Mixing Battery types in 1 Bank

[Pete7]

Originally Posted by Attan

Five years later, the dust has finally settled.. lets stir things up again shall we?

The moderators might have a different view on your suggestion
but welcome to CF

[Attan]

Originally Posted by Pete7

The moderators might have a different view on your suggestion
but welcome to CF

Just a very gentle stir I would be happy to hear many points of views, but please stay friendly everyone!

[CatNewBee]

Originally Posted by Attan

Just a very gentle stir I would be happy to hear many points of views, but please stay friendly everyone!

You can use all of them as long as they work and have no cell shortcuts.

This is not a recommendation to combine batteries at all.
With new batteries you want same brand, same chemistry, same size, age, (close serial numbers) to get the most life out of them and not wreck a new battery by an old one.

Your situation is different, you want some power out of almost dead or donated old batteries. They will die any way some soon, some later. Your charger cannot really resurrect them either, so not much to loose. Safest way, but not practical, is to use them one at a time, while charging the others, however they are weak anyway, so check the voltages, and if they are charged above 12.6V and have no cell shorts, combine them and use them as one. The stronger would deliver more energy than the weaker, as long as there is no cell short, you are ok, in case one cell goes bad, you will smell it and you will feel the heat.

To prevent desasters, add a fuse at each plus pole before joining them to a common point, this fuses may blow if one battery has a short by a broken plate inside preventing the good ones from wreckage by deep discharge. Size the fuses each to your maximum current expected on board, so every single battery can provide the energy needed alone, and chose appropriate sizes for the wiring.