Batteries are FUBAR, reconditionable? YES!

[Tankdude]

Just got three (3) battery packs from a trade.

They are 7.2volts nimh 3300mah GP brand sub c.

Using the npt it goes red for a minute and then green.

Voltage reads 7.5 volts on all of them. They can only run the car for about 5 minutes before they go kaput.

These batteries are completly drain and it only takes a min to charge them up to peak voltage.

Under load they drop in voltage very rapidly, so fast you can watch the multi meter go down.

Once the load is taken away they go back up to 7 volts.

Recondition? Throw away? Flush?

[Greylocks]

Doctor's Corner?

Voltage peaks real fast, that's normal, but dont you check the amperage? Read up on battery charging methods.

[Tankdude]

OMG. Why didn't I think of that. It's a freaking NPT charger, it only has two amp settings.

[Greylocks]

Get a better charger, or use your multimeter to check the amperage.

[Tankdude]

I use it in the car till it is dead. I plug it into the automatic npt charger. It charges for a minute and then says it is done. I check the voltage and it says 7.5 volts.

The capacitance is totaly messed up. They shouldn't peak that quick.

[Greylocks]

Listen... check the amperage. Cell by cell if you must. Then decide if you want to waste more batteries or invest in a good charger.
RC cars are not even remotely on topic, pun intended. Read the Doctor's Corner or all the posts about charging batteries.
Ask the moderators to move this where it belongs.

[Tankdude]

How can I check the amperage? Do I tear apart the battery and short circuit it? Or do you mean voltage?

Friend has a cycler, we will try that tormorow.

[Dracheous]

-.-.... AMPERAGE NOT VOLTAGE!... Google it if you don't know... and if you have a multi-meter to test your voltage... change the dial on it till it says Amp, and if you've a GOOD one you can turn it down to MAh... and if you have an even BETTER one... it'll do all this for you automatically...

[Tankdude]

Still doesn't make sense to check for amps. If I put the probes on the battery with no resistence I would get infinite amps. Don't see where that would get me besides blowing the fuse. I think your both thinking about checking the voltage of the batteries to see if any give an adnormal reading.

Saying "check the amperage" and "google it" also doesn't work. You get nothing of value. Stop giving vauge tibbits of useless information.

[Drake]

They do mean amps, they just aren't really proposing a valid solution to check them (i.e., you can't just stick a multimeter on cells to check amps).

Either way, it IS an amp problem, not a voltage problem. Voltage alone does jack shit. You obviously have your voltage; what you don't have is the amps to drive it for more than a few minutes. So basically you're charging a 7.2v 50mAH pack for yourself.

You need to slow charge them, maybe quite a few times/cycles. Really low mAH (0.5 or less). And let it run a really long time. I've restored essentially dead FRS radio battery packs (NiCD) that way.

[Mysteryfish]

I also have done so. Taken a 1700mAh battery that was holding 120mAh back up to full capacity...

Do what Drake says - And if you don't already have a discharger, get one.

Discharge the batteries fully, then slow charge them (meaning, charge them on a very small AMPERAGE setting). It'll probably take a day and a half...

Then fully discharge them (properly, with the discharger), and repeat this, checking to see that the full cycle is increasing the capacity, and reversing the effects of the memory...

I don't know the scientific details behind it, but in my experience, that's what worked.

[Greylocks]

If the equipment you have cannot measure amperage, or you dont even know what that is, open your wallet and get yourself a really good computerized charger.
That's cheaper than tossing batteries away.

I'll try one more time to explain this... You have a 30 liter gas tank, you put 1 liter in because it overflows too fast or you are impatient.
You then run your car and it dies a few minutes later. Do you toss the car away or are you willing to learn how to fill that gas tank properly?

A decent charger, even when you know electronics, is one of the most amazing things you can buy because it does everything AND monitors what you do. They are worth every buck; get one and solve all your problems in one shot.

[Tankdude]

The word you guys are look for is capacitance.
Check the capacitance of the cells.

Thanks Mysteryfish and Drake.

[mcguyver]

No, actually, they do mean current. Slow charge the batteries with a constant current or use a pulse charger to deliver larger square wave pulses to recondition the battery. Other tricks include discharging the battery and then throwing it in your freezer overnight, then charging it the next day and see how it recovers. If your charger is not capable of a low current charge setting, get one that does. It's worth every penny!!!

[Dracheous]

I love idiots... they make me feel better about my drinking every day...



Greylocks... you tried... game over though man... game over... cause really... if he typed Amperage into google and got NOTHING?!... then yeah... game over



Although Drake... what you can do if this guy has the type of charger I think he's talking about... there are two little imputs... you can stick the multi-meter in there... I have one for charging my Newphews RC car batteries... used to use it too for the RC airplanes before switching to gas engines... and I thought it better to lead the guy to where he can get ALL the information instead of try to explain it myself and miss some things that might have been important somewhere anyway... tried... thats all... he doesn't want to take the collective problem is with the charger...


Edit: I also assumed that he was using such ports in the charger to check the voltage as linking your multimeter up to a battery can be damaging to your multimeter... like sticking it in a socket plug :P