Generator/Shore Power Work, Battery Power Doesn't

[BrocNeal]

So I just bought this motorhome. It's a 1979 Dodge Tioga Class C. It's in great shape, but the past owner hooked up the battery wrong it appeared. To where one of the little 2 post circuit breakers would heat up indicating a direct short. I corrected that and still dont have any battery power in the motorhome. The battery rests at about 12.4, so it's not like new but from what I've read it's not considered dead. Could it still have screwed the battery up? The generator keeps it steady at about 12.4ish. I'm thinking the inverter or converter is fried? This is my first motorhome so I have no idea what I'm really looking at. I found the transfer switch I believe, it clicks off when the generator shuts off so I believe that's it. Where would I find the converter or inverter at and how do I know if they're bad? I found a little blue box looking thing that looks similar to a stereo amp under the hood and saw something similar at an rv store in the converter or inverter aisle. Other than that I dont really see anything that looks like what I'm looking for. Thank you guys.

[BrocNeal]

whemme wrote:
BrocNeal,

OK, look at the schematic on page 20 of the maintenance manual. You will notice the SCR in the upper left corner of the schematic. The SCR acts like an electronic on/off switch. How the system works is that the battery charger PC board monitors the charge level of the house battery(s) by inputting the current battery voltage level onto the red wire going into the board. The board analyzes this voltage level and determines if further charging of the battery(s) is necessary, If so, the board sends a signal to the SCR's gate terminal via the green wire shown which then turns on the SCR connecting the output of the DC voltage output of the transformer module via the blue wire shown into the SCR and since the SCR is now turned on the SCR now conducts that DC voltage to the output terminal of the SCR which connects to the battery9s) via the orange wire.

Actually, the SCR is never fully turned off. The charge board varies the signal to the SCR gate via the green wire on a pulse basis with the turn on pulse being longer when the battery(s) are heavy discharged to a turn on pulse being shorter when the batter(s) are fully charged and only requiring a low level maintenance charge level.

If this SCR was destroyed when the former owner connected up the battery(s) reversed polarity, of course the charge board would be trying to turn on the SCR to try and make it conduct a charge current to the battery(s) to no avail.

Okay that makes sense. I'll have to look a little more into that. I just got home from a vacation so that's why I haven't been on here. I did have a chance to crawl underneath the motorhome and didn't find any fuses or circuit breakers. I did redo some grounds because they looked pretty rough. Still no luck on fixing the problem. I dont remember if I already said this, but I got an outlet tester and plugged it in to every outlet when plugged in to shore power/generator and they all say "Hot/Neutral Reversed". So I assume that definitely is part of my issue. I dont know what that means but its good to know. Still doesn't make any sense that the lights would work when I brought it home and then I change out the circuit breakers in the house battery box and get the lights working off the battery that the issue would reverse into what it is now. But I'll get it, there's only one way to learn!

[whemme]

BrocNeal,

OK, look at the schematic on page 20 of the maintenance manual. You will notice the SCR in the upper left corner of the schematic. The SCR acts like an electronic on/off switch. How the system works is that the battery charger PC board monitors the charge level of the house battery(s) by inputting the current battery voltage level onto the red wire going into the board. The board analyzes this voltage level and determines if further charging of the battery(s) is necessary, If so, the board sends a signal to the SCR's gate terminal via the green wire shown which then turns on the SCR connecting the output of the DC voltage output of the transformer module via the blue wire shown into the SCR and since the SCR is now turned on the SCR now conducts that DC voltage to the output terminal of the SCR which connects to the battery9s) via the orange wire.

Actually, the SCR is never fully turned off. The charge board varies the signal to the SCR gate via the green wire on a pulse basis with the turn on pulse being longer when the battery(s) are heavy discharged to a turn on pulse being shorter when the batter(s) are fully charged and only requiring a low level maintenance charge level.

If this SCR was destroyed when the former owner connected up the battery(s) reversed polarity, of course the charge board would be trying to turn on the SCR to try and make it conduct a charge current to the battery(s) to no avail.

[BrocNeal]

whemme wrote:
BrocNeal, well your replacement battery charger PC board is on the way to you. Sure hope this fixes the no charging problem. If not the only other thing that I can think of is a failure of the S.C.R. as shown on pages 3, 17 & 20 of the Service Manual. I can believe that this component may have been destroyed if as you said the former owner of your rig connected up the house battery(s) reversed polarity. The SCR is mounted in a heat sink as shown on page 17 in the transformer module. Leads to it would have to be unsoldered and then the part would then have to be unbolted to remove it. Then hopefully the SCR has brand and P/N on it in order to purchase a replacement.

