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Battery drain?


Guest Stephen Lyons
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Guest Stephen Lyons

Hmmm.....<P>After three weeks of not driving it, I went to start my 1988 & the battery was completely, totally dead. It appears to be a new Diehard Gold, so I'm guessing something drained it. Is this a common problem with the Reatta & is there anything I ought to check first?

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I think it is a common problem. I am guessing one of your relays is sticking. This seems to happen when the voltage goes down. Not 100% sure, but I know when I have an older battery, day 3 or 4 without driving, it is fine. If I try the same on day 5-6, it is dead as a doornail. I believe it is the headlight relay for me.

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To check the battery drain with an ammeter, go down to Harbor Freight and purchase a DVM, Digital Volt Meter, for under $10.<P>Be sure everything in your Reatta is turned off, including closing both doors, closing trunk and glove box. Disconnect one battery lead, set the DVM to ma, millamps, and connect the two meter leads in <B>series</B> with the disconnected battery lead. That is, one meter lead to the blank battery post and the other meter lead to the dangling battery cable end.<P>A ma. is 1/1000 of an amp. Twenty ma. for 24 hours is 480 ma or 1/2 amp per day. Since your battery is rated at perhaps 60 AH, ampere hours, at 1/2 amp per day, the battery should last for 120 days or four months.<P>If the current draw is greater, the battery will discharge faster.<P>Best bet is to measure the current draw and check back here. There's lotsa help available on this forum.<BR> smile.gif" border="0

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Few other comments now thast I've had some sleep - when measuring current unless you have an autoranging meter is best to start on a 10A scale to avoid popping a fuse.<P>To avoid loosing all of your presets when measuring current, either connect a jumper cable from the negative lead of the battery to the negative cable (can measure current on either side but this is less likely to produce sparks on an "oops") - this is easiest if your battery has both top and side terminals.<P>Next remove the negative battery cable from the battery and install the meter in series (battery->meter->negative cable. Turn meter on to AMPS. Remove jumper and read current.<P>20 milliamps (.020 amps) is normal<BR>1-2 amps will drain good battery in 3-5 days<BR>more and something will probably be warm.<P>Suppose this should be in the FAQ somewhere.<P>Keep in mind that with cars this old, so is the wiring and components. Cars from the rust belt often have problems that are not in the book.<P>The other most common fault is some ham handed mechanic in the past that screwed something up. My Fiero did the same thing unitl I found that the ignition had been rewired to keep power to the ignition/coil all the time. Only reason engine would shut down with key was because the injectors turned off.<P>Anything is possible.

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Guest Greg Ross

I agree, no inherent heavy drain in the electrical system if everything is up to snuff. I've had mine parked for 4-6 week intervals numurous times and she always bursts to life. A lazy relay makes the most sense. While you've got the meter hooked up it will be necessary to remove relays one at a time and check the draw on the meter to find the culprit.

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Guest Stephen Lyons

Well, with a recharged battery (the auto parts store claims it's good, although the charging pattern I was observing last evening with the battery out of the car suggested otherwise to me), on the 10A scale, I'm consistently showing a draw of 4.7 amps!<P>Plus my turn signal indicators, which had started to work properly when I last parked it, are now both going off again for either direction selected, just like before. Plus I still can't get the dash lights up.<P>Nothing against the group here, the advice given on this issue in particular is excellent, but I am really getting frustrated with this car, & beginning to be sorry I bought it.

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Been there & have the grey hairs. Some days the battle just seems endless. Funny thing how often it all turns out to be related to the same simple thing.<P>For instance if you have an '88 it will tell you what the voltage is. When both lights flash what is it reading ?<P>These electrical problems can look like anything but is often just a matter of being slow, methodical, and assuming nothing. Particularly when an auto store says anything.<P>A quick comment though: computer cars *really* do not like battery chargers & will do all sorts of odd things if you try to run one with a charger connected.<P>It could well be a flakey battery but the only real way to tell is to measure the drain, then you know.<P>Where are you ? - The part of the country a car is in often is an indicator of what might be wrong.

