DONE! Building a battery box

AlumniCU

Member
Hello all. I am looking for DIY wiring schematics and/or guide to build a battery box in a larger Pelican case. I want to create a single power box that I can keep in my vehicle, at a camp site or at home that will sustain power for my needs, and can be charged from various sources. I’m hoping this wise group can point me to wiring diagrams or guides that will help me to design the system. I’m fairly novice to the electronic side of things but I think it could be a fun hobby to build knowledge.

What I think I want to do includes the following:
  1. Option to charge from solar, AC through Battery Tender and 12 DC from vehicle (direct from battery when engine running)
  2. Power ARB fridge w/ DC
  3. Add additional USB and 12v DC outlets
  4. Add voltage meter
  5. Add DC-AC pure sine wave inverter
I have:
  1. large pelican case
  2. 100ah AGM battery
  3. 100W x2 solar panels
  4. 30a PMW solar controller
  5. 3a Battery Tender
  6. ARB Fridge Freezer 50
I currently run the fridge off the vehicle battery, or from the 100 ah AGM battery which is connected to the charge controller and solar - that’s great. I think I want to be build a box that will be able to run the fridge and charge the battery from my vehicle when driving, charge and run with solar when stationary, and plug in to an AC outlet to charge and use power at home or hotels. This seems to be the complicating factor. It seems wiring outlets and an inverter is the simpler task.

Are there good resources out there that can help?
 

dreadlocks

Well-known member
you need a bigger 120v battery charger/maintainer.. I'd suggest ~10A Onboard charger for your size for decent recharge times in the field.

Get your self a BlueSea Terminal Master Fuse (around 20-30A fuse should be good for you), BlueSea BlueSea Fuse box w/Neg Bus, Master Disconnect Switch, perhaps a Low Voltage Disconnect if you plan on using more than that ARB.. I also wired up a power monitor inline.

I built one of these in a milk crate, wire the fuse box up to the disconnect switch then wire the Solar Charger/AC Charger/Fridge/USB etc up to the fuse box.. I used anderson powerpoles for connectors and crimped all appliances for that, then installed a high amp, fused anderson powerpole connector near where I stored the battery and just used a short jumper cable to hook battery up to vehicle..

the problem was when overlanding I never drove the 6-8h+ required to recharge a lead battery so using the vehicle to recharge was largely impractical.. When on a holiday I like to keep driving down to 3-4h a day max so I dont feel like crap after weeks on the road, that was a loosing battle with trying to keep battery full while draining it rather quickly.. I'd spend 2-3 days then find a new place to go, so battery was flat and only got a lil charge and then would not make it 2-3 days at next stop unless I got ideal solar conditions.. Ideal solar (8h of solid sunlight) turned out to be rather difficult to obtain as I really favor woodland environments.. Frequently I'd have to find 120v electricity to fully recharge my portable bank, making stop overs at friends and family along the way the first thing I'd do is plug that thing in... this is why you need a better AC charger, so you can use it when the opportunity presents its self.
 
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john61ct

Adventurer
Do you want the actual batteries in the box, or just the ancillary gadgets, ports, wiring etc?

Lead is not too portable
 
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AlumniCU

Member
The box I have is a Pelican 1600, and my 100 Ah battery fits with extra room for other equipment. It’s heavy for sure, but thinking if it could be all in one it would be convenient, albeit unwieldy. My use case is in the back of a 4Runner, in camp or elsewhere.



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Superduty

Adventurer
AlumniCU

What battery is that you are using?

Is it safe for an AGM to be an airtight pelican box?

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AlumniCU

Member
It’s a Renogy 100Ah AGM. I’ll put vents, potentially a fan, on the box - won’t run anything without airflow. When I use the battery now, it just sits out in the open.



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dreadlocks

Well-known member
Sealed Lead Acid (AGM/GEL) are safe to be in unvented locations and on their sides.. its like the only valid justification for paying that much for something that has to be so coddled.

Just make sure you put that master fuse on incase something breaks loose it wont short out the battery terminals and start a fire.. as you can see in my picture I did not have a terminal fuse and if a wrench or something woulda fell in there I'd of had a bad day..
 

jonyjoe101

Adventurer
instead of a voltage meter get a coulomb meter. Something like the " DROK LCD Digital Multimeter Charge-Discharge Battery Coulometer Tester " they sell on amazon for less then 30 dollars. It counts amps going in/out of battery, if the day before you use 30 amps, you know next day you need to put at least 30 amps back. Its the only way to know exactly how your battery is performing. You program your battery ah, 100ah and it gives you a percent of battery left, at 50 percent it should read 12.1 volts, if it reads less then that, your battery either wasn't fully charge or its lost capacity.


505823
 

trae

Adventurer
instead of a voltage meter get a coulomb meter. Something like the " DROK LCD Digital Multimeter Charge-Discharge Battery Coulometer Tester " they sell on amazon for less then 30 dollars. It counts amps going in/out of battery, if the day before you use 30 amps, you know next day you need to put at least 30 amps back. Its the only way to know exactly how your battery is performing. You program your battery ah, 100ah and it gives you a percent of battery left, at 50 percent it should read 12.1 volts, if it reads less then that, your battery either wasn't fully charge or its lost capacity.


View attachment 505823
I’m building something similar. How did you attached the shunt (the circuit board part of the coulombmeter) to the box?


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john61ct

Adventurer
Because some SoC meters are not of the coulomb-counting type, don't use a shunt.

Synonym to AH meter, but a true battery SoC meter is more complex.
 

dreadlocks

Well-known member
Data is always good IMO, eventually you learn your systems characteristics and notice when something goes sideways before it becomes a huge issue.. Oh I'm using too much power, Too little power, my voltage is way lower than it should be for this consumption, etc.. Helps you keep your system healthy, predictable and you can do dry runs before departing and feel confident everything good to take deep into the bush.

Also helps alot when you go to design the next power system, because now you have a point of reference.. or you can just have 4 led's that tell you little to nothing, you do you.
 
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