That's what I'm hoping, I don't know if it'd fix the no lights when hooked up to shore power but I hope so. I know I called progressive dynamics and that was what the guy said he would think the problem would be after I told him my issues, so let's hope for the best!
Now what exactly is the SCR and what does it do? It sounds complicated but the motorhome is from 1979 so I wouldn't think it would be too crazy!

[whemme]

BrocNeal, well your replacement battery charger PC board is on the way to you. Sure hope this fixes the no charging problem. If not the only other thing that I can think of is a failure of the S.C.R. as shown on pages 3, 17 & 20 of the Service Manual. I can believe that this component may have been destroyed if as you said the former owner of your rig connected up the house battery(s) reversed polarity. The SCR is mounted in a heat sink as shown on page 17 in the transformer module. Leads to it would have to be unsoldered and then the part would then have to be unbolted to remove it. Then hopefully the SCR has brand and P/N on it in order to purchase a replacement.

[2012Coleman]

This is the most awesome thread I've read on here in a while. Please continue to update it!

[whemme]

BrocNeal,

Andy with PD sent me an email this morning and unfortunately he had already shipped the charger board to me. So, send me your real name and shipping address and I will reship it to you after I receive it. You can contact me via PM (private mail) with that info if you prefer.

[BrocNeal]

whemme wrote:
BrocNeal,

Just for my own interest I contacted Progressive Dynamics about availability of repair of battery charger PC boards or replacements. I have copied the email I sent and the email I got back from Andy at the factory below.

-----Original Message-----
From: William R Hemme
Sent: Thursday, July 23, 2020 2:03 PM
To: service@progressivedyn.com
Subject: PD734Q Repair

Does Progressive Dynamics still repair or have replacement battery charger
PC boards for the PD734Q RV power center?

Bill Hemme


-----Return Message-----
Andy Giesen
RE: PD734Q Repair
To: Bill Hemme

Hello,
We do not repair the charger boards.

I found a 6 pin charger board in our old inventory. I am not even
positive it works as I have no way of testing now.
It should work though.

I am happy send it out to you at no charge

I will put it in the mail and send it to the address on Elmwood dr.

Let me know how it works for you.

Andy

I emailed Andy back to not send the board to me and I would contact you about it. Please contact Andy at his email address agiesen@progressivedyn.com if you want to receive this board free of charge. This of course assumes that your board is the model with a connector that has slots for 6 pins. Best I can tell from your photos is that describes your board.

Sorry I'm just getting back to you, I had a chance to email him yesterday and I haven't heard anything back yet, so he may have already sent it to you. But either way, thank you for reaching out for me, you're awesome! I'm really thinking that's my issue so hopefully I hear back from him!

[bobndot]

whemme, nice job. Good deeds don't go unnoticed. You have restored my faith and that's important to me in this world we live today.

[whemme]

BrocNeal,

Just for my own interest I contacted Progressive Dynamics about availability of repair of battery charger PC boards or replacements. I have copied the email I sent and the email I got back from Andy at the factory below.

-----Original Message-----
From: William R Hemme
Sent: Thursday, July 23, 2020 2:03 PM
To: service@progressivedyn.com
Subject: PD734Q Repair

Does Progressive Dynamics still repair or have replacement battery charger
PC boards for the PD734Q RV power center?

Bill Hemme


-----Return Message-----
Andy Giesen
RE: PD734Q Repair
To: Bill Hemme

Hello,
We do not repair the charger boards.

I found a 6 pin charger board in our old inventory. I am not even
positive it works as I have no way of testing now.
It should work though.

I am happy send it out to you at no charge

I will put it in the mail and send it to the address on Elmwood dr.

Let me know how it works for you.

Andy

I emailed Andy back to not send the board to me and I would contact you about it. Please contact Andy at his email address agiesen@progressivedyn.com if you want to receive this board free of charge. This of course assumes that your board is the model with a connector that has slots for 6 pins. Best I can tell from your photos is that describes your board.

[whemme]

Since I am not there to actually trace out each wire connection to the battery charger PC board, I can’t tell by looking at your photos which are power input wires and which are power output wires to the board. On one of the manual pages it references sending in the board for factory repair at $22.00 plus return freight charges. Since this manual is rather dated, I would contact Progressive Dynamics to see if they still repair this board or have replacements and the current costs.

