Quick mod for getting small charge on 9.6v RC battery.

[BatteryNoob]

I just checked out this thread.

http://www.societyofrobots.com/robotforum/index.php?topic=319.0

I have a cheap RC car I just bought from Goodwill, want to mess around with it.

It has a 9.6v .6amp battery. I really dont want to buy a smart charger unless I know this RC car works. Can I hook a DC transformer plug from an old phone up to the charger for a small amount of time to put a bit of charge on it?

The block is rated 12v @ .5 amps. I realize I would be risking a fire if I am not careful. Again I just want to see if the motors work ect. on the car.

The battery is also a NiCd battery. Let me know what you think?

[Soeren]

Hi,

It has a 9.6v .6amp battery. I really dont want to buy a smart charger unless I know this RC car works. Can I hook a DC transformer plug from an old phone up to the charger for a small amount of time to put a bit of charge on it?

The block is rated 12v @ .5 amps. I realize I would be risking a fire if I am not careful. Again I just want to see if the motors work ect. on the car.

The battery is also a NiCd battery. Let me know what you think?

If you have a voltmeter, measure the battery voltage. One or more cells could be dead.

A 9.6V NiCd battery is an 8 cell stack
Each cell, which is marked as 1.2V will need to charge to 1.40-1.45V, meaning that your battery needs to be charged up to 11.6V

If you put a resistor in one of the leads, say 10..33 Ohm  for starters, you are limiting current to a value that doesn't do harm to the battery. You should monitor the voltage while charging, as if one or more cells are dead, either it won't take a charge at all, or it will charge to a lower voltage (depending on whether the dead cells are open or shorted).

A multi-cell battery is very easy to kill by neglect and since you probably don't know the least bit about how the battery was treated previously, you should be cautious.

If you haven't got a multimeter, get out and buy a cheap 'meter before attempting to charge the battery.

[BatteryNoob]

My friend suggested hooking up a 9v block to the car and seeing if it runs that way.

I find this safer as I do not want to explode a battery, lol

I have no idea what a resister is, My dad has a VOM I could try and hook that up. I really dont know what I would be looking for. Should I check and see if the battery puts out anything for volts? Then go from there?

[BatteryNoob]

Well, I decided to try it. I hooked it up and let it sit, checking for heat on the cells.

I let it charge for about 4 mins before I got paranoid and unplugged it.

IT WORKED!

And the really weird thing is, I was able to use the RC car for about 3 minutes. Super charged lol.

I am not going to do it again, I am going to buy a smart charger for it. But if anyone wants to know.

Used a 12v .5amp transformer block on a 9.6v .6 amp battery. I think It could charge for a while with out issues. I am not going to try it again tho.

[waltr]

NiCad batteries are not that hard to charge. Soeren gave you some good information and if you Google then you will find detailed specs on how to charge NiCads. By learning how to charge these manually you will also learn a little about batteries.

It sounds as if you do not have a multimeter. If you are going to do any playing with circuits then a multimeter is a MUST HAVE.

[Soeren]

Hi,

IT WORKED!

Great 

And the really weird thing is, I was able to use the RC car for about 3 minutes. Super charged lol.

That may not be so weird.
The car takes slightly less than 1.5 times the charge current (~500mA) multiplied with the 4 minutes of charge time divided with the 3 minutes of runtime (which equates to (an average running current of around 450mA), This may be somewhat higher though, as there may have been some "sleeping" charge on the cells that just needed to be "woken up", if they haven't been used for a while.

I am not going to do it again, I am going to buy a smart charger for it. But if anyone wants to know.

Used a 12v .5amp transformer block on a 9.6v .6 amp battery. I think It could charge for a while with out issues. I am not going to try it again tho.

Good call, you should never proceed with anything that you feel really insecure about.

A voltmeter on the battery terminals and a finger on the cells to tell the temperature (anything below 35°..40° and the cells are fine) would tell you how it goes however.
If your dad has got a voltmeter, perhaps he could help you out with that (people who's got a voltmeter usually know at least a little about the stuff )


When you get a charger, you'll probably see the capacity (runtime) rising some the first couple of charges - this is normal with a battery that have been inactive for a while.