How can I check battery drain?

spider rick · #1 (**permalink**) 10-18-2007, 07:03 PM

I recently replaced the carpet in my spider (because one of the previous owners wore a hole in it right behind the driver's heel pad). I believe this same previous owner had installed an alarm system, which was really good at draining the battery. I removed most of the components of this system, but today when I went to take the car for a drive the battery was dead.

The culprit may have been the courtesy lights. I've corrected that problem but I'd like to hang a voltmeter on the system to see if that really was the problem or if I have to remove more of the alarm system wiring.

**Subtle** · #2 (**permalink**) 10-19-2007, 07:42 AM

My Spider came to me with an off/on switch as part of the battery hold down frame.

It is also an effective immobilizer.

**lowmileage** · #3 (**permalink**) 10-19-2007, 07:50 AM

A Voltmeter gauge installed in the car is a very important informative and diagnostic tool IMO

Dolce86 · #4 (**permalink**) 10-19-2007, 08:56 AM

Quote:

Originally Posted by lowmileage

A Voltmeter gauge installed in the car is a very important informative and diagnostic tool IMO

**lowmileage** · #5 (**permalink**) 10-19-2007, 09:50 AM

My car didn't have a Voltmeter only the dreaded

idiot discharge light. With the Autometer gauge, my system is putting out 13 + volts while the

above mentioned light faintly glows. What kind of battery did you get the krapped out in 2 months? I trust you always have a Battery Tender connected -right

. You didn't get one of those Red top Optimas did ya' cause if you did let it discharge, its toast.

**Gubi** · #6 (**permalink**) 10-19-2007, 10:11 AM

You don't want a voltmeter, you want to use an ammeter. Disconnect the negative battery cable and put an ammeter in series (with the car not running, of course). The current draw with nothing turned on should be 30 mA or less. If it's more you've still got a drain somewhere.

**lowmileage** · #7 (**permalink**) 10-19-2007, 10:19 AM

An ampmeter doesn't tell you everything - just tells you what's going into the battery - doesn't tell you what's going out. And you better make sure you wire it up correctly and with some high output alternators they don't IIRC recommend them. JMO

Alfacliff · #8 (**permalink**) 10-19-2007, 10:25 AM

the way tom said is right, to check for current draw, use an ampmeter with the engine off. pull the fuses one at a time till you find the circuit thats bad.
current drawn all the time is probably an alarm oe clock. some radios pull a little current to keep memories.
cliff

**lowmileage** · #9 (**permalink**) 10-19-2007, 10:34 AM

Quote:

Originally Posted by Alfacliff

the way tom said is right, to check for current draw, use an ampmeter with the engine off. pull the fuses one at a time till you find the circuit thats bad.
current drawn all the time is probably an alarm oe clock. some radios pull a little current to keep memories.
cliff

**Gubi** · #10 (**permalink**) 10-19-2007, 10:47 AM

The S4 already has a voltmeter built in. He is asking about finding a drain, Lowmileage. Two different subjects.

Dolce86 · #11 (**permalink**) 10-19-2007, 10:50 AM

Quote:

Originally Posted by lowmileage

My car didn't have a Voltmeter only the dreaded

idiot discharge light. With the Autometer gauge, my system is putting out 13 + volts while the

above mentioned light faintly glows. What kind of battery did you get the krapped out in 2 months? I trust you always have a Battery Tender connected -right

. You didn't get one of those Red top Optimas did ya' cause if you did let it discharge, its toast.

**lowmileage** · #12 (**permalink**) 10-19-2007, 11:13 AM

Quote:

Originally Posted by Gubi

The S4 already has a voltmeter built in. He is asking about finding a drain, Lowmileage. Two different subjects.

**lowmileage** · #13 (**permalink**) 10-19-2007, 11:21 AM

Quote:

Originally Posted by Dolce86

I do not utilize a tender. My car gets used every week and does not sit for more than 5 days without being run. No Optima for me - I purchased an Interstate battery (I think a size 24) which I am told are decent batteries.

I'm wondering if the new Alpine I had installed a few months back has anything to do with this? I realiuze that there is a constant draw to keep the memory in--tact. Sort of like the Borg digital clock I have.

Dolce86 · #14 (**permalink**) 10-19-2007, 02:29 PM

Quote:

Originally Posted by lowmileage

I use a Tender all the time. It's said to extend battery life 2-3X. Plus I then know my batteries don't discharge and will start the car all the time. I think it is a good idea for you to get one - they are only about 30 bucks. You hook up a "pigtail" and it's very easy to attach/detach. Plus, you need a battery disconnect switch. I also have a CD with a clock in it - I wish it didn't have the clock. I turn the battery disconnect switch off when the car is garaged. Something else you should have if you don't already IMO.

**lowmileage** · #15 (**permalink**) 10-19-2007, 02:56 PM

The pig tails I refer to is the plug in connector - it's included in the Battery tender. You permanently (but it's removable) connect one end to your battery. The Tender goes into the electric plug. You then just plug them together. They also include a clip connector but that is a PITA.

Batterytender.com - Home of All Your Charging Needs Battery Tender Jr.

If you shop around, you can get them for around $30. You can probably (but I don't know where) buy them local. Buy the Junior model as above - that's all you need. It's the same one I use on my Motorcycle. I have 5 of them continuiously on 4 vehicles & the bike. Getting one you wouldn't have to use the battery disconnect - but I'd advise putting one on anyway.
You (I) route the wiring down the engine compartment underneath when the car is covered.