Another Battery Question

[Norm Green]

I have been having difficulty starting the engine in my '06 Thunder, even with the boost switch.  After investigating with my muti-meter on the chassis batteries, Interstate 31ESL, I find that one appears good, holding a good charge while the second is only about 4.8 volts.  I have only had the coach 6 months and I don't know if these are the original batteries, although I suspect they are.  The CCA on these batteries is 700 amps.  I have shopped for batteries here in the Nashville area and have found some at NAPA (Deka brand) with 950 CCA for $115.00 each.  Similar Interstate batteries are $140.00 each.  Costco and Sams Club do not carry any group 31 batteries.

I have two questions.  First, anyone have any experience with the NAPA batteries?  They have the same 18 month replacement, pro-rated afterward for 36 months, just like Interstate.  My second question, is there anything wrong with replacing only one of the batteries at this time, even if the new battery has a higher CCA than the existing good battery and is a different brand?

As usual, thanks for the help and I hope all are having a great holiday season.

[Edward Buker]

Norm,

Napa batteries are typically good batteries. My last group 31 came from an International Truck Service Shop that brings them in by the pallet and offfered better pricing and cca rating than the ones stocked at my local Napa. Have the one that you think is good load tested when you go to purchase a new one. If it passes then just replace the one. My experience has been that I would get some early battery failures, which I think is caused by vibration, and some batteries just by chance seem to last better than another before it fails even if it was bought as a pair. The worst case is that you have to replace the other along the way. If the load test is weak then do the two.

Later Ed

[Tom and Pam Brown]

I have NAPA batteries in my coach.  I bought them 3.5 years ago with no issues.

[Keith Oliver]

I wouldn't overspend for chassis batteries.  Chances are that those will suffer a total discharge at some point long before their normal lifetime should be over and you will be replacing them early.  This will affect expensive batteries every bit as much as cheap ones.

I have NAPA batteries, that I bought in March 2011.  I expect to be replacing them within the month, as my rooftop solar panel (the 14"square one) is not capable of keeping up with the draw put on them by the ECM and whatever else is always on.  Although, knowing this, I had installed a small charger just for those batteries, ie not connected to the house batteries, they still died in under a month.  They are now on a new charger, while we are home for Christmas, and I will see if they have come back to life after being deeply discharged.  I won't be surprised if they don't, so I expect to be back at the NAPA store and to find out how good they are about their pro-rated warranty.  Although I am still going to take precautions to preserve my batteries for a normal lifetime, this experience convinces me not to overspend for the replacement batteries.

I will also try to find out how much power I am getting from the solar panel.  Located in El Centro Calif at the moment, I know that I am getting more hours of sunshine while there than I can expect to get at any other location in the US or Canada, so elsewhere, that solar panel will be unable to provide anywhere close to the same total power, so having a separate charger on teh Chassis batteries will be even more important.