Dual Battery isolator setup

[Nd4SpdSe]

Nd4SpdSe: Are those Optima D34 or D34/78? They are the same dimensions so it really doesn't matter; just curious.

I was looking into getting 2 D35's or D25/75's as they are a bit shorter in length and marginally less wide.

The one on the left is a D34 and the one on the right is a D34/78. The side posts on the D34/78 are used for my winch; makes for a cleaner setup rather than to have a ton of things off of the same post.

Forgot to share my wiring diagram for the setup as well

For the PAC-200 isolator, it's basically just a 200amp solenoid. I have a 165amp alternator and affordable diode-based isolators are really only affordable up 125amps so they're connected in direct parallel when charging. They're close enough to being the same type of battery that it shouldn't be a problem. I connected the solenoid trigger on a feed that's only hot when the motor is running, but not on when cranking (Red wire off the tumbler) so that they're not connected and fighting to equalise the charge WHILE the truck is attempting to turn over, BUT, I put in an override switch inside so I can do a self-boost; the benefit of having them on an isolator rather than always in direct parallel, so they don't both drain together. A function I that's come in handy a few times or when you need those extra CCA's on those -30*C days...


As a note, the problem with the D34's is that the terminals are too inwards on the battery, so the angled factory positive terminal can't reach.

 

[Bklyn.X]

... I connected the solenoid trigger on a feed that's only hot when the motor is running, but not on when cranking (Red wire off the tumbler)...

Can you tell me where and how you connected the trigger? Thank you.

Is your winch hooked up to the side terminals of your battery or just pictured that way?

 

[Nd4SpdSe]

It's connected to one of the main wires coming off the key/column harness. I'd have to drop the cover to tell ya. Let me know how critical you need this info.

Nope, it's actually connected tht way. It makes it easier to organise wires and ensures a solid connection for the winch. Although not pictured, the winch ground is connected directly to the battery ground post as well. Normally I keep it as short as possible and go to chassis, but the winch is *right* there, and brings the connections inside the engine bay.

 

[Bklyn.X]

Not critical. I was hoping there was a circuit within the engine bay fuse box I could tap into.

I had my winch connected to the side terminals of the battery and on an off road trip the winch would not pull. I thought I had a defective winch but one of the guys running the trail with me said that the side terminals are for accessories and cannot provide enough amperage to run a winch. I still do not understand how this could be however my winch pulled fine after switching to the top terminals…
I was curious if you have used your winch since hooking it up that way and if it works ok.

Thanks again.

 

[metzican]

Not critical. I was hoping there was a circuit within the engine bay fuse box I could tap into.

I had my winch connected to the side terminals of the battery and on an off road trip the winch would not pull. I thought I had a defective winch but one of the guys running the trail with me said that the side terminals are for accessories and cannot provide enough amperage to run a winch. I still do not understand how this could be however my winch pulled fine after switching to the top terminals…
I was curious if you have used your winch since hooking it up that way and if it works ok.

Thanks again.

I have also heard that about the side terminals there not designed for high amp outputs.

There has to be something under the hood you could tap into I just can't think of any fuses right now for that.

 

[Nd4SpdSe]

I honestly never heard of that. I had always thought that the side terminals were used for vehicles that required side terminals. I used my winch like that for a few years with no problems and could winch all day long. I unfortunately took it out last year cause it was siezed up and plan to replace it eventually, it just hasn't been priority.

You know, I never checked under the hood to see if there was one. I perfer to tap into something in the passenger compartment to reduce the chances of being exposed to the elements

 

[Bklyn.X]

I honestly never heard of that. I had always thought that the side terminals were used for vehicles that required side terminals. I used my winch like that for a few years with no problems and could winch all day long. I unfortunately took it out last year cause it was siezed up and plan to replace it eventually, it just hasn't been priority....

Sorry for the thread jack folks, however;

I just looked deeper into the battery/winch question I posed to try and satisfy my own curiosity and found that Optima, the battery I have, says to “Never connect a winch to the side terminals” (Optima Users Guide under “Installation Tips”).

So hooking a winch up to the side terminals on Optima voids its warranty!

Looking into this on a few other "off-road" boards I found out that apparently the side posts of an Optima battery are connected to the top posts by a strip of metal so although they are ok for low amperage constant draw and intermittent high amperage draw (for starting) a high amperage consistent draw from a winch load can actually melt the side posts right out of the case. Yikes!

I’ve never dissected one of these batteries so taking this explanation on faith. I also don’t know if this is the case with other manufactures’ but I have an Optima so that’s what I looked into…that’s right, it’s all about me…

I assume that when I had my winch hooked up the side terminals the “strip of metal” was acting like a resistor and limiting the amount of amps the winch could draw in turn limiting the load it could pull. It probably damaged the battery but that was many years ago and I can not remember if its demise was premature.

I’m not smart enough or have enough information on your situation but wonder if your winch failure had anything to do with it over working with low amperage??? An interesting theory…

Any-who I guess we should all connect our winches to the top posts.

 

[Nd4SpdSe]

Not off-topic, it's really good-to-know information and I honestly didn't know, and used for years with no issues. However, now knowing this (a sad poorly designed feature), when I get a new winch, I'll have to unfortunately wire it up differently. It was so nice to use those connections, it was really convinient and cleaned up the wiring. I didn't take that info seriously, but after you posted that up, I looked online and it seems to be a valid issue. Thanks for clearing that up.

 

[ellisfamilyokc]

The president of my off-road club runs a piece of 2 gage wire from the top posts to the side posts of the same polarity to avoid this whole issue of overloading the side posts.


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[Bklyn.X]

The president of my off-road club runs a piece of 2 gage wire from the top posts to the side posts of the same polarity to avoid this whole issue of overloading the side posts.

I understand that this would take care of the "high amperage consistent draw" issue but that "fix" doesn't clean up the wiring for me (the reason I hooked up to the side). It would kinda make it busier, no? Why not just run the winch wire from the top? Is he running other high draw accessories besides the winch?

 

[ellisfamilyokc]

He has a large 12v air compressor and a large power inverter he is also running.


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