Re: [electricboats] Max amp in parallel?

Hi Ryan! Good name, lol. 

So current through parallel drops or sources works the same as voltage across series drops or sources; that is to say, they add directly together. 

So if you have 4 batteries in parallel, then yes, you will be quadrupling their individual current specs working as a unit together, as for max draw, ampacity, etc. 

That also means that your conductors and circuit protection devices need to be suitable after the nodes where the batteries join together to handle that current being quadrupled, of course. 

Depending what type of batteries you are using, having another bms type system to balance those batteries may be a good idea to extend battery longevity... but many systems get by with parallel batteries in a bank without any bms (most cordless tool batteries with a few recent exceptions being the most prevalent example in my mind)

On Wed, Oct 28, 2020 at 9:57 PM, john via groups.io

<oak_box=yahoo.com@groups.io> wrote:

Ryan,

There are some subtle things about tying batteries in parallel.

If you are building your bank from basic cells, with large conductors, that's one thing.

If you're using 48V battery systems with built in BMS's, that may or may not work.

In any event, you have to be sure you have thick enough cables running everywhere.

In that regard, parallel batteries are easier to use for extending range than increasing the max amperage (for shorter periods of time).

Technically, in theory - you can either increase the max load or increase the range by adding more batteries in parallel.  Just be careful.  The hard part with parallel systems is ensuring that the power is being equally drawn from all systems, and then that all systems equally charge at the same time/rate/voltage.

Good luck!

John

On Wednesday, October 28, 2020, 07:39:09 PM CDT, Ryan Sweet <ryan@ryansweet.org> wrote:

Ok, I adjusted my googling terms and was able to answer my own question, yes in parallel the max draw will increase. Sorry for the super basic question. Was one of moments of second guessing myself after having figured this out once previously and then the doubt turns to imposter syndrome and well, you get the idea.

> On Oct 28, 2020, at 17:11, Ryan Sweet via groups.io <ryan=ryansweet.org@groups.io> wrote:

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> I'm looking at battery options and I see a 48v 200ah battery with a max discharge of 60a. If 4 of this this battery is in 4p, at 800ah, will that also allow for increased max draw to the motor or will it still be 60a?

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