Vampires and multimeters |
Post Reply | Page <1234 6> |
Author | |
spydie
Senior Member Joined: 25 Jul 2017 Location: New Mexico Online Status: Offline Posts: 159 |
Topic: Vampires and multimeters Posted: 08 Aug 2017 at 10:58am |
+1 Paul
|
|
2018 R-pod 176
2017 RAM 1500 5.7L Hemi |
|
CharlieM
Senior Member Joined: 23 Nov 2012 Location: N. Colorado Online Status: Offline Posts: 1797 |
Posted: 08 Aug 2017 at 11:21am |
Two 12V batteries are not necessarily any better. Most 6V batteries used are 220AH GC2s. Together they provide 12V at 220AH. The usual 12V battery is a Gp24 with about 86AH so a pair would provide 12V at 172AH, which is significantly less than the two GC2s. That said it still seems the OP has a significant constant load on his batteries. The only way to confirm this is to put the ammeter in series right at the battery terminal or use a clamp on ammeter around all wires right at the battery terminal. This means all connections including the load distribution (fuse) panel, solar panels, breakaway brakes, and power tongue jack if applicable. If a significant load is confirmed the isolation and troubleshooting process can begin. If no significant load is found it points to the battery or charging system. |
|
Charlie
Northern Colorado OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD |
|
GLBCamper
Senior Member Joined: 30 Jun 2015 Location: Oregon Online Status: Offline Posts: 274 |
Posted: 08 Aug 2017 at 12:45pm |
In my driveway (so not camping) I am am fully charging the batteries by plugging into 30A shore power for several days.
Then I disconnect shore power and am checking the batteries on the battery terminals without the solar panel hooked up and bypass is PULLED. I check it everyday at the same time using a multimeter. It shows around 12.85 first day, 12.83 second day, 12.80 third, etc. as expected. Then I put the bypass back in and get a slightly quicker drop (again, as expected) due to my identified parasitic loads. But when camping, the only thing I am adding is running the fridge (mine does not have 12v function), running the water pump for maybe a total of 5 minutes and turning on one LED light for maybe a total of 10 minutes and I will go from 12.6 to 12.0 by the next morning. None of those things seem like a HUGE draw. So I guess that narrows it down a bit, but I'm not sure what to do next.
|
|
Old: 2014 177 HRE
2015 Tacoma V6 4x4 Double Cab New: 2016 EVO ATS 200rd 2016 F150 4x4 Sport |
|
pgoelz
Groupie Joined: 22 Jul 2016 Online Status: Offline Posts: 70 |
Posted: 08 Aug 2017 at 1:12pm |
Well, them SOMETHING you do while camping is the culprit.... or the batteries have much less capacity than you think they do. Without better instrumentation and data, there is no accurate way to tell. But some possibilities I can think of would be: 1. Water pump firing intermittently all night. 2. One or more lights is NOT an LED and is on and drawing more power than expected. For example, all interior lighting in our 2014 171 is LED. However, our porch light and trailer hitch lights are incandescent. 3. Brakes engaged? Feel the drums after a while and see if they are warm. 4. Faulty converter, drawing power when not charging. 5. Vent fan running and drawing lots of power. 6. Refer drawing more power than expected.... like either defective or running a mullion heater or defroster (just guessing). 7. Trailer plugged into the tow vehicle and powering something unexpected in the TV. Draining 200+ AH of battery from 12.8 to 12.0 overnight is a LOT of power.... if the batteries are healthy. That would be a 10-20 amp discharge and more than ANY single device in an Rpod should draw. But as was said earlier, if you can't identify the culprit you MUST measure the steady state drain directly from the battery in "camping" mode or you will never know what is going on. Paul
|
|
CharlieM
Senior Member Joined: 23 Nov 2012 Location: N. Colorado Online Status: Offline Posts: 1797 |
Posted: 08 Aug 2017 at 1:14pm |
Try a simulated camping trip in the driveway. Everything hooked up as you would at the CG. Hook the ammeter up in series and leave it. I'd also check the drain with the solar hooked up but dark. The panels may be drawing current when they're dark. If the measured load is minimal and the battery drains overnight you're a candidate for a battery transplant.
|
|
Charlie
Northern Colorado OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD |
|
pgoelz
Groupie Joined: 22 Jul 2016 Online Status: Offline Posts: 70 |
Posted: 08 Aug 2017 at 1:18pm |
I should add that it might be time to take a closer look at your batteries. Have a local battery house measure and evaluate the specific gravity for starters. And if you can access each cell, measure each cell as the battery is being charged.... and then discharged in camping mode. They should all be the same voltage. A low or high cell at any point would be very suspect.
Paul
|
|
Guests
Guest Group |
Posted: 08 Aug 2017 at 3:15pm |
I agree with CharlieM: The only way to confirm this is to put the ammeter in series right at the battery terminal or use a clamp on ammeter around all wires right at the battery terminal. This means all connections including the load distribution (fuse) panel, solar panels, breakaway brakes, and power tongue jack if applicable. If a significant load is confirmed the isolation and troubleshooting process can begin. If no significant load is found it points to the battery or charging system. I run two of these: batteries Under "normal" camping conditions, they'll last for days. |
|
GLBCamper
Senior Member Joined: 30 Jun 2015 Location: Oregon Online Status: Offline Posts: 274 |
Posted: 08 Aug 2017 at 4:34pm |
Brakes are good. I check them regularly with a laser thermometer. Hubs and brakes run low 100's while towing, even on VERY hot days.
I think my next step is to add each item to the mix one at a time while in the driveway. I'll start with the fridge and leave it on a couple of days. See what happens.
|
|
Old: 2014 177 HRE
2015 Tacoma V6 4x4 Double Cab New: 2016 EVO ATS 200rd 2016 F150 4x4 Sport |
|
pgoelz
Groupie Joined: 22 Jul 2016 Online Status: Offline Posts: 70 |
Posted: 08 Aug 2017 at 4:52pm |
Why not just use your multimeter to measure your total battery current? Doing it by enabling one item at a time could take a long time. Set it to the 10A scale and insert it between the two batteries. Observe polarity and it will tell you if you are charging or discharging and at what current. If your MEASURED parasitic current multiplied by the number of hours it is being drawn is less than the assumed battery capacity, one or both batteries is bad or they were not fully charged in the first place.
Make sure you do not power on anything that draws significantly more than 10A with the multimeter in the circuit or you could either damage the meter or blow an internal fuse. The answer is out there....... Paul
|
|
pgoelz
Groupie Joined: 22 Jul 2016 Online Status: Offline Posts: 70 |
Posted: 08 Aug 2017 at 5:25pm |
Also, you never stated what the assumed battery capacity is. We are assuming you are using a pair of 6V golf cart batteries, which would get you 12V at >200AH. What are you actually using and exactly how were these batteries tested for capacity? It is not possible to do accurately in any short term test. You can infer capacity using a cold cranking amp tester but the most reliable way is simply to discharge at a constant known current for a known period of time to a known state of charge and do the math. Does the AH consumed (discharge current X discharge hours) roughly equal the capacity removed based (starting % charge - ending % charge X rated battery capacity).
Like I have said, you are either drawing significantly more current than you think you are (and the ammeter will reveal that immediately) or the batteries are way below rated capacity. Or another possibility.... your multimeter is not well calibrated or is measuring low due to wiring drops..... do your voltage measurements with the meter directly on the battery terminals. Paul |
|
Post Reply | Page <1234 6> |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |