Home » Public Forums » GMCnet » aux house batteries up front
| aux house batteries up front [message #167779] |
Fri, 27 April 2012 14:43  |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
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Managed to get my Ragusa 3-batt tray installed and engine battery mounted. Very happy. Well-designed, fit with no wasted space. Now I need to figure out how to string the big wires to the back to tie in to my main house batteries.
Lots of questions:
* Is 1-ga sufficient?
* Planning on using welding cable. Any downside other than cost?
* Have a Xantrex battery monitor with shunt so I'll need to run both + & - all the way back. Thoughts?
* Heard that running it in "conduit" of PVC pipe is a good plan. Can't see an easy way to route it. Figure the most logical would be to run it along the frame rail, but the top won't work as that's where the body mounts, the bottom exposes it to road debris damage, the inside is complicated by the lateral frame pieces, and the outside is blocked by the bogies. What has been done that worked?
* Any other tips? I already have a battery selector switch in the rear.
Thanks much.
Jay Rabe
76 PB
Portland, OR
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| Re: [GMCnet] aux house batteries up front [message #167788 is a reply to message #167779] |
Fri, 27 April 2012 16:03  |
rssbob
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
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On Apr 27, 2012, at 12:43 PM, Jay Rabe wrote:
>
>
> Managed to get my Ragusa 3-batt tray installed and engine battery mounted. Very happy. Well-designed, fit with no wasted space. Now I need to figure out how to string the big wires to the back to tie in to my main house batteries.
>
> Lots of questions:
> * Is 1-ga sufficient?
> * Planning on using welding cable. Any downside other than cost?
> * Have a Xantrex battery monitor with shunt so I'll need to run both + & - all the way back. Thoughts?
> * Heard that running it in "conduit" of PVC pipe is a good plan. Can't see an easy way to route it. Figure the most logical would be to run it along the frame rail, but the top won't work as that's where the body mounts, the bottom exposes it to road debris damage, the inside is complicated by the lateral frame pieces, and the outside is blocked by the bogies. What has been done that worked?
> * Any other tips? I already have a battery selector switch in the rear.
>
> Thanks much.
>
> Jay Rabe
> 76 PB
> Portland, OR
>
>
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Jay,
I ran 5 batteries, 4 house and one engine, all up front. I had the 3 batt tray and the 2 batt tray to house all of the batts. Because of where I had my inverter (where the old oven used to be, I pulled the driver's side wheel well liner and ran the cables up and over to get me into the coach then put the liner back on protecting the cables. Here is a link to the album. Cruise around the album and you can see how mine came out.
http://www.gmcmhphotos.com/photos/inverter-converter-install/p15235.html
Bob Sobrito
1978 Palm Beach
La Mesa, Ca
antique pocket watch repair
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78 Palm Beach
La Mesa, Ca
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| Re: aux house batteries up front [message #167789 is a reply to message #167779] |
Fri, 27 April 2012 16:08 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
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Hi Jay,
The aluminum structure is an EXCELLENT conductor. You can definitely use it as your negative. Only thing you have to do is be sure you have good connections. Aluminum oxidizes easily so you'll need to clean both sides of your attachment hole down to shiny metal, coat the area liberally with a good anti-oxidant (Lowes, etc.) use star washers between bolt head and lug, between lug and structure and between structure and nut. I prefer locking nuts like nylock.
I ran my cable across the front of the radiator in a piece of conduit then along the frame past the left front tire, then into the coach and through conduit under the couch and behind the kitchen.
Drop by, I may just have some welding cable in your size.
Glenn
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: aux house batteries up front [message #167854 is a reply to message #167779] |
Sat, 28 April 2012 02:35 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I do not understand. You already have one big cable going back there that was installed by GM. Why do you want another one?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #167885 is a reply to message #167865] |
Sat, 28 April 2012 13:47 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| emerystora wrote on Sat, 28 April 2012 08:29 |
Ken
I believe they said it was made by Coachmen so it would be a GMC Transmode chassis. So I don't think it came with a cable installed by GMC.
Emery Stora
On Apr 28, 2012, at 1:35 AM, Ken Burton
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His signature line says 76 PB
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #167887 is a reply to message #167885] |
Sat, 28 April 2012 14:04 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Ken
I think that you are looking at the wrong message.
