Its not bad. I had that one before.
A delco one waa given to me, so i gave the other on to my son.
Only thing i didnt like was no stop when you back off the load.
No idea if you have stopped pulling amps.
Average cca rating on bateries is rated at 0 degrees f.
Load test 50% of battery rating.
800 amp should load test 400 and hold 3-5 seconds. Imho.