88 RoadTrek Wiring Cleanup

[unclebob]

Been spending as much time as I can working on the RT wiring in the Texas Summertime heat. Averaging maybe 3-4 hours of actual work per day. My previous thread (fixed it til it was broke) was a pretty pathetic introduction - sorry 'bout that. Anyway, more has been revealed, and I've learned enough to at least ask better questions. I appreciate your knowledge and patience.

I have a Progressive Dynamics Power Converter Model PU7231. I found the manual with a google search and it and the discussion of the operation of their converters are very enlightening.

Elsewhere on this site I found a reference to "Roger's My Roadtrek website", which looked like it would have many valuable answers for me, but the links all lead to a website building site. Does anyone know what happened to Roger's site info??

Tucked away in a cabinet, I found the manual for the fridge and was able to determine the purpose of the terminal strip I referenced in that earlier thread. It's the DC power input from the converter! (and boy do I feel dumb!)

The engine compartment wiring shows signs of being 26 years old, but the van was running as expected, so I'm just cleaning up worn and damaged pieces and insulating with fresh Scotch 33+ electrical tape. And I found an old solid state battery isolator under the vehicle battery tray and the windshield washer bottle. Haven't had time to check it for shorts or replace the vehicle battery yet, but it seems like I'm on the right path.

I'm still a little confused about the connection between the vehicle and RV battery charging from the alternator with its associated isolator and the DC output of the converter. It looks like the only connection between them is the RV battery. Further separating and combining the two DC systems seems like it may require fusing, switching and/or diodes to isolate the vehicle 12 volts from its battery isolator and the 12 volts from the converter. At least it seems that way if both the vehicle alternator and the converter are to charge the RV battery and the RV battery is to supply 12 volts to the house.

So, basically this is just an update/progress report and another chance to say thanks and that I deeply appreciate any observations, tips, or opinions anyone would care to share.

BC

[markopolo]

This is what a typical charging setup looks like:



The converter usually only charges the house battery.

Newer Roadtreks are setup with a battery separator that permits charging the chassis battery along with the house battery.
I have the typical isolator setup in my van but with the addition of a manual 1, 2, Both, Off, manual marine type battery switch that does double duty as a master house battery disconnect switch and a battery bank combiner for easy charging when plugged in. It would also be handy if ever needed to boost the chassis battery to start the van.

Rodger retired his website after maintaining it for many years. I have some of the info from his site and he gave me permission to post it here. Unfortunately I have less saved than I first thought. Let me know if there is some specific info from his site that you'd like to see and I'll see if I have it.

[unclebob]

Finding the converter was capable of boiling the battery dry, and that the P.O. had connected the vehicle and house batteries in parallel explained my two dead batteries and the warning (that I ignored) about leaving the RoadTrek plugged into shore power for "too long". This first part of the learning curve has been pretty steep, and I still have lots to learn. I should have the vehicle systems operational today, and will be replacing the house battery very soon.

Since the house battery is under the floor of the cabinet, the recommendation to check its water level regularly, in the PD manual, leads me to seriously consider an AGM battery because they need less maintenance. A remote cutoff switch, a circuit breaker and a voltmeter with a momentary pushbutton switch ('cause the meter would draw a little current all the time without it) mounted inside that cabinet seem very desirable. I am concerned about the original Progressive Dynamics converters ability to properly charge an AGM battery, though. Any input here would be appreciated.

I found another repository of info on converters here:

http://dave78chieftain.zxq.net/ConverterInfo.html

That seems to have answered most of my questions in that area.

I'll look again at the link titles and be in touch about info I would like, in the hope that you have it.

Thanks again!

BC

[booster]

If you have high enough charge voltage to boil dry a wet cell in a short time, an AGM will be damage equally fast, if not faster. You need to have a good multistep charger to charge safely without battery damage.

