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Eagle40W · 09-28-2022, 08:02 AM

I have a 05 Monaco Dynasty Diamond IV and my house batteries don't charge while driving. The chassis batteries are charging 13.9 - 14 volts but the chassis batteries stay at about 12.5 volts and continue to drain as time passes. I'm thinking it's the Big Boy, but don't want to buy one until I'm certain that's my problem. Is there any way of isolating the problem?
The house batteries charge fine when plugged into shore power or on generator.
Also the Big Boy is quite warm when plugged into to shore power and hums. When I push the battery boost switch the humming stops.
I've tried running the coach for extended periods and measuring the voltage at the big boy terminals. With the coach running, the chassis side measures 13.9-14 volts and the house side stays at whatever voltage I measure at the batteries which is usually around 12.3-12.6 volts.
Any help would be appreciated.

twinboat · 09-28-2022, 08:20 AM

If the big boy is warm and the large terminals are not reading the same voltage, it's bad.

Many can be opened up so the contacts can be cleaned.

Eagle40W · 09-28-2022, 08:48 AM

Thanks for the info.
I just ordered a new one, so we will see if that fixes it. Once I have the new one, I will remove the old one and try cleaning the contacts. If it works, at least I will have a spare.

shootist · 09-28-2022, 02:01 PM

Quote:

Originally Posted by Eagle40W

Thanks for the info.
I just ordered a new one, so we will see if that fixes it. Once I have the new one, I will remove the old one and try cleaning the contacts. If it works, at least I will have a spare.

A blue sea acr is a better fix. Another thread on this in class a or motorhomes above. The big boy being warm is normal. It's not a latching relay so it always draws current if engaged. The contacts are a constant problem. https://www.amazon.com/Blue-Sea-Syst...a-434132500260

153stars · 09-28-2022, 02:18 PM

The price is actually down about $20

Eagle40W · 09-29-2022, 08:39 AM

Thanks for the info on the blue sea acr. Unfortunately, a new big boy is already on its way to me, but I will definitely look into the blue sea acr for the future.
I do allot of mechanical work, but I'm not good with electrical. Is it difficult to convert to the blue sea acr from a big boy?

shootist · 09-29-2022, 05:36 PM

Quote:

Originally Posted by Eagle40W

Thanks for the info on the blue sea acr. Unfortunately, a new big boy is already on its way to me, but I will definitely look into the blue sea acr for the future.
I do allot of mechanical work, but I'm not good with electrical. Is it difficult to convert to the blue sea acr from a big boy?

no, it's pretty straight forward. You do need a little 12v wiring skills. There is a large thread on it from 2 or 3 years ago. Search it on this sight. Nice thing is you can manually operate it the minute you get it bolted in.

153stars · 09-30-2022, 06:02 AM

As long as the bird module or board is pulling it in the new BB should last a while. There are supposed to be silver contact kits available to rebuild your old one. Others just clean and polished out old copper contacts.

moisheh · 10-02-2022, 03:37 PM

There is either an Intellitec module or a board that works with the Big Boy. Be carefull when you undo the battery cables on the relay. You don't want do any welding! I cover the ends with poly tubing. Of you post a picture of the rear run bay someone will be able to tell you which Intellitec item you have. Make sure you get the correct Big Boy. There are 2 models. One is for Intermittent contact. The other is not
You can bench test the bigboy by applying power to the small terminal and checking voltage at both large terminals.