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Discussion Starter #1
From the beginning, we have had a parasitic draw which rounds up to 0.1A, presumably from the sum of all the LEDs on USBs, etc. Totally acceptable.

Last week we added a second battery. Everything else stayed the same. Suddenly, the parasitic draw started jumping around between 0.8A and 2.0A. This is only when the van is on DC. It goes back to the 0.1A when the van is plugged to shore power. No, this is not the fridge. When the fridge kicks in, the draw increases accordingly.

Inverter is turned on only when it is to be used. Never left on. Charger is wired only to shore power. We have a Surepower 1315 bidirectional isolator.

There is a battery cut-off switch between the van battery and the isolator (not sure why). I can make the numbers change by turning this switch on and off.

We'd like to get this figured out before we add solar to the mix.
 

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2014-159 HR in CT
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Hmmmmm.

Could the 120V to 12V shore power charger be putting a small load on the batteries when not powered by shore power?

Because the isolator is bidirectional, could the aux batteries be charged a bit higher than the van battery and be trying to equalize the voltage? Your cutoff switch comment points me to this possibility.

Do you have a "start lamp"? The data sheet says the start lamp indicator provides about .25 amps to the indicator light (or led)

ed
 

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Discussion Starter #3
When not on shore power, the battery charger is off. No lights, nothing, nada. Its power is effectively an extension cord from shore.

We wondered about power draining to the van battery. They do seem to track pretty closely voltage-wise, but why now this huge draw that wasn't there before?

Or could there be something mis-wired to the meter, given that coincidentally or not, the total apparent draw is approximately twice what it was? The argument against that is that the incremental increase when the fridge turns on is the same as before.

What is this "start lamp"?
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
Seems like Proeddie might be on the right track -- ie that it has to do with the isolator.

The isolator relay/solenoid might draw about that much current. Maybe disconnect the wire going the isolator that activates the relay and see what happens.

If you have DC fuse panel, try pulling fuses one at a time so see if one of the DC loads is associated with the extra drain?

Gary
 

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Ms,

According to the data sheet...

Start Lamp output: This is the start lamp drive output. The start lamp is powered when the start signal input has caused the relay to close. This output can source up to 250mA to an incandescent lamp.

Do you have an indicator light that tells you when the van battery is connected to the aux batteries? (ie. when the van is running and the aux batteries are charging)

When I mentioned the charger, I was thinking that, even though the charger is not connected to the shore power (120VAC), the aux batteries are still connected to the charger terminals. Some charger circuits might show a small load on the batteries if the charger is connected but not powered. It's like if you have a battery charger for your AA cell batteries. Some chargers say to remove batteries if you're not charging them. OTOH, and RV type charger should not show any load on the batteries when not charging....note the word "should"

"We wondered about power draining to the van battery. They do seem to track pretty closely voltage-wise, but why now this huge draw that wasn't there before?"... the addition of a second new battery might make just enough differential between the aux batteries and the van battery to create a little more flow toward the van battery as it tries to bring it up to aux battery voltage

ed
 

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Discussion Starter #7
We do not have the indicator light on the isolator.

Flipping the battery disconnect switch should stop any flow from house to van batteries, yet it can increase the draw.
 

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On my system the aux battery voltage can be high enough to close my 2 way voltage sensitive relay and the van battery is at a lower voltage so I'll get current flow from the aux battery . I avoid that by manually switching it off, but I see from your last comment that you tried that and it increased the draw, so that has me stumped.
 

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"There is a battery cut-off switch between the van battery and the isolator (not sure why). I can make the numbers change by turning this switch on and off."

Is this a high current switch between the isolator and van battery or a low current switch that connects to the isolator and then works to cut off the van battery? If it's the second, it still points to current leaking thru the isolator. If so, then disconnecting the big + wire at the isolator that goes to the van battery should make the voltage flow stop for sure.

ed
 

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So basically the current flows when the aux batteries are connected to the van battery (via the isolator and thru the aforementioned switch).

I'm back to this --> the addition of a second new battery might make just enough differential between the aux batteries and the van battery to create a little more flow toward the van battery as it tries to bring it up to van battery voltage thru the isolator... Or, the isolator coil puts a small load on the batteries when it's in the circuit. My concern is that 2A is no small load. That's enough to keep the fridge going!

ed
 

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Aye... thus my earlier comment/request to disconnect the second battery, back to the original single, and see if the problem persists.
 

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Discussion Starter #13
Eddie, that draw could power the fridge several times over.

