End to end lead acid battereies?

[Stinsy]

I have 4 Rolls 500 batteries in series. They are 11 years old, and apart from being a bit thirsty, still do the job. J read somewhere that it is a good idea to end to end them occasionally. I never have, partly because they way a ton and not brilliantly accessible. Any ideas?
Thanks,

Mike

What are your plans to replace them?

[Sunrisemike]

Bit of a dilemma ere, was thinking about lithium, but it seems hard to get them sorted for a 24 v system. mine are basically a yachtie version that I am familiar with bigger batteries than we had on the yachts. Had gel and AGM, but that was sometime ago. Looks as if these lithiums need a load of monitoring and would cost as much as a house to replace the Rolls 20 kwh I have at the moment. What say you? I'd be interested to know the options.

Mike

[John_S]

Mike

I can't answer all your questions, but I can give a few thoughts and ask a few questions which might help you narrow down your choices.

I have been sailing most of my life, sometimes offshore racing when young and single, cruising when newly married, not much when kids were young, latterly in a family partnership where, in a Covid mistake, we bought a 15m Dutch steel trawler displacement yacht (24v system). Alas, a bit big and heavy and one of the partners wished to sell, so sold at a loss after two years. now, a small share in a day planing motor yacht.

I too looked at Lithium batteries, albeit with no urgent need to replace. I never quite got my head around whether Lithiums could cold crank enough amps to power a bow thruster and/or stern thruster and/or anchor windlass with/without main engines running. However your setup of big Rolls and small daily load looks much more manageable. TBH, three years ago, I new much less about battery management systems and balancing lithium cells etc than I do know.

Are you going to stick to 24v or go the 48v and invert to AC for everything route?

I reckoned that it would be fine to replace lead acid with lithium having ~50% of the Amp hours of the lead acid bank.

Hope this helps

John

Edit - PS, I have 2 Pylontech 5000 house batteries for 9 months now. Alos 2.1kWp solar and an EV with Octopus Intelligent Go

[Sunrisemike]

Sounds familiar! I too am from a sailing background since the 1960's, mostly on classic yachts. The Sylvia was a 1927 120ft ketch that had 2 enormous banks of singe cell batteries wired in series to 120 volts d.c. Everything on board was 120 volts DC, including the anchor windlass! Most of the yachts I have been on were 24 volts that could handle most things, except cooking, that was gas. I am already set up here in the house, which is off grid, with 24 volts and don't want to change it due to the expense of changing the chargers and inverters. There are the 3 Trista controllers for the 4 kw solar panels which are 12 years old, and I'm not sure if they can be set to handle lithium batteries, I need to find the manuals. Actually, I'm hoping these present lead acid's will last a couple more years, which should give me time to research further the best way to proceed..

[Stinsy]

Bit of a dilemma ere, was thinking about lithium, but it seems hard to get them sorted for a 24 v system. mine are basically a yachtie version that I am familiar with bigger batteries than we had on the yachts. Had gel and AGM, but that was sometime ago. Looks as if these lithiums need a load of monitoring and would cost as much as a house to replace the Rolls 20 kwh I have at the moment. What say you? I'd be interested to know the options.

Mike

It is pretty standard for boats with a 24V system to swap in 8s LiFePO4 packs. The only thing you need to worry about is the internal resistance of lithium is very low indeed. This results in the batteries pulling more power from the alternator than it can deliver at low RPMs wich can let the smoke out of the alternator. Solutions are: changing the pulley size and introducing a helix of wire in between the alternator and the batteries.