Inverter won't power my fridge?

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lmichel

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Jun 28, 2014
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First the Specs:
4 GC2-XHD-UTL Batteries in series-parallel.  Total Ah (C/20)  232 x 2 = 464  Less than a year old.  Watered, carefully maintained.  Specific Gravity on all cells shows about 1.265 to 1.270
Xantrex RV2012 Inverter (Capable of 2000w continuous)  W/RC6 remote
Dometic  New Dimensions NDR1062 Fridge with 2.7Amp 120AC stamped on the model number plate.

The Issue:
When I'm all freshened up and in float, I switch off power to everything I can think of, including the fridge and check the input to the inverter with a clamp meter.  2.4Amps typical.  This is probably the draw just to stay in float at very roughly 0.5%

I power on the fridge and force it to go on AC instead of Propane.  The clamp meter jumps to 22Amps and the RC6 complains of overload.  After about 5 seconds of this, the inverter powers down to protect itself.

On shore power or propane, the fridge cools down just fine.  In fact I have to keep it set on 3 of 5 or it will actually get too cold. 

2.7Amps AC should draw about 27Amps from the batteries, or somewhere around 324 Watts - Plenty of headroom for the inverter to handle it.  Even if we add 15% for loss, we're still under 400 Watts.

I'm stumped! 
My best guess is the inverter is faulty? 
Is there something wrong with my math?

Oh, I should add, that this is a 2004 Kountry Star with original equipment (except for the GC2s)
It's somewhat new to me.  Owned if for almost a year.  And the fridge has never run on battery since I've owned it.  I'm just now getting around to diagnosing the issue..

What else can I check?



 
Your inverter is seeing a voltage drop below its input threshold, which is probably 10.5 or 11.0 dcv. If the batteries are indeed good, then you have either a poor connection (hot or ground) or the wiring to the inverter is too small and can't deliver the required current without a voltage drop. Since 22A isn't a lot of current, I lean toward a bad battery connection or bad connection somewhere between it and inverter.

Not sure what the RC6 is seeing. It's pretty basic, but if its shunt is really being overloaded then maybe the inverter is drawing too much amps but still functioning?  That would be a rare failure for an inverter, but not impossible. I had an RV2512 that failed that way.

Try the Xantrex with some other modest load, e.g. a table lamp (just plug it into a wall outlet). If you have access to the outlet used by the fridge try that one.
 
What the Xantrex is really telling you, is that the input voltage (under that current load) has fallen below the 10.5vdc threshold.

I would check all the battery connections from inverter input all the way back through the batteries (both positive and negative cables).  Cable size and connection quality is very important where heavy loads are concerned.  Inspect all cables where they attach to their ring terminals for corrosion in and under the cable insulation.

OOOps! Gary beat me to it, as usual.  :)
 
First I would hook a digital Volt Meter to the batteries,, Hook right to the batteries, NOT the cables but the batteries (Clamp on the bolt if you have to)  See if the voltage there is like 12 when the Remote shows 10.

IF so, clean every connection,, question 2: What size wire?  I think Xantrex suggests 0000 gauge for that (4/0) and a couple more zeros would not hurt.

Finally:  I used to kill a battery a season till I got a better converter,, What is the make and model of your converter? (And learned a whole lot more about care and feeding of batteries).
 
Hmmmm... All good ideas.
The connections are squeaky clean but I did check them again.  I thought maybe the rings to cable connections might be something to check as well.  Nope, all solid.  BTW everything is 4/0 all the way to the inverter input.

Ok, some new data points to consider;
Placing a meter directly on the posts to the input of the inverter and forcing the fridge to switch to AC causes the meter to go from 12.8 to 12.3.  Nothing there..

The inverter jumps to a pretty audible hum when under such load and before it powers down.

The RC6 continues to show an overload error as before.

However, the right side led meter on the RC6 does not show any reading.  So no amps indication.

When I finished all my testing and went back to shore power, the inverter reads a low battery error and that it is bulk charging.  Um... the batteries were just in float before my tests.  I doubt they are low.  a meter also shows they're not low.  Also, the voltage led bar shows 14.5.

I know that inverters do not last forever.  This one is at least 10 years old.  Maybe it's done?

If I knew for sure, I'd have no issue replacing it.  But I don't want to shell out the big bucks and be wrong..


 
I would be concerned that the shunt for the RC6 is bad. Or that one of the batteries has an internal short that shows up under load. Even a almost new battery can fail. Both are possibilities, I think.

