Identify electric device

[peer oliver schmidt]

My chassis and house battery are utilized at the same time for house
stuff. Not nice.

Anyone care to tell me what the device is that red arrow points at?

https://tinyurl.com/y7sry8q6

Up where the blue arrow is, I have the isolator.

Thanks.
--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH

 

[peer oliver schmidt]

Peer Oliver Schmidt GMC schrieb/wrote
> My chassis and house battery are utilized at the same time for house
> stuff. Not nice.
>
> Anyone care to tell me what the device is that red arrow points at?
>
> https://tinyurl.com/y7sry8q6
>
> Up where the blue arrow is, I have the isolator.
>
> Thanks.

Okay, a german GMC friend told me, it is the relais that is engaged when
the Battery Boost switch is pressed. Seems I have to check out why it
currently does not do its job of NOT combining the two.

Oh, and on a side note: Is it true, that all GMC MotorHomes were
originally equipped with an isolator?

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH

 

[Ken H.]

That's the boost solenoid relay, used to tie the house and chassis circuits
together. Controlled by the Boost switch om the dash, which may be either
momentary or latching action.

Ken H.

On Wed, Dec 20, 2017 at 12:50 PM, Peer Oliver Schmidt GMC <

> My chassis and house battery are utilized at the same time for house
> stuff. Not nice.
>
> Anyone care to tell me what the device is that red arrow points at?
>
> https://tinyurl.com/y7sry8q6
>
> Up where the blue arrow is, I have the isolator.
>
>

 

[1976GMC]

That is a booster solenoid. You should have your Main Starter battery going to one side of it (I believe it is right side) and the Auxiliary or House
Battery going to the other side (left). When you press AUX BATT switch on the dash, this solenoid connects both batteries for a short time and gives
you a boost for starter.
It is possible that your batteries are not connected to it correctly or that the booster solenoid is stuck "ON" all the time, thus draining the
starter battery together with the house batteries.

> My chassis and house battery are utilized at the same time for house
> stuff. Not nice.
>
> Anyone care to tell me what the device is that red arrow points at?
>
> https://tinyurl.com/y7sry8q6
>
> Up where the blue arrow is, I have the isolator.
>
> Thanks.
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II 26', VA
> '73 Sequoia 23', Germany, SH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA

 

[peer oliver schmidt]

The relay does click clack when the switch changes position. Unfortunately both settings cause continuity between house and chassis. Tomorrow I shall investigate some more
--
Best regards

Peer Oliver Schmidt
'76a Eleganza II, VA
'73 Sequoia, Germany

 

[thomas phipps]

Time to replace the boost solenoid. Cheap and easy.
I think all GMC's (dangerous to assume) came with an idolater to separate the house and engine batteries. Idolater is basically two diodes encased in
the metal heat shield that is the outside box with fins. The diodes are electrically isolated from the case.
Tom
--
2012 Phoenix Cruiser model 2552
KA4CSG

 

[Rdenney]

Looks like an isolator. If it is bypassed, it may because it does not work.
There should be three terminals on the front of it.

The isolator uses a diode from the center terminal to each outer terminal
to all current from the center to the outer terminals, but not from the
outer terminals to anywhere else. The center terminal is wired directly to
the alternator output, and each outer terminal goes to a battery bank.

Rick "preferring a combiner if it has to be replaced anyway" Denney

On Wed, Dec 20, 2017 at 12:51 PM Peer Oliver Schmidt GMC <

> My chassis and house battery are utilized at the same time for house
> stuff. Not nice.
>
> Anyone care to tell me what the device is that red arrow points at?
>
> https://tinyurl.com/y7sry8q6
>
> Up where the blue arrow is, I have the isolator.
>
> Thanks.
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II 26', VA
> '73 Sequoia 23', Germany, SH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com

 

[Rdenney]

Never mind--I misread the original post.

Rick "NOT what the blue arrow is pointing to" Denney

> Looks like an isolator. If it is bypassed, it may because it does not
> work. There should be three terminals on the front of it.
>
> The isolator uses a diode from the center terminal to each outer terminal
> to all current from the center to the outer terminals, but not from the
> outer terminals to anywhere else. The center terminal is wired directly to
> the alternator output, and each outer terminal goes to a battery bank.
>
> Rick "preferring a combiner if it has to be replaced anyway" Denney
>
> On Wed, Dec 20, 2017 at 12:51 PM Peer Oliver Schmidt GMC <

>
>> My chassis and house battery are utilized at the same time for house
>> stuff. Not nice.
>>
>> Anyone care to tell me what the device is that red arrow points at?
>>
>> https://tinyurl.com/y7sry8q6
>>
>> Up where the blue arrow is, I have the isolator.
>>
>> Thanks.
>> --
>> Best regards
>>
>> Peer Oliver Schmidt
>> PGP Key ID: 0x83E1C2EA
>>
>> '76a Eleganza II 26', VA
>> '73 Sequoia 23', Germany, SH
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com

 

[d c *mac* macdonald]

Isn't what the red arrow points at the "boost" relay to parallel both batteries when the boost switch is engaged to allow the house battery to be used to start the engine?

