Backup Lithium Solution

PaulRainbow said:
Looks like you are trying to solve two problems with one solution, which doesn't seem feasible.

You want something like the powerstation for other purposes and as a backup for the boat, i don't see a sensible solution to both with a single device.

If you want more power on the boat, fit another battery, or have an extra, removable battery to take home, or fit some solar etc. Lots of solutions that needn't cost a fortune.

If you want portable power for something else, the powerstation might be the answer, but at a cost. Perhaps if we knew what the other uses might be we could offer more useful suggestions ?
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I'm not sure it isn't feasible. What's wrong with the suggestion in post #34?
 
goeasy123 said:
Spot on. To reiterate the requirements, and I think there are a lot of people in this situation. I'm resolved that none of the available powerstations will do it. They do not have a high current 12vdc out. I'd have to build DIY a solution, of which there a many examples on YouTube.

Ideally, I do not want Lithium on the exiting LA load buss. I want a way to charge a small Lithium battery for off-boat purposes.

Optionally, it would be nice to be able to use the Lithium in an emergency if the LA went down. You might have an Anderson connection in the boats buss with an either/or switch so that the LA's and Lithium's (Potential Difference) PD's would never meet each other.

Optionally, it would be nice to be able to charge the LA from the Lithium on the very odd occasion when the other charging sources run out. You could do this with a DC-DC converter on a different high current plug/socket arrangement. Different, so you don't accidentally make the wrong connection.

To charge the Lithium it could sit on the LA buss through a voltage sensitive relay and charge only when the LA was also being charged. It might need a step up of the voltage to get sufficient PD. I think there are MPPT chargers that would do this. You could also size the MPPT to use the boats main PV of have a small dedicated panel.

So the DIY powerstation might be a 100Ah battery with built in BMS, a 3000W/230VAC inverter and an MPPT controller...+ fuses, switches etc. and maybe a few USB outs.

The DC-DC converter and VSR would be wired-in on the boat in convenient places.

What do we think?.... appreciated.
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When you say the LA went down. What do you mean? Flat or failed cell? It seems to me that a simple drop in lithium battery might be you solution with a Victron b2b charger. Use the lithium battery via the b2b to charge the lead. Take it home with you if you want to charge it. If the lead drops a cell. Remove it and run off the lithium battery in emergency mode. Ensure you can't charge it with you alternator. Simple and not expensive
 
geem said:
When you say the LA went down. What do you mean? Flat or failed cell? It seems to me that a simple drop in lithium battery might be you solution with a Victron b2b charger. Use the lithium battery via the b2b to charge the lead. Take it home with you if you want to charge it. If the lead drops a cell. Remove it and run off the lithium battery in emergency mode. Ensure you can't charge it with you alternator. Simple and not expensive
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That doesn't meet the requirement to have something to do off-boat stuff, which need a portable battery and inverter. And there is no other home. Home is the boat.
 
I appreciate that the parallel hybrid issue is not where goeasy123 wanted the thread to go, but threads do have lives of their own. So, just to complete my comments on the LFP -Lead acid parallel hybrid model, I checked on the Zwerfcat site and Emily and Clark YouTube channel, both of which crop up in discussions. It's notable that both of these are using a modified BMS of their own construction to try to ensure that the lead acid does have a greater opportunity to charge. This confirms (for me at least) that simply paralleling lead acid and LFP will not make much use of the lead acid and attempts to do so will give the lead acid a shortened life.
 
Tranona said:
See posts#9&13
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Doesn't say he's a liveaboard, just that he wants to use the powerstation "for other purposes, off of the boat"

Everyone has assumed that meant charging ashore and bringing it onboard for extra power. Several people have said as much, without correction.

Anyway, we hopefully have all of the facts now and can offer some suitable solutions for the OP.
 
tbh, i very much doubt there is a solution for what OP wants.
OP also make some claims (fe LA failing) which are imho made to justify his quest for this elusive solution.

shouldn't really post as I've not got anything constructive to add, so apologies

V.
 
goeasy123 said:
That doesn't meet the requirement to have something to do off-boat stuff, which need a portable battery and inverter. And there is no other home. Home is the boat.
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Perhaps you could build your own "powerstation". Basically a Lithium battery and an inverter in a box. You need to protect the Lithium from over discharge, a Victron battery saver should do that.

Connect the battery to the inverter with an Anderson connector. Fit a second connector on the boat and connect the Lithium in parallel to the LA. Fit an isolator switch between the connector and the LA to stop arcing when you connect the Lithium and to isolate the Lithium when charged.

Obviously need to consider fusing both on the boat and withing the "powerpack", plus an RCD in the "powerpack".
 
