270ah DIY LiFePO4 build

[gregcope]

@Poey50 do you plan on dissembling your pack to put them in parrallel to balance? Or have you made some balance connections you can connect when the pack is in serial config?

 

[Poey50]

@Poey50 do you plan on dissembling your pack to put them in parrallel to balance? Or have you made some balance connections you can connect when the pack is in serial config?

I dealt with the lack of balance that built up unbeknown to me during last summer by charging to full (but not holding the charge for long) on 3-4 occasions about a day or two apart. Once any cell gets above 3.4 volts then the BMS starts burning off the surplus (passive balancing) allowing others to catch up. I was surprised how much they had gone out of balance since, with the flat charging curve, there was little sign of that at mid-range. The boards on cells 1 and 4 do take a little more charge because of their extra duties so they tend to fall behind 2 and 3 over time. 123Smart recommend a charge to full about once per month to neutralise that imbalance. This winter I'm thinking of adding a Heltec active balancer which some have found very effective so I can stay at mid-range - or any range I want - as long as I like. I will never separate the pack unless there are much more serious problems involving changing one of the cells. My bottom line would be to manually balance. I have made up some resistors to manual burn off power and I also have a 3.5 volt 5 amp changer from GWL if it is easier to bring one cell up.

 

[gregcope]

@Poey50 thanks.

Did you not have on of the smaller active balancers?

Do you know what the quesant current is on those Haltecs?

 

[Poey50]

@Poey50 thanks.

Did you not have on of the smaller active balancers?

Do you know what the quesant current is on those Haltecs?

I took them off as I wanted to see how the system worked without first. Since then the capacitor-type have emerged as a better bet. My understanding is that there is little or no power when not in operation.

 

[gregcope]

Ah. Found it

“The quiescent current is about 12 mA. It is recommended that the battery capacity is 60-300AH.”

 

[gregcope]

They also have a switch for a sleep mode;

“with manual sleep switch, sleep current mode is less than 0.1mA”

 

[Poey50]

Ah. Found it

“The quiescent current is about 12 mA. It is recommended that the battery capacity is 60-300AH.”

My long-term storage strategy (at around 60% SOC) is to have a solar controller on 13.3v for absorption and float and have the Victron Orion B2B to take care of the small AGM start battery probably at 13.2 volts in float so that small amount of active balancing current is no problem in that set-up.

 

[vas]

As another data point that may be helpful:

We have 1005w of solar. I suspect we are a little further from the equator than most at over 51°N. Today was a mixture of blue sky and heavy rain, so was reasonably representative, although perhaps a little better than average.

Our peak production today was 825w. Total production so far was 2.9 kw hours. This included around two hours of regulation, and the solar day is not yet over. Without these factors I would estimate total potential production would be a little over 3.5 kw hours.

At 4pm we were regulating, but turning on a high load, during a sunny patch produced 440w.

I hope these numbers are of some help, although overall the best way to test if your solar system is producing what it should be is to look at the peak production at the best part of the year. If you are in an area of reasonable solar insolation you should see a peak production around the rated output of the panels. These peaks will only be brief, but show the system is working well. Even slightly above the rated output is possible.

The most I have seen from our 1005w is 1182w.

thanks noelex for the info,
sorry late coming back to you, two Qs:

A. monocrystaline panels, what brand/model?
B. laying flat on an arch (maybe remembering wrong!)

I vaguely recall seeing values close (or even above!) rated power on the first and second year. now on the fifth (and with an exceptionally hot summer) I don't think I've seen a peak of 550 (more like 510-520 for half a minute) Will check the victron logs again carefully

cheers

V.

 

[sailaboutvic]

@ noelex
That's interesting what you said , I have 4 180w panel two in series and two in parallel all the same age on two victron mppt , looking back over the last few week my best 275W a set ,

 

[noelex]

thanks noelex for the info,
sorry late coming back to you, two Qs:

A. monocrystaline panels, what brand/model?
B. laying flat on an arch (maybe remembering wrong!)

A. We have three Sunpower X21 335w panels (monocrystalline) feeding three Victron 100/20 controllers.

B. Yes, you are remembering correctly, they are flat on an aluminium arch. I have taken some care with the installation to make sure there are no aerials etc that can shade the panels, and they are behind and above the boom, so the potential shade is about as low as can be achieved on a sailboat. There is also very good airflow underneath the panels, but they cannot be tilted.

