Foretravel Owners' Forum

With the boost switch on, ALL batteries will discharge as well without hookups or generator on. That's why the boost switch is illuminated. A reminder.

Hey guys, I'm looking for some info...

The INVERTER/CONVERTER is connected to the COACH batteries.  When plugged into shore power (or generator running) it can only charge the ENG batteries (unless the BOOST switch is ON).

I believe he means the COACH batteries.

Chuck and Jeannie, After I got the MH a friend of mine needed it to live in for a year and half.
So I am just now going through it...

inverter

1992 Unihomes and earlier had one battery bay. One of those 8d batteries is the start battery. Someone may have tied them together by the looks of the red jumper cable.

That is the conclusion we came to back in 2018.  The questions are:
1.  Why?
2.  What other "modifications" were made to the battery and charging systems?

Hey guys, I'm looking for some info on how the battery charging system works on my 92 320
while plugged in at home.  50 amp line to the MH.  I have 3 new 8d batteries all connected
together.

1992 Unihomes and earlier had one battery bay. One of those 8d batteries is the start battery. Someone may have tied them altogether by the looks of the red jumper cable. Do all have equal voltage?

So now, having seen your two photos, I can tell you my opinion of how your charging system should work while plugged in at home.

You have three batteries, all connected together.  The PD9180 has two functions.  It is a battery charger, and it is a 12 volt power supply.  It must be plugged into (or hard wired to) a 110V power source to function.

IF your PD9180 is connected to a 110V outlet, and IF it is connected to one of the 3 batteries, and IF the coach is plugged into 50 amp shore power, then all three batteries should receive a charging current.

The PD9180 in base configuration is a "dumb" battery charger.  It may not provide the optimal charge rate for your new batteries.  There is a optional add-on module called a Charge Wizard that will upgrade the PD9180 to a "smart" battery charger.  If you do not already have this module added to your converter/charger, it would be highly recommended.

Cool, where would I get this upgrade module?

Might as well start out by using the correct terminology.  The PD9180 is not a inverter - it is a convertor/charger.  See description linked below:

PD9180A - 80 Amp Electronic Power Converter - Progressive Dynamics (https://www.progressivedyn.com/rv/power-converters/pd9100-series-rv-power-converters/pd9180a-80-amp-electronic-power-converter/)

If you DO have a inverter on your coach, it is located in another place.  It might possibly look like the Taytronics pictured below (in the storage bay under the entry steps):

I have the inverter in the bay with the compressor.

The INVERTER uses battery power to provide 110V power to the coach when it is not plugged into shore power or when the generator is not running.  When using the inverter, you must monitor the voltage on your "combined" battery bank so that it does not drop too low.

The biggest problem with having all three of your batteries tied together is that it is possible for them to be depleted to a point where you cannot start the big engine or the generator.  To avoid this situation, your coach was originally equipped with the battery isolator which separated the two battery circuits.

It is not "wrong" to have all three batteries tied together, but it requires additional vigilance on the part of the owner.  If your coach will be plugged into shore power most of the time, it probably won't be a problem.

That coach originally had 2 house batteries 8D and 1 engine battery 8D in the same compartment. Someone apparently tied them all together. Not a good idea as that is a single bank so if one goes down they will all be down. I would figure out how it was originally wired and then correct the wiring. There should be a battery isolator located on the frame behind the left rear wheel accessible through the small door behind the left rear wheel.

So in reality the inverter would be seldom used maybe for lights in an emergency.

I removed the OEM Taytronics MSW inverter a few months ago and installed my old Trace inverter and a new pure sine wave inverter. I did have to modify the wiring at the changeover box because of the Taytronics switch. Saying that because you can't just install a new inverter where the old one was and have it work correctly.

The OEM inverter worked flawlessly since the coach was built but used a lot of juice at idle. As soon as it was powered on, the voltmeter took a dive. The new sine wave inverter goes just to the microwave and the big wall TV with the Trace powering everything else. Both are much more efficient. The Trace surprisingly so since I purchased it in 1989. It pulses ever second to see if anything is on and then turns itself on. Even when on. it does not draw much current. I still have more wiring to do.

REMOTE SWITCH FOR INVERTERS WITHOUT A PORT: If you buy or have most any inverter without a remote switch, I found a trick to run a telephone type wire and turn the inverter on or off from most anywhere in the coach. It even works on the '89 Trace inverter. Your inverter does NOT have to have a port for a plug but you will need to pull the cover to connect a set of wires to the on/off switch. I can post a DIY for inverters without a port for a remote switch. With a port, it's a no brainer plug and play.

Pierce

What size inverter should I look for?

Then back to the FT.

Before you spend a bunch of money (and time and effort) replacing your old inverter, it would be a good idea to think about how you will use your coach.  With your coach in stock factory configuration, you will only NEED to use your inverter if you do not have a shore power hookup AND you do not want to run the generator.  How often will you be in that situation?