PaulRainbow said:
Perhaps you could build your own "powerstation". Basically a Lithium battery and an inverter in a box. You need to protect the Lithium from over discharge, a Victron battery saver should do that.

Connect the battery to the inverter with an Anderson connector. Fit a second connector on the boat and connect the Lithium in parallel to the LA. Fit an isolator switch between the connector and the LA to stop arcing when you connect the Lithium and to isolate the Lithium when charged.

Obviously need to consider fusing both on the boat and withing the "powerpack", plus an RCD in the "powerpack".
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Thanks PaulRainbow. You have confirmed exactly what I want. I am not bothered about charging the Lithium from the boat, I will just use a mains charger when I reach dry land. I am also not too worried about the slow charging / absorbtion rate to the lead acids as I can leave the Lithium connected for ever with an Anderson (rather than jump leads) so no danger of an accident.
 
PaulRainbow said:
Doesn't say he's a liveaboard, just that he wants to use the powerstation "for other purposes, off of the boat"

Everyone has assumed that meant charging ashore and bringing it onboard for extra power. Several people have said as much, without correction.

Anyway, we hopefully have all of the facts now and can offer some suitable solutions for the OP.
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Read 13 again. He wants to use it ashore for running amplifiers and a PA system. Bit pedantic about the "liveaboard" - he says he sails in remote areas - does not matter if it is his only home - and he has never mentioned he would charge it ashore - that was just your assumption - and not everybody (including me) made that assumption as he was very clear about how he was planning to use it!
 
Tranona said:
Read 13 again. He wants to use it ashore for running amplifiers and a PA system. Bit pedantic about the "liveaboard" - he says he sails in remote areas - does not matter if it is his only home - and he has never mentioned he would charge it ashore - that was just your assumption - and not everybody (including me) made that assumption as he was very clear about how he was planning to use it!
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I'm perfectly capable of reading past post, don't be facetious.

There is a big difference between living ashore with mains power, where the powerstation can be charged by plugging it in and taking it out with the band or taking it to the boat for a backup supply and living on a boat on a mooring with no mains electricity.

Do you have any useful solutions, or are you just trolling ?
 
OP here... In these kind of threads (especially FB) people rarely respond to user requirements. Hence my imprecise question. Apologies for that and thanks for asking. So here's my thinking.

We're a couple on a Najad 400 with substantially the original 12V system with a 1500w inverter an a 3500W generator. We recently added 460W of PV. Gas cooking. Eventually we want to buy a bigger boat so don't want to do an significant permanent upgrades.

We sail from region to region never going backwards for 3 or 4 months at a time flying back to the UK for a month leaving the boat where it is. I'm a musician. We occasionally do long passages and find ourselves on remote islands with little or no local support (gas, spares, engineers etc.)

I'm looking for a solution that does 3 main things.

1. Allow us to use electric cooking appliances to save on gas.
2. Replace the LA AGM's should they go down completely. This has happened to us. Being able to disconnect the AGM's and replace them with a 100Ah fully charged lithium battery would be enough to run the essential system to get-you-home. Having it charge while it's in place is a bonus but not essential. Any of the suitcase/commercially available things won't do this 'cause there is no high current output.
3. Take a system with an inverter and battery off the boat to run the PA and instrument amps... for example on an island beach.
 
goeasy123 said:
OP here... In these kind of threads (especially FB) people rarely respond to user requirements. Hence my imprecise question. Apologies for that and thanks for asking. So here's my thinking.

We're a couple on a Najad 400 with substantially the original 12V system with a 1500w inverter an a 3500W generator. We recently added 460W of PV. Gas cooking. Eventually we want to buy a bigger boat so don't want to do an significant permanent upgrades.

We sail from region to region never going backwards for 3 or 4 months at a time flying back to the UK for a month leaving the boat where it is. I'm a musician. We occasionally do long passages and find ourselves on remote islands with little or no local support (gas, spares, engineers etc.)

I'm looking for a solution that does 3 main things.

1. Allow us to use electric cooking appliances to save on gas.
2. Replace the LA AGM's should they go down completely. This has happened to us. Being able to disconnect the AGM's and replace them with a 100Ah fully charged lithium battery would be enough to run the essential system to get-you-home. Having it charge while it's in place is a bonus but not essential. Any of the suitcase/commercially available things won't do this 'cause there is no high current output.
3. Take a system with an inverter and battery off the boat to run the PA and instrument amps... for example on an island beach.
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Post #49 is your best solution IMO.

