my 800 cca batt. installed 9/21, I started figuring out & charging with Romondes RD 510 15 mo.s later on 12/22. my IBR was 3.54. I de-sulfated on 4/23 when IBR was 3.6. I started keeping monthly charging records on 6/23. my IBR was 3.45, 7/23 was 3.41, 8/23 was 4.3, 9/23 was 3.85, 10/23 was 4.05, 11/23 was 4.15, 12/23 was 4.22. considering all the hapless monkeying around I've done, I wonder what the range would be for IBR de-sulfating ? What have I done to my 2 year 3 month old battery ? any ideas ? Thanks

 

Between December 2022 and December 2023, your IBR has risen from 3.54 to 4.22 -- an increase of 0.68 meghoms, and has taken a roughly linear path across that increase (I charted it).

At this rate of increase, presuming it stays linear (it may not, but that's part of the mystery), your 2.25 year old battery will have an IBR of 6.26 or thereabouts in another 3 years, when it is 5.25 years old.

When I replaced my weirding-out battery, it had an IBR of 9.42 megohms. And it had been heavily stressed out by a 24/7/365 parasitic draw for nearly 15 months. And while auto stop/start wouldn't work any more, the car never failed to start normally using the start switch. I wouldn't even have known the battery was worn down had I not been chasing electrical issues caused not by the battery, but by the parasitic draw depriving systems of power in real time (even with the engine/alternator running).

Because there is still a bit of mystery here, I won't claim the increase in IBR will follow this linear path. But if it does what it is doing now, I don't think you're "killing the battery."

Three things I have kept in my head as I care for mine (installed 11/2022):
- Most AGM charging solutions try to bring the battery up to an 80% charge, rather than keeping it up at tippety top. This is, IIRC, part of a strategy of extending battery life by avoiding overcharging/pushing the battery to the limit.
- AGM-smart chargers are the way to go. The Romondes is one of these, obviously.
- Trickle charging with as low amperage as possible is better over the long term, if one is going to manually charge up.

I ultimately decided to start using an AGM-smart, 0.8A (aka 800mA) trickle charger on mine, and I am using it maybe once a month. Just kind of depends on how much I'm working the battery in terms of starting cycles, how much driving in general, blah blah.

One Q - your data shows a bump going from 7/23 to 8/23. Anything interesting going on that month, drivingwise, chargingwise, whateverwise?

Still lots of mystery but maybe this will give you a little confidence. Very curious to hear what others have to say about desulfation timing and frequency recommends.

 

when I did de-sulfate it seemed like the thing to do at the time, being 1.5 yr.s old & neglected up to that point. I wanted to start from scratch. I can't recall any changes, July-Aug. other than using A.C., a little more ? my driving habits were the same. I did short-charge one month, that may have been then. I'm not elec. minded individual & rely on people that are knowledgeable like yourself. I feel somewhat relieved after reading this reply. Believe Me when I say I do feel a little more confident & Thank You Big Time. you've enlightened & relaxed me, hearing about others on this road is a good thing.

 

Glad to help -- I'm still learning myself to be sure, but I have definitely picked up a lot within the last couple of years.

For your own reference, here's a graph of your IBR values. The gaps are just months where your original post didn't provide any data; regardless, the trend is pretty straightforward to see. Slow creep, emphasis on slow, which is exactly what you are going to get with even a well-cared-for battery.

 

Thanks Man, I likey. it looks like I'm on the right road, most reassuring