Here is the one that discussed the two wires going back to the rear:
********************************
I just installed new batteries, cables, and boost relay in the GMC. In cleaning all my connections I have two wires that I am not sure where they go. These two wires run together across the lower radiator support and down the driver
s side frame rail to the back of the coach. One wire is a #4 gauge battery cable and the other is a much smaller grey wire. The smaller grey wire runs up into the coach floor toward the rear with a bunch of other wires. The larger #4 cable runs to the generator box.
I did look at the online wiring diagrams but could not figure it out. I think they both ran to the lower lug on the round electrical component mounted just underneath the boost relay. What is the name of that component and can anyone confirm that connection for me? Right now I have no wire going to that lug. I just am not sure if they are both suppose to be connected there.
Benson
76 Birchhaven
Florida
*************************************
It sure looks to me like that would be a Coachmen build if its a Birchaven.
Emery Stora
77 Kingsley
On Apr 28, 2012, at 12:47 PM, Ken Burton wrote:
>
>
> emerystora wrote on Sat, 28 April 2012 08:29
>> Ken
>> I believe they said it was made by Coachmen so it would be a GMC Transmode chassis. So I don't think it came with a cable installed by GMC.
>>
>>
>> Emery Stora
>>
>> On Apr 28, 2012, at 1:35 AM, Ken Burton
>
>
> His signature line says 76 PB
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] aux house batteries up front [message #167963 is a reply to message #167887] |
Sun, 29 April 2012 17:12 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I don't know at this point. I'm confused. Here is what I was what I saw and responded to. It is two up in the thread from my response:
On Apr 27, 2012, at 12:43 PM, Jay Rabe wrote:
>
>
> Managed to get my Ragusa 3-batt tray installed and engine battery mounted. Very happy. Well-designed, fit with no wasted space. Now I need to figure out how to string the big wires to the back to tie in to my main house batteries.
>
> Lots of questions:
> * Is 1-ga sufficient?
> * Planning on using welding cable. Any downside other than cost?
> * Have a Xantrex battery monitor with shunt so I'll need to run both + & - all the way back. Thoughts?
> * Heard that running it in "conduit" of PVC pipe is a good plan. Can't see an easy way to route it. Figure the most logical would be to run it along the frame rail, but the top won't work as that's where the body mounts, the bottom exposes it to road debris damage, the inside is complicated by the lateral frame pieces, and the outside is blocked by the bogies. What has been done that worked?
> * Any other tips? I already have a battery selector switch in the rear.
>
> Thanks much.
>
> Jay Rabe
> 76 PB
> Portland, OR
If it is a 76 PB then he already has a heavy cable. If it is a Birchaven then I have no idea what he has.
Ken
| emerystora wrote on Sat, 28 April 2012 14:04 |
Ken
I think that you are looking at the wrong message.
Here is the one that discussed the two wires going back to the rear:
********************************
I just installed new batteries, cables, and boost relay in the GMC. In cleaning all my connections I have two wires that I am not sure where they go. These two wires run together across the lower radiator support and down the driver
s side frame rail to the back of the coach. One wire is a #4 gauge battery cable and the other is a much smaller grey wire. The smaller grey wire runs up into the coach floor toward the rear with a bunch of other wires. The larger #4 cable runs to the generator box.
I did look at the online wiring diagrams but could not figure it out. I think they both ran to the lower lug on the round electrical component mounted just underneath the boost relay. What is the name of that component and can anyone confirm that connection for me? Right now I have no wire going to that lug. I just am not sure if they are both suppose to be connected there.
Benson
76 Birchhaven
Florida
*************************************
It sure looks to me like that would be a Coachmen build if its a Birchaven.
Emery Stora
77 Kingsley
On Apr 28, 2012, at 12:47 PM, Ken Burton wrote:
>
>
> emerystora wrote on Sat, 28 April 2012 08:29
>> Ken
>> I believe they said it was made by Coachmen so it would be a GMC Transmode chassis. So I don't think it came with a cable installed by GMC.
>>
>>
>> Emery Stora
>>
>> On Apr 28, 2012, at 1:35 AM, Ken Burton
>
>
> His signature line says 76 PB
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #167967 is a reply to message #167963] |
Sun, 29 April 2012 17:25 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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Senior Member |
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OK, well I was pretty confused too, but getting back on track...
Yes, it is a 76 PB, and yes, I have a large cable going from front to back. I thought that was the boost cable. Hadn't even thought about using it. I'd have to dig into the schematics, but it's pretty fuzzy in my mind right now how to use that same cable for both boost and tieing the batteries together.
Then back to original question, whether it's large enough for continuous use, vs. intermittent boost use. What size is big enough for the continuous use of tieing the batteries together?
But I would still need to run a large ground cable from the aux batts back to the shunt in the rear so that my battery monitor was accurate.
Thanks,
Jay Rabe
76 PB
Portland, OR
> To: gmclist@temp.gmcnet.org
> From: n9cv@comcast.net
> Date: Sun, 29 Apr 2012 17:12:25 -0500
> Subject: Re: [GMCnet] aux house batteries up front
>
>
>
> I don't know at this point. I'm confused. Here is what I was what I saw and responded to. It is two up in the thread from my response:
>
> On Apr 27, 2012, at 12:43 PM, Jay Rabe wrote:
>
> >
> >
> > Managed to get my Ragusa 3-batt tray installed and engine battery mounted. Very happy. Well-designed, fit with no wasted space. Now I need to figure out how to string the big wires to the back to tie in to my main house batteries.
> >
> > Lots of questions:
> > * Is 1-ga sufficient?
> > * Planning on using welding cable. Any downside other than cost?
> > * Have a Xantrex battery monitor with shunt so I'll need to run both + & - all the way back. Thoughts?
> > * Heard that running it in "conduit" of PVC pipe is a good plan. Can't see an easy way to route it. Figure the most logical would be to run it along the frame rail, but the top won't work as that's where the body mounts, the bottom exposes it to road debris damage, the inside is complicated by the lateral frame pieces, and the outside is blocked by the bogies. What has been done that worked?
> > * Any other tips? I already have a battery selector switch in the rear.
> >
> > Thanks much.
> >
> > Jay Rabe
> > 76 PB
> > Portland, OR
>
>
>
>
>
>
> If it is a 76 PB then he already has a heavy cable. If it is a Birchaven then I have no idea what he has.
>
> Ken
>
>
>
>
>
>
>
> emerystora wrote on Sat, 28 April 2012 14:04
> > Ken
> >
> > I think that you are looking at the wrong message.
> > Here is the one that discussed the two wires going back to the rear:
> >
> > ********************************
> >
> > I just installed new batteries, cables, and boost relay in the GMC. In cleaning all my connections I have two wires that I am not sure where they go. These two wires run together across the lower radiator support and down the driver
> > s side frame rail to the back of the coach. One wire is a #4 gauge battery cable and the other is a much smaller grey wire. The smaller grey wire runs up into the coach floor toward the rear with a bunch of other wires. The larger #4 cable runs to the generator box.
> >
> > I did look at the online wiring diagrams but could not figure it out. I think they both ran to the lower lug on the round electrical component mounted just underneath the boost relay. What is the name of that component and can anyone confirm that connection for me? Right now I have no wire going to that lug. I just am not sure if they are both suppose to be connected there.
> >
> >
> > Benson
> > 76 Birchhaven
> > Florida
> > *************************************
> > It sure looks to me like that would be a Coachmen build if its a Birchaven.
> >
> >
> > Emery Stora
> > 77 Kingsley
> >
> >
> > On Apr 28, 2012, at 12:47 PM, Ken Burton wrote:
> >
> > >
> > >
> > > emerystora wrote on Sat, 28 April 2012 08:29
> > >> Ken
> > >> I believe they said it was made by Coachmen so it would be a GMC Transmode chassis. So I don't think it came with a cable installed by GMC.
> > >>
> > >>
> > >> Emery Stora
> > >>
> > >> On Apr 28, 2012, at 1:35 AM, Ken Burton
> > >
> > >
> > > His signature line says 76 PB
> > > --
> > > Ken Burton - N9KB
> > > 76 Palm Beach
> > > Hebron, Indiana
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #168026 is a reply to message #167967] |
Mon, 30 April 2012 01:29 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| jayrabe wrote on Sun, 29 April 2012 17:25 |
OK, well I was pretty confused too, but getting back on track...
