off the solar at that point. This give me a 30 amp buffer before a potential HVE. With the best sun we are currently reaping 25 amps - so again with the best sun I have a 1 hour window - and phones have underused timers
Jonathan
Cheap Drop in lithium batteries are not suitable for boats. Not being able to see what is happening at cell level is their major failing. None of them use active balancers. You only need to go on some of the dedicated lithium forums to read the tales of woe.
The basics. Cheap drop in batteries use passive balancers. These balance at mV level. If you have a bad cell or the cells were not balanced well when assembled, there is little you can do to correct the problem. You can't even see what the problem is as you have no access to cell voltages. The BMS can only shut down if a cell spikes to the high voltage threshold setting. You don't want this on a boat.
Passive balancers use resistors. They simply burn off the excess voltage on the highest cell using resistors. These resistors sit on the cell pack within the battery case. Often they can create a hot spot on one or more cells. Long term this can damage a cell, increasing the need for cell balancing. Something that passive balancers do badly.
With a good charging regime, you could probably manage a lot of the issues associated with Cheap drop in batteries. Cell voltage spikes are more of a problem at high states of charge. Using a top quality shunt to control the MPPT could keep the battery less that 80% charged where the poor top balance of the Cheap battery won't cause a HVE. You won't achieve this any other way, regardless of what you think.
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noelex
Well-known member
Enough with the petty insults.
You started the series of posts on your lithium install in this thread:
DIY lithium for novices!
Here in post #27 you even posted a photo of your catamaran discussing where lithium batteries, fuses etc of the new electrical system would be fitted in this vessel. In reality you had sold this catamaran long before this post. Why this subterfuge?
In subsequent threads it is clear that you have actually installed a lithium battery in a camper trailer or something similar. You have never pointed this out, or clarified exactly where this lithium battery and electrical system are installed.
I don’t understand the reason for this misrepresentation. It is unfair to forum members taking the trouble to offer you advice and it is misleading for those who may try to copy your system believing it is a system that can be safely installed on their yacht.
You now claim this lithium installation will be duplicated in some future yacht. If this is the case (and frankly I am skeptical) you need a total rethink. The idea of relying on the BMS to terminate the solar charging, while acceptable in a camper trailer, is not safe in a yacht. You need to install a solar controller. With a drop-in lithium battery, if there is no automatic termination of the charging from a solar controller then sooner or later you are bound to have an event where the BMS will totally shut down the battery. This will leave the yacht suddenly without vital systems such as navigational equipment, depth sounder, VHF, navigational lights and autopilot. This is not safe.
In addition, if you want electric cooking (and this seem to one of your goals) you would be silly to give up the added solar yield given by an MPPT controller. With a camper trailer there is plenty of ground space around the campsite to add additional solar panels (foldable solar blankets are often used), but on a yacht shade free space to fit solar panels is at a premium. You need to extract the maximum yield from each watt if electric cooking is the goal. This is only possible with an MPPT solar controller.
The type of solar panels will also make a difference. The foldable solar blankets used when camping are comprised of "12v" panels which do not require voltage conversion. Yachts incorporating electric cooking typical install higher voltage panels. These require a controller with MPPT technology.
So for numerous reasons you cannot leave out a solar regulator if you want to install something identical in a yacht at some stage in the future.
The essential nature of a solar controller is just one difference between a lithium install in a camper trailer and a yacht. Concentrating just on the charging system, you also need to design the alternator, and shore power charging based on the application. For example, a perfectly acceptable and simple shore power system on a camper trailer could cause expensive stray current corrosion if duplicated on yacht.
I don’t see anything wrong with discussing the techniques and equipment you have used installing your lithium system in a camper trailer, providing you make this distinction clear. Your desire to continually obscure this important detail is unnecessary and unhelpful. You need to stop attacking members who point out the technical differences between this and a marine system. It is important people are aware of these differences if considering duplicating your system on yacht.
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Pete7
Well-known member
This is new and 700w for £72 able to run off a 1000w inverter. Add a Renogy PSW inverter or Sterling 1000w from their clearance range and for £200 you are in business. Probably be able to run it off a couple of lead acids.
Also, at a width of 195, two will fit in the space of a previous standard 450mm wide gas cooker.
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