Marine Battery, Group Size 31, 800 Cca - D31M

Used for motorhome

Purchased the group 31 battery and a new battery analyzer. The battery came promptly and packaged well. The battery is supposed to be AGM but I can shake it and hear/feel liquid a lot of inside. I thought AGM shouldn’t do that but I could be wrong. It is sealed so it’s possible to mount in different ways. I tested with new battery analyzer. I selected AGM battery type and readings were 12.5v and MCA read way below the 1150 stated and it concluded it was a bad battery. I did test again but switched type to liquid acid. Test came back 12.5v MCA was better but still way lower than stated and the battery passed but the state of health and charge were low percentages. I charged the batteries on 6amp charger with auto conditioning for 1 week. I tested battery analyzer on new batteries at battery plus and the analyzer works perfectly. I fully charged the battery got volts to read 13.2 then disconnected for 30 hrs. Tested the battery again it held a charge at 12.8v. My big concern is the highest battery MCA rating I got was 972 out of 1150 and the state of health was 92%. This leads me to be believe the battery sat for a long period without a proper charge being maintained. I’m sure the battery will work properly but if the readings are correct I’ve already lost 8% of full capacity which means I’m not getting a new battery. Since you shouldn’t drain your battery past 50%, 8 % is a lot to not have out of the box. It’s not AGM or giving full MCA as advertised.

Works great