Help modding battery-bank to power interior lighting

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Help modding battery-bank to power interior lighting

Postby Tortoise » Sun Jan 03, 2016 2:42 pm

I am adding a battery-bank to use with my solar-system to power my needs inside the trailer. The HaulMark trailer came stock with LED interior lighting, that only works when plugged into the truck, and the ignition is in the "ON" position (which keeps all the dash lights and navigation screen on in the truck as well).

I found the junction-box, underneath the trailer, with seven colored wires all connected with those little twist-on wire connectors. Can I tap in here to route different wires to the new battery-bank, assuming I can figure out which wires feed the interior lighting?

I'm concerned with the trailer's frame already being used as the ground for the truck's electrical system (when connected). If I also ground the new battery-bank to the same frame, will I have a problem sharing a ground like that? Would it be wise to also make a connection to allow the truck to charge the solar-battery-bank while driving?

Okay, there are white wires at this junction-box that are supposedly for ground. Can I run a conductor from that to the negative terminal of my solar-battery-bank? (I'm beginning to confuse myself just trying to ask these questions.) Or would sharing the ground between the solar-battery-bank and the truck's battery pose a problem?

Any tips on figuring out which wire powers the interior lights? There's a red wire at the junction-box that is all alone - doesn't seem to be connected to anything, but it's capped off. What could this red wire be for? (I'm asking because the trailer's owner's manual says red is for the "AUX LIGHTING", which seems like it'd be the interior lights.)

Any tips on converting the interior lights to run off the new battery-bank, instead of the truck's electrical system? Thanks in advance for any help.
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Re: Help modding battery-bank to power interior lighting

Postby MtnDon » Sun Jan 03, 2016 4:23 pm

1. Don't worry about the grounds. Just connect every battery negative to the frame. That's fine. It is just a ground, more or less just a safety. Or at least it should be just that. Relying on the frame to act as the negative wire connection in a DC circuit can be a source of much frustration at a later date. Every DC device in the trailer is best served by using both a positive and a negative wire to each device.

2. If you have PV panels I would forget about trying to use the truck while driving, to charge what we'll call the coach battery in the trailer. You would need to increase the positive and negative wire size from the truck alternator / battery in many vehicles to enable a meaningful number of amps to make it to the trailer system.

3. Every trailer manufacturer could make the trailer interior system "their own". No real standard at work for that. So advice from any of us would be as good as your guessing. With a multimeter and/or some plain old trial and error you should be able to find the wires that the trailer maker used for the interior lighting. Do that and then setup a separate fuse block from the new trailer battery to the existing interior lights. Use extra new fuses in that block for all the new DC things you will add. Reserve the truck to trailer wiring for just the tail, brake and marker lights.

Hope that helps you.
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Re: Help modding battery-bank to power interior lighting

Postby Tortoise » Sun Jan 03, 2016 4:49 pm

MtnDon wrote:Hope that helps you.


Yes! Thank you very much for your help! I found the +/- wires that power the interior lighting, and turned them on with a 12V DC Power Supply to test. I found them underneath the trailer at its "junction box" - so I guess from there I'd need to drill a small hole to run wires back inside the trailer, where my "coach battery" will be living. I will add a fuse on the positive side as well, right next to the "coach battery".

So, should I completely disconnect all power from the truck to the interior lights? That way they'll only run off the "coach battery" and lose the functionality of being able to run the interior lights from the truck in the future? I think that's what I gathered from what you wrote . . .

That sounds like a plan. I'm sure the interior light's wires are already somewhere inside the trailer - but it's got white vinyl walls and they're all siliconed together, so I'm not sure if I want to start ripping the interior walls down to track down two wires.

Looks like I'll be removing the interior lighting's wires from the trailer's connector, and rewire it on a completely separate circuit to the "coach battery" instead. I won't worry about sharing the trailer's frame as the ground for both my "coach battery" and truck's electrical system when it's plugged in then. Thanks for your help.

:D
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Re: Help modding battery-bank to power interior lighting

Postby Dale M. » Sun Jan 03, 2016 9:42 pm

If you have found the proper terminals in junction box for "auxiliary power" from tow vehicle, yes you can "just" attach you battery there (with inline fuse and maybe disconnect switch), also investigate "charge while towing"...

viewtopic.php?f=30&t=28620

Also if you are going to put solar panels on setup you may need to think about disconnects and if truck is "charging" battery maybe you would want solar panels "disconnected" so ther eis not a conflict of whart is going to charge battery and under what conditions....

