Lithium setup on a boat (+ can I top balance my new bank using only solar?)

[Mubarto]

The current setup:

I have 3x 340W panels each going through a Victron 100/30 MPPT and 25A breaker, then directly onto an AGM battery. Each MPPT is connected to a different AGM battery. The AGMs are in parallel and connected to thick wires which appear to travel to the other hull of the catamaran and into the switchboard etc.
The AGMs no longer hold their charge, so while it is light outside I have power, but as soon as it gets dark I turn all loads off (and my headtorch comes on)

The only high-draw item currently is a Dessalator 60L 12V Watermaker, which uses about 38A (and in winter can be run by solar alone close to noon on a blue sky day), and is on the same hull as the switchboard and opposite hull to the batteries.





The new arrivals:

12x 3.2V 280Ah EVE Grade A cells, intended for use as a 3P4S 12V 780Ah “house battery” for the catamaran

8x 3.2V 105Ah EVE Grade A cells, intended for use as a 2P4S 12V 210Ah “dinghy battery” to power a 768W trolling motor on the dinghy (I’m already using this trolling motor but with an 80Ah AGM)

1x JBD 80A BMS, intended for use with the new dinghy battery

1x Nice-Power 30V/10A max bench top charger

What I don’t have yet is the permanent BMS solution for the house battery, but I figure initially I can use the JBD I have, at least until I’m ready to install a Multiplus and starting using a 1500W cooker.


The plan:
I’ve built a compression setup for the house battery, and I’m ready to top balance. The issue is I’m still away from shore power, so I need to figure out the best way to do this using my current solar setup.

I would like to use my MPPT to get the cells (in 3P4S config with BMS attached ) charged to a safe high level, before reconfiguring into 12P for last bit of top balancing using bench top charger. I plan to only attach one of my 340W solar panels for this.


My question: is this plan feasible?

If so, what settings should I put into the Victron MPPT and the JBD BMS to make this as safe as possible? e.g. what voltage should I be charging at?

Should I be adding anything else e.g. fuses into the setup before I start?



As a reminder, if I don’t buy anything else, it would be 340W solar —> 25A breaker —> Victron 100/30 MPPT —>

(+) —> Positive of 3P4S battery

(-) —> 50cm 25mm2 cable —> C- of JBD 80A BMS, B- of BMS —> 50cm of 25mm2 cable—>Negative of 3P4S battery

(all balance leads also attached)


The next stage:

I also have to decide what the best permanent BMS setup is for this, as I also plan to install a Multiplus II 3000 (2400VA), which will require something much more capable than an 80A. I was thinking a REC ABMS, but having recently seen this https://community.victronenergy.com...ed-bms-av.html?page=3&pageSize=15&sort=oldest, I’m wondering if for less price I could get three JBDs instead of the REC ABMS.

This should allow me to make three individual 1P4S batteries and monitor each cell individually instead of each block of 3, and presumably change setting and monitor the BMS which needing the expensive extra REC BMS wifi module - what am I missing?

Would love to hear people’s thoughts, any questions, and anything I might’ve missed in my thinking - thanks!

 

[NVS]

You can build it with you current bms as stated and add a 5a active balancer. Charge the battery and then leave it sit overnight. This will give the active balancer time to balance out the cells. Then re top off the battery. Then you can leave the balancer on all the time it will help to always keep your cells balanced.

This is the balancer I used.

Cywhrvzsf 3S 4S 5A Active Equalizer Whole Group Balancer Lifepo4 Lipo Lto Lithium Active Battery Energy Transfer Equalization Capacitor https://smile.amazon.com/dp/B09G74W...t_i_RF3TRJQ8ZKK59P521X7C?_encoding=UTF8&psc=1

 

[chrisski]

My question: is this plan feasible?

Yes it is feasible to pre-charge your batteries using solar power prior to moving to the bench tester.

I did this. I used a 15 amp Victron SCC to charge 2 X 8S packs to 3.45 volts per cell. For the BMS cutoff, I set individual cell to 3.5. It was recommended to me to test the individual cell cutofff voltage, but I did not. I simply could not come up with a practical way to test the BMS cell cutoff voltage. If you can, I recommend you test.

I then moved it to a bench charger to finish it. Took 3 hours or the 8S pack to go from 3.45 to 3.65. Much better than a week for each battery with no pre-charge.

I recommend you don’t do this with a 3P4S pack as stated, but set the batteries up individually to charge each of the three 4S batteries once. If you charge 3P4S it could hide some discrepancies that would trip a BMS.

I would not use a 5 amp active balancer to top balance. I’m not saying its wrong, “It’s just not the way top balancing is done in the guide.”

Should I be adding anything else e.g. fuses into the setup before I start?

I had overcurrent protection for my pre-charge. For the 15 amp SCC, I used a 20 amp breaker. If this is an expeditionary set up, just make sure the parts are rated Like Don’t force 50 amps through a 12 gauge piece of wire on a 3/8” ring terminal.