I vaguely recall seeing values close (or even above!) rated power on the first and second year. now on the fifth (and with an exceptionally hot summer) I don't think I've seen a peak of 550 (more like 510-520 for half a minute) Will check the victron logs again carefully

There is some deterioration in solar panel performance over time. For good quality rigid panels the the effect is minimal. The Maxeon solar cells are particularly good in this regard, but with any of the good quality rigid solar cells few owners will own the boat long enough to see even a small change in output. Unfortunately, flexible panels and occasionally some of the poorer quality inexpensive rigid cells deteriorate much more rapidly, despite the manufacturers' claims. Occasionally they do not deliver their promised output even when new. Like most marine equipment, owners need to budget periodic replacement of these items (especially flexible panels) to maintain reasonable performance.

Solar panel technology is improving so inexpensive panels can sometimes be a good choice, although the better panels also deliver slightly more power in poor solar conditions so this needs to factored into the buying decision.

Given the above factors, it is helpful to keep track of solar panel performance to see if when new the panels and installation are delivering what they should be, and if this deteriorates with time. Keeping track of this performance is best done by looking at the peak performance in ideal solar conditions. This peak output will only be brief and does not have much impact on the more important average total output, but this peak output is the best guide to health of your panels and installation. Given the changing solar conditions, it is much harder to determine from the average output if the performance when new is correct and if subsequently there has been any deterioration.

Providing the panels are in a shade free location (even briefly), under good solar conditions (even in the UK with flat panels providing it is near the peak of summer) with a good quality MPPT controller you should occasionally see an output the same or at least very close to the rating on the panels (it is important the controller is in bulk mode). The better panels tend to be conservatively rated and peak output can occasionally be higher than sticker rating. Don't expect to see these peaks frequently. These very high outputs are typically seen when there is small amount of scattered cloud which reflects some of the scattered light and combines with the direct sunlight (this is called the cloud edge effect) to briefly produce very high luminance above the STC rating of the panels. Solar controllers that record the peak output (such as the popular Victron models) make this test easy although they update this value peak reading slowly so for the real, brief peak produced will typically be a fraction higher. Unfortunatly some solar controllers exagerate the output. 10% or more is not uncommon. The output is always higher than the true reading as this creates the impression the solar controller is super efficient (the Victron controllers I have tested have all been reasonably accurate). So check the accuracy of the solar controller display using a good battery monitor or multimeter.

As an alternative to the above, you can measure the performance of each panel separately by disconnecting each panel and using a multimeter to check the short circuit current and open circuit voltage. In bright sunlight with the panels angled, the output should be close to the manufacturer's specifications. Don't worry if it is a fraction lower unless you manage to do the test under absolutely ideal conditions. This test can be useful for troubleshooting, but is usually only done if you suspect there is a problem.

PS sorry for the thread drift. This thread is a great resource on lithium and we should try to get back on topic.

 

[sailaboutvic]

@poey
Has you know I only charge to 13.8v , at times I change it to 14.1v
Here to days snap shot at 13.8v 14.0v 14.1v ,
14.1v have changed a bit since two months ago .
There0.15 between 1 and cell 4
I see your thinking of a balancer , one of my earlier complains about 123 smart is it's not a balancer

 

[Poey50]

@poey
Has you know I only charge to 13.8v , at times I change it to 14.1v
Here to days snap shot at 13.8v 14.0v 14.1v ,
14.1v have changed a bit since two months ago .
There0.15 between 1 and cell 4
I see your thinking of a balancer , one of my earlier complains about 123 smart is it's not a balancer

Thanks a lot for taking the trouble to do that, Vic. They look pretty balanced to me. These are my cells the first time I charged up after many months at 50 - 80% SOC. As you know, but others may not, the cells that are balancing turn orange. Although it is only passive balancing (power is burnt off rather than transferred to a lower cell as in active balancing) this is done at 1 amp which is better than many BMSs. As said above, I had to charge up 3-4 times with a mains charger to do enough passive balancing to get them close again. This might not have happened it I had fully charged about once per month as 123Electric recommend but I'm going to try out the active balancers to see how much difference they make.

 

[sailaboutvic]

Thanks a lot for taking the trouble to do that, Vic. They look pretty balanced to me. These are my cells the first time I charged up after many months at 50 - 80% SOC. As you know, but others may not, the cells that are balancing turn orange. Although it is only passive balancing (power is burnt off rather than transferred to a lower cell as in active balancing) this is done at 1 amp which is better than many BMSs. As said above, I had to charge up 3-4 times with a mains charger to do enough passive balancing to get them close again. This might not have happened it I had fully charged about once per month as 123Electric recommend but I'm going to try out the active balancers to see how much difference they make.

