Weird Battery Question

I didn't know where to post this, but I though this forum might know the answer.

As an after Christmas necessity, I had my car taken in for basic maintenance. Through the dealer's multi-point "inspection," they said that my four-month old DieHard AGM battery failed. They even included the test results. While I noticed that the car struggled to start due the severely cold temperatures, I never thought that it would fail. Hell, I have dash cam footage of the techs charging the battery.

I took it to Advance Auto Parts (where I bought the battery) and it tested fine. Now for the stupid question: is it possible for the battery to "hibernate?" The car sat for several days when the temperatures where on the wrong side of zero degrees Fahrenheit (which is never normal where I live) If only 51R wasn't such an undersized battery...



Yes I should do my own maintenance, but I do not have the wherewithal to do so.

 

Battery health is a fickle thing. AGM's can be more sensitive to charge and depending on the test, may show failure unless completely charged.

I would say it was discharged and the recharge the shop did helped regain the battery health.

Maybe if it shows signs of weak or slow starts have autovalue test it one more time.

New doesnt matter, batteries can fail in weeks. Sometimes they also sit on the shelf for months.

 

Did the vehicle come with an AGM? If not, it may not be charging the battery at the correct voltage. Most AGM's require 14.5ish volts. If your vehicle did not come with an AGM from the factory, it probably is only charging at 13.8ish volts. This lack of proper voltage will kill AGM's quicker than normal (but would think that 4 months is faster than expected).

Also, you said the dash cam was on when being serviced? Do you normally leave it on? If so, it could be a parasitic drain. Regular AGM's don't perform the best with multiple discharge/recharge cycles unless done so within certain limits. Most manufacturers only warranty a certain number of cycles below a certain percentage of life (i.e. 200 cycles below 80% life, 80 cycles below 50% etc)

 

Drive it as you normally would for a few days and then get it retested.

Could just be that the dealership tested the battery when it was in a low charge state for whatever reason and therefore failed which would be true even for a newer good condition battery. When people ask me to test batteries I will first charge them up then test, and also do a quick test of their alternator as more than once have I found a good battery discharged by a bad alternator

 

I failed to mention a few points on my original post. The car didn't come with an AGM originally. It may be only charging at 13.8 volts. Though spoofing the ECU is out of the equation. I went with AGM due to the fact that I have a relay harness for my retrofitted headlights. And the stock Honda battery is hit or miss. Besides a few other 51R batteries, there is an option to upsize to an H5. Though that means using parts for a Civic Type R.

And I should have said that the dashcam is plugged into the OBDII port and senses when the car is on. Now thinking about it, charging the battery did trigger the dashcam and cause some on-off cycles, switching to parking mode when it thinks the car is off. That may have played a factor to the "failure."

I have looked at the NorthStar battery thread for ideas. But out of the top three, only Optima makes a 51R. And I've heard they're not worth it. Unless I'm wrong. Though I will admit I am a bit dense.

Edit: If it makes a difference, my car does have driving assistance features. That was another factor in play in my choice going the AGM route.

 

I just went and read the specs/warranty on the Die Hard 51r-agm and saw no mention of charging voltages or warranty cycles, so disregard what I stated above.