If, when traveling, you spend most or all nights at campgrounds with 30 or 50 amp shore power connections, then you won't need a new inverter.  If you tend to camp mostly in the HOT summer months, and you don't have shore power hookups, you will be running your generator to power the roof air conditioners.  In that case, you won't need to use the inverter.

The most likely time that you would want the inverter is when boondocking in cool weather conditions where the roof air is not needed.  THAT is when you will appreciate a good inverter, AND a large capacity battery bank.  Using the inverter to power ac loads avoids having to listen to the irritating (to you and other campers) racket made by the generator.  Of course, there is no free lunch.  If you deplete your batteries running the inverter, you will eventually need to recharge them.  If you are driving every day, you can let the alternator do the recharge work.  If camped in one spot for multiple days, you'll probably need to run the generator for several hours each day, but you can do it in the middle of the day when the noise will be less annoying to everyone.

Of course, as Pierce suggests, you can always add solar to supplement the generator, but that is another subject entirely.

All I'm saying is think about how you will use your coach, come up with a long-term plan, and then spend your upgrade money where it will do you the most good.

Many of the good modern inverters also have a built in multi-stage battery charger. If you are considering upgrading the existing converter/charger (which you should do because they are battery cookers) and are also wanting a pure sine wave inverter (many modern electronics require that) then you have the option of replacing those two units with a single inverter/charger...I have one and it works perfectly...this is my third project vehicle that I've used AIMS inverter chargers on and haven't had a single failure..

I did order a smart charge adapter...

Wait until you get the Charge Wizard - try it - see how it works.  The charger you have will probably work just fine.

Are your 3 new batteries AGM or are they traditional "flooded" wet cells (the kind with removable caps so you can add water)?

They are old style flooded with removable caps.

Your coach came originally with a battery box, the lower portion in your picture has deteriorated somewhat. Do you still have the top section? When covered the top portion has a vent hole which a 2" pipe  attaches to vent wet cell batteries. Pretty easy to rebuild bottom section with fiberglass but will have to be taken out to repair.

Was it hard to combine all wiring into one location? Or did you have to?

.......The one bit of rewiring I did do was to put the refrigerator on one of the circuits that the inverter supplies (I have no idea why Foretravel didn't do that) as I always use the inverter to run my fridge while driving (unless I have the generator fired up to run roof air cond.).

They are old style flooded with removable caps.

You have to check to see if you have removable caps or two flat plates that would have to be pried off.

The pic shows the grounds connected. The red cable connects the outer positives but the center positive fades into the solenoid area. All 3 may not be linked . IMHO

Good pick up Mike, I'll have to investigate further. 

The pic shows the grounds connected. The red cable connects the outer positives but the center positive fades into the solenoid area. All 3 may not be linked . IMHO

I guess the middle battery is the start battery.
The booster enabled me to crank the engine.
So does the booster need to be on to charge that 3rd battery?

Normally, the answer would be YES.  However, we don't know if (or how) the wiring has been altered (modified) on your coach.

In stock configuration, the BOOST switch activates a solenoid that connects the Start (chassis) battery to the Coach (house) batteries.

In stock configuration, the factory installed battery charger is only directly connected to the Coach (house) batteries.

In stock configuration, the BOOST switch must be ON if you want the factory installed battery charge to charge the Start battery.

In stock configuration, BOTH battery sets should charged by the alternator, through the battery isolator, when the big engine is running.

...what does the off/on switch at the door effect as far as battery usage?  Is it ok to leave it on while connected to shore power and not occupied?  Which batteries does it turn off/on?

The switch at the door is called the "Salesman Switch".  It is powered by the Coach (house) batteries.

Why is it called the Salesman Switch?  I was told:  When a coach is For Sale - sitting on a dealer lot - it makes a better impression on potential buyers to step into a brightly lite coach.  The salesman would turn on all the interior lights, then (to conserve battery power) turn OFF the Salesman Switch when he exited the coach.  Later, when he takes the customers to look inside the coach, he opens the door and cuts on the switch.  Voila!  Customers enter a bright cheerful coach.

Leaving the Salesman Switch on all the time is no problem.  The one on our coach has not been turned off in over 7 years.

The Salesman Switch occasionally gets turned off accidentally, by kids or pets or careless owners.  Causes considerable consternation until discovered.

You have to refer to the B-2126 Automotive Wiring Diagram for your coach to find out exactly what is controlled by the Salesman Switch.  It typically cuts power to such things as interior lights, storage bay lights, the water pump, some items on the dash, etc.

1.  According to the Diagram, I am supposed to have 3 start batteries and 3 coach batteries.
2.  Not sure where they would all go.
3.  Is there a way to monitor or test each battery without having to disconnect the heavy terminal lines.  They are in the way of some of the water caps.