Dual battery install 05 GMC Sierra with pics

[OllieChristopher]

Hi guys I'm new here. Thought I would share some pictures and my procedures for a dual battery install. This is model specific but can cross over to many other makes and models.

First a little background. I have been a lurker here for many years. I'm getting to a point in my life to do some more mellow stuff like off the grid in my truck with some luxury. I have experience riding motorcycles and simple camping. I have a heavy background in my younger years in fabrication, temporary power, and generator field.

First off I think we all can agree that solar and lithium technology is advancing at an alarming rate. As with any project there are 100's if not 1000's of different ways to approach and achieve a project such as mine.

With that in mind I decided to go simple with room to grow in the future. For now I will be doing a basic relay system with a pair of Group 78 AGM batteries fitted to factory trays under the hood.

The heart of the system will be my Mechman 250amp alternator. Holiday deliveries are a mess so I'm still waiting on it.

First step was to remove the OEM ground system from battery. I have the GM RVC (regulated voltage control) which makes it tricky. I'm doing the big three with 1/0 (actually it's the big 4 depending on how you look at it).

The RVC measures ground current and adjusts alternator voltage and amps according to system demands . It consists of 2 wires. OEM is #2 to the block and a #10 to the front crossmember for the headlights. So my do around to get the best efficiency out of the system is to squeeze two 1/0 cables through the regulator.



All other "big" grounds including the second battery will be going through a busbar. All ground and power cables are 1/0. Start battery grounds: One to front crossmember, other to busbar to alternator to OEM block location. Busbar to chassis, busbar to aux battery, etc. I spoke with the techs at Mechman and this is the very best way to get the most out of GM's RVC. Bottom line is every ground in the trucks system has to go through the RVC in order for it to work properly to regulate amps/volts to the batteries.



For the panel I have the aluminum but starting out with cardboard until I figure out my configuration. I am still deciding if I want to add a solar charge controller or not. Also figuring out which Bluetooth battery monitor I'm going to use. Right now I have a cheap solar battery maintainer I'm using. The Contura switch is going on the panel. Down the road I will be going with wireless bluetooth switches connected to CarPlay.



After I get done under the hood I'll be running wires to the bed of my truck for various 12V outlets. Being I'm old school, inverter generator will be first choice to use in conjunction with battery powered outlets. IMHO, solar generators are still evolving and not quite as capable as a good old 1000 - 2000 watt small gas generator.

Any ideas for a reliable under hood solar charge controller and bluetooth battery monitor? I'm all ears. I will be using somewhere between a 100-200 watt suitcase solar panel system as my primary source of charging system when parked with gas inverter generator backup.

I'm on the injured list so the project is going slow. I'll keep coming back here to this thread and update.

 

[OllieChristopher]

So here is what I have been waiting for. The Mechman is an outstanding upgrade from the OEM weak 145 max amp alternator. I have dealt with GM's poor alternators for many years. I finally bit the bullet and got one that should outlast what I have been using. For me it was simple math adding up amp pull on all the stuff I am currently and plan on using. The OEM 145 amps is barely enough to keep up with current system demands.

I compromised and went with a lower powered 250 amp model that puts out almost 200 amps at idle. Should be plenty for what I need. The 370 amp one is a beast and needs a smaller pulley to spin it up to get the amps. Mine runs on a stock size pulley. The positive post is in a different location which forces you to change out the wire to reach. The provided lug is 1/0 x 5/16.

I also included a cheat sheet for anyone here that want's to know how to properly hook up one of these high output alts. The key is to at least do the big three and use 1/0 wire for all connections. If you are running a new smart alternator and need high draw items such as winch etc, Mechman can customize an alternator with an external voltage regulator with voltage adjustment knob.

 

[WVI]

That is some cool gear!

 

[OllieChristopher]

That is some cool gear!

Thank you. I know it's not as nice as some others but I'm pretty sure it will serve the purpose. I tend to overbuild for reliability. I honestly have no idea how reliable the Blue Sea products are going to be other than knowing if they are good enough for marine use they should be good for for a daily driver.

Right now I'm struggling to find a solar charge controller that will go under the hood and have at least blue tooth capability. No manufacturer seems to make one. Closest I can find is a Renogy Voyager with IP67 rating (and many other off brand ones) but no way of monitoring remotely. I don't care to get a separate bluetooth monitor with a shunt. I'm wanting to keep it simple.

I'm really tempted to get the Victron 75/15 or Renogy Rover but those are both indoor use only. I could seal them with epoxy myself once the wires are hooked up. Finding a known durable under bonnet charge controllers is proving to be a challenge.

If anyone has suggestions or experience with a good under the hood solar charge controller I would appreciate the input. Either PWM or MPPT will work for me as I am not going much more than 200 watts max on the panels. I want to keep the max footprint of the controller at at around 6" x 4".

 

[ConcordCarlos]

I have that Victron mounted under my hood, no issues after having it there for the past two years. Bluetooth output is weak, as I need to be no more than 10’ from the vehicle. Compared to my switch-pro which I can read 25’-30’ away.

 

[OllieChristopher]

Thanks Carlos. I'm leaning toward the 75/15. Victron's look to be the very best bang for the buck with lots of adjustments to match the battery. I will more than likely just dab some dielectric grease on the connections and call it a day. With an IP43 rating I figure it will do just fine.

 

[ConcordCarlos]

No problem . If you want pics of the mounting location , or even how the connections look after 2 years let me know. If i were to do it Differently, I’d want the Victron without the built in Bluetooth . Then use the external BT dongle so I could have the transmitter in a location that would provide decent range.

 

[Buddha.]

