[PSUBS-MAILIST] Batteries

[Sean T. Stevenson via Personal_Submersibles]

That is fundamentally no different than using a battery at all, which is just a bunch of series-connected cells in a housing. Fancy batteries may have a battery management module with individual cell control, but basic batteries of any type that are higher than cell voltage just rely on cell similarity and minimal resistance connections to prevent cell imbalance. You can approximate this yourself by keeping your interconnects short and huge (if possible, use bus bars instead of cables), and ensuring that all batteries in the string are subject to identical environmental conditions throughout their lifetime. As strings get longer, the risk of cell imbalance increases. As I mentioned in a previous post, you want to connect to opposite ends of your parallel strings, and only ever draw from across the entire series-parallel arrangement at once. Other than that, your only concern is finding or making a charger for the appropriate voltages and currents required for your resultant
"battery", and just accepting that it will have somewhat less life than it would if you had cell level control.

Sean


On June 19, 2016 7:44:48 AM MDT, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>I have what I think is a similar setup in Shackleton. There will be 12
>batteries in all, with each pod having two series sets of three
>batteries,
>and the two three-battery sets being in parallel for 36 volts.
>
>As far as I know the "proper" way to charge would be to decouple all
>the
>batteries and charge them individually, for which you would use a bunch
>of
>charging relays to temporarily undo the battery interconnections, and a
>multi-output charger. However, with 12 batteries and especially
>considering
>all I have is two conductors coming out of the pod, I've concluded the
>"proper" way just isn't practical for me. I've got a dual output 36
>volt
>charger and am just going to treat each pod as a giant 36 volt battery.
>
>If anyone thinks this is a huge no-no that would justify opening up the
>pods and disconnecting every battery every time I charge, please do
>speak
>up!
>
>
>Thanks,
>
>Alec
>
>On Fri, Jun 17, 2016 at 10:43 AM, James Frankland via
>Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>
>> did anyone get my post re batteries?
>>
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