Coast Resorts Open Roads Forum: How many of us are there? Owners of Dodge based RV's?

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Topic: How many of us are there? Owners of Dodge based RV's?

Posted By: TreeSeeker on 09/16/14 06:05pm

Do you have a multimeter? If not get one. If you have a Harbour Freight store nearby you can get one for free with many of their flier coupons, or $9.99 without. Anyone with an RV needs one.

You may have a battery disconnect switch. Mine didn't come with one but maybe yours did, or a previous owner added one.

Are you saying that your water pump is now working but none of the 12v lights are working?

Posted By: TreeSeeker on 09/16/14 06:08pm

Quote:

Fridge was replaced by former owner to a standard household fridge. We were told that it will not run on battery power... we are curious if he could have fried the converter when attempting to?

What I have been trying to explain is that no 110v AC items are going to run on the battery. Thus the previous owner couldn't have fried the converter with a 110vac frig.

Also, if the water pump is working when on shore power, then the converter is working. The water pump runs on 12vdc. When on shore power the converter supplies the 12vdc. When not on shore power the water pump (and all other 12vdc items) run on the battery.

Posted By: Tmmltn on 09/16/14 06:14pm

No, the water pump and panel that monitors the status of everything did work, we disconnected and reconnected everything to check wires, connections, etc, and now nothing is working. I don't see any switches anywhere, there is a fuse in the battery box that looks and tests well, and it is the only one we have not changed out. Otherwise a straight red wire from battery to converter.

I do have a multi meter, but am not sure how to test these connections, i am handier with a wrench than the probes [emoticon]

Posted By: TreeSeeker on 09/16/14 06:34pm

Put the positive lead from your meter (red) on terminal C in your converter's fuse box (I got that from the picture you posted). Put the negative lead (black) from your meter to terminal D on your converter. This should read about 12v. If you are not getting anything then either there is a disconnect switch or the battery is not connected.

Oh, and wear safety glasses and rubber gloves if you have them. If you don't have them, you should (in the RV).

Posted By: TreeSeeker on 09/16/14 06:47pm

I forgot to mention that you need to set the proper range on your multimeter (if it is not auto-ranging). Mine needs to be on the 20vdc range.

Posted By: Leeann on 09/16/14 06:52pm

So what exactly (besides the 110v fridge) doesn't work when you're on 12v power?

'73 Concord 20' Class A w/Dodge 440 - see profile for photo

Posted By: TreeSeeker on 09/16/14 07:09pm

Before I forget, do not leave the shore power connected or you will cook your new battery. Those old converters put out a constant 13.6vdc and this will boil your battery dry. If you need to leave the shore power on, then what I do is disconnect the battery.

Posted By: Tmmltn on 09/16/14 07:16pm

Nothing works in the coach on 12v, no lights, plugs. There is no propane furnace, and we have not lit any pilots yet. We disconnected and reconnected the battery to do some tests and now the water pump and panel are working properly again. I am starting to think, based on what i recall of the wiring before we re-installed insulation and ceiling panels... that all of the wiring is for 110v.

The power converter seems to test somewhat ok, the lowest reading i got between c and d was 10v while connected to shore and negative lead on battery disconnected. 12v with both leads connected, off shore (from what i understand that just reads the battery).

So, *if* the converter is good, and my electrical does indeed run off 110v... my next question is, what would a small (harbor freight) 45watt solar panel system and 300w inverter do for our system, if anything? (We want better panels, but this is all we have on hand at the moment.)

Posted By: Griff in Fairbanks on 09/16/14 07:24pm

TreeSeeker wrote:

From the pictures, it looks to me like this has an older-style (relay-type) voltage regulator. Either that or the relay is to switch on/off depending on whether shore power is hooked up.

If it's a voltage regulator, it's one of the better converters from that era and should over-charge (boil dry) the battery.

If 12v lights & stuff work when shore power is connected, the problem is with the battery side of things.

Trying to run a 120v refrigerator off a 12v system will cause something to fry ... the refrigerator, wiring, and/or power converter. (Yes, some people think a power converter is an inverter ... especially when they're dealing with older converters. I've seen it before, usually along with complete bewilderment as to why it didn't work.)

Assuming a 15 amp draw at 120v, a motor will try to draw 150 amps if connected to 12v. (Simplified but essentially correct.) Also, running a motor at a lower voltage will cause the motor to overheat. For example, connecting a 240v table saw to 120v supply will run like **** and destroy the motor.

Besides the refrigerator motor, the 150 amp draw will burn up wires and fry the converter (unless it's rated for that much amperage.)

1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A

Posted By: Griff in Fairbanks on 09/16/14 07:37pm

Tmmltn wrote:

A 300w inverter won't so squat.

15 amps (the standard household outlet) at 120 volts equals 1800 watts. So, I'd recommend at least a 2400 watt inverter.

Also, even a 300 watt inverter will drain a battery quickly. So, if you're going to try to run 120v appliances off an inverter, you'll need a fairly good battery bank to make it reasonably useful.

Also, a 45 watt solar panel is only putting out 3.3 amps at 13.6 volts, under ideal conditions (aimed correctly under full sunlight). Basically, that solar panel is just a trickle charger.

In a nutshell, think off-grid power systems ... That's what you're looking at if you're thinking along these lines.

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