Diagram of my proposed upgrade with lithium house and AGM starter battery

[barrymac]

I currently have two banks of 4 Optima Blue top 75Ah batteries. the vessel has two yanmar diesels with 80A alternators.

After some research and confusion, I'm going to try the following setup, for each engine in a two engine setup.

I don't want to invest in upgrading alternators, and I found the Sterling BB1260 which I think can be configured to support mixed battery chemistry setups. I believe this should server to protect the alternators and charge both battery types as quickly as the alternators can manage.

I'll keep one of my old AGM batteries as a starter battery because I'm fairly sure they have plenty life left in them. I'm upgrading to lithium mostly because after adding a freezer I no longer have enough usable capacity in my 600Ah AGM bank.

The lithium batteries I'm using for the upgrade are these:
https://www.aliexpress.com/item/4001...27424c4dqShWTl

3.2V 200Ah

which will use this BMS: https://www.aliexpress.com/item/1005...27424c4dqShWTl
on each bank, one in each engine room.

Total cost of upgrade is 3221.05 Euro

632.47 for BB chargers

2588.58 for 800Ah of LiPo batteries and two BMSs

Anyone see any issues with this proposal?

[Spot]

Would both engines (through their Sterling boxes) be feeding a single house bank charge controller?

[barrymac]

I was going to install one in each engine room.

My updated diagram is more correct.

[tkeithlu]

BarryMac, I blew up you diagram to take a careful look, and lost so much detaail that I could not read your notations.

I have not spotted a problem, but there are people on the forum more knowledgeable than me on this subject.

My only concern is that you have a way to charge both banks from one side, or combine both sides as needed. Those tasks can be covered by carrying a set of jumper cables, or you can add in "1,2,Both" switches.

[Spot]

BarryMac,
The diagram is quite small, 260 x 120 pixels, could you save it out to be larger please?

Schematics are brain teasers for me, I am not an expert in charging system either.

Alternator-start battery-Sterling-charge controller-house bank (each engine)
then combine house banks to load

-What are the 'new' boxes to the left of the Sterlings?

[barrymac]

Sorry about that I didn't check the output of my diagram software.

This one should be much better!

[barrymac]

Originally Posted by tkeithlu

BarryMac, I blew up you diagram to take a careful look, and lost so much detaail that I could not read your notations.

I have not spotted a problem, but there are people on the forum more knowledgeable than me on this subject.

My only concern is that you have a way to charge both banks from one side, or combine both sides as needed. Those tasks can be covered by carrying a set of jumper cables, or you can add in "1,2,Both" switches.

It's a 20 year old boat and things have changed over the years. So the way I found it was set up with just one big house and starting bank, and both sides bridged in parallel.

So currently both are charged from either side.

There's 1,2,All switches in both engine rooms however.

But as far as I know the Sterling BB charger has a automatic relay that will switch out the starting battery when it should, which I believe would make the selector switches somewhat redundant.

[AMX]

I don't know where you are shipping these batteries to, these 280 ah cells are cheaper and you would only need 3 sets instead of 4. https://www.aliexpress.com/item/1005001563505796.html?

Check out https://diysolarforum.com/ for more information on your project.
I just ordered 8 272 ah cells for $804 Delivered to the US through a group buy from a well known member of this DIYsolar forum.

[barrymac]

I'm having them shipped to Spain from their Poland warehouse. I didn't realise that the 280ah were cheaper per Kwh in fact I thought the higher energy density was actually more expensive.

In any case, I have a slightly irrational OCD thing about having a symmetrical setup same in both engine rooms. Perhaps this is crazy, or perhaps it's more redundant to have everything swapable between each side.

[CruiserAD]

I plan a similar setup on my catamaran, but I'm going to use a Sterling Pro-Split with TWO alternator inputs, so I only need one B2B charger charging the Starter Battery and the LFP house bank. See that attachments for details.

[barrymac]

Very interesting thanks for sharing! The splitter seems to compensate for the voltage drop to the farther away alternator. It seems to be a more cost effective setup.

[bstreep]

OK, I'm going to be honest. These batteries scare the carp out of me. I talked to my brother who is an EE, along with another EE, and they convinced me that GOOD Lithium batteries are safe. So, we went with Battleborn. These batteries...

[CaptainRivet]

i suggest to use Lishen 272AH, much cheaper and better.
https://de.aliexpress.com/af/lishen-...20210131123923


also the BMS, suggest to get a Daly in the appropriate size:
https://de.aliexpress.com/af/daly-bm...20210131124049

[CaptainRivet]

Originally Posted by bstreep

OK, I'm going to be honest. These batteries scare the carp out of me. I talked to my brother who is an EE, along with another EE, and they convinced me that GOOD Lithium batteries are safe. So, we went with Battleborn. These batteries...

nothing to be scared off. a good Battery monitor with low and a valtage cut off, 2 or 3 BMS in parallel (so if one fails the other disconnects) and all is fine. especially if you are liveaboard and can consantly monitor them what you automatically do. and if you leave the boat for long, just completly disconnect them.

[CaptainRivet]

Originally Posted by CruiserAD

I plan a similar setup on my catamaran, but I'm going to use a Sterling Pro-Split with TWO alternator inputs, so I only need one B2B charger charging the Starter Battery and the LFP house bank. See that attachments for details.

the sterling B2B is a huge energy killer, just get two Balmars regulated and run them directly to the bus bar of the bank. each will regulate what is needed and field shutoff if the battery is full they don't produce any power but still turning when engine is on.