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Re: Help modding battery-bank to power interior lighting

Postby Shadow Catcher » Sun Jan 03, 2016 10:36 pm

What are you doing for a fuse panel and are you planning on 120AC?
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Re: Help modding battery-bank to power interior lighting

Postby Tortoise » Sun Jan 03, 2016 11:40 pm

Shadow Catcher wrote:What are you doing for a fuse panel and are you planning on 120AC?


I guess I should buy something for that, but was just going to get an inline blade-fuse holder for the interior lighting circuit (what amp fuse should I use for two LED lights? the smallest I can find?).

Yes, 120V AC is provided by a 1500W PSW inverter (or "shore power") - with huge gauge cabling. Everything is fused or on a circuit breaker, and I have switches (Blue Sea Systems) for controlling the flow of currents.

I've been postponing getting the fuse-panel, because the only thing I'll have running on 12V DC will be these interior LED lights (hopefully by tomorrow), otherwise I'd probably wire my batteries up for 24V. If I end up getting a fan for the roof-vent, I imagine that might want 12V DC, but I'll cross that bridge later.

Here's what I've got so far:

8.5 x 24 cargo trailer with two vents and a 14" roof-vent (no windows)
Yamaha EF2400iSHC inverter generator (171cc)
GoPower 1500W PSW inverter
BoonDocker PowerMax 60A 4-stage converter/charger thing
Renogy MPPT Solar Charge Controller
4 x 100w Solar Panels
4 x Trojan T-105 batteries (450 Ah @ 12V)

All of my gear that needs electricity is basically 120V AC, because I'm just using my household stuff. I have a tiny energy-star fridge, a tiny washing machine, a Bosch worksite radio (that can also be powered by tool batteries), etc.

To start off, the only electrical needs I'll have is for my laptop, television, charging my phone, a couple lights, guitar amp / pedals, interior lights and radio . . . and battery chargers (I do have a hobby charger that runs off 12V though) for AA, AAA, 18650, etc. I have an electric heater, but it uses so much juice that I'm not sure I'll use it without shore power. I have a portable/camping woodstove, and hopefully I'll end up somewhere where I can utilize a swamp-cooler in the summer. I have a 56V lithium-ion cordless chainsaw that I'll charge off the PSW inverter for sourcing timber for the woodstove. It's quiet, and semi-clean.

I know traditional campers utilize 12V DC for a lot of stuff, to avoid the 30% losses, but I'd have to buy a lot of new stuff to get there. I just prefer AC extension cords and power-strips. The only other thing I own that runs off 12V DC is an old audio power amplifier, but it's been collecting dust for years, and I don't really need to use it.
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Re: Help modding battery-bank to power interior lighting

Postby Mike S » Mon Jan 04, 2016 5:26 am

Tortoise wrote:
MtnDon wrote:Hope that helps you.


Yes! ......

So, should I completely disconnect all power from the truck to the interior lights? That way they'll only run off the "coach battery" and lose the functionality of being able to run the interior lights from the truck in the future? I think that's what I gathered from what you wrote . . .

Looks like I'll be removing the interior lighting's wires from the trailer's connector, and rewire it on a completely separate circuit to the "coach battery" instead. I won't worry about sharing the trailer's frame as the ground for both my "coach battery" and truck's electrical system when it's plugged in then. Thanks for your help.

:D


You've recieved great advice so far. I have a couple more suggestions. Between your generator, solar, and shore power, you've got plenty of sources of power to charge your coach batteries. I wouldn't plan to charge from your tow vehicle. Like Don said the truck's circuit isnt beefy enough to give you enough amps to make much difference. Plus, your other means of charging are "smart", which means they sense the battery condition and adjust charge status accordingly. The 12v from the TV wouldn't do that.

I would still ground your coach battery to the frame. Its not good practice to run heavy amp draws off the chasis ground but it can work well for LED lights that only draw a few milliamps. Don't worry about the common ground between coach and TV. Unless you connect the "+" side between the TV and trailer, there's no complete circuit.

I also have an "ignition hot" circuit coming from my TV into my trailer that originally powered a single light in the trailer. I wired that original light to my coach battery. Then I couldn't decide what to do with the TV circuit. . Eventually I ended up wiring it to a small LED light strip that I placed inside the trailer next to the side door. It's always on during towing. It makes a nice entry footlight for when I need to briefly get in the trailer while we're stopped at a rest area. It also puts out a dim glow from the trailer window, which I think is kind of neat looking while towing.

Sounds like your off to a good start.
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Re: Help modding battery-bank to power interior lighting

Postby Shadow Catcher » Mon Jan 04, 2016 9:29 am

Unless you are using high voltage panels intended for a grid tie system achieving the necessary voltage to power your solar controller can be difficult, or are you using the panels in series? There are a great deal more goodies for 12V than 24 and while you can use buck converters to get down to 12V there is a loss there.

