# Sealed lead acid batteries in parallel- amp hours? **URL:** \ **Category:** Factual Questions\ **Created:** [March 14, 2012, 12:45am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705 "2012-03-14T00:45:55Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Rysdad](https://avatars.discourse-cdn.com/v4/letter/r/7cd45c/32.png) [@Rysdad](https://boards.straightdope.com/u/Rysdad)\ **Post date:** [March 14, 2012, 12:45am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/1 "2012-03-14T00:45:55Z")
If I had, say, three fully charged sealed lead acid batteries, connected in parallel, rated at 40 amp hours each, would I have the equivalent of 120 amp hours? I’m thinking about installing a 100-watt solar panel (along with all of the other required stuff (rectifier, charge controller, etc), and I’m wondering about the storage/usage capacity. So, what say ye? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 14, 2012, 1:00am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/2 "2012-03-14T01:00:28Z")
cells/batteries in parallel- voltage same as a single cell/battery, capacity (Ah) adds. cells/batteries in series- voltage adds, capacity (Ah) stays the same. ---
**Author:** ![Rysdad](https://avatars.discourse-cdn.com/v4/letter/r/7cd45c/32.png) [@Rysdad](https://boards.straightdope.com/u/Rysdad)\ **Post date:** [March 14, 2012, 1:21am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/3 "2012-03-14T01:21:48Z")
Thanks. I also found an answer [here.](http://www.gizmology.net/batteries.htm) I’ve never even heard of Peukert’s number before. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [March 14, 2012, 2:10am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/4 "2012-03-14T02:10:16Z")
If all of the batteries are identical and in good condition, then yes, connecting them all in parallel will add the amp-hour ratings together. It’s generally not a good idea to parallel batteries, though. They won’t necessarily share the load evenly, since even the slightest difference will cause one battery to supply more or less current than the others. If one battery dies (or gets a damaged cell) then the other batteries will constantly try to charge it, so a single failure may take the other two batteries down with it. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 14, 2012, 2:15am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/5 "2012-03-14T02:15:29Z")
> [@engineer\_comp\_geek](#): > > If all of the batteries are identical and in good condition, then yes, connecting them all in parallel will add the amp-hour ratings together. > > It’s generally not a good idea to parallel batteries, though. . eh? what do you think a “battery” is? ---
**Author:** ![Rysdad](https://avatars.discourse-cdn.com/v4/letter/r/7cd45c/32.png) [@Rysdad](https://boards.straightdope.com/u/Rysdad)\ **Post date:** [March 14, 2012, 2:24am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/6 "2012-03-14T02:24:16Z")
> [@Why I don't like religious tracts](https://boards.straightdope.com/t/why-i-dont-like-religious-tracts/74203/57): > > It’s generally not a good idea to parallel batteries, though. They won’t necessarily share the load evenly, since even the slightest difference will cause one battery to supply more or less current than the others. If one battery dies (or gets a damaged cell) then the other batteries will constantly try to charge it, so a single failure may take the other two batteries down with it. I guess I understand the concern, but I could check them with my meter periodically just to make sure. It’s not like they’re going to be moved around a lot or anything. I mean, I have to rely on _something_, and I have a couple of generators as well. Maybe I’ll have backups for my backups. 🙂 ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [March 14, 2012, 2:42am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/7 "2012-03-14T02:42:18Z")
> [@jz78817](#): > > eh? what do you think a “battery” is? Most multivolt "battery"s are in SERIES, which is a whole nother kettle of fish compared to cells/batteries in PARALLEL. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 14, 2012, 3:42am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/8 "2012-03-14T03:42:25Z")
> [@Rysdad](#): > > If I had, say, three fully charged sealed lead acid batteries, connected in parallel, rated at 40 amp hours each, would I have the equivalent of 120 amp hours? > > I’m thinking about installing a 100-watt solar panel (along with all of the other required stuff (rectifier, charge controller, etc), and I’m wondering about the storage/usage capacity. > > So, what say ye? This is a standard configuration. Read up on charge controllers and “equalization” charging. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [March 14, 2012, 9:29am UTC](https://boards.straightdope.com/t/sealed-lead-acid-batteries-in-parallel-amp-hours/615705/9 "2012-03-14T09:29:08Z")
If you’re going to do this yourself, make sure you read up on how to maximize battery lifespan (don’t deep cycle them unnecessarily, for example). The DIY environmental wiki [Appropedia](http://www.appropedia.org/Photovoltaics) is a sometimes-great resource for this type of endeavor, though it needs better cleanup and categorization. (Disclaimer: My professor helps administer the site)