mA draw w/ truck turned off?

My 2018 TRD Offroad will barely start after sitting for about 2 days at lower temps (15 at night, 30 during the day) and will only last about a week when it's a bit warmer.
Dealer checked the battery and said it was OK (big surprise ha!) --- CCA was about 40 amps lower than specs but otherwise "no issues". I had asked for a full inspection but they just checked capacity instead so I have to bring it back middle of January. Decided to measure parasitic draw myself and saw about 0.25 amps after it settled down...is this normal? I did a search on this forum and found ranges deemed "normal" ranging anywhere from a few ma to 0.5 amps. I have a few aftermarket things, but none should contribute much (if anything).

Appreciate any insight....

Thanks,

Bernie

 

I work for another Japanese auto manufacturer and our spec is .025 amps, anything higher then that is considered a draw.

That being said, if your battery is testing 40 cca's lower then spec I would think that battery is on it way out. It also could have a bad cell. I would recommend making sure they load test it after it sits over night. Another method I do is turn the key to accessory, turn everything electrical on, and see if that battery last 10 to 15 minutes. Then retest it. It will usually fail then. You could also pull in the service drive and do the same thing, leaving all electrical loads on, and hopefully by the time it's written up it's dead.

 

It is very hard to measure DC mA current draw without a very accurate meter. Background noise from the neighbourhood will almost always skew the results unless you use an inline meter or take care to zero you clamp meter.

How were you measuring current?

 

At 0.25A for 48 hours, that equals 12 Amp-hours. Even a small auto battery is good for around 45 Amp-hours, so either your battery is bad (significantly decreased capacity) or you are getting a higher current draw at times other than when you measured it. I'm not knowledgeable of Tacoma parasitic current draws, but I sure wouldn't be happy if I found out mine draws a quarter amp with the truck shut down. I found a link to a good video in the forum for checking parasitic current. I would start by checking the fuses in the interior fusebox, then if the problem is not there, the fusebox under the hood. He gives good safety advice to protect you and your meter in the video as well.
https://www.youtube.com/watch?v=KF1gijj03_0

 

That is an odd spec to be rating the battery on when tested? When I test a battery I don't look at the CCA, (outside of noting the CCA for testing purposes) I look for the voltage drop when the battery is loaded up to ½ the CCA over 15 seconds. If the battery drips below about 10 volts (depending on temp) then it has failed. I personally don't like the capacitive battery testers. I have seen them pass a died battery.

 

Well, just between the disconnected negative cable of the car loom and the battery terminal. My go-to meter is an old Fluke ET73DMMA - but I did confirm with my secondary meter (and different leads). I do have to admit that I don't know how modern cars behave, so I might not have waited long enough after closing the doors etc. (maybe 15 min tops). The battery voltage is also quite low at 12.25 V so I might have to charge it first. Either way, 250 mA seems way too high for my liking - but again, I don't know if the truck was fully "asleep" or not...

 

Yea, I thought so, too....
This was Toyota's "maintenance" department - I don't think that the people there are overly qualified (hope I'm not offending anyone).

 

Toyota spec is 0.060A

Usually takes 2 hours, and need the smart key in another time zone.

 

What's the consensus on pulling fuses to do the test? I thought that's a no-no on modern cars, as pulling the fuses can computers to wake up etc. I was going to measure the mV drop between the fuse terminals and then look up the associated amp draw on one that doesn't drop to zero...

 

Oh wow...OK, will rerun the test tomorrow. Doesn't the truck always search for a smart key? I guess I don't understand what it does if the key is out of range?

 

It does always search, but if the key is close, it stays "ready".

Some luxury cars will actually cycle the fuel pump when the key is near.

 

That’s within spec. Usually anything over .5 is considered a current draw. Most modern vehicles are around .25 - .30 after all the CAN Modules and everything shut down and the BCM goes to sleep.

Also if testing on a vehicle with a smart key, just make sure the key is 10ft or more away from the vehicle

 

Ive been testing a capacitor type battery setup over the past year or so. Capacitors have very little reserve so I've been watching my mA draw closely. For a couple minutes after shutoff, mine's around .25 amps. After that it drops to a resting state of .01 to .02 amps. I have zero accessories added on and no keyless entry. Those decimals are in the right place.

 

You’ll only need to pull fuses if there is an actual draw. Yes pulling fuses will wake up modules and cause a spike, until the network goes back to sleep. However nothing should go above the 10amps or whatever your meter is fused at. Also make sure the battery in your fluke is good otherwise it can give you a bad reading. I learned that the hard way on my fluke once.

 

Mines sits for days at a time in freezing weather in a detached unheated garage and no problems

 

Your battery voltage is 12.25v with no load? That is dead! It should 12.6v

 

Well you have a good meter. Based on your added details, I would check it again

I'm seeing numbers all over the place in this thread, some are not credible, but yours is. Do you have a source for that spec? It is consistent with other things I've read. I'm an electrical engineer, but not automotive, and learning all I can about my new Tacoma. From what I've found so far, I would not think that anything above 50 ma (0.050A) or the spec you provide is normal, unless aftermarket devices have been added, or maybe even OEM add-ons.
https://shop.advanceautoparts.com/r...ned-overnight-how-to-fix-parasitic-power-loss

 

@maybeme, this might be your answer right here, he also measured 0.25A initially, then later at the lower values. Try it again using his advice and waiting a good while, doors closed, everything off
After all I've read on the forum and at auto sites so far, 0.25A continuous is way too much current draw to be normal.

 

Toyota stopped publishing a drain spec a long time ago, but in training they teach us 0.060 to 0.080 (varying accessories, we have lots of remote starts in canada)

 

Good enough for me, thanks. Do you see any concerns with disconnecting the negative cable for measuring the current, or pulling fuses to try to identify the source of a current draw (as someone mentioned above)? I would think that it should not be a problem, that any control module computers would reboot on power up, however for disconnecting the battery cable I would expect that the radio might require a code as is the case with my Honda cars?