One suggestion for a converter is the Progressive Dynamics in your case a PD 4060 makes sense http://www.progressivedyn.com/all_in_one_pd4000.html I wired mine using a DPDT switch so that I can switch from shore power to inverter, in this case it switches off the PD converter and the inverter on.

Battery Monitors, To keep battery banks happy and long lived You need to monitor SOC (state of charge) to keep them above 50% SOC I chose the Victron because of ease of set up and place I needed to mount the meter. The two most accepted are
http://www.bogartengineering.com/
https://www.victronenergy.com/battery-monitors/bmv-700

I have a plug to the battery (we have only one) that attaches to a set of jumper cables so that I can charge off of the TV at a greater rate than the 10 ga wires in the seven prong plug. a 90+ A alternator can be useful when sustained cloud cover or tree shade blocks the solar panel. If you want to get esoteric and do more charging from the TV Balmar http://www.balmar.net/ makes multi stage charger regulators...

One of the persistent problems in grounding to the frame is that you be fairly certain you will have problems with poor contacts at some point, think galvanic action between copper and steel. Steel is also not as good a conductor as copper. I am frankly surprised no one else has mentioned it as it is a subject that comes up with regularity. I have nothing grounded to the frame.
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Re: Help modding battery-bank to power interior lighting

Postby Dale M. » Mon Jan 04, 2016 9:52 am

The tow vehicle's smart charge comes from the vehicles alternator system ( usually 14.0 (+/) volts)to regulator the batteries as they are connected in parallel..... I disagree with the comment about TV battery charge system is to weak ... My Chevy truck is fused at 40 amps to supply the connector at back bumper.... IF 40amp will not charge a battery in "coach" with 'charge while towing' then none of your internal smart devices will either becasue all are sort of wimpy compared to what tow vehicle can do.... Also its a pretty good source of power to charge battery becasue when "connected" it will charge battery when you are on the move and you will have a fully charged battery each time you setup camp for the night....

People are so caught up in external charger outputs and current, what they forget is a battery itself is a self regulating device (chemically) and only accept enough current that will bring it up to full charge (providing charge voltage is correct)...

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Re: Help modding battery-bank to power interior lighting

Postby Shadow Catcher » Tue Jan 05, 2016 12:32 pm

Dale
I did not say the line from the battery is too weak. We have the 30A line from the TV battery to the tear and I have yet to use the jumper. But for getting a charge in faster by idling the TV (ours is .34 GPH on idle) a larger line (6ga) helps.
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Re: Help modding battery-bank to power interior lighting

Postby Dale M. » Tue Jan 05, 2016 3:28 pm

Mike S wrote:
Tortoise wrote:
MtnDon wrote:Hope that helps you.


Yes! ......

So, should I completely disconnect all power from the truck to the interior lights? That way they'll only run off the "coach battery" and lose the functionality of being able to run the interior lights from the truck in the future? I think that's what I gathered from what you wrote . . .

Looks like I'll be removing the interior lighting's wires from the trailer's connector, and rewire it on a completely separate circuit to the "coach battery" instead. I won't worry about sharing the trailer's frame as the ground for both my "coach battery" and truck's electrical system when it's plugged in then. Thanks for your help.

:D


You've recieved great advice so far. I have a couple more suggestions. Between your generator, solar, and shore power, you've got plenty of sources of power to charge your coach batteries. I wouldn't plan to charge from your tow vehicle. Like Don said the truck's circuit isnt beefy enough to give you enough amps to make much difference. Plus, your other means of charging are "smart", which means they sense the battery condition and adjust charge status accordingly. The 12v from the TV wouldn't do that.

I would still ground your coach battery to the frame. Its not good practice to run heavy amp draws off the chasis ground but it can work well for LED lights that only draw a few milliamps. Don't worry about the common ground between coach and TV. Unless you connect the "+" side between the TV and trailer, there's no complete circuit.

I also have an "ignition hot" circuit coming from my TV into my trailer that originally powered a single light in the trailer. I wired that original light to my coach battery. Then I couldn't decide what to do with the TV circuit. . Eventually I ended up wiring it to a small LED light strip that I placed inside the trailer next to the side door. It's always on during towing. It makes a nice entry footlight for when I need to briefly get in the trailer while we're stopped at a rest area. It also puts out a dim glow from the trailer window, which I think is kind of neat looking while towing.

Sounds like your off to a good start.


My reference to tow vehicle charging relates to this statement by Mike S.... I believe he is wrong, and if you are putting even 50 miles on trip between camp sites, why not use that to charge battery...

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