2nd Gen Non-Engine/Transmission Is 1 amp enough to kill batteries?

[Swamp Donkey]

My sisters 99 24v is having some dead battery issues. I hooked up a clamp meter to the positive clump of wires off of the batteries. With everything off, doors closed etc there was about . 8 or . 9 of an amp draw. I pulled every fuse and relay in both locations with no change in amps. The only reason I ask this is because just recently her radio started staying on, even with the ignition off and key in her hand. Not sure what is going on there, but when I pull the radio fuse, I only drop about . 2 of an amp. So I put it back in... ... ... ... . she needs her tunes. LOL Fired truck up after boosting for about 20 minutes and everything seems fine. Alt was putting out about 80 amps and charging @ 14+ volts. The batteries were new NAPA ones that I put in about 4 months ago.

 

[zstroken]

Yes it will kill them. We had a vehicle that pulled about 2 amps and within 20 secs be to zero and spike back to 2. About 3 days and if the vehicle hadn't been started then it would dead. I had a single automotive relay left on a vehicle for about 1. 5 weeks and when I came back the battery was completely dead and bulged You might by some deep cycles if you aren't planning on getting it fixed.

 

[JGK]

Any draw at all will eventually drain your batteries. He11, for that matter, they'll loose charge sitting unconnected to anything if they sit there long enough!



There's always a little draw on most batteries for such things as keeping settings in radios and so forth, but usually its not enough to make an impact for weeks or even a few months. An amp seems like a lot. You could have a corroded connection or a weak short somewhere that's causing a higher than normal draw. But it might be impossible to find.



-Jay

 

[WDixon27]

most vehicles draw under 50ma and you are reading 800-900ma that's a huge draw, just to be sure id connect up direct to see what it really is drawing, the average clamp i find is not always reliable at really low readings (unless it's a "low amps probe" like the little weird snap on unit), id unhook one battery and test off of one, hook one side of the meter to a good ground and touch the point of the other to the center of the post and slip the cable up till it's off the battery post, this keeps everything connected in the truck so you don't get any surges if you just unhook the battery and then connect the meter

 

[jdrury]

Make sure the top of your batteries are clean also,acid fumes/moisture will create a slight short between the terminals.

 

[proflow]

I remember way back in the day my buds piece of junk Ford Grenada did the same even with a new batt. she'd be dead in the morning. This car went to many shops with no results. Guess what it was. OK, I'll tell ya--alternator diode. Crazy I say --Proflow

 

[fest3er]

I remember way back in the day my buds piece of junk Ford Grenada did the same even with a new batt. she'd be dead in the morning. This car went to many shops with no results. Guess what it was. OK, I'll tell ya--alternator diode. Crazy I say --Proflow

A bad alternator diode can be easily seen using a scope. I had a marginal diode in my '84 200SX as I drove through D/FW one time. Hot, it wouldn't keep up with ordinary engine usage and A/C. Cold or cool, it charged great.



As to discharging. Let's say our batteries will produce 100A for 30 minutes. (That's based on one intake heater grid draining the batteries in about that time. ) So each battery is good for 200 amp hours, or 400 total. Derating, it should take at least a week to drain sister Swampy's batteries, if they are fully charged.



I would first suspect the alternator; remove the 140A alternator fuse in the PDC to see if the current draw goes away. Next up would be the ignition switch; unplug the steering column harness and see if the current draw goes away. Next, if it has an auto trans, there *might* be a problem with its electronics; remove the auto trans relay from the PDC and check the current draw. IIRC, the trans relay has constant (B+) power (according to the Sadist's Manual).



Otherwise, in general, look for places where B+ power and switched power run near each other; something might be bridging them together, *especially* if other switched things (wipers, etc) work with the key off.

 

[DPapworth]

You have it backwards. 100A for 30 minutes is 50A for one hour or 25 amp-hours per battery, which is about right. (It's a bit low, but batteries have less storage capacity when they are drained quickly).

A one amp standby load will thus drain the pair of batteries in about two days.

One of the fuses is designated "IOD" (Ignition off draw). The factory pulls this fuse during shipment, the dealer re-installs it during "dealer prep". This is supposed to eliminate most of the non-switched power draw and allow for 30 days or more of sitting idle. Try your measurement again with this fuse removed.

 

[RRees]

Just in case you can't find the "culprit" that is causing your mysterious battery drain.



This might help: Wire a 12 volt weatherproof receptable to your front or rear bumper and of course connect wiring to battery. Plug in a battery tender/charger to the 12 volt receptable. This should keep the battery topped off at least while parked at your house. This is assuming you have a "out of weather" parking spot for the vehicle in question.



Just a thought. I actually did this to my Jeep and my Dodge so I can plug in an invertor.