Charging and testing the Auxiliary Battery

[Higher_Ground]

Ok, I have read through what seems like a dozen threads on ESS issues and battery replacement.

I had the "Service ESS" warning and when I checked JSCAN, I had code B2199-16 (battery voltage - circuit voltage below threshold / stored - Body Controller) and P00FD (battery ""b"" state of charge performance / active - Powertrain Control)

I bought a Noco Genius 10 and have charged it overnight (~12hrs) twice. To charge, I have been using the following procedure: 1) open hood, 2) place positive clamp of charger on positive post of main battery, 3) place negative clamp on fender ground bolt/nut, 4) plug in charger and set to 12V AGM.

It takes 1-2 min to go from red to green. Once at the green, it pulses and when I took it off in the morning it was still pulsing green. If I understand correctly, that means "bulk charging" was finished in 2 min but after 12 hrs it was still "conditioning" and not quite 100%?

I think my next step is to isolate, charge and test the batteries independently. It has been ~20 yrs since my last circuits class... I could use a quick refresher.

How do I charge and test the aux battery? Where would I put the clamps to charge (main pos and aux neg cable?) and where would I place the leads on the DMM to check the aux?

I have read that it is important to be careful with the loose neg cables - that I should place plastic bottles over them or similar. Do I need to take any precautions with the positive cables?

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[Jeepin in Ohio]

Haven't heard any issue with the negative cable touch ground. Seems most issues are letting the positive touch ground when changing or removing the aux battery: blow a fuse in the high amp array, on the side of the battery. You can disconnect the aux negative cable to just charge it, and test. Tester goes on positive and the aux negative.

 

[Lost1wing]

The way that you described charging charged both batteries. To independently charge both batteries, you will need to place the positive charge cable on the main positive terminal. Take both cables off of the main negative. One will be the aux negative and the other will be the fender ground. Place your negative charger cable on the aux negative. You will know if it is the aux neg if the charger starts charging.

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