advice needed charging and testing cells

[dutchlincoln]

Hello,
I have 2 Victpower battery packs here of 48 volts, 40Ah (32 cells)
Also busy with other cells and packs (18650's)

So, i need to get me a good battery charger, but a good battery discharger as well.
I'm thinking about a good Hyperion, but they all seem to discharge "just" 40 watts max.
Now, with RC hobby packs it may be sufficient, but with these A123 cells its a bit slow...

Can anyone advice me a good and affordable power analyser/discharger/capacity tester/etcetera?
Also, a good Ri meter is a nice gadget on my list 8)

Its all for the hobby, so it has to be a bit affordable. The wife reads here as well...

Thnx.

 

[dnmun]

why do you need a battery discharger? you actually charge a 30Ah pack with a balancing charger? you have no bulk charger and no BMS on the pack to protect it?

 

[dutchlincoln]

Yes i have, but i need to check it cell by cell, as my pack has some puffed cells in them, and i like to know what the capacity and quality of the remaining cells are.

Besides that: the bms that came with it has big fat wires on it for the main current, but rediculously small wires for each cell to balance. When it really would need to balance it, it would have to be done with such small current, it probably would take a week to do so i guess...
So, just for checking, and being sure.

Besides this i have some rc cars as well with a bunch of lipo's, and its great to be able to fast charge them as well, and being able to check and well balance them.


Dnum:

Dutchlincoln is it pack solder togethere ? I think victpower just that's any cells off the self for a pack build. Dumumn has wrote about the steps to that to find out about the capacity of a pack and how to check. Can't find it right now.

Can you tell me where to find this great info!?

Thnx!!

 

[dnmun]

you can discharge your pack into a dummy load like the rest of us. i use two 1500W electric oil bath heaters and have no trouble measuring cell voltages.

 

[dutchlincoln]

Thats nice, and naturally a good optiun, but how do you compare each cell in accordance to one and other, and how do you determine the Wh capacity/cell ?

 

[dnmun]

you discharge the pack until the lowest cell reaches 2.1V, stop the discharge and record the Ah discharged at that point, add some charge back to the low channel with a single cell charger until it is high enuff in voltage to remain outa the way while you continue discharging the pack and reach the second weakest, and so on.

you have to charge each cell up to full charge of 3.65v first. so you have to balance the pack with all the cells reaching 3.65v or more before starting the discharge.

 

[wesnewell]

The Hyperion 1420i can discharge up to 10A through the main power leads.

 

[migueralliart]

For discharging LIPO packs I use 2 250w halogen bulbs (24V) paired with a switch and cell log datalogger FTMFW.