Vampires and multimeters - R-pod Owners Forum

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GlueGuy

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Topic: Vampires and multimeters
Posted: 10 Aug 2017 at 12:36am

Originally posted by GLBCamper

Honestly I feel like an absolute idiot here, but I have a multimeter and not an ammeter, which should do the job, but I'm confused what you mean by "across the open battery cutoff."

In order to measure current, your meter must be in series with the batteries.

In your case, you have an easy way to do this. First, remove the wire/cable that runs between the two batteries. It will be connected to the (+) on one battery, and the (-) on the other battery.

Then put your meter into DCA (DC Amps) mode. based on what we've been seeing, you hopefully have a meter that can go to 20 amps (because I think that may be in the neighborhood of what your drain is). Set it to that mode (if it has it, or higher if necessary).

Now here is the tricky part. You want the meter to measure the flow of current. The meter will be polarity sensitive, so you want to connect the red (positive) lead to the (+) terminal on one battery, and the black (negative) lead to the (-) terminal on the battery. This is the same terminals that you removed the jumper in the first step.

At that point, your meter should be showing you the amps that are being drained. If your meter is not big enough, you may blow a fuse in the meter.

bp
2017 R-Pod 179 Hood River
2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost

CharlieM

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Posted: 09 Aug 2017 at 11:55pm

You are correctly measuring voltage and they seem reasonable for what you're doing. What we need are current measurements. You should disconnect the jumper between your two batteries and insert the multimeter in place of the jumper. With the jumper disconnected :

Plug the red test lead into the jack marked 10A on the multimeter
Plug the black test lead into the jack marked COM on the multimeter.
Set the multimeter range selector switch to 10A on the DCA section of the meter switch.
This is all described on page 5 of your instruction manual under "DC Current Measurements".
Be very careful with the following steps. An error here can destroy your multimeter.
Connect the positive (red) lead of the meter to the positive terminal of the battery that has its negative terminal connected to ground.
Connect the negative (black) lead of the meter to the negative of the battery that has its positive terminal connected to the camper.

The meter should read positive values for current flowing out (discharge) of the battery and negative values for current flowing into (charging) the battery. Start with everything off and the battery disconnect switch in the disconnected position. It should read zero. With everything off in the camper, close the disconnect switch and you should see a small value much less than 1A. Continue turning things on and recording the readings. Let us know what you find.

Charlie
Northern Colorado
OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD
PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD

GLBCamper

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Posted: 09 Aug 2017 at 11:19pm

I am using a CenTech multimeter model 98025. I have it set to DCV 20 and am touching the red lead to the positive on the battery with the positive line connected to it and the negative lead to the negative terminal on the other battery with the ground wire attached. Wrong? Here is my log: I'm not seeing a smoking gun yet.

7/31 @ 10:00am 12.86 w/battery cutoff

8/1 @ 10:00am 12.87

8/2 @ 10:00am 12.83

8/3 @ 10:30am 12.81 Plugged in cutoff switch. Everything off except LPGas Detector.

8/4 @ 9:30am 12.60

8/4 @ 12:00pm ran power jack several times (bummer for my tests, but the neighbor was spray painting his house and I had to move it.)

8/5 @ 9:15am 12.51

8/6 @ 10:45am 12.45

8/7 @ 9:45am 12.42

8/7 @ 10:10am plugged into 30A shore power

8/8 @ 9:00am unplugged from shore power

8/8 @ 9:45am 13.00

8/8 @ 2:43pm 12.93 turned on fridge on propane

8/9 @ 10:00am 12.60

8/9 @ 3:20pm 12.47

Old: 2014 177 HRE
2015 Tacoma V6 4x4 Double Cab
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2016 F150 4x4 Sport

CharlieM

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Posted: 09 Aug 2017 at 8:48pm

As Paul says, until we get some real current measurements we are just shooting in the dark with no sights. Putting the ammeter across the open battery disconnect switch will measure the current drawn from the battery but I'd rather you measure directly at the batteries. Sometimes loads are connected before the disco switch so, to be sure, measurements should be made right at the battery. With two GC2s in series the easiest method is to disconnect the jumper between the two batteries and connect the ammeter in place of the jumper.

