Charging Problems

[MrMikey83]

I bought a Triton battery Charger off Ebay and recieved it yesterday.
It requires 10-15 volts at 13 amps to fuction properly.
I attempted using an old computer power supply, but aparently it didn't have enough juice.
So, today I bought a Radio Shack 12v 15A supply.
I hook up my batteries (a set of 16 NiMH cells in series). I press the charge button and the display tells me its puting 40 volts and 1 amp into the batteries. It does the same on Auto or a pre set variables.
Well, the batteries dont get too hot, but within seconds, the battery holds I am using are deforming. I found that the parts that are getting how are the springs in the holders and they are pushing up through the plastic because the the heat and spring tension.

What am I doing wrong? Should I try and build a better battery pack without using the spring loaded holders? Has anyone else used the Triton Charger?
Thanks!
~Mike

 

[fredsm]

What is the cell capacity? Is a one-amp charge appropriate?
Is the charger rated for NiMH? A constant 40V is entirely too
much for a 16-cell pack. Especially at a 1A level.
<als>

 

[MrMikey83]

I agree 40 is way too much.
The individual batteries are 1.2 volt at 1600mAh AA cells.
The charger is capable of charging NiMH's and has a automatic setting that is supposed to check the pack and decide the correct settings on its own.
I just dont understand why the battery holder springs would heat up and melt the plastic.
~Mike

 

[FRIED]

I just dont understand why the battery holder springs would heat up and melt the plastic.

Poor contact. This is possibly where the extra voltage is being lost. I have had trouble with the rivets on the end.

 

[MrMikey83]

OK< so if I wanted to make a real battery pack and permanently connect the batteries end to end with metal strips, how would I go about doing so without having to heat up my NiMH's?
~Mike

 

[FRIED]

You can solder them. Speed is the thing. You need an iron that has plenty of heat reserve. Tin the cells first, only tinning enough area to connect. Allow to cool.
Then connect using pre-tinned wire.

 

[MrMikey83]

OK, I will solder them into a pack. SHould I put the heat sensor in the middle or on the end of the pack?
~Mike

 

[fredsm]

Put the thermistor in the middle of the pack,
preferably sandwiched between two cells.
It will be chance, anyway - the worst/best
cell will seldom be right in the middle, anyway.

A 40v terminal voltage is not unusual for a
severely depleted or damaged battery pack
with 16 cells, but it certainly should not be
at 1A at this voltage. If your cells are the
"fast charge" type, they can be charged at
C/1 (i.e., 1.6A), otherwise the maximum
rate is C/10 (0.16A).

If it is not too difficult to get to the internal
cell connections, you will have better results
charging fewer cells in series (2 to 6).

16 cells is an unusual pack (19.2v). Are you
sure that the charger has this in its range?

As for soldering the cells, use a soldering gun,
preferably a 250W or so. Tin the cell ends
and the tabs first, then solder them together.

<als>

 

[MrMikey83]

Yes, the charger is capable of charging up to 24 cell packs.
I finished the pack last night. I have a hole cut in the bottom to slip the temperature sensor inside and I just need to solder the wires to the pack. I didn't have shrink wrap so I used electrical tape.
Below, you can see the 4 cell cases I was holding the batteries in. I had originally planned on a 20 cell pack which is why I have 4 extras.
When I strap it to my bot, I may add some extra aluminum angle stock to dissapate more heat and keep the batteries cooler.
~Mike

**broken link removed**

 

[MrMikey83]

ok, I connected the battery wires and attempted a charge. Looks like it has automatically picked .1 Amp, after 1 minute it went to .7 Amp and now 1Amp after 2 minutes of charge. The batteries are capable of fastcharge. I guess the charger sensed this and took the apropriate action.
Oh yes, the voltage lowered to 22.24V with the new battery pack setup.

Looks like it is working great. I guess you were right about the springs ont he old holders not making a solid enough contact to the battery. I guess that made the charger jump the voltage up to 40v.

Thanks!
~Mike