It appears that the board can be removed by unplugging the 6-pin connector and removing a couple of mounting screws.

[BrocNeal]

whemme wrote:
Well that means to me if your voltmeter connections were correct that the 22 vdc coming into the battery charger PC board would appear to be somewhat normal so the transformer module seems to be working OK. However the 9.4 to 11.5 vdc coming out of the charger board is way too low to cause any charge to your batteries. Also if there was any significant battery charging current coming out of the charger board, that LED indicator light as shown in the schematic on page 20 of the manual would be illuminated which it isn’t. My conclusion again is that the charger PC board is toast.

That's kinda what I'm starting to think. So let me see if I understand the board correctly (This is my first RV and I'm only 24 so I'm still learning, but doing my best). I assume just by looking at it, the power comes in from the top 1 or 2 wires in the plug, goes through the board, and then goes out through the bottom 3 wires into the relay and everything?

[whemme]

Well that means to me if your voltmeter connections were correct that the 22 vdc coming into the battery charger PC board would appear to be somewhat normal so the transformer module seems to be working OK. However the 9.4 to 11.5 vdc coming out of the charger board is way too low to cause any charge to your batteries. Also if there was any significant battery charging current coming out of the charger board, that LED indicator light as shown in the schematic on page 20 of the manual would be illuminated which it isn’t. My conclusion again is that the charger PC board is toast.

[BrocNeal]

whemme wrote:

BrocNeal wrote:

So mine doesnt have a blue wire going to the charge board. But I don't have 16 going into it anywhere. Then the 2 orangeish wires I have going anywhere go to a circuit breaker and I have 12.48 going to both posts on that. Looking at the manual, I should have a light doing something if the charger was working. And I have no light whatsoever no matter what it's doing. So I dont know if that means the charger is bad and that's my problem with my lights or what.

BrocNeal,

Both pages 3 and 20 of the service manual show a blue wire going into the battery charger PC board. Why you don't or can't find that blue wire is a puzzle. However, at this point I believe the 14.28 vdc you are measuring on the orange wires on both terminals of the Auto Breaker is actually the voltage coming from your batteries and not the voltage being generated by the battery charging circuit.

So, do this next. Temporarily disconnect all leads going to the positive terminals of of your batteries. Then connect up to shoreline power (you won't now be abe to start your generator). Then measure the voltage on the two orange wires and post what it is. Then please find the blue wire (or what ever the color is in your system) that connects the blue wire input to the battery charger pc board as shown on page 20 of the manual. Then measure that voltage going into the battery charger board. If you have significant voltage there but no voltage on the orange wires then that tells me that your battery charger pc board is bad and you need to find a replacement board.

So I did as you said to and disconnected the batteries and took voltage readings after I did that. So, the two orange posts read between 9.4-11.5 without the batteries hooked up. Then the wires going into the charge board, 4/5 read the same 9.4-11.5. Then the top wire, which ended up being white, read 22.8. I have the picture attached that show the readings on the relay that switches power over as well. Then hooked the batteries back up and they read the same as before.

[ron_dittmer]

Just a general statement here without reading through every little detail.

When exclusively on shore power plugged into 110V (main engine off, generator off) if you are getting a voltage reading higher than battery voltage on any terminal, then your converter (wherever it is) is working.

[whemme]

BrocNeal wrote:

So mine doesnt have a blue wire going to the charge board. But I don't have 16 going into it anywhere. Then the 2 orangeish wires I have going anywhere go to a circuit breaker and I have 12.48 going to both posts on that. Looking at the manual, I should have a light doing something if the charger was working. And I have no light whatsoever no matter what it's doing. So I dont know if that means the charger is bad and that's my problem with my lights or what.

BrocNeal,

Both pages 3 and 20 of the service manual show a blue wire going into the battery charger PC board. Why you don't or can't find that blue wire is a puzzle. However, at this point I believe the 14.28 vdc you are measuring on the orange wires on both terminals of the Auto Breaker is actually the voltage coming from your batteries and not the voltage being generated by the battery charging circuit.

So, do this next. Temporarily disconnect all leads going to the positive terminals of of your batteries. Then connect up to shoreline power (you won't now be abe to start your generator). Then measure the voltage on the two orange wires and post what it is. Then please find the blue wire (or what ever the color is in your system) that connects the blue wire input to the battery charger pc board as shown on page 20 of the manual. Then measure that voltage going into the battery charger board. If you have significant voltage there but no voltage on the orange wires then that tells me that your battery charger pc board is bad and you need to find a replacement board.