Recommendations for a Bad Auxiliary Battery

[tonyramz]

I am getting some variations on my battery monitor from 12.3 V when the truck is not on, to 14.5 V when the truck is being driven. I decided to check each battery individually by disconnecting them to check their charge and found that the auxiliary battery is bad. Any recommendations for a replacemen? Does it need to be an AGM battery?

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[Kodiak]

You will find some good threads on this subject. Here is one. I went with the AGM replacement in post 20 in this thread but other are using an LFP technology for a replacement. I stuck with the AGM larger O'Rielly one. Good luck.

(4) Auxiliary Battery Problem? | Page 2 | F150gen14 -- 2021+ Ford F-150, Tremor, Raptor Forum (14th Gen) | News, Owners, Community, Discussions

 

[Jmitchelltfo]

Cliff notes from most of the auxiliary battery threads.......

LFP provides more energy than a similarly sized AGM

Need to keep an eye on LFP when used in very cold climates, if your vehicle is stored outdoors. (This was not a problem for my LFP through several weeks with temps around -7°F )

-Parallel LFP setup is very easy with minimal modification needed to your battery cover. (X2 was $200 but has a 10-year free replacement at Batteries Plus)

-LFP replacement in OEM location will possibly require some modification to your battery box.

-Oreilly's or other AGM 12-14 AH replacement requires a little bit of Dremel work to fit. (Typically, a 90-day warranty on powersports batteries like these)

-OEM replacement.......you already know that isn't the best option since you're here looking.

 

[tsigwing]

Make sure that you disconnect the main battery when doing any work on the aux battery...

 

[tonyramz]

Thank you for your replies and recommendations. I will certainly be getting a new battery today, probably the O’Reilly one since it is less than half a mile from my house.
For the record, I did disconnect both batteries and tested them as standalone. I noticed that when I tested the main battery it kept giving me a good battery but the numbers on the monitor did not lie.

 

[Jmitchelltfo]

Thank you for your replies and recommendations. I will certainly be getting a new battery today, probably the O’Reilly one since it is less than half a mile from my house.
For the record, I did disconnect both batteries and tested them as standalone. I noticed that when I tested the main battery it kept giving me a good battery but the numbers on the monitor did not lie.

No matter what battery you choose, I would recommend a bluetooth monitor. It will help keep track of resting voltage and has some other nice features too.

This is the one that I bought after several recommendations in other threads.

https://www.amazon.com/ANCEL-BM300-...2906950&sprefix=bluetooth+batt,aps,308&sr=8-8

 

[HammaMan]

I am getting some variations on my battery monitor from 12.3 V when the truck is not on, to 14.5 V when the truck is being driven. I decided to check each battery individually by disconnecting them to check their charge and found that the auxiliary battery is bad. Any recommendations for a replacemen? Does it need to be an AGM battery?

That's the specs of the batt -- it's not a fail for that batt. That's not a starting batt and it's fused for 125a.

 

[UGADawg96]

That's the specs of the batt -- it's not a fail for that batt. That's not a starting batt and it's fused for 125a.

Is that test tool not accurately reporting SOH of the little batt ?

 

[HammaMan]

Is that test tool not accurately reporting SOH of the little batt ?

No, the CCA is like 90 -- that's still connected to the 12v bus.

 

[JEB]

I am getting some variations on my battery monitor from 12.3 V when the truck is not on, to 14.5 V when the truck is being driven. I decided to check each battery individually by disconnecting them to check their charge and found that the auxiliary battery is bad. Any recommendations for a replacemen? Does it need to be an AGM battery?

I have the same battery tester. Did you reset the specs for the smaller battery before running the test?

 

[tonyramz]

This is why I love this community. I went back and rechecked the settings and I had it set to 500 CCA on the test above. I changed it to 150, since I could not find the proper CCA on the battery and the first test indicated 127 CCA, and the results this time were 64% State of Health and it said Good - Passed. Thank you. I will continue to monitor it on the weekend to see how it is after several days of not putting the charger on the truck.

 

[JEB]

This is why I love this community. I went back and rechecked the settings and I had it set to 500 CCA on the test above. I changed it to 150, since I could not find the proper CCA on the battery and the first test indicated 127 CCA, and the results this time were 64% State of Health and it said Good - Passed. Thank you. I will continue to monitor it on the weekend to see how it is after several days of not putting the charger on the truck.

The correct setting for the aux battery is 90 CCA. Your results will improve at that setting.

 

[EcoBeastCA]

No matter what battery you choose, I would recommend a bluetooth monitor. It will help keep track of resting voltage and has some other nice features too.

This is the one that I bought after several recommendations in other threads.

https://www.amazon.com/ANCEL-BM300-Bluetooth-Automotive-Motorcycles/dp/B07WCW49YM/ref=sr_1_8?crid=1NKVBK3LZZN13&dib=eyJ2IjoiMSJ9.fjaXtlT2R6v9G3oa0HLCw87K_n5cjP2wygDDSrxRz6XP_R174G9Sn91U-6RCE0g6fPteQqHkpb52Hb5ZiZghoXNCn-3SwnAuv5jUCSKbDW_rgVf_WAa5xXLceLIGq0U-AFua1gocydrpBSxVGpJvmnrc4RrcoTAt_oYQ8g5UithjZYsqeoMhwOnfyvKtgwacE5zbYCXEUPmxCqAQxiW6wofO-NEaGi_fvUkM3mRKpWhcmaIvaMD6eGolmwNFu6CqNxcSlS38xxwOeV-ZavMQ99J2lGdm5kejB6hDkpeD8OQ19bY_Xazvnxo7hSOZIBhe6NfyfZZs5IKnx2OFzXsepCpPNINsN3n_EU9YQi6EPWbW6zLs_xdtWqapkST3HpLJTXkJqKcsF7vPkNXalPDUbna6dB64HLPYoWRivdLDAGAjaOi-HespWC3dQ-x_Bp72.z1J-_AsymY--Aqvk7yvX8qogYr8lXweNeLAoamBARvQ&dib_tag=se&keywords=bluetooth+battery+monitor+12v&qid=1742906950&sprefix=bluetooth+batt,aps,308&sr=8-8

That seems like a great option if you want the red Chinese knowing everything about you given all the reports of irrelevant data harvesting the app does. Caveat emptor.

 

[kantonburg]

That seems like a great option if you want the red Chinese knowing everything about you given all the reports of irrelevant data harvesting the app does. Caveat emptor.

Do you have a recommendation?

 

[EcoBeastCA]

Do you have a recommendation?

Sorry no. I was interested in that one at first until I read some reviews and discovered it's virtually a Chinese spy bot.

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