battery bank

Hi guys
In the new boat she has 3 130 amp hour lead acid deep cycle bats in parallel i have them charging now the electrolyte level was well down iam thinking of hooking up the 3 100 amp hour bats i reclaimed from previous boat to the chain what do you recon

Anything is possible but just remember, after you have finished connecting all these batteries in parallel and charging them up, the good ones will discharge into the worst one out of the set. The worst one being the one that holds the least charge, hence the lowest voltage reading when the charging is completed.

What could happen is your charging rate may be influenced by the poorest battery and the good batteries may end up being overcharged.

On my boat I have 5 batteries in parallel, but they are all the same age and capacity. When they were installed, they we're all individually charged prior to paralleling up. And the cables that connect each battery to a common charging link, are exactly the same length to the millimetre.

You could probably get away with using all your batteries if you were to isolate (install an isolator between the batteries) the different types of batteries after charging. Maybe have one set for running the fridge and the other for the rest of the things on the boat.

isolate the 3 100 amp hour bats is a good idea iam concerned that there is a lot of stuff that will put a big demand on the batteries big screen electronics radar sonar ais elec toilet gps elect winch lights auto helm etc will all take a large amount of amps out of the bats when sailing and it looks like one of the 130 amp batteries is the start battery so not in the chain maybe hard to tell at this stage as they are flat and i cant yet start the motor.

good advice thanks lads