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Originally Posted by JOE540CI
I use a lot of cordless tools on a dailey basis 18v and 24v. most sit out in the cold trailer overnite , I know for a fact that the batteries run at a less rpm when cold ,and they dont charge untill they warm up. (the charger just blinks in a no charge mode) To day i drove several errands and i seem to get better milage the longer i drove and noticed more help from the batts once everything was warmed up.Does anyone notice this with there hihy or other vehicles. Also do the batts weaken when the sit a few daysin cold weather ?...joe
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most batteries' efficiency goes down with colder temperatures [higher internal resistance, maybe .... slower chemical reactions...], so i don't think it should be very surprising. even flashlights are dimmer, and anyone who's tried to start a conventional car at minus degrees knows that not only is the oil thicker, but the batter itself doesn't have the "oomph" that it does when it warms up.
at college one year, a friend of mine couldn't get his car started. he ended up with somthing like four other cars "jumpered" onto his at once, and his still wouldn't start. i drove over, we hooked my battery to his, and i said, "ok, now get in my car and give me a dollar for gas." we sat, warm as toast in my car, charging and warming his battery, for nearly half an hour, until my ammeter showed that his battery was finally getting full. he jumped out, cranked his engine, and it fired right up. he paid me the dollar [back in the days of much cheaper gas, of course...
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ps. the electrical equivalent of a "dead battery" is a short circuit, as most EE's know. you can't start a car with a dead battery until it charges up, even a little. you're better off just taking some time to charge the dead battery first, and in the long run, it's nicer to the battery, too.