Yes, it is a 76 PB, and yes, I have a large cable going from front to back. I thought that was the boost cable. Hadn't even thought about using it. I'd have to dig into the schematics, but it's pretty fuzzy in my mind right now how to use that same cable for both boost and tieing the batteries together.
Then back to original question, whether it's large enough for continuous use, vs. intermittent boost use. What size is big enough for the continuous use of tieing the batteries together?
But I would still need to run a large ground cable from the aux batts back to the shunt in the rear so that my battery monitor was accurate.
Thanks,
Jay Rabe
76 PB
Portland, OR
|
First, you do not need a long cable to the rear for the ground side. The aluminum coach body is the master ground for the house battery system. Just hook the minus side of the battery battery to anyplace on the coach body.
There is a jumper strap across the front body isolator on the passenger side that could be convenient place to remove the bolt and attach the added ground battery cable to.
Now on the positive cable side. You could attach the positive battery cable to the boost solenoid on the house side. Then you will have a big heavy cable running to the rear battery(s).
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #168048 is a reply to message #168030] |
Mon, 30 April 2012 11:47 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| jayrabe wrote on Mon, 30 April 2012 06:03 |
Thanks Ken.
I'll sure look into using the boost cable for the pos. Sounds like it should work.
But the way I understand my battery monitor, ALL current must go through the shunt. One end of the shunt goes to the battery, the other end goes to chassis. Everything that uses current and is connected to the chassis, which is most things, has to have that current go through the shunt before going back to the battery. If I put the front battery neg on the chassis, it skips the shunt. Appliances and devices that get their ground direct at the chassis would be invisible to my shunt and the monitor loses it's accuracy.
Am I missing something?
Jay Rabe
76 PB
Portland, OR
> First, you do not need a long cable to the rear for the ground side. The aluminum coach body is the master ground for the house battery system. Just hook the minus side of the battery battery to anyplace on the coach body.
> There is a jumper strap across the front body isolator on the passenger side that could be convenient place to remove the bolt and attach the added ground battery cable to.
> Now on the positive cable side. You could attach the positive battery cable to the boost solenoid on the house side. Then you will have a big heavy cable running to the rear battery(s).
> Ken Burton - N9KB
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Jay,
I'm not sure how your battery monitor is set up, but my Trimetric 2025 has inputs for two separate batteries fed from two shunt resistors. It might be cheaper and easier to add an additional shunt to your new battery bank and run the control wiring back to your monitor panel. That way you could keep an eye on the battery banks separately. I am somewhat electrically challenged (like Rob) so I may be all wet on this, but it seems like it would work.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] aux house batteries up front [message #168054 is a reply to message #168048] |
Mon, 30 April 2012 12:30 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Both of you are correct on this.
I do not at the moment see a simple work around for that shunt wiring problem. Let me think on that one for a while.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #168061 is a reply to message #168048] |
Mon, 30 April 2012 14:10 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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Senior Member |
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Hi Carl,
I think you may have the best solution. Yes, my Xantrex can be set up to monitor two batteries as well, and yes it would require a second shunt. But thinking about it, I'm sure you're right that it's a lot cheaper/easier to buy a second shunt and string some 20ga sense wires than to run 30' of heavy gauge welding cable. Thanks, I'll investigate that direction.
Jay Rabe
76 PB
Portland, OR
> Jay,
>
> I'm not sure how your battery monitor is set up, but my Trimetric 2025 has inputs for two separate batteries fed from two shunt resistors. It might be cheaper and easier to add an additional shunt to your new battery bank and run the control wiring back to your monitor panel. That way you could keep an eye on the battery banks separately. I am somewhat electrically challenged (like Rob) so I may be all wet on this, but it seems like it would work.
> --
> Carl S.
> '75 ex Palm Beach
> Tucson, AZ.
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| Re: [GMCnet] aux house batteries up front [message #168075 is a reply to message #168030] |
Mon, 30 April 2012 17:53 |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Jay,
Quote. > "ALL current must go through the shunt. One end of the shunt goes to the battery, the other end goes to chassis." <
Think of yourself as the shunt. Your right hand is connected to the house batt +(positive) only, no matter where the house batteries are located. Not the chassis batt ( that's a separate independent system).
Your left hand is connects to all your house loads and charging power (amps), such as lights,12vdc outlets, refer, converter, solar, engine alternator.
