charger won't charge?

[94smasher]

Just yesterday, I bought a Wraith RTR, and a Reedy Wolfpack 4200 battery, and their 447-S charger. I charged the battery this morning (took about 2.5 hrs...seemed long) ran the truck, but the battery took forever to die. It was at low voltage for about 15 mins, after running good for about 20. Never could get it to completely die (is this normal? been away from R/C for at least 10 years) Now, it won't recharge. I let it sit for about an hour before I tried, but all it does is stop after a few seconds, beep twice, and then the led just flashes...what gives?

[benoj]

what type of battery is it? nimh or lipo? if lipo it shouldnt be ran low otherwise the charger wont charge it

[Trubble]

Originally Posted by 94smasher

Just yesterday, I bought a Wraith RTR, and a Reedy Wolfpack 4200 battery, and their 447-S charger.

Not sure if Reedy makes a 4200mAh in their LiPo lineup.

Originally Posted by 94smasher

It was at low voltage for about 15 mins, after running good for about 20. Now, it won't recharge. I let it sit for about an hour before I tried, but all it does is stop after a few seconds, beep twice, and then the led just flashes...what gives?

Going under the assumption it's NiMh, sounds to me like a sulfated cell. Runs good while it's on all cells, but once the buggered up cell is done, the truck slows down while all the other cells push electricity through the bad one.

The charger hitting false peaks (stops charging after only a few seconds), seconds that and pretty well convinces me that's probably what's going on.

[94smasher]

nimh...I'm really unfamiliar with lipo, so I stayed away for now.

[94smasher]

Originally Posted by Trubble

Not sure if Reedy makes a 4200mAh in their LiPo lineup.



Going under the assumption it's NiMh, sounds to me like a sulfated cell. Runs good while it's on all cells, but once the buggered up cell is done, the truck slows down while all the other cells push electricity through the bad one.

The charger hitting false peaks (stops charging after only a few seconds), seconds that and pretty well convinces me that's probably what's going on.

that sounds almost exactly like what's happening. So, need a new battery? Like I said, I've only run this once.

[Charlie-III]

Originally Posted by 94smasher

that sounds almost exactly like what's happening. So, need a new battery? Like I said, I've only run this once.

Trubble may have hit it on the head.

What charge rate are you using to charge the pack?
I used to use ~"1C" which is related to the pack capacity. A 2000mah pack would get charged at 2amps. A 4200mah pack would get charged at 4.2amps.

I would try a nice low charge rate (maybe 1amp on a 4200mah pack) and try again.
Since it's a NiMH pack, memory effect is not much of an issue (compared to NiCD). A few full charge/discharge cycles may bring it back.

[94smasher]

I was using the 4 amp charge rate. So, is a sulfated cell something that's actually physically wrong with the battery? How do I say it...hardware vs. software problem?

[Charlie-III]

Originally Posted by 94smasher

I was using the 4 amp charge rate. So, is a sulfated cell something that's actually physically wrong with the battery? How do I say it...hardware vs. software problem?

Yes, it's physically wrong, but internally and you can't see it. It's usually related to age, who knows how long the pack was sitting on a shelf before you got it.
A lower charge rate can sometimes bring back a cell, sometime a very high charge rate (for a short time) can also fix a cell.

I would do a low charge rate and see what happens. High charge rates also increase the odds of very bad things happening.

[tenbow]

I had the exact same problem 10 minutes ago. do you still have the Reedy box? if so it came with a spark plug and fuse, i guess they go out rather quickly because i havent had my reedy all that long. but they were the exact same "symptoms" and i fixed it by replacing the two of them so, it should work for you. P.S. i made this account just to tell you that as i was looking for help not a moment ago. i dont even own a rock crawler :p but i hope that helps

[Olle P]

Regarding charge rates:
When using delta cut-off, as normally used in present day chargers, you should use charge currents in the 0.3 to 1.0 C range to avoid overcharging.

At lower currents there's a risk the charger won't recognize the voltage dip, and at higher currents the risk is that the charger overshoots the dip.
In both cases the result is an overcharge with resulting battery performance decrease.

A better way to do a smooth charge is to feed the (empty) battery 0.1C for 16 hours.
Another good way is to use IU-charge, where maximum (limited) charge current and voltage is used. The voltage should be 1.4V per cell and the current anywhere from 0.1C to whatever the battery limits.