I also have to decide what the best permanent BMS setup is for this, as I also plan to install a Multiplus II 3000 (2400VA),

I like the idea of three different batteries with three different BMS. To me that gives me redundancy to take one battery out if once cell goes bad until I get a new cell. If one cell went bad in a 3P4S, that means rebuilding the battery pack to get it functional until the new one comes in.

 

[Mubarto]

Yes it is feasible to pre-charge your batteries using solar power prior to moving to the bench tester.

I did this. I used a 15 amp Victron SCC to charge 2 X 8S packs to 3.45 volts per cell. For the BMS cutoff, I set individual cell to 3.5. It was recommended to me to test the individual cell cutofff voltage, but I did not. I simply could not come up with a practical way to test the BMS cell cutoff voltage. If you can, I recommend you test.

I then moved it to a bench charger to finish it. Took 3 hours or the 8S pack to go from 3.45 to 3.65. Much better than a week for each battery with no pre-charge.

I recommend you don’t do this with a 3P4S pack as stated, but set the batteries up individually to charge each of the three 4S batteries once. If you charge 3P4S it could hide some discrepancies that would trip a BMS.

I would not use a 5 amp active balancer to top balance. I’m not saying its wrong, “It’s just not the way top balancing is done in the guide.”

I had overcurrent protection for my pre-charge. For the 15 amp SCC, I used a 20 amp breaker. If this is an expeditionary set up, just make sure the parts are rated Like Don’t force 50 amps through a 12 gauge piece of wire on a 3/8” ring terminal.


I like the idea of three different batteries with three different BMS. To me that gives me redundancy to take one battery out if once cell goes bad until I get a new cell. If one cell went bad in a 3P4S, that means rebuilding the battery pack to get it functional until the new one comes in.

Thanks for all the detail in here. With your Victron SCC did you set Bulk, Absorption and Float all at 27.6V (13.8V in my case, 3.45V per cell)?

 

[mikefitz]

Building a battery with 3 cells in parallel for a marine application may not be the most reliable. I would suggest building three separate 12v batteries , each with a BMS. Not only do you have redundancy, there is the ease of mechanically fixing the cells in a secure casing to prevent issues with shock, vibration and water/moisture ingress.
Sooner or later a BMS will fail when the boat is in commission.

As for balancing the cells without a PSU, charge up 4 series cells with a BMS attached and manually pull down the high cell with a suitable DC load. The manual balancing is undertaken when the battery is reaching full charge as the cells start to diverge.

In my view active balancers are in general masking a serious issue with one or more cells. The pack should stay in balance with low power passive BMS balancing if quality cells are correctly top balanced. Using active balancers adds an extra risk of battery failure.

The Victron charge voltages, 14.0 charge , 13.4 float, no absorption period. ( when batteries are in use).
Use JBD BMS, 120 to 200 amp smart units are available, default protection values , cell 3.65, pack 14.60.

Use quality fuses and fuse holders, Blue sea and/or quality breakers. Consider Lynx Distributer

Cable selection, fuses/breaker and mechanical installation will have a significant impact on the performance and reliability of your system.

Mike

 

[chrisski]

For me, bulk was 27.6. I set float to the delivered battery voltage. At about 3.32 per cell, it came to 26.7.

I Set a lower float because once bulk was done, I wanted no more current going in. Once it gets to 3.45 per cell with the “knee” in the charging profile, the cells are between 80% and 95% charged, and I wanted the rest to be done by the 10 amp charger.

I’ll have to check my Victron when I get back today, but I think my model only has two voltages: bulk and float. I could be wrong.

In a top balance video, Will mentions pre-charge. I did not find a video where he did it. I know I got some help from others on this forum for voltages but I can’t find the thread.

I did a top balance with 16 cells for a 25 ah pack with a power supply twice. Once prior to capacity testing. Once after capacity testing to take each cell from 2.5 back to 3.65. That took days. I’d hate to see what the process was for a 280 ah cells. That was a big reason for me not doing the lengthy top balance on the power supply.

Also, top balance with a power supply has no secondary fail safe. Twice in my limited top balancing experience, the power supply drifted above 4 volts. This cut down the amount of time my 280 ah cells were unattended on the power supply from days to 3 hours per batch.

 

[WYtreasure]

Welcome to the show Mubarto, enjoy the cruise.

There is a link in my signature which may be helpful to many things marine related.

 

[manly]

Mubarto, I'm currently installing 16 280ah cells in my 39' catamaran. Right now I live aboard so all the work is happening in a cramped forward locker. My plan is 4 12v batteries. Each battery controlled by a seperate Overkill Solar BMS which are rated at 120 amps continous. I'm capacity testing the second battery now. Using solar to get the batteries close to full won't be any problem.

 

[Mubarto]

Mubarto, I'm currently installing 16 280ah cells in my 39' catamaran. Right now I live aboard so all the work is happening in a cramped forward locker. My plan is 4 12v batteries. Each battery controlled by a seperate Overkill Solar BMS which are rated at 120 amps continous. I'm capacity testing the second battery now. Using solar to get the batteries close to full won't be any problem.

Thanks, would love to see a photo of your setup!