Red battery light - new battery

[starrzo]

Hi guys, on my w204 C220 2009 (OM646.811) I replaced the big battery in the boot last month.

Starting to intermittently get a red battery symbol with no wording when driving. Some electrical things shut down when this happens, radio, AC, etc.

Voltage at the new battery is good. I started the car and the voltage went to 14.8 (although this is before driving and getting the red battery symbol).

Is this likely to be the alternator?

Is there a small auxiliary battery in my car somewhere, if so maybe that could be it?

Thanks in advance!

 

[DREAMER NO2]

When items cut off like this on your car, thats because the voltage is too low and the computer switches items off to keep all information in the computer .

 

[Chrishazle]

My C220 is 2008, there's a little trick allowing you to monitor battery and alternator voltage. Ignition key in position 1, press and hold (all 3 at once) steering wheel buttons "answer call", "End call" and OK, after a few seconds I get a menu choice, with the first one highlighted. Press OK, display now shows battery voltage etc. You can start the engine and see how much oomph the starter motor takes and the alternator voltage, the display stays active while driving until you either press "Back" on the steering wheel or turn the engine off.

Also - on my car there's only 1 battery, the big one in the boot.

 

[starrzo]

Plot twist:

Wife phoned to say the car won't start in a car park about a mile away. I grabbed the old battery (thankfully hadn't dumped it yet) and went over with a few spanners. Multimeter on the new battery in the car was showing 12.6v, yet when I turned the key it would sound like it was about to attempt to start then just quit.

I removed the new battery and put the old one in. On removal I noticed a liquid underneath (see attached).

The old battery is fairly knackered but had 12.3v in it. Stuck it in and car started fine and drove home with no problems.

Is this new battery faulty then?

Old battery: 12v 95Ah 850AEN
New battery: 12v 100Ah 900AEN (Yuasa)

Thanks.

Also thanks to @Chrishazle - good info to know, I was able to monitor the voltage on the way home and the alternator seems to be supplying around 14.5v to the old battery.

 

[Rotorhead500]

I was going to suggest a dodgy earth connection.

A mate's wife had to get theirs replaced a couple of weeks ago... the battery centre forgot to tighten up the earth lead, gave intermittent starting, rough running, stop/start playing silly gibbons, etc.

 

[DREAMER NO2]

As for voltage 12 volts is nbg

 

[Blobcat]

Plot twist:

Wife phoned to say the car won't start in a car park about a mile away. I grabbed the old battery (thankfully hadn't dumped it yet) and went over with a few spanners. Multimeter on the new battery in the car was showing 12.6v, yet when I turned the key it would sound like it was about to attempt to start then just quit.

I removed the new battery and put the old one in. On removal I noticed a liquid underneath (see attached).

The old battery is fairly knackered but had 12.3v in it. Stuck it in and car started fine and drove home with no problems.

Is this new battery faulty then?

Old battery: 12v 95Ah 850AEN
New battery: 12v 100Ah 900AEN (Yuasa)

Thanks.

Also thanks to @Chrishazle - good info to know, I was able to monitor the voltage on the way home and the alternator seems to be supplying around 14.5v to the old battery.

Did you connect the overflow pipe? The battery gasses off when charges and needs the pipe connected to vent those gasses away (they’re explosive). The gasses also take away some of the electrolyte - which is what that fluid maybe - be careful if it is as it’s a powerful acid and will eat through clothing, not do your hands any good and will also eat through that paint and rust the steel beneath…

 

[starrzo]

I was going to suggest a dodgy earth connection.

A mate's wife had to get theirs replaced a couple of weeks ago... the battery centre forgot to tighten up the earth lead, gave intermittent starting, rough running, stop/start playing silly gibbons, etc.

Thanks! Although unfortunately it wasn’t this, the leads were on nice and snug

Did you connect the overflow pipe? The battery gasses off when charges and needs the pipe connected to vent those gasses away (they’re explosive). The gasses also take away some of the electrolyte - which is what that fluid maybe - be careful if it is as it’s a powerful acid and will eat through clothing, not do your hands any good and will also eat through that paint and rust the steel beneath…

I actually did connect it. The open vent in the replacement battery was on the wrong side so I popped out the little red plastic cover and put it back on the other side so I could connect the tube. I assume that was the correct thing to do.

I’ll clean it up as best I can to prevent any damage

 

[mioba]

Your alty is obv fine as its putting out good V.

you didnt check voltage of new battery when not running?

Seems you found the problem.

 

[tpn]

I would imagine a battery with a faulty cell. I recently got a new battery. Acting the same way. Put it under test and it had a faulty cell.
Voltmeter is not really much good for testing a battery, it must be put under load....and a faulty cell will boil and may force out some of the acid.

Also your new battery may be an AGM battery. These are usually not fully charged when new.....and an ordinary charger will not charge them properly