Chum lee wrote:
I was totally amazed once when my li-ion portable battery booster actually jump started an older GM V8 diesel with totally dead wet cell batteries. (2-12 volt starting batteries from the factory)
Chum lee
There are varying degrees of "totally dead".
The small packs depend on the internal battery still being partly functional. They also depend on the stricken vehicle being fairly healthy so it will start right away.
I bet you wouldn't have fared so good if they had gone OPEN.....so that they couldn't help supply any current at all.
OR if it was -30 F and the engine was about 10 years beyond needing a tune up.