I may have an answer I don't like. Our separator is the Surepower 1315-100. Ignorant me assumed that with the second battery, we would need to upgrade to the 1315-200. MrNomer nixed that notion--said I was confusing amps with Ah again (which I do frequently). But then I noticed that the separator gets hot and stays hot, like 120° in a 95° van. Heat means wasted energy, so I called the supplier of the separator. Sometimes it's no fun to be right. :(

He said that not only is the 1315-100 the wrong one now, but also even the 1315-200 may not be adequate--that we need wiggle room of maybe 240A. ?? He also suggested that we might need "an isolator instead of a separator." I don't understand the difference, but I've always liked the function and simplicity of the SurePower.

That means back to the shopping cart for separator/isolator. Would rather not break the bank, and we do have a serious space limitation. Suggestions appreciated.
 

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Suggestion... Wirthco Battery Doctor 150A

I have one with my (2) 100Ah AGM aux batteries. No strain, no pain... affordable!

Others on the forum have used them too. I haven't heard anyone with an issue yet. It's an isolator, so it is one way - van battery to aux batteries. If you need it to jump start your car, you push a button to (temporarily) reverse the flow.

"But" you say, "it's only 150A!". My setup has a 100A breaker in line with the wire going to the 2 aux batteries. The breaker has never tripped in a year. I suppose if you ran your aux batteries down to 10% and started the van, there might be an excessive load and trip the breaker. If so, I would just use the shore power charger to get 'em up a bit before using the van to charge them.

ed
 

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Eddie, that draw could power the fridge several times over.

I may have an answer I don't like. Our separator is the Surepower 1315-100. Ignorant me assumed that with the second battery, we would need to upgrade to the 1315-200. MrNomer nixed that notion--said I was confusing amps with Ah again (which I do frequently). But then I noticed that the separator gets hot and stays hot, like 120° in a 95° van. Heat means wasted energy, so I called the supplier of the separator. Sometimes it's no fun to be right. :(

He said that not only is the 1315-100 the wrong one now, but also even the 1315-200 may not be adequate--that we need wiggle room of maybe 240A. ?? He also suggested that we might need "an isolator instead of a separator." I don't understand the difference, but I've always liked the function and simplicity of the SurePower.

That means back to the shopping cart for separator/isolator. Would rather not break the bank, and we do have a serious space limitation. Suggestions appreciated.
Hi,
I don't know how large your house batteries are in amp-hrs?

But, 200 amps sounds like way to much charging current to me.

I have two 220 amp-hr golf cart batteries (flooded lead acid) and the recommended maximum charging current is about 35 amps maximum -- according to Trojan batteries, charging currents in excess of this are had on the battery, shorten its life, and result in more outgassing.

I put a 50 amp breaker in the line between the van battery/van alternator and the house battery so that If it tripped I would know that the batteries were getting too much charge current. It has never tripped, and when I measure charge current with a clamp on amp meter it has never been more than 38 amps, and this only briefly when the house batteries were relatively low.

You (I think) have agm batteries, and they may take somewhat higher charging currents with their lower internal resistance, but not that much more. I would check what your battery manufacturer recommended for max charging current and size your isolator/separator and the breaker you have in this line for somewhat above the max recommended charging rate. This way you will be alerted if the charge rate is too high as the breaker will trip, but I'd guess this is unlikely.
For example, this pdf from US Battery recommends charging at 10% of the batteries 20 hr amp-hr rating for their agm batteries -- this would only be 22 amps for a 220 amp-hr battery. Charging currents of 200 amps would be about 10 times the recommended rate.
http://usbattery.com/wp-content/uploads/2014/05/usb-charging-recommendations.pdf

Gary
 

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One thing I noticed when I changed my dome lights out to LED bulbs, they have a faint glow to them. If I flip the dome light from auto to off they turn off completely. I changed back to the standard dome light bulbs they do not glow, but their is current flowing through them with the switch set to auto.

Turn all the dome light switches from auto to off and then see if you still have the draw.
 

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Discussion Starter #19
Gary, you make a lot more sense than the guy I talked to today. Two 100Ah Trojan AGMs, for a total of 200Ah. Currently charged from the van and on shore power with a 15A charger that Trojan recommended. Will be adding 300W solar soon. So no, there's nothing approaching 100A in our system. I'm wondering if this separator is just defective--they do go bad and this one was bought used.
 

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Discussion Starter #20
SewerRatz, I turned the dome lights off long ago. We'd rather flip a switch than have the lights come on automatically.
 
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