[PIDDLER95]

I have three 12v batteries for my Hilti cordless drill but I can't keep them charged. Can anyone tell me how to resurrect these batteries to get full power? I also need to replace one of my 12v chargers . Do you know where I can find one?

[MOWERMAN2468]

Go to the store where you purchased them.

[progunr]

What I have found out about rechargeable batteries is this.

Do not leave them on the charger.

Always drain them to fully exhausted prior to recharging.

Don't partially charge them, from full dead to full charge every time.

Occasionally, if you are not using them, drain them to full dead, and do a full recharge.

Many batteries will develop a memory as to how low they get used, before they are recharged. If you use half, and recharge all the time, soon, the battery believes it is dead at half use instead of full.

It may be too late for the ones you have, I'd try the fully drain, and full recharge on the newest one just to see if it can be saved.

Good Luck!

[ballengerb1]

Be cautious about how you go about fully discharging a rechargeable battery. If you take it down to dead zero volts it will likely not take a charge. Hilte doesn't make their own batteries, they just bundle 8 cells together to fit their drill. Rechargeables are getting better but ,many can only be recharged about 50 times, then they are ready to be recycled.

[biggsie]

It will take some doing, but you can repair cordless drill batteries. An 18 volt battery pack is made up with 12 "C" sized rechargeable cells. These are available at Radioshack or any place that sells rechargeable batteries. After your battery pack has been on the charger long enough, take the cover off the pack and identify the positive end of the first cell in the chain. Using a multimeter, check and make note of the voltage reading between that point and the negative end of that cell and then from the negative end of each cell in sequence. From cell to cell you should see a 1.5v jump. If the voltage jump is less than .8 volts, the cell your checking is bad. Mark the cell and keep checking the cells until you get to the end. You will probably have to cut or de-solder the leads going from cell to cell to beable to extract the bad cells. Be certain, when putting new cells back in, that the polarity is correct. Again, you will have to solder the leads back on. Warning, this can be tricky.

I just resurrected a pair of 12v DeWalt batteries ($56 each new) for $9 in rechargeable batteries and an afternoon of fussy work. For me, being a cheap S.O.B. who likes fixing things, it wasn't so bad.

If a battery pack is allowed to go very dead, the cells holding a higher charge will actually start recharging the weakest cells and reverse the polarity of those cells. For my 12v Dewalts (9 - 1.5v cells) having 3 bad cells each, it meant that I wasn't even getting the benefit of the remaining 6 good cells, because they were giving up their charge to the three bad cells with reversed polarity. Essentially I was only working with 4.5v of power.

[Flying Blue Eagle]

Piddler95- I do't know what your local is
, but not to far from me is a place called ( Battery Plus ) they will repair your old batterys to new . A lot cheaper then buying a new battery, If I remember right they also have new chargers, maybe theuy repair them also I have had some batteries rebuilt by them for my Makita drills and they done OK on them:: Here is their ADDRESS & phone NUMBER< IF YOU DON'T HAVE ONE NEER YOU . Batteries Plus. 100 VANN DRIVE , JAckson TN. -731-660-0600, when you call them - ask them if there is a store near you::: Hope this helps, IF it does rate my answer below Good Day & GOD BLESS

[KISS]

Battery chemistry anyone? NiCd's can sometimes be resurected.

[biggsie]

I had a 9.6 volt battery drill that I bought at a garage sale -- there was no charger with it

I decided to see if I could bring battery back to life -- used a car battery charger -- small

One -- with 6 volt -- 12 volt switch -- think I have another drill now... Used 6 volt setting

To charge but wanted to use a DIMMER switch to control output of charger -- set charger

To 12 volt and adjust output to 10 volt loaded output... Charger and drill were just waiting

For me to find a use for them -- test them