TimC300

Just tested using the EN setting and the SOH was showing less, tested it twice for fun. The state of charge was different by quite alot between the two testers. Im thinking its coming up with the state of charge based on the voltage, and the voltage is all over the place when you start unlocking the car, things turn on and off. I put the charger on the battery to get it fully charged and will throw the tester on again and see what I get.

Im a bit upset at the 76% state of health reading, since I bought the battery around 1yr ago, but from the date printed on the battery post it was made 2 yrs ago. Wish I noticed this when buying the battery, i would have requested a brand new fresh battery.

Also i had fully charged the battery Monday and didnt even drive the car, all i did was unlock the car and turn the headlights on for a few seconds each time. Now Wednesday morning the testers are telling me its at 50-60%. I researched how to find parasitic draw, I guess you can just use a multimeter and check each fuse to see voltage drop. i plan on doing that today, see what is running without the key in the ignition.

TimC300

I removed the Ancel monitor 2 days ago because i dont really think its showing the state of charge accurately and to see if that was effecting battery charge. I Used the Konnwei tester 2 days ago also. Heres what it showed after charging the battery and turning the headlights on for 10 seconds to drain surface charge, or so the instructions say.



yesterday I drove a few miles then parked the car until earlier today, so almost 2 days later. Went out to the car, unlocked and turned the headlights on for 10 seconds then off. then hooked up the Konnwei tester and got this:





I was happy to see the state of charge was still up there. Im sure if the Ancel monitor was on that thing would be reading around 60%. The reason i dont think the Ancel is accurate is because it doesnt know its an AGM or know the amp rating.

Im thinking the Ancel is good for seing voltage in real time, to see when and how the alternator is working. Thats about it, and maybe the starting test is a good feature also. Im not going to hook it up again unless I think im having battery or alternator issues.

The Konnwei seems to be good for giving a ball park rating for state of health and state of charge.

I think the best thing is just keep using my Noco Genius 4 charger, hook it up once a week to maintain the battery, hopefully it does work at keeping the battery from getting sulfated or whatever batteries do when they arent fully charged every so often.

TimC300

Its 9 months later and the cars running fine. I still get the red battery warning turning on as im pulling out of the driveway, but only seems to happen if i dont drive the car for two days or longer. If the warning pops up I pull over at the end of the street, stop and restart the car and it does not come back on.

Im thinking maybe it has to do with the brushes in the voltage regulator, maybe moisture or rust forms on them while the car is parked. Im totally speculating.

Im keeping my eye out for a new voltage regulator to pop up on sale in the mean time.

The Konnwei battery tester has come in handy twice now to test neighbors batteries, the tester said the batteries were bad (SOH) so they were replaced and no more issues.

pistonslap

just read thru this thread, good stuff. my w211 e55 has this same problem, its been driving me crazy for a month now lol

TimC300

It seems to only happen when I dont drive the car for a day or two. I didnt drive it yesterday and it rained all day, started it today to go somewhere and as im leaving my driveway the red battery warning popped on the dash. I pulled over at the end of the street, stopped then restarted the car and its fine. I dont think it has ever come on when I drive the car daily.

I scan the car for fun every once in awhile with my Foxwell scanner with Mercedes software and no codes.

If something happens ill update, but its nothing im worried about in the mean time.