Tell me if I'm doing this right with my multimeter (UPDATE)

[Tinstar]

I'm trying to measure the parasitic drain on my battery. I know how to do it with a multimeter but I'm not positive about the digital reading after the measurement.

I've got my meter set to DC current with the leads on COM and the 10A MAX ports. I take the reading between the negative battery post and the negative battery cable. The battery is at 13.4 volts (fully charged). Everything is turned off, no lights, no radio, key off, etc. etc. etc. Everything is as it should be to check the current draw. I know there should not be any more than 1/2 of an amp draw reading (unless there's something wrong). That half amp is the parasitic drain and keeps the radio setting, computer/s, etc. active.

Now for my question about the readout: My reading is 0.24 on the 10 amp scale OR 2.5 on the 200m scale. As I understand it, I have 1/4 amp draw. Am I correct in my assumption? If so, all is good and there is no out of the ordinary parasitic drain.

[All_I_could_aff]

Use alligator clips or similar devices so you could attach the leader to both sides and then walk away for at least 5 minutes and then take a reading. Most cars go through a few minutes of higher than normal draw when electronics our first connected. It Will likely drop but also keep in mind many electronic meters will go into an auto shutdown mode after a few minutes, so maybe take a look every two minutes or so and note the readings

[babock]

Let the car sit for at least 20 minutes while keeping the meter connected and the doors shut. Reason is that many cars have ECUs that go into sleep mode once all the doors are shut after a certain time.

[Tinstar]

clotus wrote:
13.4 volts? Seems too high. A fully charged 12-volt battery sits at or around 12.7 volts. For more accuracy I would let the battery rest a bit before you start testing.

That being said your testing was probably "close enough for government work."

Hahahaha, "close enough for government work". You are right but I had just disconnected the charger when I took that reading. I don't know if that made a difference or not. I may check it again tomorrow after it has sat for 24 hours without a charger.


BTW, for those of you that commented on the 2.5 reading on the 200m scale. You're probably right. My amp draw was more than 200 milliamp and was actually 250 milliamps. I don't think I could get an accurate reading since I was exceeding the 200 milliamps.

[Tinstar]

theoldwizard1 wrote:
BTW Tinstar you get a GOLD STAR for using the proper procedure with the multimeter ! When measuring an unknown amount of Amps, always start with the HIGHEST amperage scale, which usually has a separate input.

For individually fused circuits, if you can find a chart of fuse resistance on the internet and know how to use Ohm's Law, you can measure the individual circuit draw by just measuring the voltage drop across the top of the fuse (yes, there are spots to do this on top of all automotive type fuses). No adapters reqired. Nothing to unplug.

Thanks for the Gold Star. I did read about the procedure you described but it got confusing to me so I went old-school.

[theoldwizard1]

Tinstar wrote:
In further research, I got out my owners manual. There is a section on fuses that clearly states. "IF THE VEHICLE IS PARKED AND NOT OPERATED FOR PROLONGED PERIODS. PULL THE "ROOM" FUSE.

Not the best design !

Most auto manufacturers shoot for about a 2 week window before running a battery flat from those types of loads.


BTW Tinstar you get a GOLD STAR for using the proper procedure with the multimeter ! When measuring an unknown amount of Amps, always start with the HIGHEST amperage scale, which usually has a separate input.

There are some reasonably priced (<$50) "amp clamp" meters on Amazon. I bought a Uni-T B4Q094 last year.


For individually fused circuits, if you can find a chart of fuse resistance on the internet and know how to use Ohm's Law, you can measure the individual circuit draw by just measuring the voltage drop across the top of the fuse (yes, there are spots to do this on top of all automotive type fuses). No adapters reqired. Nothing to unplug.

[theoldwizard1]

Tinstar wrote:
I guess I need to correct my original post.

I just watched a YouTube video and it says I should have no more than 50 milliamps. That makes me have a draw 5 times higher than the max it should be. I think........

CONCUR !


You might get an OCCASIONAL jump up to 500ma (0.5A) if a computer wakes up and reads a few sensors. This should be for a brief (< 30 seconds) period, not more often than about 10-15 minutes apart.

[clotus]

13.4 volts? Seems too high. A fully charged 12-volt battery sits at or around 12.7 volts. For more accuracy I would let the battery rest a bit before you start testing.

That being said your testing was probably "close enough for government work."

[shepfly]

You can buy fuse taps which attach to the separate blades on a fuse, giving you a jumper across the fuse where you can place a switch and an additional fuse holder. Now you use a blown fuse to replace you original fuse, you circuit is now fused and switchable. Dave

[Tinstar]

In answer to a few comments/questions:

The toad is a 2008 Kia Spectra. The key fob is the older style and is not proximity-activated.

I do have a Battery Minder and I've had it on there since the last time it discharged. That may be what I do instead of pulling the fuse. Either one, plugging in or pulling the fuse, is a little bit of a PITA. My previous toad could sit 3 or 4 months and there was no significant battery drain. I will avoid taking it to a dealer. It's a known "problem" according to the Kia forums so you're right. It would be money thrown away for them to tell me it's working as it should.

I thought about just wiring in a small switch and mounting it under the dash. I am trying to figure out how to wire it. The fuse is very accessible but putting it in line with the present fuse wiring would require pulling the fuse box to get to the wire. Here's how I think it could be done: I could put a small blade terminal in one side of the fuse holder, an in-line fuse, a switch then another blade terminal on the other side of the fuse holder. That way I could just flip the switch. It would be easier than pulling the fuse block cover then pulling the fuse then replacing the cover. Anyone see a problem with this wiring idea?

[azrving]

Or put a switch in that circuit.

[MountainAir05]

A lot of new vehicles required that you put some sort of charger if it sets more than a week. I have one of them. Its plug into a 4.3 amp charger anytime it not on the road. Even says in my manual put on charge or be prepared to purchase a new battery.

buy a good charger like this one Ctek. My vehicle has been on one since 2012 and still the same battery. I have a lot more draw than you.

[time2roll]

Yes you are reading the meter correct. The draw is what it is and even described in the manual. An alternative to the fuse would be a small charger on the battery for storage such as Battery Minder or Battery Tender brands.

You could have it checked at the dealer but I doubt they would know what is normal. They would just give you a half baked look like you were another crazy customer. Then they would take it in and charge $150+ to tell you all is normal.

If you have a buddy with same car you could compare numbers.

[ScottG]

I agree, 250mA is rather high. Is the key/fob kept nearby? This would keep the vehicle from "going to sleep" for some brands.

[Tinstar]

I guess I should have gone into more detail. This is on my toad. I've been having to recharge the battery if it sits for more than a few days (about a week, give or take a day).

I did start pulling fuses and I found the draw is at a fuse called ROOM. It's also known as the MEMORY FUSE. It controls the memory from the audio and A/C controls, door chime, clock and interior lights. Upon checking the draw with the ROOM fused pulled the amp draw drops to 0.00.

In further research, I got out my owners manual. There is a section on fuses that clearly states. "IF THE VEHICLE IS PARKED AND NOT OPERATED FOR PROLONGED PERIODS. PULL THE "ROOM" FUSE.

This seems really weird that a fuse should be pulled if parked for a week or longer but I didn't build it so it is what it is.