Two Charging Indicators - an indicator lights during charging for each battery type (Ni-Cd or Ni-MH), and turns off when charging is complete. I yelled out, "Explosion!!!" and we hit the deck.Your RadioShack Compact Ni-Cd (nickel cadmium)/Ni-MH (nickel metal hydride) Battery Charger is designed to charge two or four batteries - AA and AAA types. Immediately he took it out of the charger, and indeed the battery rapidly continued its upward heated climb until it started burning his hand.
He wondered why, and I explained that if it continued to rise in temperature (outside of the charger), it could explode. One day, my partner was loading a battery into the charger and he commented that it seemed unusually hot. Sometimes I could tell if a particular battery was going to fail, just by looking at it or touching it. I had spent years studying the battery and charger characteristics. The batteries had to be up to specs or equipment performance could fault. When I worked in the Laboratory, we frequently charged batteries for scientific equipment. "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney I honestly can't believe they let me bring it to school!
Great for the Scribbler, but I am going to upgrade the Stingray to an RC 7.2 volt system (which I have - but really want to upgrade to a higher mAh rating). I charge them all - that gives me two runs on the Scribbler or Stingray. I only have 12 cells (batteries) right now. I do not know if the mAh rating would have anything to do with charge time or recharging life.
The highest mAh, I found locally is 2500. Maybe I shoud be keeping a log though, just to see.
90% plus of the time there will be no problems, but "the consequences of failure can be extreme". When all is said and done, high performance charging should only be done in an "attended" situation. The faster the charge, the greater the risk. NiCad => NiMH => LiPO in order of increasing risk). The higher the energy density, the more risk (i.e. Any of the "quick chargers" can be a risk, not so much because of the charger, but all it takes is one bad battery to make a mess. In terms of "what won't leave my homeless" - about the only option would be a "trickle charger" (if that). When multiple cells are used in an application (series and/or parallel), these slight differences can be significant to performance, safety and battery life. The mixing also applies to old and new cells. It is also generally not a good idea to mix brands/types on the "usage end" either. The charger still should have shut down, but if one cell has a lower resistance than the other, it will get more current, especially when they are charging as a pair in series, as appears to be the case with this charger. This can contribute to the problems Phil saw. Different brands of batteries may have a slightly different construction and/or chemistry, and as a result, a different internal resistance and charging rate. It appears that there were at least two different types in the picture Phil posted. Maybe I should build a concrete "charging bunker" some distance from the house, though.Īnother comment on charging (and using) multiple cells: It is not a good idea to mix types/brands of cells on a charger like this. Plus, I don't have to buy a new washer and dryer - yet. If I had not been home, this thing could have burnt down my house! As it is, I'm just thankful all I lost was the charger and some batteries. I've heard of Li ion chargers and/or batteries doing this, but never NiMH. So I grabbed an oven mitt and carried it out to the picnic table in the yard, where it spent the night. I quickly yanked the plug and tried picking it up to throw it out the back door, but it was much too hot to handle. About an hour later, I heard a sizzle and pop and saw smoke coming from the NiMH battery charger on the kitchen counter.
I had just done a load of clothes in my ancient washer and figured its time had come, so I turned on a vent fan to air out the house, and the odor dissipated. Last evening, when I came into the house from the shop, I detected what smelled like burnt plastic.