A recent disscussion about having batteries rebuilt sparked my attention and I copied and pasted an e-mail from WJ which May be of interest.
A question about whether or not rechargeable batteries could be revived or have their "memory" erased sparked a healthy discussion, and we asked you to add your experiences to the fray. Here are some of your responses. - Editor
"I've tried the freezer method of recharging several times. I've never had it work for me." - Brian Walker
"I have used the freezer method many times for my battery-powered drills, and it seems to work very well. Just remind everyone to make sure the battery is completely up to room temperature before recharging." - Earl
"I tried the method of placing a battery in the freezer for approximately 12 hours, and then allow it to defrost fully before re-charging, and it did accept a full charge. Thanks for the great ideas." - Kevin Elswick
Clearly, there seems to be some disagreement as to whether freezing works, but several folks wrote in to tell of some different methods.
- Editor
"In the Air Force, we would periodically pull the battery and discharge each cell individually to a totally discharged state, then recharge the battery as a whole. As a safety note, a NiCad cell can generate upwards of 50 amps for a very short period of time if shorted." - Rick Gibson
"Small shorts can appear inside a battery, causing recharge problems. I have hooked the negative terminal of a 9.6-volt battery to the negative terminal of a 12-volt car battery, and the positive terminal to one end of an old metal file. Take a lead from the positive of the
9.6-volt battery and 'stroke' it down the file. The teeth on the file cause the lead to make and break the connection to the car battery, which clears the short in the 9.6-volt battery. You can then place the battery back in the charger and fully charge it again. I have used the method numerous times with good success." - Harvey Leckie"I have revived NiCads by zapping them with an electrolytic capacitor charged to about 12 volts or so, and zapping a single cell a few times in both directions. It seems to give it extended life, depending on the cell." - Ajmal Rahman
"I don't bother reviving batteries. I rebuild them. The cells inside the packs may look like standard size AA or C cells, but the dimensions are slightly different. However, an electronic components shop near me sells these odd size NiCad and NiMh cells. A little care in disassembling the case, some soldering and duct tape, and you have a cheap new battery pack." - Anthony Kerstens
One of the more unusual responses directed us to a web site of a company that sells what it claims is a "Battery Resurrection Guide." Their web site describes it as "an online, password secured, step by step guide that will enable anyone who can use a few common tools to resurrect rechargeable Ni-Cad batteries to their full potential so they will hold a charge. You will need access to individual cells within the battery, therefore some disassembly will be required for most power tool batteries." Here's what one reader said about his experience with this company. - Editor
"My scam alert was on high, but I took a chance on the $12.95 and was promptly e-mailed a manual describing the process of resurrection. There are no special tools. Most required items can be found around any household. The resurrection did not work on my DeWalt batteries, but it has worked on several Craftsman batteries. As an extra benefit, my knowledge of rechargeable batteries is greatly improved. I ended up rebuilding the DeWalt batteries with higher quality battery cells and saved more than the $12.95 investment." - Gary Powers
One final note for owners of Ryobi tools: Ryobi has recently cut its battery price to $25 ($20 when bought in pairs) to make replacement more enticing. For more on that, and on Ryobi, check out the Tool Maker Insider section of this issue. - Editor