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NiMH battery pack upgrade for cordless tools


NAXJA Forum User
Central Iowa
I have an Ingersol Rand 3/8" cordless impact. It has been the handiest tool I have ever bought, especially when going to the u pull it yards or when working away from power. I spent the extra cash for the IR since it was the most powerful 3/8" I could find at the time. The batteries that came with it were the last of the old school NiCad flavor and they are shot. They won't hold a charge for more than 2 hours and they never get full power any more, im sure there are a few dead cells in each pack. So I got on the mighty Ebay yesterday and ordered me up some purty new NiMH cells to rebuild my tired old battery packs. The originals were rated at 800 mah. The new NiMH are rated at 4600 mah and have a 46 amp current drain so we will have to see how much real world improvement I get out of them. I will keep you all posted!
neer run the 4600mah right flat dead, it'll ruin them, stop when it gets slow and recharge. And always drain and fully recharge NiHh are pickey
cool thanks for the tip....have you done this before?
So I soldered the packs up today and HOLY CRAP what a difference!! double if not triple the power that it ever had and I have yet to run one dead and I have been trying to! I definately suggest you use these if you need new batteries.
I would imagine you could do this to any cordless tool. If your battery packs contain sub-c cells then just order the NiMH replacements and solder them together just like the old packs are.
Should work for any tool, just make sure you reinstall the thermal fuses (unless you like exploding battery packs instead of packs that stop working when overheated.) I would worry more about the charger being able to handle the increased capacity, the tool will use the power it needs as long as you use the same number of cells in the new pack as the old.
Hmmm....my Rigid 14.4 NiMh batteries are toast. They don't hold a charge for more than a couple of days and drop off fast when in use. Replacement packs are spendy, I ever thought about just ordering replacement cells.......
I need to do this to my IR also. I've got one pack that works decent...and 3 that don't work for any longer than about 3 seconds.
just thought I would add a little to this post. These things are sweeeet. I have not charged this impact since I put the packs together and it is STILL going strong. I can't believe it. And before you wonder NO, i have nothing to do with anything or anyone in the battery business lol.
I dont have any pics but if you just google NiMH battery pack you should find several articles. Thats where I got the idea
This site appears to be a good source for replacement NiCad and NiMH battery cells and they also offer a service to swap out your cells if you don't have the skills to DIY. 14.4 Ridgid NiCad packs are about $75 each and both of mine are toast, so for approx $80, I can rebuild both of them with NiMH cells.


I wondered if my Ridgid NiCad charger would support the upgrade to NiMH cells, which is answered below.

NiCad (Nickel Cadmium)
NiCad batteries like to be fast charged and then removed from the charger. Please be sure to check the charge rate of your charger and make sure the battery can safely handle that charge rate. Our charge rates can be found with our rebuild services and also on the individual cells page. Many battery chargers DO NOT completely shut off after the one hour quick charge. This makes it necessary for you to remove your batteries after the batteries finish charging. If you leave the batteries on the charger too long too often premature failure will occur. It is important to keep a close eye on your batteries when charging, especially if you do not have a thermistor or thermostat in your battery to tell the charger to stop charging when it gets too hot. These sensors typically hook up to an external contact on your battery and it marked with S or T. Batteries should be recharged when you notice a drastic loss in power/performance. Over discharging a NiCad battery can cause fire and permenant battery damage.

NiMH (Nickel Metal Hydride
NiMH batteries also like a steady charge just like the NiCad batteries. The NiMH batteries we use can be safely used in a NiCad charger without problem. Many battery chargers DO NOT completely shut off after the one hour quick charge. This makes it necessary for you to remove your batteries after the batteries finish charging. If you leave the batteries on the charger too long too often premature failure will occur. Typical NiMH battery packs will have both a thermostat and a thermistor to accurately monitor and control charge rate but in most cases this still does not fully isolate the battery from the charger. The biggest difference from NiCad to NiMH is the capacity. A NiMH will typically hold a lot more mAh and therefore run longer on each charge.

LiIon (Lithium Ion)
Lightweight battery that CANNOT be charged on a NiCad or NiMH charger. Doing so WILL CAUSE FIRE and/or EXPLOSION. Lithium Ion batteries require a LiIon charger and a regulator board which keeps the cell voltage from dropping too low during use or going to high during charging. Without this regulator board the use of LiIon batteries is extremely dangerous. It is recommended to charge LiIon batteries in a fire proof area that can accept a fire should one occur.
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you should also keep an eye on what cells you are getting. Not all are the same. Mine are the 4600 milliamp/hour cells with a 46 amp high drain current. They were the second highest amp hour rating I could find. I went with the second highest though because they had a higher drain current than the 5000 mah ones. Just a tip......