Need confirmation on diagnosis of 12V electrical problem

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(mods pls move if this is posted in the wrong location)

A friend has a trailer he just bought.

5 days ago when we picked it up everything worked - lights, A/C, fridge, stove, heat, water heater, etc. I towed it over to his house and dropped it off.

Yesterday he had some time to go out and check out the new toy he had bought, so he plugged in the 110V shore line to a 20a 110V plug in his garage (and yes, it was 110V outlet not 220). The the clock on the microwave came on, but no lights in the trailer. A quick check found the following - no 12V.

Pulled the 50A fuse that was in line w/ the battery and the battery only had 0.3 volts. 50A fuse was good. Checked all breakers and fuses and none were open/blown/tripped. Leaving the battery disconnected and connecting the 110V (so the converter would have power), still had 0V on the 12V line.

There is a Parallax Power inverter (http://www.spectrum-x.com/PPS/Products/Converters/PowerCenter/7100/7155/) model 7155 inverter in the trailer. This inverter is in a box that holds your breakers and fuses, along w/ the inverter. I disconnected the blue wire that supplies the 12v and goes from the inverter itself to the fuse panel and reconnected the 110V. At that time I was able to get 4 volts out of the inverter. Re-connecting the line and the output would go back to 0v

I suspect the inverter itself has failed. I can get a replacement for just the inverter from Amazon (http://www.amazon.com/Parallax-Power-081-7155-000-Replacement-Section/dp/B002SSEWD8) but before I blow $160, I would like to make sure I have not missed anything.

I know I will have to get a new battery. My best guess is the output transistor(s) on the inverter shorted/failed after we picked up the trailer (or maybe they were already toasted before we picked it up and the battery was supplying the 12v during out inspection - the prior owner did have the battery disconnected before we started our inspection) and leaving the battery connected for a few days to a failed inverter (with the loads from the CO and methane detector) killed the battery.

Has anyone experienced something like this and was able to fix it without spending $160?

Thx!!!

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Well we got our Progressive Dynamics PD4655V and I finally got time to get it out of the box and get it installed.

Glad I inspected it closely!

Somebody overtightened the screw that holds a bridge rectifier on the heat sink and the screw broke off. The bridge rectifier was floating around inside. Got to ship it back and get a replacement.

If it weren't for bad luck......

[Bobbo]

Exactly what I did. In 2011 I replaced my 7345 with a PD4655V and upgraded my wire to the battery from 8g to 4g. In 2014, when my batteries finally died, I got a pair of 6v batteries. You won't be sorry.

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We are getting 110VAC to the input. I measured it and when there is no load on the output of the converter we get 4 VDC. (as opposed to 12 VDC)

We have a new battery box on the way (to hold the (2) new 6V golf cart batteries that are going to replace the (1) dead 12 v battery) and a Progressive Dynamics PD4655V as it will replace fit in the same space as the current busted converter.

Thx for all the feedback!!!!

[Old-Biscuit]

BarneyS wrote:

coolmom42 wrote:

BarneyS wrote:
I suspect a ground fault interrupter has tripped somewhere in the trailer. Look in the bathroom first. Same thing happened to me and after about an hour of trying various solutions I found the tripped breaker. Probably your fix is going to be as simple
as pushing a button. I hope so. 🙂
Barney

GFCI is on the 110 outlets, not on the 12 V lighting system. OP states microwave comes on, so at least 1 of the 110 outlets has power.

Don't think GFCI is the problem here.

Sounds like a new battery is in order, and then possibly an upgraded converter.

Yep, you are correct. Brain Fart here. Sorry.:o
Barney

Not necessarily.....if converter 120V AC is from an outlet that has GFCI protection
Converter needs 120V AC before it can convert :B

[BarneyS]

coolmom42 wrote:

BarneyS wrote:
I suspect a ground fault interrupter has tripped somewhere in the trailer. Look in the bathroom first. Same thing happened to me and after about an hour of trying various solutions I found the tripped breaker. Probably your fix is going to be as simple
as pushing a button. I hope so. 🙂
Barney

GFCI is on the 110 outlets, not on the 12 V lighting system. OP states microwave comes on, so at least 1 of the 110 outlets has power.

Don't think GFCI is the problem here.

Sounds like a new battery is in order, and then possibly an upgraded converter.

Yep, you are correct. Brain Fart here. Sorry.:o
Barney

[wa8yxm]

First... Make sure 120 volts is getting to the converter module.. It eats 12o after all. Then there should be some fuses about,, Check them

IF you determine the converter portion of the power center is bad you can replace JUST IT without replacing the entire unit.. I recommend Progressive Dynamics series (match the last two digits as close as possible with your Parallex)

Your parallex is a single stage unit (Assuming it does not have a model number ending in "T") so it takes a long time and never quite re-fills the battery

The PDI is a wizard controlled replacement that is a 3-stagewith an added feature..This is one major improvement.

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Another update -

Per the manufacturer's instructions:

"Although the converter is an excellent battery charger, the converter
does not require a battery to be connected to it for proper operation."

Web site clicky

Instruction manual clicky

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Dakota98 wrote:
First off, I believe you have confused yourself somewhat with terminology. You have a Converter, not an Inverter.

