LiFePO batteries with external BMS

[Cruising Sea Venture]

Hi Bud,

The balance transformer was critical with the 2 inverter set up. Otherwise your power would be limited to first inverter hitting 3,000 watts - with the balance load transformer you can, in theory, draw up to 6,000 watts on the inverters.

The chargers are also victron, part of the inverters.

If you want, here is a link to our video we did on our YouTube channel that details, as best I could with my limited knowledge, the electrical upgrade we did.

https://youtu.be/sLq0faThyaU


Jim
M/V Sea Venture

 

[Bud]

Hi Bud,

The balance transformer was critical with the 2 inverter set up. Otherwise your power would be limited to first inverter hitting 3,000 watts - with the balance load transformer you can, in theory, draw up to 6,000 watts on the inverters.

The chargers are also victron, part of the inverters.

If you want, here is a link to our video we did on our YouTube channel that details, as best I could with my limited knowledge, the electrical upgrade we did.

https://youtu.be/sLq0faThyaU


Jim
M/V Sea Venture

Jim, Great video. I enjoyed it. I like all the new products. I really like the isolation transformer for several reasons one being a ground fault on the boat does not take out the whole 50 amp shore power service. The two inverters using a load balance transformer is a good idea. The point you make about how alternators work is a good one and that there are better ways to use that charging power. The fact that the solar cuts your generator run time in half is impressive.
The need to better utilize our solar power was mostly what lead me to my lithium battery project. We have an abundance of consistant sun down here in the Florida keys.

Bud

 

[Cruising Sea Venture]

Bud, Glad you enjoyed the video. It's a complex topic so it was hard to do given my very basic knowledge. One thing I did not mention in the video or this thread we also had to consider was that lithium batteries are sensitive to temperature, especially cold. I believe the Victron's will shut down at about 40 degrees. It could be an issue if you are planning on boating in colder environments. It might then play a role in where you place the batteries. For us, the engine room still worked, since our engine room is heated and air conditioned, when needed. In Alaska, in the summer months, you can have 18 - 20 hours of sun a day, so the solar can be very effective. Of course, right now, not so much. We actually have our panels, which are built into our Bimini top, covered so we can shovel off the snow and ice. Jim

 

[twistedtree]

The point you make about how alternators work is a good one and that there are better ways to use that charging power.

What is the part about? I don’t recall that from the video.

And Jim and Rosy, keep up the great channel. It’s one of my favorites.

 

[Bud]

What is the part about? I don’t recall that from the video.

And Jim and Rosy, keep up the great channel. It’s one of my favorites.

He pointed out in the video that if the two alternators are in parallel the alternator regulator of the first engine you start is going to sense the lower voltage And kick in with maximum charge. When you start the second engine the alternator regulator sees A higher voltage and Consequently goes to a less charge or float. Not fully using both alternators equally or to potential. I am paraphrasing Jim.

Bud

 

[Comodave]

Our Lion Energy LiFePO4 batteries shutdown for charging at 32 degrees. They will supply power down to -4 degrees. They will shutdown at 111 degrees. That is why I am installing them in a cabinet in the salon. I insulated the deck below the batteries so the heat coming up from the engine room should not get to the batteries. I will have an intake vent low and an exhaust vent high with a 50 mAmp fan exhausting any heat from the cabinet.

 

[CMS]

I'm on the project technical committee that created it, though I came in pretty late in the process.

Did not know that as I only know you by your screen name. I am also on the committee and have been since 2013.

 

[w8n4sun]

... Of course, right now, not so much. We actually have our panels, which are built into our Bimini top, covered so we can shovel off the snow and ice. Jim

Would you mind posting more information on your solar panel installation and set up?

 

[twistedtree]

He pointed out in the video that if the two alternators are in parallel the alternator regulator of the first engine you start is going to sense the lower voltage And kick in with maximum charge. When you start the second engine the alternator regulator sees A higher voltage and Consequently goes to a less charge or float. Not fully using both alternators equally or to potential. I am paraphrasing Jim.

Bud

Oh, yes, I do remember now. Thanks for the reminder.


That should be adjustable so if in bulk charge, both alternators will go balls to the wall, even if one comes on line after the other. But once you reach bulk/absorb voltage, the alternators will never balance, and it's not worth trying or worrying about it. Just let them sort it out.


And as I think about it, this should be much less of a problem with LFP since you don't get a big bounce in voltage when charging. I'll have to look at the video again. Maybe the alternators charge LA batteries, which in turn charge the LFP?

 

[twistedtree]

Did not know that as I only know you by your screen name. I am also on the committee and have been since 2013.

Yes, I dumped a truck load or two of comments into the review last year, and January was my first actual meeting. Were you on the phone for that? I remember your comment about the hazards of paralleling LA and LFP. Or maybe Nigel relayed it to me. But it stuck. Everyone thinks about and LA battery protecting alternators from an LFP disconnect, but don't think about what happens when an LA battery melts down, which they are prone to do. Now you have a LOT of energy from the LFP bank that will dump into the melting LA battery. Not pretty. Keep 'em separate.