Any power drawn or fed back to house batt is on your left.
This way you're monitoring all that comes out, or goes in to the house batt.
Quote > "If I put the front battery neg on the chassis, it skips the shunt. Appliances and devices that get their ground direct at the chassis would be invisible to my shunt and the monitor loses it's accuracy." <
Again, the house batt - (negatives) need to be connected anywhere to the house frame (the house frame is the return wire back to the house batt), along with all house 12vdc loads (the negative can't bypass the shunt).
The chassis negative is connected to the chassis, even though there's a cross over connection between the 2 systems, the positives of one system doesn't cross over to the other anywhere.
If your intent is to monitor both systems, then duplicate the monitoring, the 2 system positive must remain separate.
Now, did I managed to stir the mud a little bit more?
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: [GMCnet] aux house batteries up front [message #168080 is a reply to message #168075] |
Mon, 30 April 2012 18:14 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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Any "shunt" goes across something. I.E., it shunts current around.
You are speaking here of "meter shunts" where an extremely low
resistance is placed in SERIES with the path from battery to load
but ACROSS a meter. The current THROUGH the shunt will cause
a voltage drop which is then measured by the meter in parallel
with the shunt. Needless to say, the resistance of the "shunt"
must be VERY low, so that very little energy (and consequent
voltage drop) will be "lost." A typical meter shunt might be as
low as .01 Ohms. At a 10 Amp current draw, the voltage drop
across the shunt/meter pairing would be .1 Volt. This would
probably be excessive. A more reasonable shunt resistance
might be .0025 Ohms which would deliver a voltage of .025 Volts.
Assuming a desire to measure a 100 Amp current in the circuit,
a meter movement with a 250 millivolt full scale capability
might be required.
As always, the devil is in the details. My guess is that you
are likely to be dealing with stray resistances in the various
connections to throw off any real accuracy in such circuits.
As usual, large conductors and VERY good connections
are mandatory.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
*[ ] [][ ][|\
*--OO--[]---O-*
> To: gmclist@temp.gmcnet.org
> From: fixman54@syix.com
> Date: Mon, 30 Apr 2012 17:53:41 -0500
> Subject: Re: [GMCnet] aux house batteries up front
>
>
>
> Jay,
>
> Quote. > "ALL current must go through the shunt. One end of the shunt goes to the battery, the other end goes to chassis." <
>
>
> Think of yourself as the shunt. Your right hand is connected to the house batt +(positive) only, no matter where the house batteries are located. Not the chassis batt ( that's a separate independent system).
>
> Your left hand is connects to all your house loads and charging power (amps), such as lights,12vdc outlets, refer, converter, solar, engine alternator.
> Any power drawn or fed back to house batt is on your left.
>
> This way you're monitoring all that comes out, or goes in to the house batt.
>
>
> Quote > "If I put the front battery neg on the chassis, it skips the shunt. Appliances and devices that get their ground direct at the chassis would be invisible to my shunt and the monitor loses it's accuracy." <
>
>
> Again, the house batt - (negatives) need to be connected anywhere to the house frame (the house frame is the return wire back to the house batt), along with all house 12vdc loads (the negative can't bypass the shunt).
>
> The chassis negative is connected to the chassis, even though there's a cross over connection between the 2 systems, the positives of one system doesn't cross over to the other anywhere.
>
> If your intent is to monitor both systems, then duplicate the monitoring, the 2 system positive must remain separate.
>
> Now, did I managed to stir the mud a little bit more?
> --
> "When we avoid the mistakes we might have made, we sometimes make the mistakes that we might have avoided."
>
>
>
> Adrien & Jenny
> 75 Glenbrook
> Yuba City,Ca.
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| Re: [GMCnet] aux house batteries up front [message #168084 is a reply to message #168080] |
Mon, 30 April 2012 18:35 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Beyond Mac's explanation, there are other possible complications, which
your insistence on using the ground lead as a location for the shunt seems
to indicate. If the readout is digital, chances are its ground must be the
same as one side of the shunt. There ARE digital readouts available which
have isolated inputs which allow the shunt to be placed in any location,
but they're less common than those which require the same ground. I don't
think your readout type or requirements have been mentioned.
Ken H.
