Strange question - could my coolant level sensor be draining the battery?

[repenttokyo]

Does it draw enough to do this overnight?

[Tiger]

No, no power to coolant sensor when ignition is off.

Most likely your battery is weak/old. Have your battery tested. Or test it yourself... charge up the battery and wait a while... and then check your battery voltage... new is like 12.70V for full charge... I think like 12.2 is weak and 25% reserve.

Or do battery load test and see how low the voltage dip in 10 second.

[repenttokyo]

No, no power to coolant sensor when ignition is off.

Most likely your battery is weak/old. Have your battery tested. Or test it yourself... charge up the battery and wait a while... and then check your battery voltage... new is like 12.70V for full charge... I think like 12.2 is weak and 25% reserve.

Or do battery load test and see how low the voltage dip in 10 second.

it's not the battery - i've had it tested, it's an optima red top that's about 15 months old. that was my first thought as well.

i have some strange sounds in my dash that could also be stuff running with ignition off. this is a real bitch to track down, and it's worse when the weather is cold. I essentially have to drive the car once a day or forget about it.

thanks for eliminating that worry for me re: sensor.

[Tiger]

Didn't relize you got Optima battery.

It is easy enough to track down the draw. With a multimeter set to DC Amp... go to both fusebox and pull fuse out one at a time. When you pull a fuse out, measure the amperage draw and put the fuse back. Repeat until you find one that draw alot.

Most likely draw would be the radio and amp... if something is wrong with the radio... it doesn't shut down the amp and big draw.

[Mas (UK)]

Hi there,
I had the same thing a few years back and my car battery would go real weak or dead if the car wasn't used for a day or two. I tracked mine down to being the little torch in the glove box. I think after a while the rechargeable batteries in these torches become dead (or virtually dead) and if plugged into the charging socket in the glove box, the 'dead' torch just saps away power from your car battery. I just unplugged the sucker and guess what ... battery problem disappeared and battery strength would remain perfectly fine even if car was left unused for weeks.

I hope this helps.

Cheers,
Mas

[repenttokyo]

my car did not come with the flashlight - but i appreciate the suggestion.

[Tiger]

Still having problem?

[repenttokyo]

yes, although with the weather being warm it is not as bad as before.

i have not had the time to track it down because my first track event of the season is next weekend at Monticello, NY, and my Miata track car is taking all of my spare time for maintenance and preparations :(

[Blitzkrieg Bob]

put a multi meter between the battery and the lead and measure the draw...then start pulling fuses and relays one by one to see when the meter drops...bingo! that's the suspect system.

[genphreak]

If the fuse tests don't find a culprit, check if the power protecton relay (PPR) is triggered. If so, you have to work out what is triggering it in the circuits it protects or is controlled by. It draws a fair bit of power (and gets warm) just holding itself open. Other relays may be faulty too.

Cat and mouse it is.

[repenttokyo]

an update - tested with a new voltmeter today. Battery sits above 12.3 volts after several hours charge on my workbench. In the car, it also sits at this level when connected.

With the car off and locked, there is a drain of .15 amps - which seems to be perfectly in line with what the drain should be to maintain the computer and radio. So it would seem that my drain is "intermittent" to the extreme.

thoughts?

[Tiger]

12.3V is low... I think at that voltage, it is 25% capacity. Bring it in to Autozone to have them do a load test

Charge it up to see how high you can get it to go... you have to wait 30 minutes after charging to see actual battery condition.

[repenttokyo]

12.3V is low... I think at that voltage, it is 25% capacity. Bring it in to Autozone to have them do a load test

Charge it up to see how high you can get it to go... you have to wait 30 minutes after charging to see actual battery condition.

last time i brought it to the place i bought it from - advance auto - they tested it and told me it was fine - something like 650 amps showing as reserve. I am going to go back Sunday and be more forceful about getting a replacement, because at this point it's ridiculous.

[Tiger]

Rereading your post... 12.3V after charging is not good... battery is not accepting charge.

I don't know about BMW parasitic draw... but I think it should be lower.

Here is a good site.

http://www.aa1car.com/library/battery_runs_down.htm

[repenttokyo]

Rereading your post... 12.3V after charging is not good... battery is not accepting charge.

I don't know about BMW parasitic draw... but I think it should be lower.

Here is a good site.

http://www.aa1car.com/library/battery_runs_down.htm

thank you for that site. I will fully charge the battery sat. night overnight and then take it in Sunday in a different car to have them load test it. Any tips on how to convince them to replace it if they balk? It is still well under warranty.

I think a 15 ma draw with the car off is in line with what that site is suggesting.

[Tiger]

Just tell them that you car will die every other day. When they do a load test, it would fail expecially with the voltage you quoted...

Myself, I'd probably let the car run down the battery and then bring it in... say you are so frustrated and pissed that battery gave you so much headaches.

How old is that battery?

[repenttokyo]

Just tell them that you car will die every other day. When they do a load test, it would fail expecially with the voltage you quoted...

Myself, I'd probably let the car run down the battery and then bring it in... say you are so frustrated and pissed that battery gave you so much headaches.

How old is that battery?

that's what I tried last time !

It's an 18-month old optima red top.

[Tiger]

what is your charging voltage when car is running and at idle and 2000 RPM?

[repenttokyo]

what is your charging voltage when car is running and at idle and 2000 RPM?

i don't know @ 2000 rpm - haven't been able to test that yet as I am all alone - but my charging voltage at idle with headlights on is 14 volts.

[Tiger]

Call Optima up and ask them for their advice...

http://www.optimabatteries.com/_media/documents/Optima_Warranty.pdf

[Tiger]

14V at idle? No problem with your charging system. Definitely bad battery.

[repenttokyo]

14V at idle? No problem with your charging system. Definitely bad battery.

yeah, my voltmeter shows 13.98 volts across the terminals with headlights on at idle.

[repenttokyo]

Call Optima up and ask them for their advice...

http://www.optimabatteries.com/_media/documents/Optima_Warranty.pdf

i called - they said that i should have the store charge the battery and leave it with them for a few days so they can witness the drain. the thing is, if i do that, i can't move my car...

[Tiger]

Two things...

Go back to the store and politely tell them the problem you had... how many times it happened... that you checked for problems... and it still come to the battery problem.

Go there with the battery installed in your car... let them do all sort of test they want... and pull out the battery for them if they asked.

Just tell them you can't afford non start as it is your only car (who cares if it is not).

If that fail, go to another Advanced Auto and do the same story again... hopefully they will let you swap it out. It doesn't cost them one cent... Optima will give them replacement battery for free.

[repenttokyo]

update 2: took the battery to the shop i bought it from today. it tested at 12.5 volts and only 545 amps out of 800. replacement is mine!!!!!!!

[Tiger]

Good for you... geez... even 625 CCA out of 800 is unacceptable. I think that battery has been deeply discharged too many time. Even Optima said Red top is not good for deep discharge.

Personally, I think Autozone Duralast Gold battery is the best bang per buck... It is affordable. It got great warranty and it works very well.