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No Power to Dash/Chassis

Joeycockerspani
Explorer
Explorer
So I go out to crank my motorhome. Batteries are fine. House power is fine. Everything works on the house side. But I have no voltage to the power distribution box located under the driver area. Consequently, nothing related to dash features shows any signs of life. Turn the ignition key, nothing. No gauges come to life, no buzzers, no power to the radio. Nada, zip, nothing. We have had this coach for over a decade. We have had many little glitches to work through. But this one is a first. Anyone out there have an idea?

Coach: 2006 Forest River Charleston
Chassis: Feightliner
Hank & Winde
Cumming, GA.
2006 Forest River Charleston
CAT C7
22 REPLIES 22

MEXICOWANDERER
Explorer
Explorer
I tried to find one that looks like this that is considered "continuous duty" but failed. I have to assssssume the one pictured is a starter motor use relay. Maybe 1.2 ohms resistance across the magnetic coil.

If this rig is a pusher diesel with larger than a seven liter diesel engine, it would require an expensive relay like this to power the jump start which can range to 500+ amps and even more than that in cold weather.

This is an image of a 200-amp bi-directional SMART relay which would pass the power of all but the largest alternators.





With a 7.0+ liter diesel engine I would not elect to use the "feature" of this smart relay to jump start from bank to bank. I would retain the relay what is featured in this thread. Two relays each best suited for it's purpose.

By selecting the BI-Directional model relay the relay will operate and pass current no matter which direction the power is coming from -- alternator or converter. This keeps chassis and hotel batteries happy.

DiskDoctr
Explorer
Explorer
Gdetrailer wrote:
DiskDoctr wrote:
Gdetrailer wrote:
Why don't you simply buy a "battery maintainer"?


An isolator is designed to allow charge to flow from alternator or converter/charger (later powered by shore power or generator) to BOTH the motor battery and the house battery.

But it also allows ONLY the house battery to flow back to power the "RV parts" thereby leaving the motor battery to start the motorhome- even when the house battery is dead.

Sometimes there is a "combine" switch to allow house battery to aid in boosting the motor battery to start in the event of emergency (dead battery).

If the isolator was bad, the converter/charger cannot charge the motor battery, allowing it to slowly lose its charge to parasitic or standby losses.


Wrong.

There are TWO "types" of isolators..

Smart and non-smart.

Non-smart are the STANDARD ISSUE version which allows the vehicles alternator to charge both the starting battery AND the house battery. Acts like a one way valve and does not allow the house converter or batteries to "charge" the starting battery.

DOES NOT PROVIDE EMERGENCY START OR COMBINE OF THE BATTERIES.

Smart isolators on the other hand, can allow the house battery/converter to trickle charge the vehicle battery.

Also provides EMERGENCY STARTING WHICH COMBINES BATTERIES FOR A FEW SECONDS.

The OP obviously does not have a smart isolator or they could have simply pushed the EMERGENCY COMBINE BUTTON to get the engine started.


It's quite obvious which one I described. I've also seen diodes added to simple isolators to allow charging from the genny/converter.

BTW, starting a post with "Wrong" is not only combative, in this case it is also incorrect 😉

Gdetrailer
Explorer III
Explorer III
DiskDoctr wrote:
Gdetrailer wrote:
Why don't you simply buy a "battery maintainer"?


An isolator is designed to allow charge to flow from alternator or converter/charger (later powered by shore power or generator) to BOTH the motor battery and the house battery.

But it also allows ONLY the house battery to flow back to power the "RV parts" thereby leaving the motor battery to start the motorhome- even when the house battery is dead.

Sometimes there is a "combine" switch to allow house battery to aid in boosting the motor battery to start in the event of emergency (dead battery).

If the isolator was bad, the converter/charger cannot charge the motor battery, allowing it to slowly lose its charge to parasitic or standby losses.


Wrong.

There are TWO "types" of isolators..

Smart and non-smart.

Non-smart are the STANDARD ISSUE version which allows the vehicles alternator to charge both the starting battery AND the house battery. Acts like a one way valve and does not allow the house converter or batteries to "charge" the starting battery.

DOES NOT PROVIDE EMERGENCY START OR COMBINE OF THE BATTERIES.

Smart isolators on the other hand, can allow the house battery/converter to trickle charge the vehicle battery.

Also provides EMERGENCY STARTING WHICH COMBINES BATTERIES FOR A FEW SECONDS.

The OP obviously does not have a smart isolator or they could have simply pushed the EMERGENCY COMBINE BUTTON to get the engine started.

MEXICOWANDERER
Explorer
Explorer
OP you need more than pictures. You have an issue of not charging.

a) The relay you ordered is used for ENGINE STARTING only
b) The relay you pictured may be an engine starting relay or a different model

used for charging

HOWEVER

REGARDLESS the relay you ordered is for ENGINE STARTING ONLY. It will ABSOLUTELY and WITHOUT QUESTION burn up if left on for more than a minute or two.

You need a CONSTANT DUTY or CONTINUOUS DUTY relay to charge your batteries

Are you certain, meaning sure, you identified the correct relay? Many coaches have two, one for charging, the second for emergency jump starting.

From thousands of miles away I am unable to gaze into a crystal ball and troubleshoot your rig's electrical wiring diagram.

Without a part number taken from the relay in the photo it is uncertain as to exactly what that relay is. Maybe there are two identical looking relays one for intermittent the second for continuous duty.

Do yourself a favor. See if one of the two LITTLE connections on the relay lights up with the key turned on using a test light connected to the rig's chassis. If yes, then the relay is in the continuous duty wiring circuit. If the terminal does NOT light up twist the key to the starter motor cranking position. Does the relay light up now?

REGARDLESS! CANCEL THAT RELAY ORDER! You are making an expensive no-win mistake.

DiskDoctr
Explorer
Explorer
wnjj wrote:
DiskDoctr wrote:
BTW, did anyone else notice this single thread layout includes a boxed layout and one post in the right column while all the rest are on the left column?

I've not seen this behavior on this site before.

Something in Mex’s eBay link interfered with the page display code. Obviously something that should have been filtered. Ironic considering rv.net won’t even post percent signs.


I see that. Looks like an open 'img src=' failed to get closed by the forum software. A buffer overrun style error. Uh-oh. Invalid tags shouldn't be processed or used for page display, that's how bad guys can inject malicious code (especially into databases)

Joeycockerspani
Explorer
Explorer
Mexicowanderer, here is a picture of the unit that came with the coach, appears to be the unit I ordered.

Hank & Winde
Cumming, GA.
2006 Forest River Charleston
CAT C7

MEXICOWANDERER
Explorer
Explorer
AGGHHH!
The dreaded H19N32 infecto virus has struck. Wish I could get my hands on some of those jerks and perform interesting lab experiments on them...

wnjj
Explorer II
Explorer II
DiskDoctr wrote:
BTW, did anyone else notice this single thread layout includes a boxed layout and one post in the right column while all the rest are on the left column?

I've not seen this behavior on this site before.

Something in Mex’s eBay link interfered with the page display code. Obviously something that should have been filtered. Ironic considering rv.net won’t even post percent signs.

DiskDoctr
Explorer
Explorer
BTW, did anyone else notice this single thread layout includes a boxed layout and one post in the right column while all the rest are on the left column?

I've not seen this behavior on this site before.

DiskDoctr
Explorer
Explorer
Gdetrailer wrote:
Why don't you simply buy a "battery maintainer"?


An isolator is designed to allow charge to flow from alternator or converter/charger (later powered by shore power or generator) to BOTH the motor battery and the house battery.

But it also allows ONLY the house battery to flow back to power the "RV parts" thereby leaving the motor battery to start the motorhome- even when the house battery is dead.

Sometimes there is a "combine" switch to allow house battery to aid in boosting the motor battery to start in the event of emergency (dead battery).

If the isolator was bad, the converter/charger cannot charge the motor battery, allowing it to slowly lose its charge to parasitic or standby losses.

MEXICOWANDERER
Explorer
Explorer
"Intermittent" Yeah...

Intermittent windshield wipers.

Introduced by Lucas Electrical

Gdetrailer
Explorer III
Explorer III
Joeycockerspaniel wrote:
OK, here is what has apparently happened. My coach has a battery isolator solenoid. That solenoid should charge both house and chassis sets of batteries when either set require it. The coach has been plugged in all winter to the in-house float charging system. For ten years, that has kept both sets charged while the coach has not been in use. I replaced all my batteries a little over a year ago. The chassis batteries were almost completely discharged, even while the coach has been plugged in. I highly suspect that the battery isolator unit has gone bad. It no longer charges both sets of batteries, house and chassis, only the house batteries. So now, if recharging the chassis batteries does not work, I will not only have to replace the isolotor solenoid, but also two year-old chassis batteries. Here is the unit I just ordered. https://pdxrvwholesale.com/products/battery-boost-solenoid-1500-amps-intermittent-duty Thanks for the help. Hopefully this will remedy the problem.


Why don't you simply buy a "battery maintainer"?

You already have shore power and battery maintainers are designed to trickle charge your battery.

You can hookup to your chassis batteries then plug maintainer into one of the 120V outlets in you coach.

Can leave in circuit so no muss no fuss.



BATTERY TENDER

If you don't like the Tenders price, you can buy a Harbor Freight version for $10 or less (although you might wish to add in a series diode on the HF one to prevent battery drain in the event of power outages).

DiskDoctr
Explorer
Explorer
Joeycockerspaniel wrote:
OK, here is what has apparently happened. My coach has a battery isolator solenoid...Thanks for the help. Hopefully this will remedy the problem.


That's good news you found the problem 🙂

Be prepared to replace many of the electrical connectors, they tend to rust on all the isolator terminals and such. If so, figure anything that has a terminal on it will be kaput when you try to spin the nuts off :E

Good luck getting it worked out and as Mex has shown, it's smart to post up your proposed solution and parts to be checked before you spend the money on them 😉

MEXICOWANDERER
Explorer
Explorer
Zank you. CROOKS!