Need help with my 2004 IMA battery

[3-Wheeler]

Originally Posted by markadams

Just for kicks I hooked my DVM to the battery and my large lead acid charger (set on 10 amps) to a stick. Zapped it for about 30 seconds and now its reading 8.3 volts. Actually felt some heat after removing the charger. Just a little over room temp.

Is that all it takes to charge these?

And thank you to everyone contributing to this thread!

I think you're asking for trouble, while attempting to charge a stick that way.

My bench top power supply was set to:

175/20 = 8.79 volts

The charge on a depleted stick would start off at 10 amps, then slowly taper off as it fully charged.

I typically would let the stick charge to 8.5 volts, remove the power supply and let it settle for one minute, then apply the discharge resistor to it, and monitor voltage drop over time with a stopwatch and paper.

The next time I do this, I'll have a PIC measure each cell for performance, and feed that data to an old laptop for recording.

Jim.

[markadams]

Thanks 3 wheeler. Is that 175 in your (175/20formula) the maximum voltage the pack can handle safely? Or 8.79 volts the max per stick?

[markadams]

I am completely lost on the discharge resistor too. No clue how to make one of those.

[Eli]

Let the commercial unit handle charge/discharge. You'll cook your sticks if you try and charge them with the 12V charger. You could do it, but you would have to know precisely what you're doing.

Fully charged for a stock stick under any decent amperage is going to be over 9V while charging; ~8.7V a minute or so after coming off the charge.

[markadams]

You're exactly right Eli, while charging they all ran around 9.59-9.67 volts. I ran through all 20, just for about 20 seconds each. I'll check and document the volts tomorrow after setting overnight.

Eli, does your company sell a proper charger/discharger for these?

Thanks, Mark

[TopFuelTim]

Originally Posted by 3-Wheeler

Well, I guess the home built approach is not the most obvious, but it can be done if you're persistent, as shown below.

The picture with the "stick cycling setup" verbiage shows my home built discharge resistor, and 10amp power supply to the right.

https://picasaweb.google.com/threewh...ryRefurbishing

If you want something off the shelf, then Mike's discharger will work very well for you.

Jim.

Hi Jim,

I have to sit corrected again. I now remember reading your post about your discharger. However, I am not confident enough in my electrical engineering to attempt that, so I was really happy Mike Dabrowski offered his setup.

Tim

[3-Wheeler]

Originally Posted by markadams

Thanks 3 wheeler. Is that 175 in your (175/20formula) the maximum voltage the pack can handle safely? Or 8.79 volts the max per stick?

Yes, 175 volts is close to the maximum that the battery should see.

If you go above that, keep a close eye on the battery temperature.

Same with the stick voltage.

Jim.

[3-Wheeler]

Originally Posted by markadams

I am completely lost on the discharge resistor too. No clue how to make one of those.

I took a 1.5 inch piece of galvanized pipe if I recall, and got about 10 feet of transformer wire (varnished) and tightly wound it around the pipe, as described in one of the pictures that I posted.

I updated the caption with the picture of the pipe in the link here...

https://picasaweb.google.com/threewh...ryRefurbishing

Jim.