Micky 32

I have a battery monitor on my car. When the voltage dips to 8.5v or lower on initial crank the heated steering wheel comes on automatically during the crank. Anything above 8.5v it doesn’t. So definitely a battery/voltage issue in my case anyway. Varta AGM battery 4 years and 114k miles. A bit disappointing. My fathers 14 year old car still on original battery! Still starts even if left sitting for a week!

It could be a low cranking voltage glitch, possible weakening battery. I have a similiar issue where my heated steering wheel comes on and it’s due to my weakening battery.

Not necessarily but i’m sure for most part that is the case. My battery is now at 430-450 EN Amps 39%-44% SOH depending on temperature. The battery is rated at 680 EN. Sometimes i see “Replace” and other times i see “ Good Battery” I have a battery monitor and i get a lot of low cranking voltage warnings even if the engine is hot. First start of the day i see it drop to 8.5v, below 0 degrees i have seen it drop to 7.5 v. One cold morning about -1degrees i drove a quarter mile to a fuel station. When i started the car the starter sounded painfully slow and activated a start stop error message. I had another incident where the starter bogged down ( voltage dropped to 7.28v)after i was in a shop for 5 mins. The fans were running due to an interruption of the regen process. However the start stop system works very well. The caveat is if the outside temp is below 3 degrees i sometimes get an episode of “ power consumption is high” but the start stop system works flawlessly despite weak battery. One thing i have noticed ( maybe it’s normal) when the outside temp drops to 5 degrees and lower the energy recouperation stops working. The alternator charges the battery constantly until the temperature goes back up to 6/7 degrees. I gather that’s normal?

I would say you probably have a faulty battery. How old is it? My partners brother thar owns a 10 year old Passat and only does shortish runs and has just replaced the original start stop AGM battery. The smart charging isn’t as problematic as some people think.

My 4 year old start/stop AGM battery is down to 40-44% health already.

Interestingly my 2017 Passat 2.0 TDI 240bhp has done this since new. It’s very little though, it gradually drops from max to min. I’ve had to top it up a few times over it’s 115k miles. Never got worse. I have just done the timing belt and will see if the new pump stops it. i know someone who owns a car accessory shop and he said he sells quite a lot of coolant. He claims modern cars seem to be using coolant. Maybe engines running hot during a regen could be the issue especially drivers who have heavy right feet?

How old is your battery? Mine ( AGM)is 4 years and definitely showing signs of weakness especially below 3 degrees. I drove 6 miles and went into a shop. The fans were running because it was in the middle of a regen. I was in about 5 mins. The car started but the starter paused and everything dimmed for a second, it actually nearly didn’t start but it did. My battery monitor recorded a drop in voltage to 7.26v on that crank.

My AGM battery in my Passat is nearly 4 years old. It tests between 35/40% state of health after only 4 years. Start stop still works but when it’s cold you can hear the starter doesn’t have the same kick. I don’t think even AGM’s are immune from start/stop abuse. My fathers 14 year old Passat is still on original battery.

It Could be possible that it caused columbus freezes. If my voltage drops to 8.5v or lower when i crank my heated steering wheel glitches and turns on by itself.

Cranking voltage shouldn’t drop below 9.6v.

Did it fail to start in the end? The batteries mustn’t last long. My Passat approaching 4 years with the same battery must be failing. The starter doesn’t sound like it has the same kick and on my battery bluetooth monitor it often reports low cranking voltage ( lowest i have seen on a frosty morning was 8.06v but still started instantly) I put a battery tester on it today and it’s down to 430 amps ( 680 amps rated) and reads 40-45% state of health along with a “ replace” message. Funnily enough the start stop still works ok

My car is 3 years and 10 months old with 107k on it. Battery is a Varta AGM. I put one of those Topdon battery testers on it. It’s readings are SOH 41% , 440 A EN ( rated 680 A EN) and says “Replace”. I still started ok this morning at -1 degrees. The start stop still works. I have noticed the starter doesn’t have the same kick at times.

That’s what i’m thinking. I think my battery is wearing out but to be fair it’s done well when you consider 103k of stop starting and the energy recoup charging regime over them miles. That’s a lot of abuse even for an AGM. My battery monitor reports low cranking voltage every morning. I get a few warnings during the day also.

No don’t have a smart charger. The car gets lots of use though. 103k in 3.5 years. I was thinking of disconnecting the sensor on the battery for a few days so it might get a good charge but was concerned it might affect the charging cycle afterwards by disrupting the battery data, thinking the car might think it has a new battery fitted etc.

Yep. Set to AGM. State of charge hovers on average between 12.5/12.6 when rested as expected . My state of health at 50/60% in comparison to a new battery that reads 100% is quite a difference.

My 2017 Passat 240 was fitted with a 680 A EN Varta AGM. Car has done 103k miles. I bought one of them Topdon battery testers. I also have a bluetooth battery monitor. I can log cranking voltage on my phone with it. I have noticed the starter doesn’t have the same kick in the mornings. According to my bluetooth monitor i get “ low cranking voltage”. Lowest i have seen is 8.39v. Usually hovers around 9- 9.2 v cranking. I believe it shouldn’t be lower than 9.6v? Interestingly when cranking voltage drops below 9v my heated steering wheel mysteriously turns itself on after the crank. My start/stop works flawlessly. Now for the Topdon battery test. My battery reads circa 515A with a SOH reading of 55-60 % but says “Good Battery” For comparison i tested my friends year old Passat. His battery is a Varta EFB+ rated at 700A EN. My tester reads 840 ish A 100% SOH.