Most multimeters have a DC current function. It should be labeled DC Amperes, DC Amps, or DC current. Typical ranges will be 10A or 20A. If you'll tell me the make and model of your multimeter I'll look it up and help you with it.

Charlie
Northern Colorado
OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD
PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD

GLBCamper

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Posted: 09 Aug 2017 at 6:00pm

Originally posted by pgoelz

Put an ammeter across the open battery cutoff and measure the current in camping mode. That will tell you in seconds whether you have a parasitic drain or a battery issue.

Paul

Honestly I feel like an absolute idiot here, but I have a multimeter and not an ammeter, which should do the job, but I'm confused what you mean by "across the open battery cutoff."

It's been parked since July 29th but I plugged it into 30A on August 7th for 24hrs. Charge after being unplugged for 6 hours to allow for decay was 12.93.

Old: 2014 177 HRE
2015 Tacoma V6 4x4 Double Cab
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2016 F150 4x4 Sport

GLBCamper

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Posted: 09 Aug 2017 at 5:50pm

Originally posted by furpod

Originally posted by GLBCamper

OK, Idiot question, but can the converter draw amps when not connected to shore power? I thought the converter served only to convert AC (shore power) to DC (to charge the batteries.) But can, or does, it draw amps or serve any purpose when NOT on shore power?

The converter/charger only works, and is only energized when 120v is present. It does not do anything, nor is it energized, just like everything else 120v when 120v is not present.

I thunked right!

Old: 2014 177 HRE
2015 Tacoma V6 4x4 Double Cab
New: 2016 EVO ATS 200rd
2016 F150 4x4 Sport

furpod

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Posted: 09 Aug 2017 at 5:48pm

The converter/charger only works, and is only energized when 120v is present. It does not do anything, nor is it energized, just like everything else 120v when 120v is not present.

pgoelz

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Posted: 09 Aug 2017 at 5:29pm

Originally posted by GLBCamper

My batteries are two 6v ACDelco GC2-107. I'm not sure what that means in terms of group or amp hours.

I only turn the water pump switch on when needed so it's not coming on periodically due to pressure loss. It seems to be working normally.

The unit has been in my driveway for over a week. I just went and measured the brakes using a laser thermometer and the temp was 95 degrees (ambient temp 91 is degrees.) Pin is not pulled.

OK, so we're not talking about an Rpod. In that case, I don't know what specific questions to ask about installed equipment, but I'd be happy to keep trying. But without some specific current consumption measurements at the battery, we're just taking pot shots in the dark. Put an ammeter across the open battery cutoff and measure the current in camping mode. That will tell you in seconds whether you have a parasitic drain or a battery issue.

I can't find an exact match for that battery but it LOOKS like it is a 230AH golf cart battery. So plenty of capacity if that is what they are and they are healthy. A big IF. IF the batteries are healthy and fully charged, anything that can drain them overnight is drawing a LOT of power and almost certainly will either make noise or get hot.

If the unit has been in the driveway for a week, has the battery been connected all that time? What was the voltage before / after? What loads were connected? And was the brake system connected as well?

Paul

GLBCamper

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Posted: 09 Aug 2017 at 5:24pm

OK, Idiot question, but can the converter draw amps when not connected to shore power? I thought the converter served only to convert AC (shore power) to DC (to charge the batteries.) But can, or does, it draw amps or serve any purpose when NOT on shore power?

Old: 2014 177 HRE
2015 Tacoma V6 4x4 Double Cab
New: 2016 EVO ATS 200rd
2016 F150 4x4 Sport

GlueGuy

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Posted: 09 Aug 2017 at 4:50pm

Boy, those are obscure batteries. Looked all over the place to get a 20 hour rate in amp-hours. I "think" I found them, and they are 208 AH. That gives you approximately 1,248 watt-hours for one, or 2,496 watt-hours for both batteries (100% discharge). If they are really deep cycle, then you can safely discharge them 50%, or 1,248 watt-hours.

Assuming your parasitic load is 2 watts, that should give you over 3 weeks usage. That ain't what you got.

If you're discharging in 24 hours, then you have something in the neighborhood of a 20 amp load. Things should be getting HOT, and I mean HOT!

bp
2017 R-Pod 179 Hood River
2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost