1988 Allegro Help

88allegro · 06-06-2011, 03:20 PM

I just purchased my first motorhome. My wife and kids are excited to start using it. But I am looking for some help with it. The batteries are all charged but I have no battery power to the coach, when running the generator all lights and outlets work. What am I doing wrong??

Thanks

tomwalt · 06-06-2011, 03:33 PM

Sounds like the battery cut off switch is off. Mine is located next to the enterance just inside the door, near the fuse pannel/ckt breaker boxes.

tomwalt · 06-06-2011, 03:39 PM

I just checked and mine is labeled '12V' On/Off. This is used to save the house batteries from draining when the RV is not in use.

88allegro · 06-06-2011, 05:24 PM

Okay thanks for looking. I just went out and checked and mine is a 12v on/of toggle switch. So i turned that on and still get nothing?? Now were do I look? Also should my fridge work on electric when gen is running? Thanks

JacknKay · 06-06-2011, 05:42 PM

Quote:

Originally Posted by 88allegro

Also should my fridge work on electric when gen is running? Thanks

Yes it should if it's switched to run on 120. TVs, Microwaves, AC, power plugs all should work from the generator.

tomwalt · 06-06-2011, 06:53 PM

I think you need to get out a volt meter and trace the 12VDC. You say the generator starts ok, so you have 12V there. Next stop is probably at the battery disconnect relay (that is what the 12V On/Off toggle switch operates). Mine is located on the wall of the basement storage unit just aft of the door. It has 2 heavy duty wires - 12V in and 12V out. The 2 small wires are + and -12VDC from the toggle switch. This relay needs a good 12V to work. If your batteries reads less than 12V, try turning the generator on and cycling the 12V switch off, then back on slowly (you don't want to toggle the switch fast or you can ruin the relay). Draw out your 12VDC electrical system as you go - you will use it in the future. Mine goes from the batteries to solenoid on the firewall to the generator to the battery disconnect relay to the fuse box. Good luck. (P.S. if it is the relay, you can new relays on ebay for about $50. Get the part number off of the relay.)

tomwalt · 06-06-2011, 06:59 PM

Here is what it sounds like to me - when the generator is running, the 12V Inverter is providing 12V to the interior lights. When you don't have 120VAC to the inverter from the generator or shore power, the 12V from the batteries are not getting to the fuse box. The relay is my #1 suspect. With the 12V toggle switch on there should be 12VDC on both sides of the relay (the big wires = 12VDC when you measure this with the - lead on a good ground).

vincewarde · 06-25-2011, 09:50 PM

I have a 1978 Tiffen Allegro that was having the same exact problem - 12v power with Gen or shore power - nothing with battery only (yes it's charged).

So I did a test. I connected a ground wire to my test light. I found 12v+ in the wiring box and fuses. So I checked one of the light fixtures - yep 12v+ there too. So relay is good - must be on the ground side.

I do have a few questions:

1) Am I correct in assuming that the ground from the battery DOES NOT pass through the relay?

2) How is the battery typically grounded? The outside skin of the unit IS grounded, but nothing inside is working. Weird.... Anyone have any ideas?

Thanks!

tomwalt · 06-27-2011, 03:20 PM

The batteries are connected to chassis ground in the engine compartment near the batteries. My Allegro has a copper wire (no insulation on it) that runs through the power compartment (a plastic basement compartment next tot he door). Everything (relay, converter, refrig, etc) hooks up to this copper wire for ground. I never followed this ground wire back to see where it connects to the chassis frame. I might get a chance to look this week. Probably a significant difference between my 2000 and your 1978, but this may give you something to look for.

Macrosill · 06-28-2011, 06:36 AM

I just had to replace the negative battery cable on my coach. I could not start the genny when on battery. Turns out it was a vary badly corroded battery cable. When I finally traced the problem back to the cable I had 12v at the battery post but only 4v at the chassis negative post.