I've a length of 2.5mm2 coax cable with croc clamps and have started numerous cars at the airport but allways run the engine for 10 minutes or so before attempting to crank the other engine, seems to work fine. Of course the 2.5mm2 limits the amount of donar amps, better for my car but still works well.
How long should a 12v Car Battey last?
- Thread starter Benny5
- Start date
Whilst alternators can deliver some large currents, that mostly goes to supply the car's accessories - lighting, fans, etc., rather than recharging the battery. The battery might take 20amps initially, but as the voltage of the battery rises, that will rapidly decline.
The only way to rapidly charge a battery, is to increase the charger voltage, which was what those old 'boost chargers' did. Increase the output voltage of an alternator, and you can expect your lights and accessories to burn out, instead, the voltage is carefully controlled, at a safe level, by the alternator, resulting in a slow recharge, over many hours (if the battery is near flat).
Yes, I've watched that a few times with VCDS, the charging current goes up to ~ 14/18A initially but literally for well less than a minute, even only 20/30 secs or less then gradually falls back to 2/4A, you'd require a tank full of petrol driving around IMO to recharge a flat battery, far better off buying a £20 smart charger in Lidl or the like.
Do you not think the car would have started on its own after doing that?
Mmmmm.
I don't know, but probably not, my battery + the other battery + the ~ 40/50A that the Alternator supplies with my engine revving to ~ 2500 RPM allways does.
I abandoned jump leads decades ago, bloody awkward things to store in a family car & I never had much success with them either.
Always carry a compact jump-starter in the car these days, employ a mains charger for 24hrs every couple of months (high percentage of short journeys by SWMBO) & monitor both battery & alternator output on occasions.
Considering the importance of a good battery in a modern car it's not a horrendously expensive item to renew & I never mess about with one that shows early signs of unreliability.
Always carry a compact jump-starter in the car these days, employ a mains charger for 24hrs every couple of months (high percentage of short journeys by SWMBO) & monitor both battery & alternator output on occasions.
Considering the importance of a good battery in a modern car it's not a horrendously expensive item to renew & I never mess about with one that shows early signs of unreliability.
