Mixing Different Sized Batteries

[Roy Peterson]

In addition to my dedicated starter battery, I currently have a three gelcell battery house bank and one of the batteries died. I have been unable to locate the same battery in Greece (it's a 105AH) and I'm now considering replacing the dead one with a 95AH gelcell plus adding a 4th gelcell to increase the house bank.The question: Is there a problem mixing different sized gellcels on the same bank? I had thought of splitting them into a two house banks of two, but it seems like a lot of trouble with little to gain.Comments would be appreciated.Roy PetersonU.S. s/v Brilliant

 

[Debra Blatnik]

Type matters -- size doesn't matter

It's important to keep all of the batteries of the same type (GEL, AGM or flooded). Size doesn't matter.(this has to do with the capabilities of todays chargers. They can be set to different battery types = different charge voltages, but not on a bank-by-bank basis.)

 

[Eric Lorgus]

Age matters

Roy,Debra is right about not mixing different types -- since the recharging characteristics are different, you can't mix different types (flooded, gel, AGM).Unfortunately, you shouldn't mix new & old batteries on the same bank, either. Over time, batteries lose capacity and performance, and are no longer able to achieve their when-new capacities. If you mix old & new batteries on the same bank, your recharging system will either overcharge or undercharge some of the batteries in your age mix.If one battery out of a three battery bank has died, the others may be soon to follow. Replace all. If you want to add a 4th, do so at this time.As for two banks vs. one, in his book, "Boatowner's Mechanical and Electrical Manual", Nigel Calder recommends AGAINST two smaller banks.Are you cruising in Greece, or do you live there?Eric Lorguss/v Impulse (83H54)

 

[Roy Peterson]

Thanks

Eric/Debra,Thanks for the quick response, you probably saved me $300, I really love this forum. I will live with the two good house batteries for now and will install four new ones next year when we move aboard. The waters and sailing around Greece are fantastic! I'm currently stationed on Crete and will retire next spring. We sold our house and our Catalina 30 before moving here and found a great buy on a boat in Maramaris, Turkey. The former owner's delivered her to us here and I have less than a year to get her up to USCG specs and make the improvements that every owner must make to personalize the boat. Our plans include spending at least a year and half cruising the Med, before heading home by way of the Canaries, to Barbados, leaward islands, Bahamas, etc."Beware a man who dreams with his eyes open, he will make his dreams come true!"Roy Petersons/v Brilliant