Turning an alkaline pack into a 2500 mAH NiMH pack

[chris poteet]

I went back to the park today and found out from a park atendant where i was swinging the V3 yestarday was a under ground high voltage cable could that have hurt my V3? I now have a electrical layout of all the ball feilds. I guess we learn from our mistakes.

 

[slumpshooter]

Underground cable can cause a lot of interference, but can't damage your V3, as long as no direct contact occurs, obviously. Did you isolate your battery cells (measure voltage looking for a bad cell)? Have you tried another battery pack? How is it working at home?

 

[chris poteet]

I checked all battery cells and they were at 11.44 volts after recharging the pack .Im going to try the pack out tommorow. thanks for the info.

 

[Larry (IL)]

I think what slumpshooter meant was to check each cell in the pack when the battery pack needs charging. There are 8 cells to check and each one should have a positive charge, (not reversed), of about 1 to 1.25 volts even though they need recharged. A cell will read higher on a voltmeter that does not have a battery load built into it. What you are looking for is not so much the voltage, but to see if one or more cells has the reverse voltage when the pack needs charged. If you do, then those batteries are not as good as the rest of them and needs to be changed to have a matched set of batteries in your pack. It doesn't happen often, but I have seen it, especially when building fast discharge battery packs for racing RC cars and boats.

 

[chris poteet]

tried the pack and it done the same thing I checked each individual AA battery had one that was .89 volts the other seven was exactaly 1.39 volts before being charged. going to replace all eight AAs .thanks for the help,you guys been great.

 

[Larry (IL)]

Changing all 8 is OK, but you just need to change the one bad one, the others sounds good.

 

[chris poteet]

ok. thanks larry.

 

[slumpshooter]

HI Chris,
Larry is right, only need to change the one cell that is .89 volts. It may be that you will experience this again as you are able to discharge your pack longer once you have replace the bad cell you found. What you should observe is a slow gradual pack discharge, not an abrupt drop to half of the pack voltage. If that happens then do the same trouble shooting again and you find the next weakest cell in your pack. I assume you bought all the batteries you are using at the same time and they are all have the same a mAH rating. For instance, I used Duracell rechargeable batteries rated at 2000 mAH, so all my batteries read the same 2000 mAH rating. Anything more or less will cause issue for you. They should all be about the same age or put into service about the same time to help avoid issue like your experiencing. Sometimes however it is just a bad cell and replacing it put the universe back in sync.
Let us know how it worked out....
Good luck!

 

[Rigit]

For those in the UK you can obtain the thermistor from RS Components cat No 198-927 price

 

[chris poteet]

I changed out the one low voltage battery with a new one it now charges up the same as the other 3 batteries pack works great thanks guys.

 

[bud212002]

I just bought a new Triton charger for my RC batteries. Any way to charge my packs with it? I can make a lead, but don't want to fry it.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVRS6&P=ML

 

[slumpshooter]

Great charger, I use one my self. In order to use it, you will need to know the mAH rating of your pack and the voltage. You can't plug it into the white base unit because it has charging electronics in it. Not as good as your Triton Charger but adequate for the White battery pack. So if you are going to charge a white pack, the voltage is set on the Triton at 9.6, I am not sure what mAH rating your pack is, did you build it or is it Whites stock rechargeable pack? Set your Triton for that mAH rating hook directly to pack, and you're charging... The nice thing about the Triton is you are able to cycle your battery pack so you can monitor it's health better.
Good Luck,

 

[johnedoe]

Easier to just get this and 2500 or 2700 mAh NiMH batteries and use the standard alkaline battery holder.
This unit also has a 12 volt adapter so you can use it in your car.
It charges 8 AA, 8 AAA, 4 D, 4 C, or 2 9volt cells at a time.

Charger......... http://www.radioshack.com/product/index.jsp?productId=18409506#stuff-you-want

Here are some 2500 mHa batteries..... http://www.radioshack.com/product/index.jsp?productId=3714036

And here are some 2700 mHa batteries.... http://www.radioshack.com/product/index.jsp?productId=2437557&filterName=Type&filterValue=AA

I have been using this charger for a couple years now and the same batteries too.... It's been working great,

 

[Rob (IL)]

In the past, I built a 8 cell and 9 cell NIMH pack that charged on the Whites charging cradle. They worked fine. However, I really love my Li Ion packs.