sometime the connection between cells break, battery goes from good to total dead. Then the connection arc welds and if good for a bit.
When I work on car as you did I connect battery charger. You get one or 2 deep cycles. Then it is toast. Recharging a discharged battery stresses the alternator. It is often unavoidable but if you can recharge with a charger your alternator lasts longer. Idle with hood shut is worst for the alternator. You can let it
idle to charge, just leave the hood open. Most newer cars have huge alternators and one hour is mostly charged.
My record is 12 years out of a trunk mounted battery.
When I work on car as you did I connect battery charger. You get one or 2 deep cycles. Then it is toast. Recharging a discharged battery stresses the alternator. It is often unavoidable but if you can recharge with a charger your alternator lasts longer. Idle with hood shut is worst for the alternator. You can let it
idle to charge, just leave the hood open. Most newer cars have huge alternators and one hour is mostly charged.
My record is 12 years out of a trunk mounted battery.
