Jim Batty Posted August 28, 2016 Report Share Posted August 28, 2016 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? Link to comment Share on other sites More sharing options...
nicknorman Posted August 28, 2016 Report Share Posted August 28, 2016 No it will be fine, the batteries will share the load and charge in proportion to their capacity. Link to comment Share on other sites More sharing options...
Guest Posted August 28, 2016 Report Share Posted August 28, 2016 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. Link to comment Share on other sites More sharing options...
Arthur Brown Posted August 28, 2016 Report Share Posted August 28, 2016 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. Link to comment Share on other sites More sharing options...
Jim Batty Posted August 28, 2016 Author Report Share Posted August 28, 2016 ... I'd consider two years to be good and some people get a lot less than that. ... Less than two years? Crikey. Link to comment Share on other sites More sharing options...
Tony Brooks Posted August 28, 2016 Report Share Posted August 28, 2016 Some only get months - livaboards who never fully recharge their batteries and run them at 11 to 12 volts, or maybe weeks. Link to comment Share on other sites More sharing options...
alan_fincher Posted August 28, 2016 Report Share Posted August 28, 2016 Replace like with like - you will be fine, and anybody who has told you otherwise is, (well,errr,) just plain wrong....... Link to comment Share on other sites More sharing options...
MtB Posted August 28, 2016 Report Share Posted August 28, 2016 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. Link to comment Share on other sites More sharing options...
WotEver Posted August 28, 2016 Report Share Posted August 28, 2016 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. Link to comment Share on other sites More sharing options...
Guest Posted August 29, 2016 Report Share Posted August 29, 2016 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. Link to comment Share on other sites More sharing options...
dor Posted August 29, 2016 Report Share Posted August 29, 2016 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! Link to comment Share on other sites More sharing options...
Guest Posted August 29, 2016 Report Share Posted August 29, 2016 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. Link to comment Share on other sites More sharing options...
Mac of Cygnet Posted August 29, 2016 Report Share Posted August 29, 2016 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'. Link to comment Share on other sites More sharing options...
WotEver Posted August 29, 2016 Report Share Posted August 29, 2016 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. Link to comment Share on other sites More sharing options...
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