Sorry - had happy fingers - I meant to type converter, but they typed inverter

If I'm not mistaken, some older Converters will not provide 12 volt unless there is a functioning battery connected. I believe your battery is dead.

will check that

Most folks here on the Forum will recommend replacing the Converter with a Progressive Dynamics with Wizard, even if your current Converter is OK.

will look at that also

WyoTraveler wrote:
I would pull the inverter. Run it on the test bench. If you can get a schematic you may be able to find out what is wrong and repair it. Providing you have some equipment. To hire someone to repair it probably would cost as much as a new one.

I pulled it out of the circuit by disconnecting wires coming out of the converter from the battery and fuse panel. Then I could get 4 volts. I could trouble shoot it myself, but the time and $$ to get a schematic and chase down the parts would exceed the value of replacing it.

If initially a battery was bad in the RV like freezing, shorted plates etc. it could very well pull too much load on the inverter and destroy the output transistor.

Dont think freezing is an issue. Everything was working a few days ago and it hasnt gotten below 70F around here.

RoyB wrote:
X2 on the battery. The Parallax 7155 I think requires a good battery presence to operate an RELAY inside the converter before it will work. Some of the older converters require the battery to be in the circuit to enhance their internal poor designed regulation circuits.

will do

This would be a good time to replace the battery with two 6VDC gulf cart battery wired in series and that will give you a big 220AHs of capacity which is what you need if you ever are going to do any OFF THE POWER grid camping.

The golf cart batteries were already on the list, (along with a bit of solar) just wasnt planned for right yet. Trying to keep control of the budget

would also start thinking about replacing the 7155 Converter with a Progressive Dynamics PD-9260C Converter

researching that as a replacement.

westend wrote:
That Parallax converter may have internal fuses on a circuit board. If it's now non-functioning and there isn't a warranty involved, you have nothing to lose by opening it up to check for blown fuses. Check for incoming AC power initially, as mentioned.

There is an onboard fuse and it is good. Besides if it was a fuse issue, I would not get 4v when all load is removed

I would check the battery connections for correct polarity, too. Who knows what has been done previously.

everything was working a few days ago and I re-verified that everything is connected to the correct location.

I am checking out the suggested CONverters (there - I typed it correctly in spite of my beer soaked fingers! ;))

[westend]

That Parallax converter may have internal fuses on a circuit board. If it's now non-functioning and there isn't a warranty involved, you have nothing to lose by opening it up to check for blown fuses. Check for incoming AC power initially, as mentioned.

I would check the battery connections for correct polarity, too. Who knows what has been done previously.

[RoyB]

X2 on the battery. The Parallax 7155 I think requires a good battery presence to operate an RELAY inside the converter before it will work. Some of the older converters require the battery to be in the circuit to enhance their internal poor designed regulation circuits.

You might be able to just jumper the battery with a car battery and get thins to start working.

However once you have depleted the deep cycle below 50% charge state it is not going to be very good if you get it to charge back up.

You really should replace the battery first. This would be a good time to replace the battery with two 6VDC gulf cart battery wired in series and that will give you a big 220AHs of capacity which is what you need if you ever are going to do any OFF THE POWER grid camping.

I would also start thinking about replacing the 7155 Converter with a Progressive Dynamics PD-9260C Converter which supports the smart mode charging technology. This will automatically take care of your connected batteries...

Roy Ken

[Old-Biscuit]

CONVERTER.........

Needs 120V AC power going IN before 12V DC power can come out.
Have you checked that it is getting 120V AC power? Could be a tripped GFCI outlet, could be a tripped AC circuit breaker.

IF no 120V AC IN.........then NO 12V DC OUT

IF you find 'converter' has 120V AC then converter has failed

You also need a new battery.
Mark batteries cables (or take pics) before disconnecting so that they don't get connected backwards. IF backwards then you will need to replace REVERSE POLARITY fuses on backside of converter---they blow when battery hooked up wrong

[coolmom42]

BarneyS wrote:
I suspect a ground fault interrupter has tripped somewhere in the trailer. Look in the bathroom first. Same thing happened to me and after about an hour of trying various solutions I found the tripped breaker. Probably your fix is going to be as simple
as pushing a button. I hope so. 🙂
Barney

GFCI is on the 110 outlets, not on the 12 V lighting system. OP states microwave comes on, so at least 1 of the 110 outlets has power.

Don't think GFCI is the problem here.

Sounds like a new battery is in order, and then possibly an upgraded converter.

[BarneyS]

I suspect a ground fault interrupter has tripped somewhere in the trailer. Look in the bathroom first. Same thing happened to me and after about an hour of trying various solutions I found the tripped breaker. Probably your fix is going to be as simple
as pushing a button. I hope so. 🙂
Barney

[WyoTraveler]

I would pull the inverter. Run it on the test bench. If you can get a schematic you may be able to find out what is wrong and repair it. Providing you have some equipment. To hire someone to repair it probably would cost as much as a new one.

If initially a battery was bad in the RV like freezing, shorted plates etc. it could very well pull too much load on the inverter and destroy the output transistor. Transistors are cheap. That would be just a guess but if just an ouput transistor you could probably repair it for a couple of dollars.