12v power pack for tent camping

Kharn

New member
I've been a little jealous of my camping buddies having electricity due to their trailers while I'm in a tent, so I decided two can play that game and started researching portable power solutions. I calculated out what we'd need for the typical Friday-Sunday camping trip and it was much higher than many commercial packs provide for a reasonable price, and we wanted electricity during state park quiet hours, so a generator was out, I decided to build my own system using a 115ah Group 27 deep cycle battery. It should also be useful in the winter, we've had really bad luck with extended power outages whenever there's a big snow storm, now we'll be able to have some air circulation, light and ability to charge phones, etc, while bundled up near the fireplace.

Here's the finished product:
PPexteriorfinal12v.jpg

Interior:
PPFinal12v.jpg


Its set up for trickle charging with a Battery Tender Plus at home, with its charging pigtail hanging (sealed with a dust cap when not in use) out one of the over-hanging parts of the lid and secured with a zip tie so the entire wire won't fall out of the box if it snags on something. Main features are the Seasense 12v sockets (I can't recommend them, they're slightly bigger than 1" in diameter, meaning lots of hand-trimming to install), Bussman fuse block, a neutral bar from Home Depot re-purposed into my ground block, a random $8 battery box & 3M DPST switches from Walmart, 10 and 14 gauge wire and 0.250" connectors. I really lucked out on the 3M switches, I'd originally planned on putting them on top of the box, but my idea on where to place the outlets just happened to clear the bezels.

Total cost was $268 + tax for the pack itself, a little higher than I had thought it would cost when I set out since I did not have many of the basics like a battery charger, stranded wire, fuses, terminal connectors, etc, but it will be worth it the first time we have light when the power is out.

I'm still awaiting the trouble lights I ordered, so at the moment I just have two low-noise computer fans to play with.

Future expansion include a wiring harness for an inverter, a circuit breaker to kill the entire output from the positive side of the battery (right now it relies on the four circuits all being fused at 5amp, the 10ga line is good for 100amp per my understanding, so there's no way I can over-draw it in normal use), fast 120v (no point running my junky, 30+ year-old, oil-burning generator to trickle-charge a battery) and alternator charging.
 

dwh

Tail-End Charlie
the 10ga line is good for 100amp per my understanding

Dunno where you got 100a for #10, but unless it's some really special wire - I don't think so.

#10 with insulation rated for 60C temp is rated for 30a, 75C insulation is rated for 35a, and 90C is rated to 40a.

For "chassis wiring" (which means, "inside of a machine", and technically, that's what you are doing) you can go to 55a.


Nice clean work.
 

JIMBO

Expedition Leader
:sombrero: Mine is a 60w/ hardcase panel that keeps my trailer/boat/ lights topped off for up to nine days-

Sawmillllakejune12013.jpg


:costumed-smiley-007:wings: JIMBO
 

AFSOC

Explorer
Kharn, nice little power pack you've put together. Looks like a nice, clean assembly. I hope you get lots of good use from it. Don't be discouraged that the comments took a wacky turn over the whole 10AWG/100 amp issue, we'd appreciate a report on how it works in the field.
 

Kharn

New member
Dunno where you got 100a for #10, but unless it's some really special wire - I don't think so.

#10 with insulation rated for 60C temp is rated for 30a, 75C insulation is rated for 35a, and 90C is rated to 40a.

For "chassis wiring" (which means, "inside of a machine", and technically, that's what you are doing) you can go to 55a.


Nice clean work.

The wire is 90C; thanks for the warning, luckily I haven't bought the circuit breaker for it. Our CPAPs draw 1.5a each, the lights are ~1a and the fan box (two quiet computer fans to just move a little air inside the tent) are 0.32a total, so for the time being I'm not in danger of burning up the #10. I have another foot of the #10 so I could put the inverter on its own run, independent of the 12v outlets.

Northern Tool says that model has only a 22ah battery, mine is 115ah. With the CPAPs needing 1.5 amp each, so drawing 3a per hour and 8 hours of sleep per night, we need a battery rated for a minimum of 48ah per night (since you can only use 50% of its capacity without damage) plus a little extra for reading in bed and keeping a little air moving inside the tent. Our normal camping trips are Fri-Sun, so 115ah is just about perfect for our needs, yours may be different.
 

Borrego60

Rendezvous Conspiracy
Kharn, nice little power pack you've put together. Looks like a nice, clean assembly. I hope you get lots of good use from it. Don't be discouraged that the comments took a wacky turn over the whole 10AWG/100 amp issue, we'd appreciate a report on how it works in the field.
Not bashing the 10g wire thing please do not get me wrong, Nice little set up he made looks good and should work well. Just trying to be on the safe side that is all.
 

AFSOC

Explorer
Not bashing the 10g wire thing please do not get me wrong, Nice little set up he made looks good and should work well. Just trying to be on the safe side that is all.

Okay, I understand where you're coming from. Thanks for the explanation.

It's just a little disheartening to me to see that we (ExPo) can't reply to a thread without being critical of someone's labor, telling him what product he should of bought instead and showing off our own gizmo as superior. I'm not suggesting standing idly by to watch the impending train wreck but not one of us mentioned any positives about the posted power pack. Instead we pounced on his misconception about properties of conductors or sketchy math or typo or whatever is responsible for the skewed values. Doesn't it make better sense to acknowledge the positives of the project as well as highlight where he is straying off track? Expedition Portal has just gotten so damn critical of late. I ‘d prefer to see some constructive criticism instead the steady flow of pretentiousness.
 

CodyY

Explorer
It runs a little 12v fan all night, keeps my phone and camera charged, let's me run my little tire pump all the way back on the trailer, and makes it much easier to start my KTM 525 on cold mornings. Plus, I always take it with me on road trips and to races. Just in case

I missed the part about the cpap machines
 

Kharn

New member
We went 30 hours without power thanks to Hurricane Sandy, the pack worked great running two 10" LED strips from an Ikea Dioder set (drawing ~0.5 amp), charging my cellphone (acting as a mobile hotspot) and our tablets. Unfortunately I hadn't planned on needing it this soon and we did not have the CPAP 12v power supplies on hand, so we only drew the battery down to ~85% and did not give it a full work-out. Since we had the battery, we did not need to run our generator during the outage (we would have run it this morning to chill the freezer but power came back on around 1am).

I need to set up a better way to attach a fast charger than opening the top and clipping onto the studs, Anderson power poles might be a possibility or installing a cigarette plug rated for 20amps and use a 15amp charger. I'd hate to recharge the battery using the trickle charger and the generator during an extended outage.
 

wrcsixeight

Adventurer
I wouldn't want the battery to off gas while being charged near that fuse block and buss bar with the lid closed. A fuse blowing might conceivably ignite some hydrogen and go all hindenburg on you. Remote chance, but a chance none the less.

The corrosion alone would have me keeping the lid off while charging, or moving the fuse block and buss bar, and all the electronics/ receptacles to another container
 

AFSOC

Explorer
We went 30 hours without power thanks to Hurricane Sandy, the pack worked great running two 10" LED strips from an Ikea Dioder set (drawing ~0.5 amp), charging my cellphone (acting as a mobile hotspot) and our tablets. Unfortunately I hadn't planned on needing it this soon and we did not have the CPAP 12v power supplies on hand, so we only drew the battery down to ~85% and did not give it a full work-out. Since we had the battery, we did not need to run our generator during the outage (we would have run it this morning to chill the freezer but power came back on around 1am).

Well done! This project really performed when it needed to.
 

Crom

Expo this, expo that, exp
Nice power pack. Well done. I want to do something very similar soon. :)
 

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