Thinking of new charger

[tostino]

Hello all, I am currently charging my battery pack by putting my two packs in parallel, and charging it with a tp1010c rc battery charger. I am limited to 6.05a charging using this method, and it takes 8-9 hours on a dead pack to charge it up.

My packs are made out of konion cells, and the IR of each pack is a little different, because they were made at different times with a different batch of cells. Each parallel string in the pack stays in balance with the others in the same pack, but the two packs go a little out of balance with each other after a full discharge. So i'd like to continue charging in parallel, and discharging in series so they stay balanced with each other.

I was thinking about a 900w charger from bmsbattery: http://www.bmsbattery.com/product_info.php?cPath=2_18&products_id=117
I would want it set to charge 7s limn (4.1v/ should end cv to preserve cycle life). I am thinking that this charger should be putting out roughly 32a in cc mode, and should charge my pack from dead in a little over and hour and a half. Much better than 9 hours from my current charging situation.

How are the quality of these chargers? Would you guys recommend them? Is it possible for me to adjust the current limit, voltage, and cutoff after I receive it, or is that something they HAVE to do?

I look forward to hearing all of your opinions on it,
-Adam

 

[TPA]

I have that exact charger, and I love it. It is set for 41.5V and charges at 12.5A at that voltage.

If you order from them they will ask you what and how you want to charge and at what voltage.

They will set that, but if you specify a specific voltage, it could be off by as much as 0.2-0.3V. If that is not satisfactory, there is a pot inside that julesa showed me to adjust the voltage, but I still have not tried it.

 

[tostino]

hmm, that is only charging around 520w. Did you specify that as your charging rate? or is that as much current as it can put out at that voltage?

It is good to hear that you like the charger though! how is the build quality?

 

[dnmun]

usually they spec a charger by the current produced at a fixed voltage and that is how much power the transformer and diodes and oscillator mosfet can handle.

for an 88V output such as for a 72V lifepo4, then that would mean about 7A to make 600W.

 

[tostino]

If that is true, i'll just have to charge it at full voltage, and balance it manually afterward. I want the quickest charging time, and if I am limited to a fixed amperage, there is no point in lowering my voltage to charge because it will just double charge time.

 

[tostino]

So does anyone know for sure if these chargers are limited to a specific current range, and could not charge at say 30a at 24v, or 15a at 48v?
That is really what I need to know.

 

[dnmun]

the limit is the power that can be dissipated in the transformer. that is what sets the spec, then you can adjust the voltage up or down and adjust the current also so it stays within the range of power that the power supply can handle.

that's why they say it must be set in the factory to insure the power limits are not exceeded and cause it to burn up.

 

[TPA]

On their ebay auctions, they list the current available at different voltages for each charger they put there.

It would simply be a matter of deciding what voltage you will use, then look at each charger for the amps available for that voltage.

Just ignore the listed power rating and go bigger if you have to.

 

[tostino]

Thank you TPA! That is exactly what I wanted to see.

I was worried that the amps would be limited to like 15a at 48v, and 18a at 24v for the same charger. That is not quite the case, so it makes things much better.

I am kinda thinking the 1200w charger would be better for my needs, even if it is quite a bit more money. Time to start saving!