13.2v at Converter, 12.6v at Inverter & Batteries

WarEagleDan · 02-19-2021, 04:24 PM

I noticed the input vdc to the inverter was 12.6v. I checked the batteries and they were at 12.6v. So I then checked the output of the converter and it's putting out 13.2v. Any idea where to look for the missing .6v?

DavidEM · 02-19-2021, 04:39 PM

When you checked those voltages, how heavily were you drawing on the inverter. If a lot of load then the converter was putting out a lot of amps and there was a significant voltage drop between the converter and the batteries.

That is one of the common flaws with RV converter installations, they skimp on wire size, maybe as small as 8 gauge. If the inverter is drawing 50 amps to satisfy a 500 watt AC load then the voltage drop could easily be 0.6 volts if the distance from the converter is 8 feet or if the current is 25 amps and the distance is 16 feet.

Or there could be a bad connection that is causing a large voltage drop. Feel each connection and if hot tighten them up.

David

Trkyte@msn.com · 02-19-2021, 04:46 PM

use/store in store mode.

if you are sure its in use mode then maybe a bad relay

WarEagleDan · 02-19-2021, 05:11 PM

- Even under heaviest load it's never dropped below 13.2v.

- In in use mode. Which relay?

**16ACE27** · 02-19-2021, 06:11 PM

What David said would be true except: if you're connected to SP then the inverter would not be under load.

There is a disconnect between your converter output and the house batteries. Possible culprits are:

The Reverse Polarity Fuses in the DC fuse area
The battery disconnect latching relay (USE/STORE) open
The 50 amp DC breaker tripped.

How do you know your USE/STORE relay is in USE? You can't go by any indicating light if you're plugged into SP.

WarEagleDan · 02-19-2021, 07:13 PM

You're correct - I don't know if it is in USE until I unhook SP. Will try that next.

**16ACE27** · 02-19-2021, 07:16 PM

Quote:

Originally Posted by WarEagleDan

You're correct - I don't know if it is in USE until I unhook SP. Will try that next.

Or just push the USE button to see if anything changes.

Bob Denman · 02-19-2021, 07:16 PM

I know that when I'm plugged in: I see 13.2 volts...
Unplugged: I see 12.8...

WarEagleDan · 02-19-2021, 08:11 PM

OK, I pulled SP. The USE/STORE switch works just like it's supposed to. Also, the inverter works (TVs turn on).

Where are the reverse polarity fuses?

I assume the 50amp DC fuse is on the right side wall in the battery compartment behind the 100amp fuse? the connections are facing away from me so I can't see if there is a voltage drop across the fuse. Is there a visual indication if it's tripped?

**16ACE27** · 02-19-2021, 08:24 PM

Quote:

Originally Posted by WarEagleDan

OK, I pulled SP. The USE/STORE switch works just like it's supposed to. Also, the inverter works (TVs turn on).

Where are the reverse polarity fuses?

I assume the 50amp DC fuse is on the right side wall in the battery compartment behind the 100amp fuse? the connections are facing away from me so I can't see if there is a voltage drop across the fuse. Is there a visual indication if it's tripped?

So I assume that when you say "The USE/STORE switch works just like it's supposed to." That when off SP and the Switch is in USE all the DC loads work like the lights, fridge on propane, water heater, etc? If so, the house batteries are supplying the DC buss.

At this point your best "visual indication" is a hand held voltmeter but the DC breakers have a flag that will extend to show they are tripped. They also have a button to manually trip them:

Reverse polarity fuses:

WarEagleDan · 02-19-2021, 08:53 PM

Yes, in STORE the lights go out.

THOR sprayed a red-colored on the connections in the battery compartment so it's hard to read anything. I see the flag and it is not flipped.

I don't have those 40amp reverse polarity fuses. Good idea, though.

**16ACE27** · 02-19-2021, 09:19 PM

Quote:

Originally Posted by WarEagleDan

Yes, in STORE the lights go out.

THOR sprayed a red-colored on the connections in the battery compartment so it's hard to read anything. I see the flag and it is not flipped.

I don't have those 40amp reverse polarity fuses. Good idea, though.

Really? It would be interesting to see what you do have as I have never seen an RV power center without reverse polarity fuses.

WarEagleDan · 02-19-2021, 09:41 PM

Don't have them nor are any 40amp fuses or reverse polarity fuses listed on the wiring schematic.

Lt Keefer · 02-19-2021, 09:49 PM

What power source does the LP detector use? How about the CO monitor? Is the water pump turned on? What is the power source for your fridge? How about pulling fuses in the DC circuits to see which one is drawing the missing power?

cavie · 02-19-2021, 09:54 PM

Quote:

Originally Posted by WarEagleDan

Yes, in STORE the lights go out.

THOR sprayed a red-colored on the connections in the battery compartment so it's hard to read anything. I see the flag and it is not flipped.

I don't have those 40amp reverse polarity fuses. Good idea, though.

Yes you do. They may be 30's. You have 2 or 3. Everyone has them. They will not be on the list. They will be off to themselves.

**16ACE27** · 02-19-2021, 11:06 PM

Quote:

Originally Posted by Lt Keefer

What power source does the LP detector use? How about the CO monitor? Is the water pump turned on? What is the power source for your fridge? How about pulling fuses in the DC circuits to see which one is drawing the missing power?

It doesn't work that way. Everything connected to the DC buss receives thae same voltage unless there is a voltage drop across a high resistance connection.

WarEagleDan · 02-20-2021, 02:30 AM

There is one row of DC fuses. Each fuse is labeled and none are labeled as reverse polarity protection. There are no other fuses in that fuse block. If there is reverse polarity protection, it is somewhere besides the DC fuse block. Maybe in the spider web of wires under the bed but I couldn't see anything that looked promising.

WarEagleDan · 02-20-2021, 02:35 AM

(What power source does the LP detector use? How about the CO monitor? Is the water pump turned on? What is the power source for your fridge? How about pulling fuses in the DC circuits to see which one is drawing the missing power?)

Water pump is not running and the fridge is turned off (that's another story).
There is good (identical) voltage thru all the DC fuses in the fuse block. Whatever is going on is after the fuse block.

**16ACE27** · 02-20-2021, 02:48 AM

Quote:

Originally Posted by WarEagleDan

There is one row of DC fuses. Each fuse is labeled and none are labeled as reverse polarity protection. There are no other fuses in that fuse block. If there is reverse polarity protection, it is somewhere besides the DC fuse block. Maybe in the spider web of wires under the bed but I couldn't see anything that looked promising.

If your converter is external to your power center (as opposed to integrated in the power center) the reverse polarity fuses will be in the converter.

WarEagleDan · 02-20-2021, 08:32 PM

It has a WFCO 55amp converter. Seems like I do remember seeing a couple of fuses sticking out of it. I'll look next time I'm in there.

On a lighter note, I went down to turn the heat off this morning and the inverter input reading was 13.6v. Go figure

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