I’ve never been able to get a straight and complete answer to this. In generic terms, if I’m using one unit to jump start another unit with heavy duty jump leads, where should the leads be attached? Both vehicles have a pair of 12v batteries in series to form a 24v circuit. I know on the dead vehicle the red lead should be attached to the positive terminal and the black lead should be attached to the chassis. I’m confused about where the leads should be attached across the two batteries on the donor vehicle. Thanks
electrically speaking if the batteries in the donor vehicle are in series then the positive should go to one battery and the negative to the other so you are across both batteries
Both are 24v vehicles, each with two 12v batteries in series.
Both with negative - earth.
Connect the earth on each vehicle to the other.
Connect the (red) 24v + positive on each vehicle, one to the other.
(The terminals where the batteries are linked are not touched at all)
BEWARE! That will be easy on older vehicles, but newer vehicles have computers and other kit tht can easilty be damaged. Read the manual for any particular vehicle before doing this.