Dual Battery Install (completed)
 

A dual battery install is really very simple once you get the parts.

Parts:
Right fender battery tray for a Diesel Rams
Battery hold-down
Stinger SR200 200 Amp Isolator/Relay
http://www.stingerelectronics.com/t...t%20DIAGRAM.pdf
Isolator Relay Delay
http://www.mastertech-inc.com/intellitec/iso_re_de.html
Welding cable lugs, etc.
Deep cycle battery

After I mounted the tray I ran the negative cable from the second battery to the first battery negative cable using 4 gauge welding cable. The second battery gets it ground from my starter battery. This way I only need to pull one negative cable when I work under the hood. That way I can never forget the second and cause a short while working. Then I ran the positive cable from my starter battery to the SR200 relay. The cable from the SR200 goes to the second battery. The SR200 also has two small terminals which are used to activate and supply ground to the SR200 Relay. The instructions call for true ignition switched 12 volt source which remains powered during start-up but I did not like that idea so I added a the relay delay to give the system brains. When the SR200 gets power it connects the two batteries and assumes that they are both getting charged. Under some conditions it could be wrong so I installed the relay delay. If for some reason my starter battery has less than 12.6 volts the relay delay will not activate the SR200 so that all charging from the alternator will go directly to my starter battery. Once the starter battery is fully charged and the alternating is sending 13.3 volts it will turn on the SR200 to charge the deep cycle battery. Although they are combined each battery will only take the power it needs. In other words once the starter battery is full its draw is so low that most the charge will pass through to the deep cycle battery. If the alternator drops below 13.3 volts the relay delay will turn off the SR200 breaking the connection between the two batteries so that the deep cycle will not drain the starter battery. The power for the relay delay is tapped from the cigarette lighter fuse box next to the driver’s side door. The only thing I need to add is a momentary switch to combine the two batteries for emergency starting if the starter battery ever fails. Both batteries have 100 amp fuses between them and the SR200. Thanks for reading my notes and comments.


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RE: Dual Battery Install (completed)
 

That's a nice setup, and good write-up. Thanks for the information.

RE: Dual Battery Install (completed)
 

why would i want to run a second battery? why did you install one?

RE: Dual Battery Install (completed)
 

My reason is here:
https://dodgeforum.com/m_614999/tm.htm

But some people like having the extra power for offroad lights, high power amps, a winch, electric tools, air compressor, emergency power during a storm, and the list goes on. Most people will never need it but others can't live without extra power.

RE: Dual Battery Install (completed)
 

I do a lot of car hauling in the VW world. After a while, loading a car with a come-along gets old and dirty. I would prefer to have a power winch on my trailer (a future goal) and this is one example where an extra battery would come in handy.

RE: Dual Battery Install (completed)
 

Niec, somebody should put this in the FAQ/DIY section so we don't loose it. Good work!

RE: Dual Battery Install (completed)
 

i really do like the inverter install.
im using a 400w inverter right now, no fancy install though. just need it once in a while for my laptop/cell charger/ext hard drive for music.

RE: Dual Battery Install (completed)
 

I'm assuming that you used a new battery for the second one. I would reccomend replacing your original battery soon, most time when there are 2 batteries if you dont replace the old one it will cause the new one to go bad. That has been my experience anyway, but if it was me I would replace the old one.

RE: Dual Battery Install (completed)
 

Yes, teh deep cycle is brand new. Because the relay-delay only connects the batteries when the alternator is putting out over 13.3 volts I don't think the new battery will not have a chance to drain the old battery. As I understand it, it is the constant draining of the starter battery that causes it to fail. If I used the isolator alone the weaker battery would drain the stronger battery until it failed. Beside they are both under warranty for years to come. But thanks for the heads-up. I'll watch them and see if it really works and designed.

RE: Dual Battery Install (completed)
 

What is the use for the extra parts? I hooked up an extra battery in one of my other vehicles, by just grounding the 2nd battery to a close ground and running the positive straight to the primary battery with a fuse. Worked fine for the few years that I owned it.