But as I said previously, I had a Xantrex RV2512 that failed under any load over a few amps, so yours may be failing too. They are repairable if you can find a source for the circuit board, but Xantrex doesn't supply them any more. Maybe an RV salvage yard? There are probably thousands of RV2012's out there, so some must be in junk yards.
 
Another good thought..  Shunt bad?  Wouldn't the RV2012 work without the RC6 even connected then?
I tried that, and get the same issue.
If I had an internal short in a battery, I suppose I could just run two of them and then the other two.  If the fridge runs on one set or the other - then short it is.

Lastly, I tried increasing AC loads to see if I could find the tipping point.  Using a combination of lights, electronics, etc.  It seems to be about 5.5Amps AC (from a clamp meter).  I'm not sure that tells me anything though :)
 
The shunt is essentially a dead short by design ( a very very low resistance).  About the only way it could fail is to OPEN CIRCUIT, which is highly unlikely unless it has been physically damaged.

I don't think the shunt is an integral part of the RC6, however, I'd have to review the installation of the 2012 and RC6 to see how the shunt is implemented.  The normal implementation of a shunt is in the ground (return) path of the batteries.  However, some manufacturers use a shunt on the DC source of the Inverter/charger that only concerns itself with current flow through their particular unit.
 
Yeah,
Played with it enough..  Putting up two batteries at a time yielded nothing different.
I figured if it isn't the caps, it soon will be :) 
I'm going to replace it.  Probably with a 3k instead of the 2k that it is..
The battery bank is 460Ah (C/20).  I figured that's plenty to run the inverter at even 30 Aac for at least a day.
But, please don't hesitate to correct my math :)

 
The shunt is essentially a dead short by design ( a very very low resistance).  About the only way it could fail is to OPEN CIRCUIT, which is highly unlikely unless it has been physically damaged.
Click to expand...
A bad (high resistance) connection where the shunt is connected to the battery bank could give false indications of overload as well as restricting available power. But the shunt is probably internal to the RV2012 inverter anyway, so essentially an inverter failure.  I mentioned it only because his RC6 is giving an "overload" error indication when there does not appear to be an actual amp overload - the fridge only draws around 300-350 watts.
 
A bad (high resistance) connection where the shunt is connected to the battery bank could give false indications of overload as well as restricting available power. But the shunt is probably internal to the RV2012 inverter anyway, so essentially an inverter failure.  I mentioned it only because his RC6 is giving an "overload" error indication when there does not appear to be an actual amp overload - the fridge only draws around 300-350 watts.
Click to expand...
The OP described all connections as "squeaky clean".  I took him at his word.
 
I don't think he can see the shunt connections in this inverter. It's not an external device.
Click to expand...
I think I pointed that out a couple of replies ago, but you and I can pee on each others leg forever and still agree that his inverter is most likely the culprit here.
 
I'm not peeing on your leg, Lou. Just trying to offer some possibilities to lmichel. It's ok if we both tell him the same thing. Or even different things.  We aren't in competition.
 
Guys, you're both right.  The shunt is internal.  I also have a solar panel RE system for my home that monitors things with three different shunts I had to install myself.  So I'm confident that I could take the RV2012 apart and examine it, but it is past its prime anyway.  I might as well take the opportunity to upgrade it during the replacement.  :)  Thanks for the help!

Now, I think I'll start a new post about my rancid water issue...
Thanks again
 
"I power on the fridge and force it to go on AC instead of Propane.  The clamp meter jumps to 22Amps and the RC6 complains of overload.  After about 5 seconds of this, the inverter powers down to protect itself.

On shore power or propane, the fridge cools down just fine.  In fact I have to keep it set on 3 of 5 or it will actually get too cold. 

2.7Amps AC should draw about 27Amps from the batteries, or somewhere around 324 Watts - Plenty of headroom for the inverter to handle it.  Even if we add 15% for loss, we're still under 400 Watts."

I think you are mixing numbers up.  Unless you have a very sophisticated clamp on amp meter you are measuring 22 amps on the AC side.  The DC side is 11X's that current!  Even with your excellent system your inverter is seeing 242 amps and possibly more of DC.

It is all working well.  Using a Refrig. on an inverter will run the batteries down very quickly--even if all the wire sizes, batteries and inverter are capable of the load.

Good Luck!
 
22 amps on the A/C side of the inverter is over 2KW,, if the fridge is trying to draw that kind of current SOMETHING IS SHORTED and it should not work on shore power either.

22 Amps on the DC side, however, is very reasonable for the Fridge.  And some clamp on meters do both AC and DC.  Ford used clamp on DC meters back in the 50's.
 
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