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Guest Stephen Lyons

I'm really reluctant to charge a battery in situ, for just the reason you mention, so I had taken it out. I'm still not convinced the problem's not the battery. The damned dealer so blatantly detailed the engine compartment that a six year old Diehard could very well look new (a big gripe of mine in general is the overdetailing and especially the heavyhanded overbuffing of cars that are original and would be better off left alone - but that's another topic for another day).<P>As to climate, I'm in Pismo Beach, California, about ten miles from Nipomo, which supposedly has the least variation in winter and summer temperatures of any community in the continental U.S.<P>The turn signal indicators started working correctly again when I took the car out for a drive - then, right in the middle of a turn, they went haywire again & both arrows were going a la the hazard flasher mode. On top of everyting else today, I noticed a small door ding on the car, which I was sure was ding free when I got it - just one more aggravation to deal with.<P>I was hoping to show this car at the BCA event in Van Nuys next month, so if I could just nudge this car closer to the 100% mark right now, I'd be a lot happier of a camper, but it seems to be set on its own course to thwart me in this.<P>I just can't figure out what could be drawing nearly 5 amps and not be lit or frying.<p>[ 05-11-2002: Message edited by: Stephen Lyons ]

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Next step is to remove fuses, one at a time, until the current draw ceases. Remember to shut the car door each time you remove a fuse, otherwise the dome lamps will draw current. There are also some relays and possibly fuses in the under hood black box by the air cleaner assembly.<P>A five amp draw will kill the battery in half a day.

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My Reatta does the same thing. Drains the battery dead in days. An older mechanic told me to check the alternator for an open ground. That is my project for tommorow or the next day.I will tell you what I find.

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Guest spikey

I had two batteries die on me in a very short time - I stopped charging my cell phone in the car and havn't had a problem since.

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See my original post. (#1) Been there, done that. I hope that a new battery will help. Again, my guess is that an older battery after a couple days sitting, affects a relay. A new battery is say $65 and you probably will need one soon anyway. Trying to find an electrical problem is 2 weeks and 5 cases of beer (at least $100 worth). You do the math. Good luck and let us know how you make out. (that is, with a new battery)

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My 89 will sometimes have a dead battery after sitting a week or two, but then at other times will sit longer and start fine. I've yet to find the problem.

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My '89 with 52k miles has had 3 batteries in its lifetime. The 3rd one (a really nice Diehard) was installed prior to me buying the car. If I let the car sit for maybe 2 weeks, the car would be dead as a doornail. I got tired of having to jump the car (or start it every day) to keep the battery from going dead. I bought what is called a "Battery Tender". This is NOT a trickle charger. It only starts to charge the battery when it detects the battery getting too low. It will recharge the battery, then it shuts off. The clips and wire are small enough that you can keep the hood almost closed. I have used this thing for 2 years, during the winter when my Reatta sits in the garage for months. I have never had any problems with my battery or electrical system since. I took the Battery Tender off the car about a month ago, and 3 weeks later, the car started up like a charm! It was the best $70 I have spent in a long time.

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Guest Stephen Lyons

"LuvMyReatta" - I think your "Battery Tender" is the same thing as a more generically identified float charger, which is what I use on a car of mine that is mostly stored. I agree that it is very effective. <P>As regards my electrical problems, it turns out that my measured 5 amp drain was a phantom, with the old battery lasting out the week with a problem. But I still wasn't convinced that the battery wasn't beginning to die and since a weakening (though not yet testably bad) battery can cause all kinds of symptoms in today's electronics laden cars that will look like anything but the battery<BR>itself, I replaced it over the weekend with a new top of the line 7 year Delco.<P>Incidentally, I was somewhat reliably advised over the weekend that the DieHard Gold is made by Exide, while the DieHard Silver is a lowest-line Delco, supposedly not even as good as the Delco branded 5 year model.

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Guest Stephen Lyons

No doubt it's a drain, & it should be something in a circut that can operate when the ignition is off, plus it has got to be an intermittent fault, which is the worst aspect of this.<P>Soembody mentioned a headlight relay - where is that located, & if it was closing, couldn't or wouldn't you see the lights on even if the pop-up doors were closed?

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Guest Stephen Lyons

Another person has suggested privately to me that this drain might be due to a power lock switch that is not fully disengaging.<P>I checked the amperage draw on the battery today & couldn't get any reading at all, not even the typical 20 ma.<P>Nevertheless, for the time being, I'll just leave the negative cable disconnected....

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You sound electrically inclined so, I'll skip the obvious.<BR>I assume you've checked the output of the alternator. Have you checked for AC leakage? A significant amount of AC leakage (measured at the battery while the engine is running) indicates a failing or shorted diode (no frying, nothing lit). Generally, I would consider anything less than 100 millivolts AC acceptable. "0" would be ideal. You may have to monitor your battery output for an extended period to allow your "phantom" to re-appear.

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