On Mon, Apr 30, 2012 at 7:14 PM, D C *Mac* Macdonald wrote:
>
> Any "shunt" goes across something. I.E., it shunts current around.
> You are speaking here of "meter shunts" where an extremely low
> resistance is placed in SERIES with the path from battery to load
> but ACROSS a meter. The current THROUGH the shunt will cause
> a voltage drop which is then measured by the meter in parallel
> with the shunt. Needless to say, the resistance of the "shunt"
> must be VERY low, so that very little energy (and consequent
> voltage drop) will be "lost." A typical meter shunt might be as
> low as .01 Ohms. At a 10 Amp current draw, the voltage drop
> across the shunt/meter pairing would be .1 Volt. This would
> probably be excessive. A more reasonable shunt resistance
> might be .0025 Ohms which would deliver a voltage of .025 Volts.
>
> Assuming a desire to measure a 100 Amp current in the circuit,
> a meter movement with a 250 millivolt full scale capability
> might be required.
>
> As always, the devil is in the details. My guess is that you
> are likely to be dealing with stray resistances in the various
> connections to throw off any real accuracy in such circuits.
>
> As usual, large conductors and VERY good connections
> are mandatory.
>
>
>
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] aux house batteries up front [message #168097 is a reply to message #168075] |
Mon, 30 April 2012 20:09 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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Senior Member |
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Adrien,
Thanks, and OK in principle, but doesn't apply to my system. I have the shunt measuring the current in the ground leg, not the positive. That's just the way the mfr said to do it. I'll try to get a picture of the installation schematic to help clarify. Should have specified, "one end of the shunt goes to the battery neg terminal." Still muddy?? LOL
Like your quote!
Jay Rabe
76 PB
Portland, OR
> From: fixman54@syix.com
> Date: Mon, 30 Apr 2012 17:53:41 -0500
> Jay,
> Quote. > "ALL current must go through the shunt. One end of the shunt goes to the battery, the other end goes to chassis." <
> Think of yourself as the shunt. Your right hand is connected to the house batt +(positive) only, no matter where the house batteries are located. Not the chassis batt ( that's a separate independent system).
> Your left hand is connects to all your house loads and charging power (amps), such as lights,12vdc outlets, refer, converter, solar, engine alternator.
> Any power drawn or fed back to house batt is on your left.
> This way you're monitoring all that comes out, or goes in to the house batt.
> Quote > "If I put the front battery neg on the chassis, it skips the shunt. Appliances and devices that get their ground direct at the chassis would be invisible to my shunt and the monitor loses it's accuracy." <
> Again, the house batt - (negatives) need to be connected anywhere to the house frame (the house frame is the return wire back to the house batt), along with all house 12vdc loads (the negative can't bypass the shunt).
> The chassis negative is connected to the chassis, even though there's a cross over connection between the 2 systems, the positives of one system doesn't cross over to the other anywhere.
> If your intent is to monitor both systems, then duplicate the monitoring, the 2 system positive must remain separate.
> Now, did I managed to stir the mud a little bit more?
> --
> ”When we avoid the mistakes we might have made, we sometimes make the mistakes that we might have avoided.”
>
> Adrien & Jenny
> 75 Glenbrook
> Yuba City,Ca.
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| Re: [GMCnet] aux house batteries up front [message #168106 is a reply to message #168075] |
Mon, 30 April 2012 20:50 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| Adrien G. wrote on Mon, 30 April 2012 17:53 |
Quote > "If I put the front battery neg on the chassis, it skips the shunt. Appliances and devices that get their ground direct at the chassis would be invisible to my shunt and the monitor loses it's accuracy." <
----- SNIP -----
Now, did I managed to stir the mud a little bit more?
|
Yes, but I'm sure you know what your are saying.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] aux house batteries up front [message #168114 is a reply to message #168097] |
Mon, 30 April 2012 21:27 |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Senior Member |
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Jay,
Even though the shunt is on the negative side of the batt, if all the house power requirement from the house batt are drawn from the house batt, the shunt will only measure those electrons from that system.
And even though some grounds may be connected to the chassis, providing the ground straps have good connection (bridging connection between chassis and house), the 2 system will act separately.
I feel that the monitor should be able to measure the load weather the shunt is on the positive side or negative side. And the chassis system will not effect the shunt readings.
So, here's the mud in a different form.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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