triumphant59 Posted October 14, 2015 Report Share Posted October 14, 2015 Bought a cheap battery off eBay for my sons car 6 months ago. Last weekend, son having gone back to uni a month ago I thought I'd give his car a run. Battery dead flat, wouldn't take a charge so contacted supplier asking for replacement. He emailed back saying put jump leads to battery from a charged battery, connect charger, leave jump leads connected for an hour then remove leaving charger to do its job. I did as he suggested and low and behold it worked, battery is now fully charged! Issue is the battery I replaced wouldn't take a charge either, my guess is if I'd known this technique probably wouldn't have had to buy a new battery in the 1st place! Did everyone know this? Quote Link to comment Share on other sites More sharing options...
ditchman Posted October 14, 2015 Report Share Posted October 14, 2015 totally and uterly bumfloxed on that one............ Quote Link to comment Share on other sites More sharing options...
Stonepark Posted October 14, 2015 Report Share Posted October 14, 2015 Yes, plates become coated and ineffective, running another battery through it uncoats plate then battery can then start functioning properly and as long as not too bad will come back up to full operational status.. Quote Link to comment Share on other sites More sharing options...
barney 66 Posted October 14, 2015 Report Share Posted October 14, 2015 Possibly an intelligent charger and they won't start charging without some voltage to start with so most of the time just a few seconds with another battery is enough to start the charger going Quote Link to comment Share on other sites More sharing options...
rodp Posted October 14, 2015 Report Share Posted October 14, 2015 Most relatively modern diy chargers have this built in, It's so you can't short out the leads. They need some power in the battery to tell them to start charging Quote Link to comment Share on other sites More sharing options...
subsonicnat Posted October 14, 2015 Report Share Posted October 14, 2015 Yes, plates become coated and ineffective, running another battery through it uncoats plate then battery can then start functioning properly and as long as not too bad will come back up to full operational status.. Thats why when you have a Duff drill battery you give it a high voltage charge for a split second to desulphate the plates: High Voltage,, as with a Welder current: Quote Link to comment Share on other sites More sharing options...
triumphant59 Posted October 14, 2015 Author Report Share Posted October 14, 2015 Most relatively modern diy chargers have this built in, It's so you can't short out the leads. They need some power in the battery to tell them to start charging That makes sense, ive got a new charger and leads don't short if they touch. Quote Link to comment Share on other sites More sharing options...
Twistedsanity Posted October 15, 2015 Report Share Posted October 15, 2015 If it was only six months old I would ask why they didn't replace it Quote Link to comment Share on other sites More sharing options...
kennett Posted October 17, 2015 Report Share Posted October 17, 2015 Because it had been left on a car for a month without being used. Most car batteries I know would go flat over that time, especially if it had been started and shunted around the drive a few times without ever getting recharged Quote Link to comment Share on other sites More sharing options...
gazbev Posted October 21, 2015 Report Share Posted October 21, 2015 Should be able to leave a battery for over a month as long as nothing is draining it. The only thing I can think of is leaving the jump leads on for an hour will take the initial high current charging a dead battery needs and makes it easier on the charger Quote Link to comment Share on other sites More sharing options...
triumphant59 Posted October 21, 2015 Author Report Share Posted October 21, 2015 Should be able to leave a battery for over a month as long as nothing is draining it. The only thing I can think of is leaving the jump leads on for an hour will take the initial high current charging a dead battery needs and makes it easier on the charger Must be the case, certainly worked! Quote Link to comment Share on other sites More sharing options...
Chris Bb Posted October 22, 2015 Report Share Posted October 22, 2015 The only thing I can think of is leaving the jump leads on for an hour will take the initial high current charging a dead battery needs and makes it easier on the charger Just beware that you don't over discharge the donor battery. This happened to me once, I had an "iffy " battery, son-in-law had a dead (left standing too long) battery. We connected the two until his battery was able to start his engine. By this time, mine was so discharged that it could not start mine! At least mine was at home and connected to a charger and his drive home restored his battery to normal condition. Quote Link to comment Share on other sites More sharing options...
craftycarper Posted October 23, 2015 Report Share Posted October 23, 2015 totally and uterly bumfloxed on that one............ +1 Quote Link to comment Share on other sites More sharing options...
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