Mixing Battery Sizes (Ah) in a Leisure Bank

[Jim Batty]

After 5.5 years it has come time to replace the batteries in our leisure bank.

 

Because of miscellaneous access, placement and space factors ‘built into’ the boat by the original fit-out, our present leisure bank consists of two 170Ah and one 105Ah battery. They are all sealed wet batteries -- same type; same brand -- replaced new at the same time, but different sizes.

 

I was going to simply replace all with the same again, thinking 5.5 years (CCing for most of that time; 200w solar topping up in season) doesn’t seem bad.

 

BUT I have recently been advised that as the two 170Ah batteries will be ‘overworking’ or ‘pushing’ the single 105Ah battery, adding that single 105Ah battery wasn’t really adding much to the bank. At least not as much as I might think.

 

I didn’t have a chance to clarify this at the time. Can anyone shed some light on mixing different sized batteries?

[nicknorman]

No it will be fine, the batteries will share the load and charge in proportion to their capacity.

[Guest]

If you got 5+ years out of them then you are doing something right! I think the important thing is that they are the same type of battery, not the rating.

[Arthur Brown]

If you got 5 years out of a house battery you must be doing something right, I'd consider two years to be good and some people get a lot less than that. If the arrangement that you have works then repeat it.

[Jim Batty]

... I'd consider two years to be good and some people get a lot less than that. ...

 

Less than two years? Crikey.

[Tony Brooks]

Some only get months - livaboards who never fully recharge their batteries and run them at 11 to 12 volts, or maybe weeks.

[alan_fincher]

Replace like with like - you will be fine, and anybody who has told you otherwise is, (well,errr,) just plain wrong.......

[MtB]

There was a long and vexatious thread here many years ago on this subject and Gibbo came up with some convincing arguments as to why mixing up battery sizes is actually perfectly fine. Not just different sizes but he said old and new may be connected up into banks too, IIRC.

[WotEver]

There was a long and vexatious thread here many years ago on this subject and Gibbo came up with some convincing arguments as to why mixing up battery sizes is actually perfectly fine. Not just different sizes but he said old and new may be connected up into banks too, IIRC.

Yeah, it was fun. Once again Chris W came up with dodgy maths and Gibbo set him straight.

 

http://www.canalworld.net/forums/index.php?showtopic=9418&view=&hl=&fromsearch=1

 

Tony

 

Note that differet types (eg gel and wet) is a different matter.

[Guest]

Yeah, it was fun. Once again Chris W came up with dodgy maths and Gibbo set him straight.

 

http://www.canalworld.net/forums/index.php?showtopic=9418&view=&hl=&fromsearch=1

 

Tony

 

Note that differet types (eg gel and wet) is a different matter.

That is how I understand the situation.

[dor]

Yeah, it was fun. Once again Chris W came up with dodgy maths and Gibbo set him straight.

 

http://www.canalworld.net/forums/index.php?showtopic=9418&view=&hl=&fromsearch=1

 

Tony

 

Note that differet types (eg gel and wet) is a different matter.

Ah the good old days, when you had an entertaining discussion between Gibbo & Chris W!

[Guest]

Ah the good old days, when you had an entertaining discussion between Gibbo & Chris W!

What frightened me was how long ago that was! Seems like it was quite recent.

[Mac of Cygnet]

Yeah, it was fun. Once again Chris W came up with dodgy maths and Gibbo set him straight.

 

http://www.canalworld.net/forums/index.php?showtopic=9418&view=&hl=&fromsearch=1

 

Tony

 

Note that differet types (eg gel and wet) is a different matter.

 

Ah! I replaced my domestic batteries (2) with gel batteries a few weeks ago (they were all that were available and the old ones were shot after 9 years). But the starter battery remains an open-cell wet battery. Does this matter? I did alter the setting of my Sterling alternator controller to 'gel'.

[WotEver]

 

Ah! I replaced my domestic batteries (2) with gel batteries a few weeks ago (they were all that were available and the old ones were shot after 9 years). But the starter battery remains an open-cell wet battery. Does this matter? I did alter the setting of my Sterling alternator controller to 'gel'.

You'll be fine. The starter bat doesn't need much charging and it'll happily get fully charged at gel voltages.