Vampires and multimeters

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   Even small continuous current drains can add up.  Add all of your steady state drains together... that is the amp hours you will be consuming continuously.  So lets say you have a total of 0.15A continuous drain.  That is 0.15 X 24 = 3.6AH per day.  If you have a 50AH battery, just that drain alone will drain it to 50% in just under a week.  Not much of an issue if you have solar power, but if you are running off battery without means of recharging that is 3.6AH (or 25AH per week) that you could have been using for something else.  
On my Rpod, the antenna amp has a similar drain to yours but it is switchable.  We have solar power so I have not looked too closely at the steady state parasitic drains..... I would assume they come from the gas detector, the fridge electronics, the radio and the water pump light (if left switched on).  

One thing that is CRUCIAL since you cannot easily eliminate all parasitic drains is to MAKE SURE you have means of disconnecting the battery when in storage.  We bought our Rpod used and the battery was partially damaged because it was never disconnected.  The steady state drains ran it down to zero and it was left there for extended periods.  That is VERY bad for a lead acid battery.  Ours should have been about 50AH capacity but it measured about 32AH in a measured discharge test after a couple equalizing charges.  Frankly I was surprised it was that good.  

I have since replaced that battery with a pair of 50AH deep cycle batteries and have added a simple disconnect so I can shut things down when the trailer is not in use.  

While we're talking batteries..... if you have a battery box with a vented top cover, make sure the battery box is not full of water.  I bought two battery boxes for those two batteries and they had shielded vents in the top cover.  Unfortunately, any standing water on the top surface of the cover can easily run through the vent holes and into the box.... which does not have a drain hole.  To make matters worse, the battery boxes sit directly under the drip line off the front of the trailer.  I plugged the vents and drilled a small drain hole in the bottom of each box.  I would have preferred to leave the vents open since hydrogen can potentially accumulate in the upper part of the lid in very still air but I figured the lid is still fairly well ventilated and that was the lesser of two evils.  

Paul

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pgoelz Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 22 Jul 2016 Online Status: Offline Posts: 70	Topic: Vampires and multimeters Posted: 08 Aug 2017 at 7:26am
	Even small continuous current drains can add up. Add all of your steady state drains together... that is the amp hours you will be consuming continuously. So lets say you have a total of 0.15A continuous drain. That is 0.15 X 24 = 3.6AH per day. If you have a 50AH battery, just that drain alone will drain it to 50% in just under a week. Not much of an issue if you have solar power, but if you are running off battery without means of recharging that is 3.6AH (or 25AH per week) that you could have been using for something else. On my Rpod, the antenna amp has a similar drain to yours but it is switchable. We have solar power so I have not looked too closely at the steady state parasitic drains..... I would assume they come from the gas detector, the fridge electronics, the radio and the water pump light (if left switched on). One thing that is CRUCIAL since you cannot easily eliminate all parasitic drains is to MAKE SURE you have means of disconnecting the battery when in storage. We bought our Rpod used and the battery was partially damaged because it was never disconnected. The steady state drains ran it down to zero and it was left there for extended periods. That is VERY bad for a lead acid battery. Ours should have been about 50AH capacity but it measured about 32AH in a measured discharge test after a couple equalizing charges. Frankly I was surprised it was that good. I have since replaced that battery with a pair of 50AH deep cycle batteries and have added a simple disconnect so I can shut things down when the trailer is not in use. While we're talking batteries..... if you have a battery box with a vented top cover, make sure the battery box is not full of water. I bought two battery boxes for those two batteries and they had shielded vents in the top cover. Unfortunately, any standing water on the top surface of the cover can easily run through the vent holes and into the box.... which does not have a drain hole. To make matters worse, the battery boxes sit directly under the drip line off the front of the trailer. I plugged the vents and drilled a small drain hole in the bottom of each box. I would have preferred to leave the vents open since hydrogen can potentially accumulate in the upper part of the lid in very still air but I figured the lid is still fairly well ventilated and that was the lesser of two evils. Paul

GlueGuy Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 15 May 2017 Location: N. California Online Status: Offline Posts: 2709	Posted: 07 Aug 2017 at 4:13pm
	+1 to what spydie said. To add a teeny bit more information, .1 amp at 12 volts is 1.2 watts. That is pretty low, and I don't know how much it would be worth to eliminate it.
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spydie Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 25 Jul 2017 Location: New Mexico Online Status: Offline Posts: 159	Posted: 07 Aug 2017 at 12:33pm
	Makes no difference what you have the multimeter set at, 0.10A is always 1/10, or 10/100ths of an amp. I think there is always going to be some draw on your battery unless you disconnect the battery. Our cars also have phantom draws continuously as there are things running in the background all the time.
	2018 R-pod 176 2017 RAM 1500 5.7L Hemi

GLBCamper Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 30 Jun 2015 Location: Oregon Online Status: Offline Posts: 274	Posted: 07 Aug 2017 at 12:29pm
	I am on a quest to track down the cause of my batteries draining quicker than expected. I am trying to be methodical about it and one step I often see suggested is to pull each fuse and test the circuit with a multimeter. Everything is OFF and aside from the expected .008 (multimeter set to 10A) draw from the LP/Gas detector I was surprised to find the TV antenna circuit @ 0.11 and maybe less surprised by the radio @ 0.08. BTW, both of these were labeled unintelligibly, so I tracked them down myself and verified that they are the only thing (that I can find) on that circuit. My first question is, is that so small that I shouldn't worry about it. Is there a way to disable those two things that I RARELY use? If I just pull the fuse then the little red light next to the circuit stays on which seems like a draw, too. My second question is, not being familiar with a multimeter, is 0.10A at the 10A setting one amp or one tenth of an amp or one one hundredth of an amp?
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