What is Normal Battery Draw When Parked? - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 09-14-2010
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What is Normal Battery Draw When Parked?

I just got a 2002 Ranger XLT. The battery seems to discharge after the truck sits for several days and it will no longer start the vehicle. With the doors closed and all lights off --mine draws 0.26 amps from the battery while shut off. That is 260 milliamps. This seems excessive to me. I read an earlier thread here (2006) where a member stated that around 200 milliamps was normal. I am quite familiar with electricity. 260 milliamps equals 1 amp in four hours time. This figures out to 6 'amp hours' every day. When I pull the number 26 fuse the current draw decreases to 0.074 amps. This is 7.4 milliamps which seems more reasonable.

Has anyone put an ammeter in series with one of the battery leads and measured amperage on a parked Ranger with the doors closed? I would appreciate any info on what a normal draw on a battery while parked should be.
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Old 09-14-2010
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how old is your battery?? chances are if its still the one ford put in its time for a new one
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Old 09-14-2010
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Ill use my friends clamp and measure for you tomorrow
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Old 09-15-2010
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The minimum current draw should be 0.5 Amps
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Old 09-15-2010
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maximum battery drain with the truck sitting it .33 amps.....drawing .24 amps like yours is is within limits but on a low/weak battery will drain the battery over a week or so. i would get the battery checked on a load tester and not the electronic battery checker b.s

Last edited by SB05EDGE; 09-15-2010 at 09:10 PM.
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Old 09-16-2010
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"98rangerxlt" says the minimum current draw should be 0.5 amps. "SB05EDGE" says maximum draw should be 0.33 amps. My experience with other vehicles has shown a parasitic current drain of around 50 milliamps or less. That would be 0.05 amps. I wonder if either of you guys have actually measured the current drain with an ammeter after the interior lights have shut off and the Baterry Saver Relay has timed out.

I am familiar with vehicle batteries. The battery in my Ranger was tested by applying a 100 amp resistive load tester across the two terminals for 30 seconds. It tested on the bottom end of 'Good'. Whether the battery is good or bad --I feel that a parasitic current drain of 250 milliamps is too great.

Here's an interesting article on the subject at Scope It Out by someone who at least sounds like he knows what he's talking about, that claims that even 30ma is an excessive drain. He makes a pretty good case for his opinion; it's worth reading.
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Old 09-16-2010
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nvm
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Old 09-18-2010
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...just info to chew on, but keep in mind that a 30 sec. load test doesn't rate capacity. It's more geared to cranking voltage. Also, a bad battery doesn't leak voltage or anything but a dirty battery top will.
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Old 09-18-2010
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I am reading the 250 milliamp draw with a Fluke VOM connected in series with the battery ground cable. I temporarily installed a brand new battery in the truck today. I still measured around a quarter amp (250 milliamps) draw after the Battery Saver relay had deactivated. This means that an Amp Hour is drained from the battery in four hours. This means 6 Amp Hours are drained in a 24 hour period. Most Ranger batteries are around 70 Amp Hour capacity. Once a battery is drained to 50% of its capacity --it will have a hard time cranking the starter. That means that with a daily draw of 6 Amp Hours --in six days the battery will barely be able to crank the vehicle. 250 milliamps is way more than what the draw should be on the battery when the vehicle is turned off.

When I remove fuse #26 the current drain goes almost away (0.08 milliamps). It appears that something connected to fuse 26 is drawing more current than it should. I finally got an electrical schematic of the vehicle last night. Fuse # 26 supplies 5 different things. I got the instrument panel removed and disconnected today and also dropped down the Battery Saver relay and Auxillary relay box. I located the Restraint module. Tomorrow I'll start disconnecting the remaining items that are supplied by fuse #26 until I find the culprit. One of the things supplied by the fuse is the Generic Electronic Module (GEM). I don't know what I'll do if that is the culprit. It is seperate from the Power Train Module (PCM).

Last edited by chuck d; 09-18-2010 at 11:12 PM.
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Old 09-19-2010
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i can see the GEM module being the culprit....we have replaced many of those at our shop for various different reasons.
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Old 09-19-2010
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"SB05EDGE" -- I was very afraid that you were correct on the problem being the Generic Electronic Module (GEM). I got the thing unplugged today and checked the current drain from the battery. It was still around 250 milliamps. Thankfully the GEM doesn't appear to be what is causing the problem. Fuse #26 supplies power to the GEM, instrument panel, Battery Saver Relay and Restraint System. I have the instrument panel disconnected and removed from the vehicle. I'll hopefully have time tomorrow to pull the Battery Saver Relay and locate the Restraint System module and disconnect it. My Owners Manual says that the fuse supplies power to the Battery Saver Relay AND also to the Auxillary Relay Box . This box contains the Battery Saver Relay and about 6 other relays. The electrical schematic that I have shows fuse #26 only supplying voltage to the Battery Saver Relay, Instrument Panel, Restraint System and GEM. The other Auxillary Relays are powered from various other fuses. I'll try to find out whether the Owners Manual or the Mitchells schematic is correct.

Last edited by chuck d; 09-19-2010 at 11:02 PM.
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Old 09-20-2010
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let me look at work tomorrow on the program we have and look up a detailed wiring diagram.
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Old 09-21-2010
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'SB05EDGE" --- That would be great. Possibly you could also tell me exactly where the "Restrain Central Module (RCM)" is located. My Mitchell diagram shows it about the middle of the dash and towards the firewall. I don't seem to see it.
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Old 09-22-2010
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The RCM is underneath the cup holder on the floor
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Old 09-22-2010
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"98rangerxlt" Thanks for the info. Stupid me --I thought that was the Generic Electronic Module (GEM). I just looked at it closer --and it says "Restraint Control Module " right on the thing. Now I need to locate the GEM. My Mitchell info says it is "Behind center of dash". I'm not sure what that means. That is why I thought the RCM was the GEM since it is center of the dash on top of the tranny tunnel. I'll try and find the GEM tomorrow.
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Old 09-22-2010
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according to Mitchell fuse #26 powers the instrument cluster, restraint control module, generic electronic module (GEM), and the battery saver relay. supplies main power to all said pieces via a white/yellow wire to the IC, RCM, and the GEM. tan/yellow to the battery saver relay.

they say the restraints control module is located in the center of the vehicle behind the dash.

and then the generic electronic module says behind the center of dash.

exactly where they are located i am not sure....just pulled of some things on mitchell
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Old 09-23-2010
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If you pull the radio bezel out, the black box on the left with like three connectors going to it, that is the GEM.
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Old 09-23-2010
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Yes, remove the radio and the radio bezel/surround and its right there on the left of the opening. You can verify the GEM with its connectors from the wiring schematic. You will need a the radio remover tool from any auto shop - about 5 bucks. Its a pretty quick and easy R & R to get to the GEM and the area behind the radio. Give everything a good looking at to help track down your problem.
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Old 09-24-2010
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Thanks everybody for the help. I had already removed the radio several days ago. I have most of the entire dash torn out except the right air bag and glove box. I was able to locate the GEM now that I know where to look. One screw and then push it up an inch to un-hook it. It took a while to figure out how to release the two plugs. I unplugged one and then did a battery current draw measurement. The battery drain now had dropped from 0.250 milliamps to 0.080 milliamps. As "SB05EDGE" had predicted several days ago -- it looks like some problem with my GEM is causing the excessive current drain. There is a sticker on the unit that says; "Scrap if dropped more than 20 cm". That is about 8 inches. Maybe I need to drop mine about 200 cm and then it might start working right again!!

I wonder what the cheapest way is to replace the unit? I guess I need to check out some wrecking yards.
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Old 09-26-2010
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I skipped to the end because I had the same 200mA drain. Turned out to be the battery saver relay itself. Even though it tested fine, it drew enough to cause the GEM to keep it activated. I replaced it and all is fine now. Here is my post with pictures... Battery Voltage - Ford Truck Enthusiasts Forums
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Old 09-27-2010
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"bidwell" --Thanks for the info. I read the entire thread that you linked to. I have not pulled my Battery Saver Relay. When I leave a door open the interior dome light shuts off in about 50 seconds. This would make me feel that the GEM is turning the relay off. If the relay was staying on then the interior light should also stay on. Once the coil on the relay no longer gets power then I don't see how it could be drawing current --provided its contacts aren't welded together which would then keep power going to the interior dome light. Anyhow --I'll pull the relay and see if the current drain decreases. I'll post my result.
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Old 09-27-2010
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Chuck, did you mean 50 seconds or 50 minutes? My 40 minutes seem more practical and I believe is stock. Others have 35-55 minutes from my search.

Before swapping the GEM, a $3 automotive relay is a cheap test. It won't have the cute slide mount though. Keep us posted.
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  #23  
Old 09-27-2010
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Yesterday the dome light was shutting off in about a minute with the door open. Tonight I just timed it again and the dome light shut off after 9 minutes and 47 seconds. It was very hot today and the truck is outside so I didn't attempt to pull the Battery Saver Relay.
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  #24  
Old 09-30-2010
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Today I pulled each of the 'Auxillary Relays' (5 of them). There is a blue cased relay on top of the strip. After pulling each relay I reconnected battery with door closed and read current flow. It remained at around a quarter amp (0.250 milliamps) until I pulled either of the two smaller 5 pin relays that are mounted side by side. With either of these relays pulled the dome light no longer came on with the door open. The current draw dropped to half (0.125 milliamps). With both relays pulled the current draw dropped to less than 20 milliamps. I substituded a new 5 pin relay for each of the original ones and saw NO change. It appears that it is not the relays but something (GEM ?) that is actuating the relays. I know that with the GEM disconnected the current draw goes away and of course the two relays are no longer actuated. I would just leave the two relays removed --except there is no dome light when you open the door at night. I'm going to try and research exactly what each relay is supposed to do and how they are supposed to be activated. Any info would be greatly appreciated !
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  #25  
Old 09-30-2010
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Did you pull the BSR in back of the radio? I found it by listening/feeling for the click as I connected the #26 fuse. It is NOT visible, and slide mounted on the other side of the partition on my 2000.



Don't give up.

Last edited by bidwell; 09-30-2010 at 11:21 PM.
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