Does this sound like parasitic drain?

[DaveM]

I've been concerned about parasitic battery drain ever since my batt died on my Tacoma last year. I replaced it with a new Die Hard Platinum (same as Odyssey) last year. I get corrosion on neg terminal pretty quickly so today I thought I'd check for parasitic drain. Here's what I found (2003 DC Tacoma, all stock):

12.42v first thing this morning after sitting all night
12.81v immediately after driving today
12.64v 30 min later
12.61v 1.5 hours later

Checked for drain and found constant 50 milliamps after the computer shuts down. I have a secondary marine fuse box installed, positive to pos batt terminal, negative grounded to body where batt grounds. I pulled the inline fuse for this circuit and found it still showed 50mA.

Batt shows about 14.3v when charging off alternator.

Does this raise any alarms with anyone? I've read that a fully charged batt should read 12.75v?

Thanks,
Dave

 

[corax]

50 mA shouldn't cause any problems - is there any change if you set the alarm? sometimes an alarm will cause a drain if it doesn't see all the inputs properly

 

[java]

there are things that draw power after the truck is shut off, radio, clock etc, and 50mA isnt much. 12.8 is about as high as it will get. and 12.6 seems pretty normal to me.

 

[DaveM]

No alarm, just the clock. 50mA is supposedly the top of the range for normal drain. I'm more concerned about the 12.4v and 12.6v. I've read that at 12.4v you batt is essentially half charged? Does that sound right?

 

[java]

11.8 ish is about fully discharged.

 

[corax]

the rule of thumb I've always used is .2V drop for each 25% discharge
12.6 = fully charged
12.4 = 75% charge
12.2 = 50% charge
12.0 = 25% charge
11.8 = dead

 

[Mr. Leary]

Where is your battery located? This may have more to do with battery temperature than an amp draw. What was the weather like the day you took the above measurements?

 

[m007gunit]

^^^^^^^^agreed 50ma is very small I would test the battery and even move it if needed

 

[DaveM]

Where is your battery located? This may have more to do with battery temperature than an amp draw. What was the weather like the day you took the above measurements?

Stock location under the hood. Weather yesterday was mild, temperature range was probably between 52* - 58*.

 

[SLC97SR5]

Was the new battery fresh or had it been sitting for a few months on the shelf?

Whenever I get a new battery I slow-charge it for several hours to ensure it is fully topped off and to give my alternator a rest.

My aftermarket alarm draws 50mah on it's own.

 

[DaveM]

I just read the batt again after sitting all night: 12.4v @ 51* current air temp.

Don't know how fresh it was when I bought it, I didn't test it then. Bought off the shelf at Sears so it could have been there for a while. With that voltage, my good alternator reading and the within range drain, is it safe to assume that I don't have a heavy drain or a bad alt? But maybe just a batt that has been in need of a toping off since I bought it? Wouldn't the alternator have re-charged it all the way by now?

 

[Mr. Leary]

I just read the batt again after sitting all night: 12.4v @ 51* current air temp.

Don't know how fresh it was when I bought it, I didn't test it then. Bought off the shelf at Sears so it could have been there for a while. With that voltage, my good alternator reading and the within range drain, is it safe to assume that I don't have a heavy drain or a bad alt? But maybe just a batt that has been in need of a toping off since I bought it? Wouldn't the alternator have re-charged it all the way by now?

I think your alternator is probably fine, but its worth a check to see if it may be overcharging the battery. My alternator brings my battery to around 13.8 volts most of the time.

I always used trickle chargers on my bikes. The magnetos on the bikes don't quite function like alternators, though.

If you have really hot or cold weather, measure the voltage level during each. If I am not mistaken, the voltage should slightly increase with colder weather, and go down slightly as the battery heats up.

As long as it doesn't discharge or struggle to start, I wouldn't worry about it too much. Those batteries are pretty tough. If it is making you worry, use your warranty. I'm sure they will replace it without too much hassle.

 

[Skim]

Check the factory repair manual for the MA spec. what you have sounds high for a Toyota.

I would disconnect your dual battery set up and any other aftermarket stuff and re check your parasitic drain / MA spec. before moving forward.

Keep in mind the dealer will charge you to disconnect your aftermarket stuff so that they can parasitic drain test your vehicle.
Warranty does not pay for customer add-ons.

 

[DaveM]

Check the factory repair manual for the MA spec. what you have sounds high for a Toyota.

I would disconnect your dual battery set up and any other aftermarket stuff and re check your parasitic drain / MA spec. before moving forward.

Keep in mind the dealer will charge you to disconnect your aftermarket stuff so that they can parasitic drain test your vehicle.
Warranty does not pay for customer add-ons.

No dual batt, just a second fuse box and an LED lamp. I disconected it before checking drain, no change. Also checked while pulling fuses from cab fuse box and found no drop (didn't check fuses for flashers or wipers though).

I have the FSM in pdf but can't find a value for the expected batt drain? Anybody her with a stock 2003 DC taco want to check your drain to compare?

I'm relatively confidant that I don't have a parasitic drain or a bad alt. So I'm going to re-charge the batt with a buddy's charger, check the batt over the next few days and see what happens. If it drops below 12.65 right away I'll take it back to Sears and have them test and possibly repalce it.

 

[DaveM]

Took batt & truck to Sears. They tested the charging system, it was ok and they didn't see an excessive drain. They also said the batt was ok. They charged the batt for 10 minutes back up to 12.65 and I went home. Next morning... 12.39. Thats a bad battery right? I'm taking it back to them Saturday for a full re-charge.

BTW, they tried to tell me that I would have to pay for the test regardless of whether or not the batt was bad... I raised hell and changed his mind but beware of this BS. If they have to test the batt to validate their return policy then the dimes on them if it fails.