diy solar

diy solar

general question,,

carl2591

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How to top balance cells without a the DC adjustable power supply shown around. All i have access to is a solar charge controller and my standard battery charger at 50 amps. we live in RV so space is a premium and move about..
 
How to top balance cells without a the DC adjustable power supply shown around. All i have access to is a solar charge controller and my standard battery charger at 50 amps. we live in RV so space is a premium and move about..

Not possible with what you have. You must be able to drive each cell to 3.65V individually or in parallel.

This is an option that would still require extra $, but not much space:


You might also purchase an active balancer, but that can be a mixed bag.
 
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How to top balance cells without a the DC adjustable power supply shown around. All i have access to is a solar charge controller and my standard battery charger at 50 amps. we live in RV so space is a premium and move about..
 
How to top balance cells without a the DC adjustable power supply shown around. All i have access to is a solar charge controller and my standard battery charger at 50 amps. we live in RV so space is a premium and move about..
Do you have your BMS and everything else you need to build your battery?
 
Do you have your BMS and everything else you need to build your battery?

Yes I do have the JBD/overkill BMS already but waiting on cells from Amy Zheng
to ship from Texas warehouse soon i hope.. Seeing how i will most likely need to change out my 120 to 12v convertor to handle the lithium,, it's an older boondocker that is not adjustable enough for lithium,, to maybe just get a new one and use that to top balance the cells when i get them if needed..

with 12v- 230 ah cells what amp charger should i look at.. 45 amp or so??
 
If you get top quality cells it's not such an issue. I've built two 16 cell packs recently with cells from Docan / Amy Zheng. I thought I'd charge them and then finish top balancing when after the first cell maxed out. As it turned out both of the batteries track within less than 5 millivolts of each cell, no need to top balance them in the end. When they arrived they were all within 2-3 millivolts of each other. I've been running them in my system for a couple of months now and they're tracking just fine.

Wire up the pack and charge it, see what the voltage difference is between cells. If you do end up with signfiicant variation. you can remove the bus bars and individually top balance the cells, but it may well not be necessary.
 
If you get top quality cells it's not such an issue. I've built two 16 cell packs recently with cells from Docan / Amy Zheng. I thought I'd charge them and then finish top balancing when after the first cell maxed out. As it turned out both of the batteries track within less than 5 millivolts of each cell, no need to top balance them in the end. When they arrived they were all within 2-3 millivolts of each other. I've been running them in my system for a couple of months now and they're tracking just fine.

Wire up the pack and charge it, see what the voltage difference is between cells. If you do end up with signfiicant variation. you can remove the bus bars and individually top balance the cells, but it may well not be necessary.

A 0.1% difference in SoC can create a "runner" even top quality cells. They have to be truly "matched" in every aspect to ensure they'll be top balanced, OR you just get lucky.

As received voltage means absolutely nothing. My 9 Eve cells from Amy measured to 0mV as received, 7 weeks after ordering, but their stored capacity varied by 33Ah. I discharged them to 2.5V @ 20A prior to charging as I was curious to measure their SoC levels as-received (28-40.5% SoC).

Absolutely nothing wrong with series +BMS + charge first (first step in the top balancing guide), but expectations of being top balanced should be kept low.
 
I would do as Bvillebob said .... Wire it up ... be meticulous about your bus bar connections .... charge it with your solar setup and see where you are.
There are ways to manually bleed of cells if necessary.
 
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