No problem ,
13.8v your do seen to be straying a bit ,
If I took mine over 14.2v one cell for sure will be touching 3.64 before the others , so charging to 14.4v as some suggest would be a no no for me.

I think I started to charge mine to 14.1v more often.
Not sure if you know but I also build a friend bank with the same cells ,
We ave not Compair cell voltage for same time but there was about the same.

Fun mine is cell 4 that runs off your cell 3 and the temp are different too .
That could be because you have 4 cells and I have 8 cells .

 

[Poey50]

No problem ,
13.8v your do seen to be straying a bit ,
If I took mine over 14.2v one cell for sure will be touching 3.64 before the others , so charging to 14.4v as some suggest would be a no no for me.

I think I started to charge mine to 14.1v more often.
Not sure if you know but I also build a friend bank with the same cells ,
We ave not Compair cell voltage for same time but there was about the same.

Fun mine is cell 4 that runs off your cell 3 and the temp are different too .
That could be because you have 4 cells and I have 8 cells .

Temperature difference is only on the circuit boards caused by the heat from the passive balancing. You only get the true temperature of the cells once the balancing is finished. It shook me a bit until I realised that.

 

[Poey50]

With winter haul-out approaching fast I've been rethinking how I look after my AGM start battery. At the moment I have it permanently on float via a Victron Orion B2B charged from the LFP but I'm aware that a static battery on permanent float could suffer from stratification - even an AGM. So, having seen this method used by one of the clever folk on the Lithium Batteries on a Boat Facebook Group, I'm trialing at home the use of a small DC to DC boost device together with this voltage detection control relay to manage winter storage.

DC-DC Converter 15A 400W Step up Converter Boost Voltage Module 8.5-50V to10-60V | eBay

10.02￡ 7% OFF|DC voltage detection control relay 6 80V/48V60V battery charge and discharge timing / 30A on/off switch|Relays| - AliExpress

I've set up the relay to charge when the start battery voltage drops to 13.1 volts and to stop charging at 13.8 volts. So far this means it charges for a few minutes every couple of hours. It's possible I could dispense with the B2B altogether but it does offer some redundancy.

 

[mitiempo]

With winter haul-out approaching fast I've been rethinking how I look after my AGM start battery. At the moment I have it permanently on float via a Victron Orion B2B charged from the LFP but I'm aware that a static battery on permanent float could suffer from stratification - even an AGM. So, having seen this method used by one of the clever folk on the Lithium Batteries on a Boat Facebook Group, I'm trialing at home the use of a small DC to DC boost device together with this voltage detection control relay to manage winter storage.

DC-DC Converter 15A 400W Step up Converter Boost Voltage Module 8.5-50V to10-60V | eBay

10.02￡ 7% OFF|DC voltage detection control relay 6 80V/48V60V battery charge and discharge timing / 30A on/off switch|Relays| - AliExpress

I've set up the relay to charge when the start battery voltage drops to 13.1 volts and to stop charging at 13.8 volts. So far this means it charges for a few minutes every couple of hours. It's possible I could dispense with the B2B altogether but it does offer some redundancy.

Your start battery resting at a full charge is about 12.8 volts. If the relay kicks in at 13.1 volts the battery is fully charged and on the way down to a resting voltage. In other words you are keeping it at full charge all the time.

Better to fully charge and turn the charger off for a month or 2 , then turn it back on again. If in a cool place it will not not drop much if any voltage over that time if in good condition.

 

[Poey50]

Your start battery resting at a full charge is about 12.8 volts. If the relay kicks in at 13.1 volts the battery is fully charged and on the way down to a resting voltage. In other words you are keeping it at full charge all the time.

Better to fully charge and turn the charger off for a month or 2 , then turn it back on again. If in a cool place it will not not drop much if any voltage over that time if in good condition.

The person recommending this is one of the most experienced people on the Lithium Batteries on a Boat Facebook Group (you get to differentiate the experienced people quite quickly). He has been maintaining four start batteries using those settings for around 10 years having previously lost a few using other methods. 13.2 volts float is often used as a long term storage setting for AGM and this method keeps the voltage around this point or slightly lower most of the time but it has a more dynamic charge up to 13.8 volts every 6 hours or so for around 15 minutes. Also my AGM is no longer in top condition at 6 seasons old. I'm trialling the method at the moment with an old start battery so will see how it goes.

