They can still lose maybe 5% to 10% of charge per month, so you’ll want to put a float charger on them for at least a day every 6 months if you don’t install them right away. But they should be okay for a month.
Had one explode last week. It was on a Battery Tender for several months in a 64 T-Bird. Apparently the electrolyte dried out. We disconnected the charger, turned the key and BOOM. Louder than a shotgun. I have pics if you want to see them.
I just purchased 2 agm group 31 batteries and will change out my old lead acid ones in about a month. Is it okay to leave the agm batteries sit in their boxes or do I need to keep them charged. Thank you, Karen
Another reason this can happen and it's not the chargers fault. One battery cell goes bad with a shorted cell causing it to show low voltage. The charger is just doing it's job. It sees low voltage and tries to bring it up, boiling all the batteries in the bank.
I wrote an article about that a while back which I can repost. Here’s the numbers:
A FULLY CHARGED LEAD-ACID BATTERY HAS A FREEZING POINT AROUND -80 °F. AT A 40% STATE OF CHARGE – THE ELECTROLYTE WILL FREEZE IF THE TEMPERATURE DROPS TO APPROXIMATELY -16 DEGREES F – WHILE A FULLY DISCHARGED BATTERY HAS A FREEZING POINT AROUND +20 °F.
They can still lose maybe 5% to 10% of charge per month, so you’ll want to put a float charger on them for at least a day every 6 months if you don’t install them right away. But they should be okay for a month.
Had one explode last week. It was on a Battery Tender for several months in a 64 T-Bird. Apparently the electrolyte dried out. We disconnected the charger, turned the key and BOOM. Louder than a shotgun. I have pics if you want to see them.
I just purchased 2 agm group 31 batteries and will change out my old lead acid ones in about a month. Is it okay to leave the agm batteries sit in their boxes or do I need to keep them charged. Thank you, Karen
Thanks for the article, Mike Good advice. Im looking for the Flow-Rite device now.
Another reason this can happen and it's not the chargers fault. One battery cell goes bad with a shorted cell causing it to show low voltage. The charger is just doing it's job. It sees low voltage and tries to bring it up, boiling all the batteries in the bank.
I totally agree, with a caveat:
Another cause of SLA battery ruptures and explosions: frozen batteries.
The freezing point varies significantly with the State of Charge.
I wrote an article about that a while back which I can repost. Here’s the numbers:
A FULLY CHARGED LEAD-ACID BATTERY HAS A FREEZING POINT AROUND -80 °F. AT A 40% STATE OF CHARGE – THE ELECTROLYTE WILL FREEZE IF THE TEMPERATURE DROPS TO APPROXIMATELY -16 DEGREES F – WHILE A FULLY DISCHARGED BATTERY HAS A FREEZING POINT AROUND +20 °F.