Dual Battery Kit

[Trailfrog]

Has anyone used this kit?
http://www.dfna.info/dual-battery-kit.html

Let me start by admitting I am electrically challenged! I am thinking I want the second battery in the back of my rig instead of under the hood because 1) if I mount it under the hood I won't be able to get the River Raider snorkel I want and 2) it will be closer to the other accessories I want to run like a fridge and power to my trailer for water pump and lights and 3) it would allow me to run a larger aux battery. I have a winch that I'm assuming I would want to run off the aux battery in this setup, is that correct? And if I do I'm assuming I would have to wire it directly to the aux battery which will require running another large cable back to aux battery correct?

 

[YukonRob]

Not familiar with that kit. For about the same price you can get one that includes a monitor, but you'll need to source your own cables.
http://www.summitracing.com/parts/FEY-47-3800/

After much head-scratching and gnashing of teeth, I am leaning towards the simple but bullet-proof solution advocated by dwh here (and elsewhere):

http://www.expeditionportal.com/forum/threads/64577-cheap-and-simple-dual-battery-set-up

 

[Herbie]

Has anyone used this kit?
http://www.dfna.info/dual-battery-kit.html

I haven't used it, but I note that it includes a "ground cable", but from the picture it looks like a short length meant to ground the battery to the chassis. I much prefer a full return cable from battery to battery.

For about the same price you can get one that includes a monitor, but you'll need to source your own cables.
http://www.summitracing.com/parts/FEY-47-3800/

The T-Max kit actually includes about 20' of cable, IIRC, but it was a bit undersized in my estimation. (5mm diameter, IIRC, equivalent to ~Gauge 4-5)

I chopped up a set of 2-gauge jumper cables to make my battery cables - see my build thread for more info.

 

[Trailfrog]

Thanks for the help. I ended up getting the T-Max kit. Also got an 800 watt inverter. Now for the aux battery. I'm thinking about the Sears Marine Platinum PM-2 group size 34. It will be mounted inside my rig. My question is does it have to match the size of my starting battery?

 

[Lichen]

No, you want to run your winch off of the MAIN battery.

 

[Trailfrog]

Ok, thanks, I was hoping I could keep the winch wired to the main battery. My question has to do with the "manual overide" capability of the T-Max system:

"MANUAL BATTERY LINK(OVERIDE FUNCTION):
BATTER MONITOR WIRING
In an emergency situation (defective or empty Main Battery) or in case of higher power
consumption the two batteries (Main/Aux) may be connected together by activating the
link button AUTO/LINK (red LED manually linked is on) After a laps of time of 30 minutes
(or immediately after activating the AUTO/LINK button) the system returns to the
Automatic mode. The load sharing function with the manual battery link reduces the
stress on alternator, wiring and the batteries in conjunction with the use of electric
winches. If high power consumption is needed from both batteries for long time, actuate
the AUTO/LINK button again, the system return to automatic mode (red LED manually
linked is off) than press AUTO/LINK button within 6minutes to preventing from batteries
separation. The system will AUTO RESET after approx 30 minutes."

To use this function is it necessary that both batteries are identical?

 

[dwh]

No, the batteries don't need to be identical. You can tie together different sizes of flooded batteries or AGM batteries. You can also tie a flooded battery with an AGM battery.

What you can't do, is tie a Gel battery with anything except another Gel.

When I say tie them, I mean *temporarily* tie them - you don't want to tie two different size or type of batteries into a permanent battery bank.

For charging, no problem. For occasional heavy loads like a winch, also no problem.

But, if you plan to tie the batteries for winch use, and the second battery is in the back, then do what Herbie said and use a dedicated negative wire along with the dedicated positive wire (don't use the frame for your negative for the second battery) and use some seriously fat wire.

 

[Trailfrog]

Great! Thanks for the help.

 

[Trailfrog]

Ok, now for the fuse block. What's the difference between with ground and without ground? As you can see I am not electrically inclined!

