Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley...

[newhaul]

Originally Posted by goboatingnow

From a cost and efficiency perspective your system isn’t optimum , starter batteries require very very little charging and hence can easily be charged by small low cost b2b chargers. Redundancy can be handled by manual overide switches if required

Domestics ( in this case typically the Li battery ) require frequent often considerable charging and its best that all available power sources including alternators are optimised for this. B2B charging from starter to Li ( or worse again , just parallel LA and LI ) needs careful configs to ensure the starter isn’t accidentally run down , or overcharged as the alternator voltage needs to trigger the B2B charging only.

So by not integrating the alternator into the Li system , like all other charge sources , you end up with a less then optimal system , with more inefficiencies and for, high power B2B, Greater expense.

Agreed and each system should be optimized for the job it is expected to do. My small 250ah bank just loves the ..25C from the alternator. Now with a bigger bank and alternator as primary power source I would hook up differently .

Each system should be designed for optimum performance in that particular installation.

[hzcruiser]

Originally Posted by goboatingnow

I’ve said it 1000 times ,

Sorry, repeating it doesn't make it any more correct or wrong, it just annoys people that would come across it "1000 times".

placing LA in parallel with Li simply because you couldn’t be bothered to install field coil switching on your alternator is madness.

Set up your charging from all sources to charge your lithium bank directly , charge other batteries via battery to battery chargers such that each bank type has optimised charging

So how do you then make use of those "other" batts, if they're separate? A complete second power bus maybe?

[hzcruiser]

Originally Posted by Catapault

Thanks. Any diagrams / rules / hardware you use to manage the connect / disconnect ?
[...]

Happy to elaborate, but in a different thread, to avoid more drifting of this one...

Check out:

https://www.cruisersforum.com/forums...en-206424.html

[aybabtme]

Originally Posted by Catapault

That would be ideal, but the budget may not permit. May need to start small (400AH), and go up from there, after lots of learning !.

What's your budget? 400Ah of LFP is 2k$, without the charging equipment.

[hzcruiser]

Originally Posted by CatNewBee

Do a clean lithium install, not worth it to run zombies in parallel. They will be dead when you need them, you won't notice in advance, as you would use all the time the power from the LFP.

I'm all for LFPs, but I wouldn't discount LA batts like that. As a backup they make sense, since they're already on board. Once they age, they can be gradually replaced.

That's how I gradually replaced all my Marathon LAs over the course of 4 years or so.

[newhaul]

Originally Posted by aybabtme

What's your budget? 400Ah of LFP is 2k$, without the charging equipment.

I can get 400ah cells for $100 per cell or 400 for a 12v 400ah battery plus shipping and the bms

Charging for most of us means changing settings on your solar controller.

[aybabtme]

Originally Posted by Catapault

Still in design phase, but I likely wouldn't do it this way. I'd probably plan for each Alternator to charge its own Starter battery directly, and then charge the LFP bank via a dedicated charger. (Such as a Victron Orion).

This is primairly for redundancy reasons, Can take the engines out of circuit of anything to do with the house bank, and they continue to operate on their own, just fine. Redundancy, and ability to split systems to reduce dependancy is important to me.

Secondary, The alternators needing to charge the lithium will often be the more unusual case. The Solar (existing 3.6kw nominal) will do most of the work there, backed up by the existing 11kva Generator/Charger in the Quattro.

Note: Alternator charging is certainly desired (why waste any power), and keeping things topped up on passage is certainly important. Definitly something I'll integrate, but most likley as a tertiary charging source and one that may often be just left disconnected from the house bank.

If you have 3.6kW solar and 11kVA Victron inverter/charger on a catamaran, you've got the budget to just put 100% lithium. 🤣

Lithium isn't that expensive.

[hzcruiser]

Originally Posted by newhaul

I'm setup just the opposite my 75 amp alternator charges my grp24 fla start battery and a 60amp b2b set to charge my lfp 250ah bank. Protects my alternator from potential overheat and sudden disconnect. ( was the best cheapest option for me ) 99% of my lfp charge is from my solar .

That's a very sensible approach for your scenario, indeed.

[hzcruiser]

Originally Posted by rgleason

[...] It became clear that the discharge of the LFP to the FLA was not inconsequential, and the FLA resistance will increase as the FLA battery gets fully charged, thus depleting the LFP faster.

Batt resistance increases with the state of charge (SOC), that's correct. But why in the world would that deplete the LFPs faster?

[newhaul]

Originally Posted by hzcruiser

Batt resistance increases with the state of charge (SOC), that's correct. But why in the world would that deplete the LFPs faster?

peukert coefficient

[aybabtme]

Originally Posted by hzcruiser

That's a very sensible approach for your scenario, indeed.

Agreed, not a bad idea at all. I have a friend with this setup. Works well for him. Cheap and no need to replace your alternator with an expensive new model, and no need for a BMS with pre-disconnect signals and wires to the alternator controller, and barely any programming aside from the nice Victron iPhone app. I'd go with this approach: keep a tiny starter battery, b2b charger to the large LFP bank. Dump the extra lead batteries, just go all LFP for the main house. It's so cheap it doesn't make sense to bother keeping the silly lead batteries.

[aybabtme]

Originally Posted by newhaul

I can get 400ah cells for $100 per cell or 400 for a 12v 400ah battery plus shipping and the bms

Charging for most of us means changing settings on your solar controller.

That's very cheap, too cheap to be believable. Here's a 205Ah quality cell for ~250$ from a local US distributor (I bought from CALB USA via them before) https://www.electriccarpartscompany....ncased-battery

On Alibaba for a random CALB 400Ah listing (unknown trustworthyness) is 200$ per cell: https://www.alibaba.com/product-deta...48063e51n2Owzb

So we're talking, if you go with a DIY raw cell build, about at a minimum 800$ if you risk it on Alibaba, or 2000$ with a local distributor. Then add the BMS which is ~400$ for a quality one (REC). Then add the fuses/breakers, contactors/relays, busbars, box...

I personally wouldn't bother and would buy off the shelf like this SOK 200Ah:

https://www.us.sokbattery.com/product-page/marine-grade-12v-206ah-lifepo4-battery-sealed-plastic-box

Or even better, go all in on LFP with a 48V system using the newer server rack models, they pack a lot more capacity for a lot cheaper, and their BMS are better. (but then good luck finding all the 48V equipment, I can't find any battery-to-battery charger that does 12V to 48V or backward, nor can I find much sailing gear in 48V either).

[hzcruiser]

Originally Posted by newhaul

I can get 400ah cells for $100 per cell or 400 for a 12v 400ah battery plus shipping and the bms

Charging for most of us means changing settings on your solar controller.

$1 per Ah at 12V is an excellent price! Even on Aliexpress they charge more than double that (incl shipping to Australia).

So what is your shipping rate (to the US) ?

[hzcruiser]

Originally Posted by newhaul

peukert coefficient

doesn't matter at all with those low currents at the end of the charge cycle...

Just throwing in a buzz word here?

[newhaul]

Originally Posted by hzcruiser

$1 per Ah at 12V is an excellent price! Even on Aliexpress they charge more than double that (incl shipping to Australia).

So what is your shipping rate (to the US) ?

I don't know current but 4 years ago my 250ah calb cells it cost me 600 for them a new battery monitor with 300 amp shunt and a 200amp Daly bms single in single out custom programed for my parameters with active top balancing .

Factory direct for my marine repair company.

https://www.cruisersforum.com/forums...ml#post3063595
The list of all parts and cost posted in my refit thread .