Revisiting Electrical Questions!

[WarpathEngineering]

Hello everyone,

If we haven't beaten this horse enough yet, I guess it's my turn. Work is going like hell and my brain has turned to mush so I need your all's input.

I've finally gotten back to my Grandby rebuild and before I button up the walls, I need to run some new wiring. That's not the problem. I'm trying to wrap my head around the umbilical wiring. When I bought my used Grandby, I had wires pulled out of every corner of the thing and with no basis to start with....

Tell me if this makes sense so far.

To install a deep cell battery of sufficiant size in the empty cavity in the engine compartment. This battery will be seperated from the primary vehicle battery by the use of a Sure Power 1314 battery seperator, fused for 30 amps and sent to the camper by way of a #10 wire. The battery seperator will be installed in the engine compartment (?) along with the 30 amp fuse. The 1314 has main terminals to connect the accessory and vehicle batteries, a ground wire and ???? I'm assuming that there is also a connection to the ignition to allow paralelling of the batteries for engine start up. Is there also one that connects to the alternator to allow the accessory battery to be charged while driving? Will it allow the vehicle battery to be charged by the camper's converter when connected to shore power?

Please excuse my ignorance! I've never used a battery seperator before. I'm used to using straight up battery isolators but from what I've read, they cannot be used with my type of alternator because of a sensing issue with a voltage drop across the diodes.

Thanks for the help!
Rick

 

[winter200]

Please excuse my ignorance! I've never used a battery seperator before. I'm used to using straight up battery isolators but from what I've read, they cannot be used with my type of alternator because of a sensing issue with a voltage drop across the diodes.



I would like to hear more about this. Doesn't seem to make sense to me that an isolator wouldn't work for you.

 

[WarpathEngineering]

Here is my foundation for that statement. I got this off of:

http://www.smithae.com/surepower.html

They are a Sure Power dealer. Here is what they had to say:

"The difference in whether to use a battery isolator or battery separator will depend on whether your alternator has internal or external voltage sensing. Many of the newer alternators are internal sensing and so cannot be used with an isolator, because of the loss of approximately 1 volt across the diodes, In these cases you would use a battery separator."

As far as I'm aware, my '98 GMC with a Delphi alternator uses internal sensing.

 

[winter200]

Sounds like a good sales pitch but I don't know if I buy it. I have had many gm rigs, 95 full size blazer, 97 1/2 ton pickup, 98 3/4 ton burban, 04 duramax and my 07 yukon xl. All of which I have used to pull campers with on board batteries. The rv plug on the rigs have a direct connection to the battery (fused of course) and connect directly to the camper battery. The same drain down situation can happen if you use the camper while it is hooked to the truck. I have camped using battery power and have hooked it to the trucks with dead camper batteries with no ill effect. If you look at the rv plug the one pin is a battery feed. A isolator is simply a way to disconnect the 2 batteries so you don't draw down the vehicle battery. I would use an isolator fused at the existing battery and also at the aux battery (before it heads back to the camper) I don't know what the sure power units are worth but the specs I saw are up to 100 amp or more. This seems to me to be way overkill for a truck camper. There can be a voltage spike when the relay closes but most modern relays contain a diode to protect the systems. This is mostly a concern when the signal wire for the relay is an electronic system of some sort. A simple 12v aux feed off the midbec below the park brake on most gm rigs is fine for a "signal" and wouldn't require any diodes. Maybe some others can jump in but I intend on using a simple isolator on my setup when I get it finishe.

 

[WarpathEngineering]

Is your truck factory set up for a camper/rv connection in the bed? Mine isn't. I would much prefer to just add an aux battery seperated by an isolator mounted under the hood and fused for both batteries. Then tap the aux battery for the camper. Then I'd wire a feed from the converter back to the isolator to allow a charge to both batteries when the shore line is pluged in. I don't know, would that need a 2 alternator set up or could you use the same terminal on the isolator as the alternator and just make sure that the shore power is unpluged before you start the engine? To me that is the most simple way of doing it. The hardest part is finding room under the hood for the new battery and an isolator. In the good old days, you could have put tractor trailer batteries under the hood and still had room for your ham sandwich on the manifold.

