Dual batteries with removable Aux battery

[Ted_Z]

Let me preface this post by saying that normally I can figure this sort of stuff out, but this has me stumped. Plus I thought I'd ask for advice to save the headache for the next guy doing something similar.

I'm finally getting around to upgrading my Jeep to have an auxiliary power system. I picked up a AC/DC fridge and want to be able to power it off the aux battery when the Jeep isn't running. Furthermore I want to make the aux battery removable so I can have a portable 12V power source. Currently I have a 400W inverter and 12V socket in the rear of the Jeep and want those to run off the aux battery when it is installed, but off the primary battery when the aux battery is out. To make it more complicated I also have a 50W solar panel and controller.

My initial thoughts are for a heavy duty switch or relay to bypass the VSR when the aux battery is removed. The solar would plug directly into the aux battery.

I need help as to where to put the VSR and the other bits.

What parts I have so far:

BEP VSR (voltage sensitive relay) for charging the Aux battery off the alternator.
Vector 400W inverter (looks like Black and Decker bought out Vector).
50A Anderson power poles
ASC 4A solar charge controller
6X 12V 9Ah AGM batteries salvaged from a busted ups.
Wire, from 14awg to 2awg
Various fuse holders
Voltage gage

 

[Ted_Z]

trying to build one of these?
http://www.equipt1.com/companies/Battery Systems/product-nl/118181-portable-power-pack

I had never seen that product before. But I guess what I am making is basically the same thing with the exception of that I want to have my inverter and 12v socket toggle between power sources.

Now what I'm doing won't have fancy LED lights and such, but it won't cost $500 without a battery.

Edited to add: After reviewing the above product, where to put the VSR is clear. It will go in the box with the batteries. I will post up a schematic ASAP so anyone else can copy this project.

 

[Ted_Z]

I put together a schematic below. I welcome any comments.

Heavy gage wire goes from the main battery to the rear of the vehicle. Inside a tool box I'll put the VSR, batteries, voltmeter and another 12V socket. The hard wired inverter and 12V socket will then plug into the power box. If I take the power box out the vehicle I'll use a jumper to connect the inverter/12V to the main battery. The solar stuff plugs into a smaller connector tied to the aux. battery. There is also a toggle switch that would let me check battery voltage of either the main or aux battery.

A few other options; maybe I should come up with a way to tie the solar to the main battery if the power pack is out and how to jump start the main from the aux battery.



Uploaded with ImageShack.us

 

[keezer37]

There's plenty of switches to choose from from Bluesea.

Are you venting the toolbox? If so, by what method?

 

[Ted_Z]

The tool box in question will just be something from homedepot or the like. By no means air tight. The batteries I'm using (see above link) are sealed, no vents. I'd seriously have to over-charge them to the point they burst to get them to vent.

 

[youwillforget]

Looks like you have a good plan I like the removable auxiliary battery, I have 2 batteries under my hood and I use a solenoid to disconnect the batteries when the engine isn't running so the house battery can be dead and the truck will still start. If you match the Anderson plugs all red or all yellow for clean power then change the color for the solar panel to charge controller connections you could add and remove components as needed. I had access to gray 50amp plugs so I used those lots of them over 20 so far and I adding more to the trailer as I build it. Several companies Hella, Blue Sea and Harbor Freight make high amp manual switches if you are interested in switching manually they range from 5.99 to 20 dollars.

 

[Utah KJ]

6 AWG wire is not adequate and possibly dangerous.

 

[ldivinag]

http://www.expeditionportal.com/forum/threads/27568-Any-12V-power-packs-like-this-in-the-US

look at TREMOR's post in this thread.

i'm trying to duplicate that.

 

[ldivinag]

6 AWG wire is not adequate and possibly dangerous.

ditto...

check out local welding supply houses. they sell up to 3/0 gauge cable cheap. well cheaper than "car audio" grade cable.

i built a 25' "jumper" cable for my removable winch setup by using 1/0 gauge cable i bought about a decade ago. IIRC it was like a buck a foot. car audio cable was like $5 per...

 

[Ted_Z]

6 AWG wire is not adequate and possibly dangerous.

Can you please explain why?

A few more details:
There will be a 60A fuse at the point the auxilary system taps into the main.
The largest gauge wire you can fit into the anderson SB50 (50A) is 6 gauge.
My biggest load would be the 400W inverter or about 30A. I'm not trying to run a microwave or anything. Most of the time it would just be the refrigerator (typically ~4A).

 

[mab]

MY Home made portable dual battery kit



Put this gismo together in 2009 in preperation for a remote fishing trip with a friend. He didn't have a dual battery to run my engel fridge in his vehicle, and my hilux had no room under the bonnet for a secondary battery, so the idea came to make a portable box to use any any vehicle. It is connected by a heavy gauge cable with an anderson plug to the main battery. The isolator relay is inside the enclosure. I also have a 12v to 12v boost charger which is connected by the two pin plug above the anderson plug. The idea with it was so that I can put the box in any other vehicle and connect via the lighter socket. Gives about 10amps charge rate via this system.
Have had some issues. Discovered that the standard lighter plugs/sockets aren't suitable for extended connection to high current devices while travelling on rough tracks. Had the plug come loose and burn. Also killed the first deep cycle battery due to my 30 year old engel developing a fault which caused it to draw excessive current. But since has been going well. Now runs a National Luna 52 litre fridege for days with now issues. The box is an esky I bought from a camping store for $50. Was cheaper than any purpose built electrical box.

 

[ldivinag]

Can you please explain why?

A few more details:
There will be a 60A fuse at the point the auxilary system taps into the main.
The largest gauge wire you can fit into the anderson SB50 (50A) is 6 gauge.
My biggest load would be the 400W inverter or about 30A. I'm not trying to run a microwave or anything. Most of the time it would just be the refrigerator (typically ~4A).

for your needs, yes.

but you always want to have that overhead. i like to double it, just for safety needs. diff between 6 and 4 gauge aint that much.

also, anderson connectors can be bigger if needed.

 

[Hudson]

Here's my solution below, using a National Luna PPP installed in an aluminum dry box. Full write up here. I am likely to add a fuse block, and some watertight 12v plugs for easy access.

 

[wxmanWJ]

Any updates from the OP on the setup???

I'm looking at doing something similar- making a portable power pack that's able to be recharged using the vehicle. I think an ACR or VSR of some sort with a quick disconnect in the rear of the Jeep would accomplish this but I'm not too sure yet. Curious what the OP ended up with. Thanks!