That's some nice work there, what are you planning on powering with that fancy setup?
I did a dual battery setup but I did it with #2 wire and kept the 160a alternator. I used a basic ignition controlled solenoid. Its nice being able to jump yourself.
I'm glad the HD trucks don't have that RVC business.

 

[OllieChristopher]

That's some nice work there, what are you planning on powering with that fancy setup?
I did a dual battery setup but I did it with #2 wire and kept the 160a alternator. I used a basic ignition controlled solenoid. Its nice being able to jump yourself.
I'm glad the HD trucks don't have that RVC business.

Right on. Sounds like you have a well setup system as well. The GM HD trucks until 2015 or so have a really nice simple and redundant electrical system. I envy you!!

I'll be having some aux standard 12v sockets, USB, and Anderson plugs for a fridge and some LED lights. Possible on board/portable HD air compressor, small 1000 watt inverter for my laptop etc. In the cab I'm upgrading my OEM sound system with a moderate plug and play Kenwood DDX6707S or similar. Also moderate upgraded amp and speakers.

I added up the max amps and the 250 amp alternator should do the trick to keep things powered no problem while driving and provide enough charge to the aprox. 20 hr rate/64 amp hour (3.25 amps per hour for 20 hours) aux battery.

So with good sunlight and a 100 watt panel plugged in I should be able to keep an already 7-8 amp fridge cool when parked with just minimal hours of generator use and still not discharge the aux battery to the danger levels. My plan is to not let my battery get down much lower than 12 volts for longevity.

Once you know how the RVC system works it's not too bad (though nowhere as good as yours). So with everything working properly and the RVC sensing to drop voltage to a float charge, you can simply turn on your headlights and get 14.6 -14.7 volts for an absorption charge. When I know I'll be parking my truck for a long time I'll drive around with my high beams on and "top off" the battery.

I'll test it again when I put the pair of deep cell batteries in. I'm pretty sure it will work the same with the exception of a longer absorption time needed due to the aux battery being discharged more. I have every reason to believe that the AGM batteries are going to last as long as my wet lead acid ones have. I normally get 5-8 years out of my cheap starter batteries on the daily drivers.

My motorcycles have been swapped over to Lithium. The Earth-X ones are nothing short of amazing. Too bad they don't make one in a group 78 size. My 2012 Beta came with one and it's still going strong after almost 9 years!! In freezing temps I simply turn on my lights or fan to warm up the battery and it never fails to start my bike.

 

[OllieChristopher]

Well I ran into my first snafu of the build. The new alternator is clocked to fit 2 rectifiers (6 phase system) and 12 diodes. So this means the 2 pin plug is relocated in such a way that it hits the throttle bracket. I ended up lengthening the wire and cutting/welding the bracket. 1/16" 6013 rod and my little inverter welder did the trick. My truck is thankfully a manual transmission so I was able to chop out the automatic kick down portion of the bracket.

Before:



Weld not pretty. User error not cleaning off the paint. Strong enough and functions perfectly:



A few things to note. Old 16 year old wire loom was falling apart in high heat areas so I just put new over the old. Wire loom is amazing stuff. It really protects the wire from degrading. Project is coming along good. Using a lot more wire loom than expected.

I'm pretty set on purchasing the Victron 75/15 smart controller. I don't see myself using more than two 100 watt panels at any given time. And more than likely will be using just one to start out with. My plan is to have a dedicated pigtail coming off the controller to front and/or rear of truck using small 45 amp Anderson connectors.

 

[OllieChristopher]

Boy today was a tough one on this project. I had a heck of a time stuffing two 1/0 cables through the RVC. I made the mistake of putting the lugs on cables first. I can safely say it is impossible to fit both cables through the RVC with lugs installed. I'm happy I cut the cables a bit long and have extra lugs just in case. Got er' done!!

Tomorrow I plan on starting up my truck and checking the system with just the start battery. If everything checks out I will move forward on the 2nd phase of the project: Secondary battery wiring and components.

 

[OllieChristopher]

YES!! Phase one complete!! Charging system works like a charm. I can manipulate the voltage into the battery by simply powering up of turning off lights and fan. I checked ground in various spots and the busbar is a great choice to distribute it. It will also make servicing and repair easy. All that 1/0 wire takes up a lot of room.

The next phase is mounting the battery on the other side and building the power distribution panel up against the firewall. I'm actually surprised how heavy these components are. Just the relay and charge controller alone are over 2 lbs.

 

[OllieChristopher]

So now it is decision time. I got the aluminum plate all laid out and ready to mount. It took me a few hours just for the fact I'm no longer working in a fab shop. Not bad for hand held jigsaw to cut, hand held cordless drill for holes, and vice to bend. The mounting plate is super solid!! I did some preliminary filing and radius work. Final smoothing and fit after components are mounted.



These are the final 2 configurations I'm thinking of. I'm still deciding on where I will be mounting the Contura switch for relay (on component panel vs other remote location under the hood). I know for sure it will not be going on my dash. It's not something I will be using that much if at all. Again I'll be doing more fitting and tweaking. The battery lug is close so I'll trace component location and do a few more trial fits before mounting and pre wiring.

 

[OllieChristopher]

Getting down to the final stretch of this project. Carefully mounted everything to the panel. I broke out my 60 git drill attachment disc and gave it a nice brushed finish. Pretty darn happy with the results. Tomorrow I'll wire everything up. With this COVID crap going on I have had to make do with some connectors by folding up the stripped ends of the wire to get a tight fit in my size 10-12 AWG connectors. It has been a real challenge not being able to go to the electrical shop or hardware store for small bits and pieces.

 

[ConcordCarlos]

Curious why you would mount the ACR switch under the hood?