 

[winter200]

By the way, when i say an isolator I simply mean using a relay (continous duty). I wouldn't necessarly worry about the shore power charging the main truck battery. Normally if the relay is installed correctly, and you charging system is working right, when you shut the truck off the battery should be charged when you come back to start the truck. My truck was wired for the rv to the bumper but I had to add a line to the bed. I have a 5er also so I will probably install the battery in the camper (vented of course) and use the relay there. My concern with trying to charge the truck with the onboard charger is that most of the chargers out there for the coach batteries are not that great of chargers and in my mind, simply are not necessary. My intention is to install all the wires to come up and connect to the camper via the 7pin rv plug already in the bed of my pickup. The constant 12v on that is fused at 30 or 40 amp if I remember right and should be more than enough to do what I need it to do. It will also serve as the light connection. I will probably install flood lights on the back that are relayed to turn on with the backup lights and a switch for putting the boat in and out after dark etc. If you size your fuse lower than the capacity of the wire you are using you shouldn't have a problem with fires etc. I wouldn't assume that you would have a problem with overload on the system either. A guy could also install a light bulb between the conection and the truck battery. Simple and easy variable resistor that would limit the amout of power going to the coach battery and easy to replace if something went wrong and you needed a midnight fix. You could have it set up that if the battery was completly dead, you could run the bulb between to charge when you are driving down the road. This of course is just my thoughts which are driven by my desire to not spend a ton of extra money on my setup.

 

[benburnett]

Separator

Just went over an install today and we simply run the aux battery positive to the post on the separator marked for that. From the other terminal to the truck battery. The ground from the separator to the truck body. We don't hook up the other options. I am not aware of a way to wire it to charge the battery from shore power.

 

[WarpathEngineering]

Maybe I'm wanting too much from this!

Before my present job in plant maintenance, where I deal with mostly AC, I worked primarily on fire and emergency equipment. The ambulance manufacture that we did warranty work for did everything the old fashion way using Sure Power isolators, White Rodgers continious duty solenoids, Bosch relays, Cole Hersey battery switches and thermal breakers. In every ambulance there was an IntelliPower converter that when pluged into the shore power provided DC to any of the onboard systems as well as charged and maintained the batteries.

That was 10 years ago. I'd never heard of a battery seperator before I started working on this camper. My only concern was the statement that an internally sensing alternator may have problems with a battery isolator due to a voltage drop. I can see now how the battery seperator works but it doesn't seem to offer the ablilty to charge or maintain the primary vehicle battery in the way I'm used to wiring. I may be wrong, I may have been away from it too long to remember correctly!

 

[Puffins]

Arggg! makes my head hurt.

I just tried to put a Surepower isolator in my 99 GMC. Their instructions call for a special wiring harness to get around the Delphi sensor. I had already bought the isolator and could not for the life of me find the harness sold seperatly. So I returned it and bought a Cole-Hersey solenoid that seams to work just fine.

I know there and fancier and potentially better set ups but I had to keep cost down.

As it stands I the set up goes: truck alternator/battery>solenoid>wiring harness with 30A fuses>Optima D31M in the bed>camper.

 

[winter200]

Maybe I'm wanting too much from this!

Before my present job in plant maintenance, where I deal with mostly AC, I worked primarily on fire and emergency equipment. The ambulance manufacture that we did warranty work for did everything the old fashion way using Sure Power isolators, White Rodgers continious duty solenoids, Bosch relays, Cole Hersey battery switches and thermal breakers. In every ambulance there was an IntelliPower converter that when pluged into the shore power provided DC to any of the onboard systems as well as charged and maintained the batteries.

That was 10 years ago. I'd never heard of a battery seperator before I started working on this camper. My only concern was the statement that an internally sensing alternator may have problems with a battery isolator due to a voltage drop. I can see now how the battery seperator works but it doesn't seem to offer the ablilty to charge or maintain the primary vehicle battery in the way I'm used to wiring. I may be wrong, I may have been away from it too long to remember correctly!

If it is important to you to charge the battery using shore power maybe a guy could use a seperate system with a different wire back to the main battery. The way most of these are wired is that when the key is off, the route is gone. You wouldn't want to have the key on but maybe could use a second switch to control the feed back.

 

[WarpathEngineering]

Got it all figured now. Had a talk with a guy I know up at the local vehicle electric shop in Cincinnati. His suggestion was not to go the route of the battery isolator because of it's size and more importantly the cost since I have to purchase one that will accept a signal from the truck's alternator. He suggested the old route of the continious duty Cole Hersey solinoid but said I'd probably be happier with the Sure Power. He said that he doesnt' even bother with the 1314 model but ops for the 1315. The difference being that with the 1315 (dual directional) will allow you to charge both the aux and vehicle batteries from either the alternator or the camper's converter. With the 1314 (uni directional), depending on how it's hooked up, charging current only flows one way. Either from the alternator or the converter. He said that all things considered the cheapest route with the less headaches is the 1315. No extra wiring with the Cole Hersey and no full sized battery cables with the isolator.

Thanks for the help guys. Got to work today, took the time to draw it out on paper and everything made sense even before the call. Just a brain fart I guess. Seems to happen more often these days!

 

[Roberto]

I use one of these: http://yandina.com/c100Info.htm. It's been great.

I have shorepower in the camper, with a charger and an AGM battery. I also have a solar panel and charge controller connected to it.

Whichever battery bank gets a charge (truck/camper), the combiner will parallel the banks.