In cold or very cold temperatures with a top condition battery I'd be happy to fully charge and leave it for 5 months but south coast England for a boat hauled out can at times get quite warm in what now passes for our winter. So self-discharge will be higher and I may not get to it frequently enough to do a top-up.

 

[sailaboutvic]

Can I ask how did you look after the AGM before you fitted the lithium ?

I thing you have a small panel , could you not just keep it topped up with that ?

Mid winter which as you know was our first year with lithium we didn't need to use our shore charger so my B2B wasn't used,
other then once every six weeks or so when we started the engine to rotate the prop and bow prop for a few minutes the starter batteries never got a charge as only the lithium are connected to my panels. Although I am thinking of adding a switch just for the winter I could put a charge into the starter battery now and then .

If I think back to the early days of owning a boat ( yes I can just about remember ) before internet and all advise what we should do with batteries ,
We would just fully charge And leave over winter , then charge them when we return or take them home and top them up now and them .

I take it if your not going to use the boat over winter you going to leave the lithium at 50/60% SOC so if you have a panel wouldn't it be easier to change the setting on your MPPT and keep it on what ever setting you want that way and connect it to the AGM ? rather then adding some thing that could mess thing up .
Just saying .

 

[Poey50]

Can I ask how did you look after the AGM before you fitted the lithium ?

I thing you have a small panel , could you not just keep it topped up with that ?

Mid winter which as you know was our first year with lithium we didn't need to use our shore charger so my B2B wasn't used,
other then once every six weeks or so when we started the engine to rotate the prop and bow prop for a few minutes the starter batteries never got a charge as only the lithium are connected to my panels. Although I am thinking of adding a switch just for the winter I could put a charge into the starter battery now and then .

If I think back to the early days of owning a boat ( yes I can just about remember ) before internet and all advise what we should do with batteries ,
We would just fully charge And leave over winter , then charge them when we return or take them home and top them up now and them .

I take it if your not going to use the boat over winter you going to leave the lithium at 50/60% SOC so if you have a panel wouldn't it be easier to change the setting on your MPPT and keep it on what ever setting you want that way and connect it to the AGM ? rather then adding some thing that could mess thing up .
Just saying .

First choice for me with an AGM would be to charge to full and completely isolate for the winter. But it needs to be cold and a good condition battery. So not, I think, the best options for me. In early lockdown I left it charged and isolated and came back after a few months to find it at 12.4 volts. Not disastrous, but not good either.

Before LFP I had a Votronic Duo Digital MPPT controller which had a trickle charge connection for the start battery. I still have that but it is an old dip-switch configured unit and can't be set for a storage voltage for my LFP. My Victron SmartSolar is perfect for maintaining the LFP at 13.3v but has nothing to offer the start battery.

I'm not really an innovator - I don't have a deep enough knowledge for that - but I know one when I see one and this method looks suitable and, at cost of £20 ...? You may have come across him as SY Destiny on the Lithium Facebook Group and, posting under CatNewBee, he has this very interesting thread on the Cruisers Forum. He knows his stuff!

Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley... - Cruisers & Sailing Forums

 

[noelex]

As has been pointed out, in colder conditions for several months simply isolating an AGM battery with no drain on it can be a good solution. This is a little risky in COVID times when access to the boat may be delayed, it also it is not ideal for longer periods in hotter weather.

If you have solar, especially a system with multiple controllers, diverting one panel to the start battery is an excellent strategy. Reduce the voltage set points on the solar controller, as the battery is now in storage mode rather than cyclic use. The solar controller will initiate a new cycle of bulk, absorption and float each day. This is not ideal with a fully charged battery at the normal voltage settings. There are a few options and the exact settings are not too critical.

My personal favourite is to reduce the float voltage to around 0.5v less than the normal float so typically around 13.2v. There is some evidence that a short boost at higher voltage helps. This avoids stratification of the electrolyte in flooded batteries, but also seem to help AGM, perhaps by ensuring the cells do not go out of balance. To achieve this, set the absorption voltage higher than the float voltage, say at 14.0v, but keep the absorption time very short, say only 5 minutes.

Thus when the solar panel starts each morning, the AGM will be sitting at around 12.7v. This will rapidly climb to 14.0v (because the battery is at, or very close to 100% SOC), stay at this voltage for 5 minutes, and then drop to 13.2v for the rest of the solar day. This is only one possible charging algorithim for an AGM battery in storage mode, but something like this is close to ideal in my view.