Power station: Make a box to house the battery, a connector and a Victron Battery Saver. Fit the inverter on the outside of the box, for cooling. You are not charging the battery, so i don't see a need for a BMS as the battery saver protects the battery from excessive discharge. Make sure you choose an inverter with over current and electric shock protection etc. Fit a fuse in the short cable between the battery and the connector, this protects the battery from shorts, whether connected to the inverter or the boat.

Onboard: Make something to securely hold the lithium battery in place. Fit a connector, the same as the one in the box. Have an isolator switch between the connector and the LA batteries, make sure it's off when connecting/disconnecting the Lithium battery. You'll need to install a BMS here. All loads and charging remain connected to the LA system, as now. You now have a hybrid system that increases your power storage capacity and can be used with, or independently of, the LA batteries (in case of LA failure). Do note, that if you isolate the LA batteries loads and charging will all be connected to the Lithium battery and measures would need to be in place to protect the alternator.

This system would work best if permanently connected. Loads would draw power from the Lithium battery, rather than the LA, provided you don't heavily deplete the Lithium. The Lithium battery will also charge much faster than the LA, so would take better advantage of the solar power. Hopefully this would allow some modest cooking using electric, i'd suggest a portable induction hob.
 
PaulRainbow said:
Post #49 is your best solution IMO.

Power station: Make a box to house the battery, a connector and a Victron Battery Saver. Fit the inverter on the outside of the box, for cooling. You are not charging the battery, so i don't see a need for a BMS as the battery saver protects the battery from excessive discharge. Make sure you choose an inverter with over current and electric shock protection etc. Fit a fuse in the short cable between the battery and the connector, this protects the battery from shorts, whether connected to the inverter or the boat.

Onboard: Make something to securely hold the lithium battery in place. Fit a connector, the same as the one in the box. Have an isolator switch between the connector and the LA batteries, make sure it's off when connecting/disconnecting the Lithium battery. You'll need to install a BMS here. All loads and charging remain connected to the LA system, as now. You now have a hybrid system that increases your power storage capacity and can be used with, or independently of, the LA batteries (in case of LA failure). Do note, that if you isolate the LA batteries loads and charging will all be connected to the Lithium battery and measures would need to be in place to protect the alternator.

This system would work best if permanently connected. Loads would draw power from the Lithium battery, rather than the LA, provided you don't heavily deplete the Lithium. The Lithium battery will also charge much faster than the LA, so would take better advantage of the solar power. Hopefully this would allow some modest cooking using electric, i'd suggest a portable induction hob.
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That' excellent advice. Thanks

Is there an issue with my 2 Victron MPPT 100V 20A controllers being configured for LA rather that Lithium? What configuration would I use?

I'm always concerned about hybrid as the 'experts' say it introduces risk. I'm not sure why and is there a way to mitigate? In particular, in a system such as this where you might be frequently connecting and disconnecting the Lithium which is likely to be at an significantly different voltage vs the LA.
 
goeasy123 said:
That' excellent advice. Thanks

Is there an issue with my 2 Victron MPPT 100V 20A controllers being configured for LA rather that Lithium? What configuration would I use?
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I'd set the controllers for Lithium, but leave them connected to the LA, so they still charge if the Lithium is removed. Configure according to the battery manufacturer specs.

I'm always concerned about hybrid as the 'experts' say it introduces risk. I'm not sure why and is there a way to mitigate? In particular, in a system such as this where you might be frequently connecting and disconnecting the Lithium which is likely to be at an significantly different voltage vs the LA.
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I don't see an issue disconnecting the Lithium, as long as the battery and BMS etc are turned off before doing so.
 
PaulRainbow said:
I don't see an issue disconnecting the Lithium, as long as the battery and BMS etc are turned off before doing so.
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What if the LA is significantly depleted and I plug in and switch the fully charged lithium on? What if I've been off the boat using the lithium battery for a gig.... it's depleted. I bring it back to the boat, plug in and switch it onto the fully charged LA. I can see the opportunity for large current to flow, and the potential for transients on a buss connected to sensitive electronics.
 
goeasy123 said:
What if the LA is significantly depleted and I plug in and switch the fully charged lithium on?
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A fully charged Lithium battery is about 13.3c-13.4v, float voltage for a LA battery. The LA will basically get trickle charged.

What if I've been off the boat using the lithium battery for a gig.... it's depleted. I bring it back to the boat, plug in and switch it onto the fully charged LA. I can see the opportunity for large current to flow, and the potential for transients on a buss connected to sensitive electronics.
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Depends how much it's depleted. You can manage this scenario with the BMS and perhaps a Victron Battery saver. So if the battery if largely depleted it cannot take any charge from the LA, it has to come from the solar controller, even if that means waiting until the next day to charge the Lithium.
 
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