24volt jump start

[yogi]

Said I would post this on here because it may get someone out of a spot someday, particularly with an auto.

Imagine the scenario, your 24volt started LC has 2 flat batteries and you have (as is usually the case) only ONE set jump leads and ONE other 12v vehicle as in some kindly passerby's car.

Disconnect the drivers side battery and connect it with the jump leads to the other running car as usual. Wait about 5 to 10 mins. A few revs on the car always helps.

Next take off the leads and do the same to the other battery.

Now reconnect the batteries, and put the jump leads across the passenger side battery ONLY (obviously still connected to the other car,but if you didn't guess that bit, probably better ring the AA )

Now start your LC.

This will often work, its not guaranteed, but I have used it on many occasions to start 24volt 7.5T/10T lorries and it has rarely failed me unless they have been lying up so long that the batteries are just totally dead.

My only warning would be to not do it with very modern type cars in case there is a slight surge back into the car (I'm not sure if this actually would/could happen but I don't want to get a PM looking for a new computer for a 2014 BMW!!)

 

[moggy1968]

I can kind of see how that works, as presumably the 2 batteries try to balance their charge

 

[yogi]

I can kind of see how that works, as presumably the 2 batteries try to balance their charge

Yeah thats what I always assumed was happening today.

I actually used it to move a DAF45 lately that hadn't been started in over a year, and it worked on the second attempt.

The old MAN lorry I had used to drain charge to the point where the dash lights barely came on in about 5 hours if you forgot to use the kill switch and it used to start fine when you did this.

I came up with the idea in desperation one morning having got up at 4.30 in the morning, got 4 horses ready to show and loaded by 6.30 only to find no juice. And it was on a Bank Holiday Monday so after a night on the beer so I was too cross to just give up!