StanVan

Once again, you missed the point. The relays serve to keep the batteries charged. The switch is ONLY when the A battery fails, and you need a jump. As for the degradation thing, you speak like someone who has endless money, or someone who hasn't experienced this.

dberladyn

See, this is what I tried to explain to somewhat deaf ears. Stan is absolutely right about this. If the batteries have any differences they pull down the stronger battery and destroy it. From what I remember reading, and from what I understand, you are Ok to hook them up in parallel while left idle - if - you use two identical batteries (preferably manufactured at the same time). This is why I did not take issue with hooking up the two deep cycles, the two auxiliary batteries, in parallel like I have. They have never even run down as far as I can tell. Right now I am operating on them as the Starter/Main Battery is shot. Why it is shot is likely from a faulty GM Battery Connector and then my need to hotwire the truck while out of town. Getting on and off ferries and harassed by who knows who, I needed the truck to start. That's the third Main Battery this truck has gone through. It's still new, but to be fair it was run down too many times.

I am thinking of one other idea, or I have been thinking of it. A Relay on each battery. I wouldn't do it because I am concerned about maintaining the health of the deep cycles, I would do this for functionality.

Thank you Stan for your input.

You explained very well why I was sitting here getting frustrated trying to explain that people having theories and people making decisions on real experiences... lead to two different results. Experiences like continually having dead batteries while you are going through hell. Not a good thing. I am rather sensitive to batteries now which is why I consider dedicating one exclusively to the Starter Motor and nothing else. If I do that, I will always have amperage to turn the Starter. Powering the rest of the required modules is another - seperate - issue. They do not require a lot of power.

mountainmanjoe

I understand the point perfectly, and as a matter of fact, I have first hand experience.

So you're driving your van around. Your switch is turned to ON because you need charge your aux battery(ies). You park the van and turn it off. Inevitably, one day, you forget to flip your switch back to OFF. You start to run your toys, and you run down your starting battery. It WILL happen.

By all means show us how you implemented your system, and let us know how well it works and how long it's been running. Tell us your degradation stories. I'm always open to learning something new.

You are all overthinking this.

StanVan

Dan- another factor with batteries of this style is even the slightest corrosion on a terminal can cause an imbalance between batteries, and lead to failure. A relay for each battery isolates them from this.

Joe- You still don't get this. And part of this is because my skills lack the ability to draw out a schematic that I can post. But I'll try again. The switch would be off until the time comes when you need a jump. Isolator relays handle the charging. Both circuits exist together,and don't conflict.

dberladyn

Joe you are pretty smart about somethings, but I am definitely with Stan on this one and I am glad for his input.


If I do not decide to add a third relay I think I will just do this.

• C1A Relay will be triggered by the Alternator Charging. If that means I hook it into Ignition On, that is what I will do. For some reason that I forget right now, I was thinking of having it on a timer for something else. Maybe a delay before it kicks in and begins charging. A simple switch in the cab manually overriding the Relay Trigger takes care of a dead Main Battery.

• C1C Relay will be triggered by the Alternator Charging (as above). Again, a Manual Switch in the cab can be added to compensate for a dead battery somewhere else.

In this scenario a third relay would let me shut off the Main Battery if it was toast. Peace of mind thing I guess, that is all. What I lose is Engine Off operating time as I will be down to one battery for any function.

StanVan

I don't think you need 3 relays, but I'd use relays for B and C. I'm not sure how a relay on A could work.

What do you use to make a schematic that you can post? My graphic skills suck.

mountainmanjoe

How does the battery charge when switch is off?

Your explanation makes no sense. I think that if you try to draw it out you will realise it doesn't work.

dberladyn

The Starter (A) Battery is ONLY to turn the Starter. Nothing else. Not the Relay/Solenoid on the Starter. Not the ECM. Not the BCM. Just Engine Revolution. That is all. The C1A Relay would only engage for charging that battery - or - if everything was else dead, the required modules to run the engine via manual cheater switch in the cab. I am clear that this will work the way I intend.

I just edit the GM Upfitter docs with Microsoft Paint 3D. It actually works pretty good. I gave up the first few times, but persistence pays off. Now I am getting pretty quick at it.

This below is probably the luxury edition. It is probably also the best way to do it. A double throw, single pole manual switch in the cab for each battery would account for literally any situation. Each Relay could have a switch. Up for Pos+ 12 Volts (Manual Override), Center for 0+ Volts (Battery Disengaged), Down for Ignition 12+ (Automatic Battery Engage).

I do see a problem with this however. The Main (C1B) Battery Relay would constantly draw as it would always be engaged. I would need a Relay/Solenoid that was Normally Closed (ON), not Normally Open (OFF). Do they make those?

Maybe C1B would just have to be a 'Manual Switch' ?
Or maybe this feeds into what Stan is saying... with his Manual Switch example (kind of).

StanVan

Think of it this way, Using the circuit that Dan posted with isolator relays separating all 3 batteries when the van is off. Add the switch, connecting "1" and "2" to B and C respectively, and connect A as the main. In the off position no batteries connect to anything. Switching it to "1" connects B and A (to jump A from B). Switching to "2" connects C in the same manner. Switch to "all" connects both B and C to A (the main battery) The relays handle charging when the van is running, and isolates the batteries at rest.

dberladyn

Using Toggle Switches in the cab to manually cheat power to the individual relays accomplishes the same thing. You just need 12+ Battery power from somewhere. Either a Clock Battery which I am tempted to install so I no longer lose settings, like radio presets, or by making some kind of Absolute Power line by using Diodes. An 18 gauge wire from each battery with a diode on each merging into one 'Absolute Power' wire should give you a redundant robust 12+ feed as long as you have at least one battery functioning.

Maybe you are Right as above in Red.
Manual Switch - it is REQUIRED.