Yet Another Parasitic Draw Case

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hexibot43
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Yet Another Parasitic Draw Case

Post by hexibot43 »

Not sure why but suddenly I'm getting one after another of these vehicles. Recently, got a 2002 Lexus RX300 with a battery that would die after a couple days. I looked at it, and no sign of a drain. Parasitic @ .04 amps. Nominal. Battery OCV @ 12.45 volts. I had just finished putting a slow charge on it. Left it for a couple days. OCV @ 11.48 volts. Battery went from 75 % to 25 % in just two days. 50% loss with no sign of any drain on battery.
I'm thinking I'm missing something. I had used a battery tester after having charged the battery. It tested good at 650cca. No bad cell, or anything to indicate problem with battery.
I have tried to use my Pico scope in the past, without any real luck. I don't have an Amp clamp worth a damn to use for this type of testing. They all have too much drift in the reading, and keeping the battery good for days not working for me either. Just bought a new B41T+ datalogging multimeter. In no way am I recommending this meter over any other. It is just what I chose. I was able to log to the internal memory for an entire weekend. The battery lost 50% of it's charge and yet the log had a couple of minutes showing the computers shutting down @ about 2 amps for 15 minutes, and then .04 amps for the rest of the weekend. The log showed nothing wrong with the vehicle while the battery lost 50% of it's charge. So with the evidence I have....can I condemn the battery? One of the guys I work with runs around selling the same battery from a little truck. I tell him about the battery, and he says Oh Yeah! That particular battery is problematic. It was only 6 months old too. Customer is like the battery is brand new that couldn't be the problem.....

What else could I have done? Because this is a rare one. Usually it is just so obvious when the battery is bad. Our battery testers not able to see the issue with this one. Everyone is saying are you sure there is not a drain. I have the answer in the form of the log. It must be correct. LOL!

I am very curious what other people do in this situation? Before I bought this new multimeter. I would tell my boss I don't see anything wrong. It is not happening here in our shop. I am sure there is a problem but it is not showing itself to me. It is a cop out. But I couldn't come up with anything conclusive. I just can't wait until I get one where there actually is a drain that comes up in the middle of night. And the next morning dead battery that I charge, and everything looks all good again. I would much rather have an answer.
Last edited by hexibot43 on Tue Jun 23, 2020 1:33 am, edited 1 time in total.

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hexibot43
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Re: Yet Another Parasitic Draw Case

Post by hexibot43 »

Screenshot of the new meter at work. I was able via bluetooth to download the saved memory and map it.
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PicoKev
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Re: Yet Another Parasitic Draw Case

Post by PicoKev »

I googled that meter and ended up at this YT test....! YT Link
Fascinating but I want one and a half hours of my life back......! :roll: :roll:

Kev

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hexibot43
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Re: Yet Another Parasitic Draw Case

Post by hexibot43 »

Sorry!

I know what you mean. I honestly bought it for the data logging only. I have plenty of really good DVOMs. Youtube had lots of videos but very little on the data logging feature. You have to do some wadding....Sorry again! But, I didn't want to spend the $300 on the data logging meter I wanted. And then the fluke more like $500. It cost me basically $60. Not perfect but it did exactly what I wanted. I wanted the Uni-t 181a but wasn't willing to fork out the money for it. Was not sure if I was going to actually find this as useful as I had hoped. To be able to set up a meter and just leave it for days to record is worth it. And to have it directly record Amps even better. I wish I had bought this a while ago.
Last edited by hexibot43 on Tue Jun 23, 2020 1:34 am, edited 1 time in total.

liviu2004
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Re: Yet Another Parasitic Draw Case

Post by liviu2004 »

If you suspect battery, charge it and disconnect from auto. Check 2 days later.

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Fat Freddy
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Re: Yet Another Parasitic Draw Case

Post by Fat Freddy »

liviu2004 wrote:
Thu Jun 18, 2020 4:16 pm
If you suspect battery, charge it and disconnect from auto. Check 2 days later.
I cant find the fekking 'Like' button. Where is it?

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hexibot43
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Re: Yet Another Parasitic Draw Case

Post by hexibot43 »

liviu2004 wrote:
Thu Jun 18, 2020 4:16 pm
If you suspect battery, charge it and disconnect from auto. Check 2 days later.
That is just too simple! I've got that battery fully charged again, and sitting on the bench for the weekend.

Question - How valid is this test without a fixed parasitic draw? I'm thinking I should put a .030 Amp draw on the battery to more closely simulate real world. Or will that battery loose its charge just as quickly as it was without a nominal external drain?
Last edited by hexibot43 on Tue Jun 23, 2020 1:36 am, edited 1 time in total.

liviu2004
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Re: Yet Another Parasitic Draw Case

Post by liviu2004 »

If your suspicion is correct, battery might have some form of internal short circuit. No external load needed to prove that. I’m not a battery specialist, just trying to think along.

ronw38
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Re: Yet Another Parasitic Draw Case

Post by ronw38 »

Hi Hexibolt Liviu is on the money for a simple test it works. A further test is refit battery to vehicle batt voltage at 12.6 to 12.45V switch headlamps on 10 mins check voltage, crank to start check min crank voltage, a sulfated or weak battery will drop quickly. Test results for a vehicle I just did Rest volts 12.55 Headlamps on 10 mins 11.86V Crank and start 10V Charge rate lifting to 13.5V Switch off within 1min battery recovery voltage after a short rest to dissipate surface charge 12.54V If you have acceptable parasitic draw it only leaves driver error or battery? Cheers Ron W

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hexibot43
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Re: Yet Another Parasitic Draw Case

Post by hexibot43 »

This one is elusive. I did all the normal testing. Charged the battery fully. tested with both of our captive battery testers earlier in the week. I truly believe in running the headlights as suggested , watching what it does to Open Circuit Voltage. No sign of issue. Starts fine. None of the normal tell tales. And those usually do tell the story. I've had a new battery in the vehicle since last Monday. It has kept its charge.
Sure looks like the battery was the issue. Since Friday I've had the "Bad" battery on my bench. Tomorrow I'll take another look. But all the normal tests were inconclusive. No quick fall off in voltage with the load of the headlamps. And I swear by that test. And all of that is why I bought that data logging DVOM. Crossing my fingers that tomorrow that battery is low in charge with nothing connected to it.
And then I might finally believe what that new meter is telling me.

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