[unclebob]

Thanks, booster. I think the addition of a switch to disconnect the charger of the existing converter from the house battery would allow me to be connected to shore power to run the A/C and the interior 12 volt lights & fridge when I want to work in the RV (or just use it for a "man cave". I can easily add a digital voltmeter to monitor the house battery's state of charge. I would add a pushbutton momentary switch because even a digital volt meter will draw a little current and eventually discharge the battery.

Realizing that the existing converter was designed in the stone age, is there reason to believe that a new converter, such as the Progressive Dynamics 9100 line would qualify as "... a good multistep charger.." to use your words, would be better? I'd like to avoid the hassle of replacing the existing Progressive Dynamics PD7231 since I am not a cabinet maker and no doubt the existing wiring would need to be modified. Then there's the issue of the cost of a new converter on top of the new batteries.

Any comments are welcome...

BC

[booster]

Marko knows a lot more about Progressive Dynamics stuff than I do, but I do know that many of the older units can be upgraded to modern charging. Hopefully, he will chime in and have good information for you.

[markopolo]

I think the 9100 series is single stage output unless you add a Charge Wizard. The 9200 series comes with the Charge Wizard built in. The Charge Wizard allows for 4 modes; Boost, Normal, Storage, or Desulfation.

The easiest way to find out if there is a drop in upgrade for your PD7231 is to call Randy at Best Converter http://www.bestconverter.com - he deals with this stuff every day and would know what other PD7231 owners chose to do when upgrading. That will give you an idea of cost.

The battery "boiling" might be the result of years of chronic undercharging. Most of us think of "boiling" being caused by overcharging (over voltage). I think a chronically undercharged battery would lose capacity and in effect will no longer be a "12v" battery and will boil at lower than expected voltages. You should measure the output of your PD7231. I think they were spec'd at 13.6v. 13.6v might be an acceptable float voltage for some batteries. You'd still need to figure out how to fully charge the battery(ies) periodically though else you'll just shorten the life of the new batteries. Check the voltage output at your isolator also - it may or may not be high enough to fully charge your battery.

Typical charging voltage is 14.4v and typical float is 13.2v. Different batteries will have different requirements & tolerances. A fully charged battery at rest should measure 12.7v (or even 12.8v now).

The PD7231 had a max charge rate of 5 amps according to the docs I've seen. That's very low compared to what's currently available.

[unclebob]

That's very informative and the leads for further research are helpful as well. Thank you markopolo. I found another approach that looks promising, eliminates replacing the original converter, reworking its electrical service and cabinetry and addresses booster's comment about a "multistep" charger. http://www.batteriesplus.com/product/52 ... ialty.aspx . Possibly mounted in the cabinet with the water pump - the one that the house battery lives under. Maybe add a diode to prevent backfeeding the battery isolator in the engine compartment??

BC

[markopolo]

Something like that would work. It's only 5 amps though so more of a battery maintainer. I don't see any need to add a diode.

#1 (for me) would be to measure the voltage output from the existing charger and the alternator. For example if the charger outputs 13.6v and the alternator outputs 14+ volts and you drive the van every week then you could get away with not buying anything. It wouldn't be perfect but it is workable.

However, if the old charger outputs a continuous 13.8+ volts then you'd be better off replacing it.

[markopolo]

Just tidying up the topic - I moved the other question to here: viewtopic.php?f=9&t=3183

Let's keep this one on the topic of 88 RoadTrek Wiring Cleanup

[unclebob]

Progress report... I finally got to work on the MH before the Texas sun made the driveway unbearable today. Cut most of the rest of the dry-rotted engine compartment cloth tape harness wrapping and finally found the old junctions to the removed battery isolator. Moved the old wiring from its path to the area behind the headlight to the space above the vehicle battery where the new battery separator is going. Still need to splice in a bit of #10 wire for the separator run to the house battery and cut and terminate the old isolator runs that are moving to the new location. Got most of the wiring harness re-wrapped with new Scotch 33+ tape and reworked the electrical connections with the silicone grease treatment. Almost ready to buy the new vehicle battery and start the engine for the first time in a year and a half. It'll be good to be able to move the vehicle about and reclaim some room in the driveway, not to mention simply being able to DRIVE the thing! Neighbors have been teasing me about the immobile mobile for too long!