D C "Mac" Macdonald
Amateur Radio K2GKK
Since 30 November '53
USAF and FAA, Retired
Member GMCMI & Classics
Oklahoma City, OK
"The Money Pit"
TZE166V101966
'76 ex-Palm Beach
k2gkk + hotmail dot com

________________________________
From: Gmclist on behalf of Richard Denney
Sent: Wednesday, December 20, 2017 14:54
To: gmclist
Subject: Re: [GMCnet] Identify electric device

Looks like an isolator. If it is bypassed, it may because it does not work.
There should be three terminals on the front of it.

The isolator uses a diode from the center terminal to each outer terminal
to all current from the center to the outer terminals, but not from the
outer terminals to anywhere else. The center terminal is wired directly to
the alternator output, and each outer terminal goes to a battery bank.

Rick "preferring a combiner if it has to be replaced anyway" Denney

On Wed, Dec 20, 2017 at 12:51 PM Peer Oliver Schmidt GMC <

> My chassis and house battery are utilized at the same time for house
> stuff. Not nice.
>
> Anyone care to tell me what the device is that red arrow points at?
>
> https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftinyurl.com%2Fy7sry8q6&data=02%7C01%7C%7Ced6bf358166544acb17408d547ec0aec%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636494001467870804&sdata=clSgl6lw7aX327ZWPvUeZ2ZJ9QQgkOkgpSUkxUPtVj8%3D&reserved=0
>
> Up where the blue arrow is, I have the isolator.
>
> Thanks.
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II 26', VA
> '73 Sequoia 23', Germany, SH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> https://nam03.safelinks.protection.outlook.com/?url=http%3A%2F%2Flist.gmcnet.org%2Fmailman%2Flistinfo%2Fgmclist_list.gmcnet.org&data=02%7C01%7C%7Ced6bf358166544acb17408d547ec0aec%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636494001467870804&sdata=SG6gOxF%2F2m%2BCw8cPrEwHHGnqoFTZ%2BvRX5FO%2B3s6x3TM%3D&reserved=0
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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[1976GMC]

That is a separate part. It is intended to allow both banks of batteries to be charged when the engine was running, but not to allow battery with
higher voltage to attempt to charge the other one that is depleted.

> Time to replace the boost solenoid. Cheap and easy.
> I think all GMC's (dangerous to assume) came with an idolater to separate the house and engine batteries. Idolater is basically two diodes encased
> in the metal heat shield that is the outside box with fins. The diodes are electrically isolated from the case.
> Tom

--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA

 

[Matt Colie]

> Okay, a german GMC friend told me, it is the relais that is engaged when
> the Battery Boost switch is pressed. Seems I have to check out why it currently does not do its job of NOT combining the two.
>
> Oh, and on a side note: Is it true, that all GMC MotorHomes were originally equipped with an isolator?
> --
> Best regards
>
> Peer Oliver Schmidt
> '76a Eleganza II 26', VA
> '73 Sequoia 23', Germany, SH

Peer,

Answer for the first part you have been given. But as a practical matter, if you can't hear the boost contactor (what a BIG relay is often called)
make a THUNK when you it the switch, it is not working.
There are three possibilities:
1 - It is not getting the 12V signal to close.
2 - It is getting the 12V signal, but the winding is bad. Do not replace it with a starter type contactor as they are not continues duty and this
application should be. These are also used for things that draw power for a long time like emergency light on ambulances.
3 - The device contacts have welded. This makes it always On". It is not a common failure, but I have seen them.

To answer your side question. By my experience (not limited to GMCs as motorhomes), Yes, All were shipped with an isolator and a boost contactor.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[Ken B]

I would like to point out that the "Boost relay" is next to never used in normal operation
of your coach. It is only operational when the boost switch on the dash is energized by
the driver. In some years the switch is momentary and in earlier years the switch could be
left in the on position.

How you you know that the boost relay is conducting? If you are doing voltage checks
rather than disconnecting it from the circuit and checking it with an ohm meter, the
problem could easily be located somewhere else in the coach and you are just reading it
there.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[peer oliver schmidt]

An update:

The solenoid does click whenever the switch on the dash changes position.

And, after unscrewing the cables from the left hand side of the solenoid
(which are part of the house battery), the house lights still works. So,
I somewhere have a nice little present from a previous owner, where the
house circuit is given energy from the chassis battery. Aint this nice.

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH

 

[peer oliver schmidt]

And another update:

Unscrewing the house part from the isolator causes all lights in the
house to stop functioning - Yeahy, it is just a shot isolator, and not
some PO screwage. Sorry for even mentioning that one of the gazillion
POs of my 23' might have caused this.

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH

 

[peer oliver schmidt]

And the last update for today. Just ordered a

Victron Cyrix-ct 120A -
https://www.victronenergy.com/battery-isolators-and-combiners/cyrix-battery-combiners 

should be here on Friday and will replace the broken isolator, as well
as the working solenoid.

Thanks for all the help.

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH

 

[dave stragand1]

Can you post a photo or two of the wiring around the isolator and solenoid at gmcmhphotos.com? We might be able to spot an incorrect wire position or jumper.

>
> And the last update for today. Just ordered a
>
> Victron Cyrix-ct 120A -
> https://www.victronenergy.com/battery-isolators-and-combiners/cyrix-battery-combiners
>
>
> should be here on Friday and will replace the broken isolator, as well
> as the working solenoid.
>
> Thanks for all the help.
>
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II 26', VA
> '73 Sequoia 23', Germany, SH
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[peer oliver schmidt]

Dave Stragand schrieb/wrote
> Can you post a photo or two of the wiring around the isolator and solenoid at gmcmhphotos.com? We might be able to spot an incorrect wire position or jumper.

Afaict the wiring is correct https://photos.app.goo.gl/RH9ts3TZrzy0L8f02
- the solenoid's wiring can be looked at in more detail at the original
tinyurl I posted at the beginning of the thread.

The minute I remote the house wire from the isolator, all lights go off.
The new device is only ~50EUR and will replace the solenoid and the
insulator, so it is a helpful thing anyway.

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH

 

[Ken B]

I question your diagnosis in that to have a failure that you are describing,
it would take a double shorted diode in the isolator and no power being supplied by the house battery

Removing the isolator from the circuit should NOT interrupt the power coming from the house battery.
The isolator is part of the alternator power supply circuit and has nothing to do with the battery
supplying power to the coach.

I think that you have a wiring error and not an isolator problem. It sounds like your house battery
is supplying power to the center terminal of the isolator rather than direct to the house circuits.

I also would be careful removing the boost relay. It will be very possible to over current that new
combiner by trying to start the engine using the boost function.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Matt Colie]

Peer,

This is not any kind of a criticism of of your language capability. (Your English is much better than my German.)
The blue finned thing is the isolator and the round thing below it is the boost solenoid. Agree?
(Remember I have another '73 23' and know the issues well.)

Are you saying the the house lights stay on when you remove the cables to the outboard side of the boost solenoid, but go out when you remove the wire
from the house terminal of the isolator?

Ken wrote: I question your diagnosis in that to have a failure that you are describing, it would take a double shorted diode in the isolator and no
power being supplied by the house battery.

I have been straining to get this figured out and Ken may be mistaken.... (I never thought I would write that. - Either Ken)
If the alternator to engine battery went solid (as opposed to open) then this could happen, but it would require some creative rewiring as the
terminal that is the central to all the 12V house is that post in the boost contactor. This would also make the alternator terminal hot when it
should not be, but that should cause no other issues.

If the both diodes solid is correct, that is a very strange case. In all my years of 12V electrics, I have only seen one isolator diode go solid.
These typically fail open when they do fail and that is just not common. And the rarely both fail. (Lightning strikes are another matter.)

I have to believe that that there is something there that should not be.

A simple test with a meter will confirm that the isolator has failed. An ohmmeter reading from the center to either post should give a reading one
way and nothing the other.

Please tell us if/when you find it.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[peer oliver schmidt]

Let me try to clear things up:

When I take the house battery out of the coach, the lights of the house
still work. Removing the house battery cable from the boost solenoid did
not turn off the house lights. Removing the house battery cable from the
isolator caused the lights to go off.

This means to me, that the house battery circuit is receiving energy
through the isolator from the chassis battery, something that should not
happen.

Feel free to correct me if I am wrong

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH