Hi folks,

I'm thinking of setting up my dual battery system, and trying to find a Engine/Alternator running signal in fuse box(or wherever) to control a solenoid. I found the IG2 signal in "K Unit" in fuse box, but it's not the correct one. Can anyone tell where is the "hot" signal only when engine is running?

Side notes:
- No offence to the gentlemen I PMed for this question, I just couldn't wait for your reply.
- Don't get me wrong, I don't object to some dual battery systems like IBS, they are decent systems. They just are not my first choice.
- I know Voltage Sensitive Relay can make a such signal for you, I just wanna know if I can get a such signal in a very simple way.

Thanks!

I thought about this for a while and can't come up with any ideas on a factory wire that would provide this signal...would you happen to have an aftermarket remote start alarm though? I know those have a "ground when running" signal. Another idea would be an RPM activated switch set at a really low RPM.

Sorry I can't be of more help, but I really like where you are going with this dual battery charging setup, I hope you figure it out!

It shouldn't be that hard to find. Think of something that is only on when the truck is on. Aren't the cigarette lighters this way?

- Just kidding I think they are ACC and ON. Hmm

Fuel Pump relay output is what I'd go with - it's not perfect, bc it isn't a true run status for the engine, but it's easy enough. Correct me if I'm wrong, but when you turn the key to the "run" position, the fuel pump kicks on only until the fuel system is pressurized, then it cycles off, no?

I'm sorry I can't answer your question, but I am curious - what is it you're trying to do that the IBS system can't do?

Sorry OP....been crazy...

that "gentleman" comment made laugh..


I believe the fuse box you want to be in is the one under the driver's seat...I believe there's lots of "ignition on" fuses in there..

"CALLING ANTMAN"!!

you'll need a tap-a-fuse, and I'm pretty sure you'll have to get through the fire wall...just too damn lazy to do it.

right now the wire is hot all the time to the relay...leaving it open all time, thus allowing the second battery to be drained, and not allowing a "true" separation when the ignition is in the off position

Sorry man- I've been slacking on the PM's as of late! Got to catch up...

I think you will be fine with an "ignition-on" signal. The key has to be in the "run" position, or the "acc" position to be hot.

If that works you can use this circuit (driver's footwell fusebox) and access it with a minitap if you want:

Top right corner- 15a P/OUTLET




Hope that helps? I don't know anything that's hot when the engine is physically running only.

I do have an aftermarket Remote Starter, the only stuff dealer sold me other than the truck when purchase. I never gave a thought on that, I'll think about it.

ACC(hot), IG_ON(cold) - radio on, fan/ac off, engine off
ACC(hot), IG_ON(hot, before starting) - radio on, fan/ac on, engine off
ACC(hot), IG_ON(hot, after starting) - radio on, fan/ac on, engine on
So I don't they can tell me when engine is running or not.

Could be, I'll think about it.

IBS is a system that you wiring it up, magic happens, you are happy. I believe IBS is just a fancy voltage sensitive relay system. Yes, it works fine, I just want to know if I can do some hacking to do the same thing without using any "magic". :-)

Thanks Pat for the reply in both PM and this post. No worries, I know everyone got stuff to do. Now I know you were not tapping the IG2 in "K Unit".

Thanks Antman, you even got the chart laminated!. I just tested the P/OUTLET, is basically the same as ACC. I have a Smart-Key, I don't know if that behaves differently than the real key system.

Anyways, I'll keep researching a bit more. The plan B is VSR/Battery Isolator, plan C - IBS. Thanks everyone for chiming in and helping.

Cheers

That's great to hear you actually have an aftermarket remote start...if you do happen to want to go this route look up the model number of the remote start module, and then try to pull up the wiring diagrams to find the "GWR (ground when running)" output; it's also sometimes called the "status" output. This should provide you a ground signal while the engine is spinning. One thing I am not sure about is how long this signal persists...I forget if its only for when the remote start is in use, or if it's always active; you'd need to manually test that out, sorry!

From what I understand about the IBS, it basically only connects the two batteries when the ignition is on and it detected voltage is above ~13 volts or so; and disconnects them when it drops. It really is just a voltage sensitive controller that opens or closes the solenoid based on the voltage (along with a nifty way to monitor each battery voltage when they are isolated and a forced "link" feature).

However, this can be easily mimic by activating the solenoid with an ignition wire such as @Titanpat57 did in his write up; I rarely see our battery voltage drop below 13 volts when the engine is running so IMO, it's close enough I mean who really sits there with the key in the on position and the engine not running for a loooooong time right?

I basically agree every sentence you wrote. Actually the IG2 signal is good for almost 99% of the time, unless you keep ON position for a looong time AND your AUX battery just happened to be very drained. This is the only situation that you may have your starting battery power sucked by the AUX battery.

Starting the car will not be affected because in the few seconds of starter cranking, the IG2 is cold, so the starting battery will have the full juice to feed the starter.

And yes, a VSR/Battery Isolator is a relay that connects when above 13.3V and disconnets when lower than 12.8V, like this:12V Battery Isolator | Princess Auto

Interstingly, the one above was once on sale for $25CAD, and the below one gets a $94AUD price tag
Matson VSR Dual Battery Isolator - Matson
They seem to be from the same OEM. If that's true, you may imagine the profit margin of IBS

From reading....When you have the relay closed and the batteries are joined when initial starting it is supposed to be hard on the charging and electronics systems and one of the reason why the IBS,Surepower,Cole Hersee and other systems usually have delays before they connect them together. Our Denso 130 amp alternators for these trucks are really good.... but are very expensive.

I've had the Cole Hersee Smart 48530 isolator, Battery-Related Products | Battery Isolators48530 | Cole Hersee - Littelfuse which has the isolator and relay together, for 2 1/2 years now and no problems,works every time. Just click on the literature PDF to tell you more about it.

Super easy to hook up and connects batteries two minutes after starting every time and disconnects after a couple of minutes when I shut it down. It has a emergency connect switch I wired in the truck so if my main dies I hit the button and it connects them to jump myself.I also just wired dual voltage gauges inside the truck so I can monitor each battery. I paid like a $100 for it on ebay at the time but they've gone up but still a way cheaper alternative then the IBS if your a DIYer...Cole Hersee Smart Battery Isolator 48530 200 amp

I agree the IBS is high priced but has all the fancy voltage gauges and wiring for a complete system .....and it works.I recommend their system as they make it easy and if you have the money.I just like reading and learning from all their FAQ's and tech write ups as they really are very knowledgeable and share.
ibs-tech.ch: IBS-DBR (Dualbatt.-Relay)

ibs-tech.ch: FAQ's for IBS-DBS/DBi

Not sure if you plan to run a winch but that's a whole other topic with dual batteries and the reason why I'm putting a second higher amp manual switching relay just for winching as the relays themselves are pretty cheap..

Thank you very much for sharing this, this PDF clearly explains how it works, very nice! Other than showing the AUX battery voltage, it has everyting.
I see this "Disconnect Voltage: 12.7V after one minute at this level." on it's website, but didn't find "connects batteries two minutes after starting", is this measured by yourself or stated some where?

@harper7 out of curiosity, do you feel that connecting the batteries after two minutes of starting vs. connecting them right after the starter stops cranking would make a significant difference in terms of stressing the charging system?

I've yet to really plan out my dual battery wiring, but I was toying around with the idea of going with the standard IBS 200A relay (non-microprocessor controlled) and then just wiring that relay to activate off the IG2 signal (which momentary goes cold during cranking, as mentioned by KodeRush). Then tailoring the wiring a bit so I can add in a manual link switch of some sort.

I really like the IBS stuff since it's pretty much all you'd ever need and fitted in to a nice and neat package, but I jsut can't stomach the price

On the Cole Hersee under literature , In that pdf it tells you.....

The two batteries are electrically connected
together when either battery voltage is above
13.2V for 2 minutes
I can also hear the solenoid click close and also see the voltage on my aux battery gauge go up after two minutes.

However......
Under the IBS FAQ's..there's does kick in faster but they are still isolated for start.
The IBS Dual Battery System links the batteries as soon the charge voltage exceeds 13.1V this happens within a few seconds up to 3 minutes depending on the car.

That would probably work but not sure, without any isolator at all, if it would actually harm your alternator or electronics and/or how long it would take to harm them that way , if ever. As you see the IBS system kicks in after a 13.1V charging voltage and that happens pretty fast so you should be alright and maybe contact to see what they say about it.

I too bought a 200A IBS relay from Sierra Expeditions and going wire it in between my Cole Hersee relay and the main battery.Having a simple SPST switch in the cab to operate to be able to isolate my main by opening the circuit. Like when winching as the winch is hooked up to the big group 31 Platinum Marine that I use as my main and also when I just want to get a completely full charge my main.

Here's another system by Blues Sea some of the FJ guys swear by who run with winches and if I had to do it all over again would probably go with and may still someday but is way overkill unless you have a winch IMO......... Blue Sea Systems 7622 - ML-Series Heavy Duty Automatic Charging Relay

Thanks for the link to this one, really does look like a nice unit! I'll definitely be looking into this one more before I dive in. Waaaay overkill for my dual battery that's meant to run some LED bars and a CB, but no one else will know