The other day I had to jumpstart my dad's 80's Chevy Camper Special. It's got a 350 with dual batteries. Sitting for 2 weeks in atleast -20 froze it. If we had access to a plug, it would have been plugged in, but it was sitting at the airport.

While jumping the battery off my truck, I noticed that my battery gauge dropped real low. Lights dimmed, idle dropped, ABS light flashed on. I hammered the throttle in the hopes that it wouldn't die. Once he stopped cranking his truck, everything went back to normal as the alternator was working just fine. After 5 cranks, he finally got his engine running.

Now.... Was my battery crapping out before or after the jump? I've just never seen a battery die like that while jumping. I could understand if it was a 9V trying to jump start a diesel.... but I have a bigger battery with more CCA than his. So, is my battery toast? Can I rely on it?

 

I would definitely have the battery tested.
Yours' was the bigger battery but he had two.
You were trying to start a system that needed >1000 amps with a 6/7 hundred amp battery.
Did you allow the batteries in his truck to charge for a while before cranking it?
My guess is NO.
You may want to have your alternator checked also as you definitely drew everything it could provide.

 

We did give it about 4 minutes in between each crank over.
The alternator still seems fine as I haven't had an issue yet.
The battery level shows 1/4 of a charge after starting but then climbs right back to normal.

 

Wouldnt hurt to have it checked. But I once jumped a diesel ambulance with my old 98 4.6
f150. The lights got really dim every time we tried to crank it over. Soon as i hooked the cables up the alternator full fielded and started whining. We got it started though and i had no issues with my truck.