When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
For charging a battery while in the car, my Die-hard" charger suggests a 24"(min) length of negative cable to hook up the charger. Clamp the 24" piece to the block, then the charger's negative cable to that piece. Never hook up the charger's neg. cable directly to the battery post. So, I suppose I have to make my own 24" piece from Home Depot or such. What say you?
Just connect the negative clamp from the charger to a grounded piece of metal under the hood.
Chargers recommend not hooking both cables to the battery because of the remote chance that a spark that forms when the last connection is made will cause Hydrogen gas from the battery to ignite and explode the battery.
You;ll see this same recomendation in most instructions for jump starting a car too.