 

[dwh]

"With ground" just provides a handy "bus" to connect the negatives from the various circuits. The there is a wire from that negative bus back to the battery - or to the chassis "ground".

"Without ground" you run a hot to the fuse block to feed the fuses, then hots from the fuses to whichever circuits, and then you've got to find some other way to "ground" the negatives. Most stock automotive fuse blocks are "without ground". Like a taillight housing will usually have a couple of different hots (running, brake, reverse) but just a single negative "ground" to the body.


I prefer to run wire with a negative in it that goes all the way back to the fuse block, so a "with ground" fuse block would work better for that sort of rigging.

On a wooden or fiberglass boat you'd need a fuse block "with ground" since you can't ground to the hull.

 

[rshuckfinn]

National Luna makes a great kit with everything included.

 

[Trailfrog]

Ok, so I'm pricing 30' of 4 guage for the positive and negative cables that need to run from the back of my rig to the engine bay. WOW this stuff is expensive. It seems that I can buy a set of 4 guage jumper cables cheaper than cable by the foot. Is there any reason I souldn't use the 4 guage jumper cables? Also what is the best way to crimp the connector ends on?

 

[keezer37]

Ok, so I'm pricing 30' of 4 guage for the positive and negative cables that need to run from the back of my rig to the engine bay. WOW this stuff is expensive. It seems that I can buy a set of 4 guage jumper cables cheaper than cable by the foot. Is there any reason I souldn't use the 4 guage jumper cables? Also what is the best way to crimp the connector ends on?

Expensive. Yeah. This is one of those jobs that sneaks up on your wallet. I ended up grounding to my frame for this reason. As far as crimping goes, terminals with solder slugs is good. I crimped when I did mine and the crimping tools are for the most part cost prohibitive given they are nearly a one time use item. I managed to crimp with a pair of Ideals Side Cutting Pliers available at Home Depot. The crimper is small for 4 gauge but it gets the job done. They are stout enough to cut 4 & 2 gauge also. You can crimp with a bench vice/drill bit if this works for you. I wanted to crimp in place to ensure proper cable lengths.

I never knew what the difference was between battery cable, jumper cable and welding cable was but would like to. Moreover, if battery cable is better than jumper cable, is one company's quality jumper cable as good as another company's cheap battery cable? It's a crap shoot. Buy quality.

 

[Herbie]

I use Jumper cable all the time for stuff like this. Somewhere I have probably a dozen big battery clamps in a box.

Part of the difference in the cables will be flexibility. Welding cable is meant to be easy to move around (for the welder) so it has the highest number of small strands, so it is very flexible. Jumper cable is usually similarly flexible. Battery cable doesn't really have this requirement so it is often stiffer. In my mind, it would be worth it to spring for the more flexible cable even if it was more expensive, just for ease of routing. Go with the jumper cable, it'll be fine.

For crimping - if you were going to be doing a LOT of crimping, it might be worth it to invest in a large manual crimper - they look like bolt cutters but have crimping dies on the end instead of the cutting blade. The advantage is that you can crimp in place, anywhere. Harbor Freight sells an inexpensive (relatively) air/hydraulic crimper for like $50 that would work too, assuming you have air.

If you have access to a big swaging tool (also looks like bolt cutters), you can use those in a pinch, but the shape of the tool isn't perfect so you have to be careful to get a good crimp. The results are better than the vice method, which is what I would use if I had nothing else.

Lastly, I have seen some people do soldered ends. It has to be done with a vice and a hot torch to be done correctly, but there are industrial processes that work similarly so I suppose I trust the method. I admit that I did try it on a couple of my connections on my recent battery installation. Everything works great so far but we'll have to see what a couple hundred miles of washboard do to it. If I have vibration problems, I have enough slack to lop the connectors off and re-do with crimps.

 

[Trailfrog]

Fantastic! Thanks for all the help everyone. I also found a 43 qt Edgestar scratch and dent fridge today and bought it so I should be set just need to get it all installed now.