One big SLA battery or two smaller ones?

Thread Starter

spinnaker

Joined Oct 29, 2009
7,835
Other than making wiring more simple. Are there any other advantages of using say one 30AH battery as opposed to 2 15 AH SLA batteries in parallel?
 

THE_RB

Joined Feb 11, 2008
5,438
Sometimes the large batteries have thicker plates and more rugged internal connections, so they corrode more slowly and last longer. Over the years I've also noticed 6v SLAs give many times better life than 12v SLAs, probably for the same reason?

Once you get into something fairly large like 30Ah the difference might not be as much, so in that case a "deep discharge" battery probably gives the best life (or at least better life, it it gets abused like being discharged too far on occasion).
 

crutschow

Joined Mar 14, 2008
28,198
Charging two batteries in parallel can sometimes can an inbalance in the charging rate so, from that consideration, one larger battery would be better. Also one larger battery is likely considerably cheaper than two smaller ones.
 

Thread Starter

spinnaker

Joined Oct 29, 2009
7,835
Thanks guys. I have a 22AH on order.

How well does desulphanation work for a battery that has been abused (not charged sufficiently on occasion, severely discharged on regular basis etc.)?
 

nsaspook

Joined Aug 27, 2009
8,904
Thanks guys. I have a 22AH on order.

How well does desulphanation work for a battery that has been abused (not charged sufficiently on occasion, severely discharged on regular basis etc.)?
For GEL/AGM types it's almost useless but for standard FLA types if the Lead sulphate is still soft and not completely hard crystals you might get back 80% of capacity but 80% is the point where most batteries get replaced.
 

THE_RB

Joined Feb 11, 2008
5,438
For GEL/AGM types it's almost useless ...
Agreed. I'm no expert in desulphation or even if it is worth trying at all, but I have a lot of years experience in replacing sealed gel batteries.

My vote is to buy batteries from a good supplier that are very new and in good condition (not sat on the shelf for 6 months), and to budget for regular replacement of them (every year or so if they are used in anything important).
 
Top