BC

[booster]

Only a #10 to the house battery?

[unclebob]

That's what the Roadtrek originally had - or, I should say that's what I found running from the battery isolator I found mounted under the vehicle battery tray. I assumed that it was the original hookup, since it was mounted with square drive screws like used in the rest of the conversion pieces. I was curious, and did some research. One wire chart I found (http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity) shows #10 copper wire carrying 55 amps in "free air" and 33 amps "enclosed". It's been years since I worked in the field, but I'm pretty sure "enclosed" means in conduit. The run from my engine compartment to the house battery compartment is not in conduit, so I didn't spend the extra bucks to replace it. I think a 30 amp breaker at the separator end of that run should make it safe.

What would you recommend? How much current does it generally take to recharge a house battery like the one in the RoadTrek? The wire from the converter to the house battery is #12. I realize that going to a much larger house battery and wanting to recharge it quickly would require bigger wire, but that's not in my plans just now.

Am I making serious mistakes here??

Thanks!

BC
BC

[booster]

Originally Posted by unclebob

That's what the Roadtrek originally had - or, I should say that's what I found running from the battery isolator I found mounted under the vehicle battery tray. I assumed that it was the original hookup, since it was mounted with square drive screws like used in the rest of the conversion pieces. I was curious, and did some research. One wire chart I found (http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity) shows #10 copper wire carrying 55 amps in "free air" and 33 amps "enclosed". It's been years since I worked in the field, but I'm pretty sure "enclosed" means in conduit. The run from my engine compartment to the house battery compartment is not in conduit, so I didn't spend the extra bucks to replace it. I think a 30 amp breaker at the separator end of that run should make it safe.

What would you recommend? How much current does it generally take to recharge a house battery like the one in the RoadTrek? The wire from the converter to the house battery is #12. I realize that going to a much larger house battery and wanting to recharge it quickly would require bigger wire, but that's not in my plans just now.

Am I making serious mistakes here??

Thanks!

BC
BC

The small Roadtrek wiring must be somehow related to the very small converter they used back then, I think Marko said he thought it was only 5 amps IIRC. If that is the case, the #12 would be fine from the the converter to the house battery as that is all it could see. The #10 from the isolator might be a issue, but not a safety one if you have the 30 amp breaker, as it will have a large voltage drop on top of the isolator voltage drop (if it is not a compensated isolator). You probably have at least an 85 amp alternator, so you could see over 50 amps being available with a low battery. The voltage drop may (depending on what the actual voltages are) cause the battery to charge very slowly or not get totally full. You will know a lot more when you can get it running and put a voltmeter on it to see where you are.

IIRC, mid aged Roatreks with an isolator used a #6 wire with a 50 amp breaker, and the newer ones with a separator used a #4 wire with an 80 amp breaker. You are correct that any charging upgrades would take new wiring and protection.

For right now, you are probably fine, and will know for sure shortly.

[unclebob]

Thanks for the reply, booster, and the information about the wire sizes and amperage. I had not imagined 50 amps possible on that short run, but the 30 amp breaker I'm putting at the separator should be adequate protection. You mentioned "isolator voltage drop", and that's a subject I've wanted to explore. My years of engineering radio stations brought me into intimate (sometimes TOO intimate) contact with high power diode rectifiers. When I was shopping for a battery isolator for my first RV, I recall wondering about that forward voltage drop and how it might affect both the vehicle and house batteries. That or a solenoid separator was the state of the art then, and for some reason the solenoid system just seemed too "clunky". It all came to naught, though, as that RV went away.

I've been kinda excited at the "smart relay separator I bought ( http://www.amazon.com/gp/product/B00400 ... r_dpwidget). I just need to get the rig drivable before I can complete the installation and test as previously mentioned. That part is taking longer than planned, but who among us has not had THAT experience?

Well, enough for now!

BC