Battery drain

Has anyone else had issues with their batteries being drained after using VCDS? I started using it and both times my battery was dead the next morning. I have had the battery jumped and tested. It has read good both times. I have a 20th Gti.

^^^ hmm....... seems very odd and certainly not a systemic issue. Perhaps additional information might help. if your car supports it, a copy of the battery history might be worth posting-up. If you are new to this stuff goto Applications from the Main screen - then goto History Data - then follow the instructions HERE.

Finally, I assume that the dongle wasn't left plugged into the OBD port in the car overnight - please confirm

Don

Guitar31 said:

Has anyone else had issues with their batteries being drained after using VCDS? I started using it and both times my battery was dead the next morning. I have had the battery jumped and tested. It has read good both times. I have a 20th Gti.

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Never had that happen in over 15 years of using VCDS.

Depends on the car and how many modules are fitted. I can easily run the battery down on the A6 when coding long sessions. I always use a battery maintainer, ignition on and diagnostics running i see around 25A current dray so wouldnt take long to deplete the battery

Did you leave the cable plugged in overnight? I have had this happen before

rhinopower said:

Did you leave the cable plugged in overnight? I have had this happen before

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I didn't leave the cable in overnight. My sessions probably ran about at most 15-20 mins. When I checked the voltage on the battery after the wouldnt start it read 11.3 and would dip to 7.9 to 8.2 when trying to start it.

DV52 said:

^^^ hmm....... seems very odd and certainly not a systemic issue. Perhaps additional information might help. if your car supports it, a copy of the battery history might be worth posting-up. If you are new to this stuff goto Applications from the Main screen - then goto History Data - then follow the instructions HERE.

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In the US market, a "20th GTI" would be a 2003 model; an Mk.4. No battery history in that car.

-Uwe-

Guitar31 said:

I didn't leave the cable in overnight. My sessions probably ran about at most 15-20 mins. When I checked the voltage on the battery after the wouldnt start it read 11.3 and would dip to 7.9 to 8.2 when trying to start it.

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11.3V is a for all intents and purposes a fully discharged battery. But... Evaluating state-of-charge via the voltage is only valid with no load on the battery and after it has had a chance to rest under no-load conditions for a while.

You may want to track that battery voltage while using VCDS the next time. I would avoid letting it drop to less than 12.0V under whatever loads are present with the ignition on.

-Uwe-

Uwe said:

11.3V is a for all intents and purposes a fully discharged battery. But... Evaluating state-of-charge via the voltage is only valid with no load on the battery and after it has had a chance to rest under no-load conditions for a while.

You may want to track that battery voltage while using VCDS the next time. I would avoid letting it drop to less than 12.0V under whatever loads are present with the ignition on.

-Uwe-

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I will definently watch it next time. The only thing I know of is the fan does run for a min after the car has been switched off. I dont know why it does this but has for quite some years so I know that isn't the culprit.

That is by far to low, but need to be measured under load (or with a better tester), one can also check the acid (std lead accumulator batteries). A good battery shall have 12,75VDC or more, should be recharged at 12,5VDC or less, and need recharging at 12,3 or less. Consider it depleted at lower than 11,5VDC.
Keep in mind that deep cycles can severely reduce battery capacity, as internal wear of lead in cell structures may occur.

I would check battery, might be bad, or close to bad. Not sure of the effect a low battery would have on car modules, eg will they shut down as they should, or will some controllers be missing the "go to sleep command", if so, some modules will stay active, and you will have a depleted battery within hours (depending on size, initial charge and wear)

Regards
Gremling

Old thread, I know….

I’ve used VCDS happily for years including coding installs off head units on our two VWs and not had issues.

I recently had this happen on both cars however after just running autoscans (1 or 2 max after clearing a fault). Had it happen again after a single autoscan yesterday on one car. I’m leaning towards it just being bad luck that both batteries may be approaching end of life.

Not sure why VCDS should cause this level of drain in such a short time however. Batteries have not gone flat otherwise.

Yesterday when I did the scan, I checked that daytime lights were off first. Head unit was on but never gave auto switchoff battery warning message as it will do if you just sit listening to radio long enough with engine off. Dead this morning. Didn’t have time to check voltages as needed to get my wife to work.

When this happened the previous time, battery was fine after a short drive to recharge. Has only recurred following scan.

Only posting in case the info. is of any help to Ross Tech. Will diagnose battery later and report back if indeed it is basically on its last legs.

Remember that while you're doing an Auto-Scan the ignition is on and even with things like the climate control off there are still many amps (in some vehicles tens of amps) being drawn from the battery for several minutes, so there will be a significant amount of charge taken from the battery.

If the battery isn't in good health then this could be enough to tip the battery over into not being able to start the engine next time.

PetrolDave said:

Remember that while you're doing an Auto-Scan the ignition is on and even with things like the climate control off there are still many amps (in some vehicles tens of amps) being drawn from the battery for several minutes, so there will be a significant amount of charge taken from the battery.

If the battery isn't in good health then this could be enough to tip the battery over into not being able to start the engine next time.

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Forgot to say climate also turned off so there were no major drains. I’m not trying to claim it’s anything other than a weak battery however.

How old is the battery in the car??? Sounds like a shit battery to me. It's not possible for VCDS to cause a draw if its not connected.

When you say you had the battery jumped and tested, please explain what you mean and how it was tested or what was measured and how. Curious minds would like to know.

stuartb3502 said:

Not sure why VCDS should cause this level of drain in such a short time however.

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It doesn't , your vehicles electrical system does ! It is a good practice and habit to Always hook up a battery charger or maintainer while using VCDS , or have engine running. I don't think you realize the duration of use while diagnosing ; five, ten minutes or longer ?

VCDS can't drain the battery like that, the curent would melt the OBDII plug...