Swapped out battery for new battery--new battery only charges to 82%

[johnamyhulsey]

BACKGROUND: We are at home preparing for a 4 month trip and wanted to get a new battery. Our battery is over the 2 year mark and we were starting to see some degradation in its ability to hold a charge and power the jacks without shore power supplementing. I upgraded from a flooded lead battery to a no maintenance AGM battery. Specs were a little better on the new battery:

OLD: Flooded Lead, DieHard Silver 27M, 600 CCA, 750 marine marine cranking amps, 160 reserve capacity
NEW: AGM, Interstate Marine/RV Deep Cycle 27M, 675 CCA, 800 cranking amps, 160 reserve capacity, and 90 amp hours
Very similar batteries.

PROBLEM: The old battery, when fresh, registered 100% charge in the RV. The new battery wont charge more than 82%. I have checked the connections and they appear to be solid. My conclusion is that the Interstate battery may be having problems and that I need to take it out and get it tested. I wanted to make sure that I was not missing something on the RV to make the battery charge to 100%. RV is on 110 shore power and we have the basic solar panel configuration. We have not made any changes to the electrical system except for the new battery

Thoughts? Thank in advance!
John
2022 5th Wheel Reflection 320MKS

 

[traveldawg]

I expect our battery experts will be chiming in very soon.

How are you measuring your percent of charge? Maybe because the new battery is bigger than the old one your measuring device needs to be recalibrated?

Is it the voltage level that isn't reaching its peak or is it a SOC thing?

 

[johnamyhulsey]

You inspired me to to some additional research--I did not know what SOC meant. That lead to researching the battery monitor--a TR16. After a couple of youtube videos later, it is a recalibration issue. It is based on Ah and the full percentage. I have recalibrated it and it seems to be working well. Thank you for pointing me in the right direction! BTW, this recalibration is not in the Grand Design users manual.

 

[traveldawg]

You inspired me to to some additional research--I did not know what SOC meant. That lead to researching the battery monitor--a TR16. After a couple of youtube videos later, it is a recalibration issue. It is based on Ah and the full percentage. I have recalibrated it and it seems to be working well. Thank you for pointing me in the right direction! BTW, this recalibration is not in the Grand Design users manual.

Glad it worked out for you.

And.... welcome to the forum. Lots of nice folks here with plenty of experience to draw upon. Don't hesitate to post any questions or seek any info.

 

[Riverbug]

You inspired me to to some additional research--I did not know what SOC meant. That lead to researching the battery monitor--a TR16. After a couple of youtube videos later, it is a recalibration issue. It is based on Ah and the full percentage. I have recalibrated it and it seems to be working well. Thank you for pointing me in the right direction! BTW, this recalibration is not in the Grand Design users manual.

Good troubleshooting. You'll do just fine as an RV owner! Welcome and safe travels.