an easy question for a Battery GuRu

[SargeDiesel]

ok... this is not another dual battery setup, my ASS is broken or my cluster is lit up like a Christmas tree thread... let's talk Volt Meters !

I know the instrument panel has an option to show overall battery voltage... but it either is grouping both the main and aux batteries together or only capturing the main battery. (maybe someone can clarify).

I was wondering if a dual battery volt meter can be hard wired to show each battery separate.(take a look at the pics).

OK, I know it CAN be wired... but HOW ? Is it as simple as each battery sharing the ground connection and then running a separate positive lead from each battery to the meter ?

I found a suggested wiring diagram(see pics) is this correct for the Gladiators dual battery system ?

Any suggestions ? better options ? wiring advice ? Placement ?

Hope all is well and thank you for your feedback.

Sponsored

 

[kevman65]

Let's clarify part of that.

The JT doesn't have a volt meter. It doesn't show you the current state of the batteries.

What it DOES show is the current charging RATE of the batteries in parallel.

So, if it shows 14.7 V, you are max charging your batteries.

If it shows 12.* V your batteries are about max charged.

Can't answer the other and I wouldn't dream of stealing Bill's glory any way.

 

[sharpsicle]

You won't be able to measure each battery independently without separating them. They run in parallel with the exception of an active ESS event. That's the only time you might be able to read them separately.

The voltage you see is better described as system voltage. And because of how the system is wired (as described above), the overall voltage is really all you're going to be able to see until you go under the hood and physically separate the batteries from each other.

That gadget you have above is made for true secondary batteries, not for integrated batteries like our aux battery is.

 

[SargeDiesel]

Let's clarify part of that.

The JT doesn't have a volt meter. It doesn't show you the current state of the batteries.

What it DOES show is the current charging RATE of the batteries in parallel.

So, if it shows 14.7 V, you are max charging your batteries.

If it shows 12.* V your batteries are about max charged.

Can't answer the other and I wouldn't dream of stealing Bill's glory any way.

yeah... good ole Bill ! Thanks for the clarification... on the voltage display. That answered 1/2 of the question, so thank you.

 

[SargeDiesel]

You won't be able to measure each battery independently without separating them. They run in parallel with the exception of an active ESS event. That's the only time you might be able to read them separately.

The voltage you see is better described as system voltage. And because of how the system is wired (as described above), the overall voltage is really all you're going to be able to see until you go under the hood and physically separate the batteries from each other.

so if I tapped the positive at each battery and used a shared ground, such as in the wiring diagram I attached, it wouldn't separate the voltage of the batteries ?

 

[sharpsicle]

so if I tapped the positive at each battery and used a shared ground, such as in the wiring diagram I attached, it wouldn't separate the voltage of the batteries ?

Not without taking them out of parallel, which defeats the whole design.

Notice how in that diagram you posted, the batteries are not in parallel.

 

[KevinM60]

ok... this is not another dual battery setup, my ASS is broken or my cluster is lit up like a Christmas tree thread... let's talk Volt Meters !

I know the instrument panel has an option to show overall battery voltage... but it either is grouping both the main and aux batteries together or only capturing the main battery. (maybe someone can clarify).

I was wondering if a dual battery volt meter can be hard wired to show each battery separate.(take a look at the pics).

OK, I know it CAN be wired... but HOW ? Is it as simple as each battery sharing the ground connection and then running a separate positive lead from each battery to the meter ?

I found a suggested wiring diagram(see pics) is this correct for the Gladiators dual battery system ?

Any suggestions ? better options ? wiring advice ? Placement ?

Hope all is well and thank you for your feedback.

Not that I care to try it but I'm curious if a separate voltmeter for each battery would give you what you're looking for without taking them out of parallel.

 

[SargeDiesel]

@ShadowsPapa hey bud, you have helped me with battery related issues before, could you chime in and explain why/why not this will work ? or provide any input ? Thanks

 

[SargeDiesel]

Not that I care to try it but I'm curious if a separate voltmeter for each battery would give you what you're looking for without taking them out of parallel

that's what I was asking... I forgot to post the pic. But since there is separate positive leads for the dual and single voltage meters, I wouldn't think it would make a difference... BUT thats why Im here asking, because I'm not sure. But after digesting what @sharpsicle said... it makes sense they would need to be seperated regardless.

 

[ShadowsPapa]

Let's clarify part of that.

The JT doesn't have a volt meter. It doesn't show you the current state of the batteries.

What it DOES show is the current charging RATE of the batteries in parallel.

So, if it shows 14.7 V, you are max charging your batteries.

If it shows 12.* V your batteries are about max charged.

Can't answer the other and I wouldn't dream of stealing Bill's glory any way.

JT does have a volt meter. That's what is in the ORPs or in the cluster vehicle information pages with the tire pressure and so on.
It's showing the current voltage of things at rest if you press the button but not the brakes and get into ACC mode - but the batteries are in parallel.
So at rest it's showing the voltage of the system (since nothing is running, it's battery voltage) of the two in parallel. Like two jugs of water connected by a hose, they'll eventually equalize to a voltage that's between the two.

Start the truck and it's showing the system voltage which is the point at which the alternator is being regulated to at that point (reduced by the load on things that are running)

So if your truck is off, you press the button but not brake, go to ACC mode, scroll to the voltage you'll see what the current state of charge is - of course there's a load so it will be lower than what the batteries may be at. If it shows 12.6, the batteries may be at 12.7 if they were totally disconnected.

The maximum you'd likely ever see in a non-running system is 12.7 - and that's if the batteries were just fully charged and not sitting very long with the parasitic load of the truck.

These will charge different voltages (engine running) based on ambient temperature, battery temperature, historic data from the IBS, battery calculated resistance and state oc charge.
Mine will go to 15.0 volts when it's below 40 degrees and the truck hasn't run a lot so the batteries aren't topped off.
14.7-15.0 is pretty typical for mine in the winter until hot weather sets in.
It's a lot harder to charge a cold battery.
It's a lot harder to get that final 10% of charge in.

Anyway, the only time you can check the voltage of each independently is when you disconnect the ground cable for the aux battery from the IBS, or, if you wire two volt meters up and wait for an ESS event.

A volt meter to ground and main battery positive will measure both, or just the main if the ESS kicks in stopping the engine.

A volt meter to ground and to N1 will measure only the aux battery during an ESS stop.
Otherwise it will measure the average of the two batteries.

This alligator clip lead on N1 goes into the cab where I hooked it to my fluke.
I caught a ground for the fluke through the 12v outlet in the cab.

Follow the path in green dashed line - that shows how they are constantly connected unless the PCR opens during the start cycle to check the battery voltage/health, or during an ESS stop when the PCR opens.

 

[Jteakus]

The batteries are tied together effectively making them one battery.

 

[Jteakus]

Sorry boss, your explanation is much better than mine.

 

[KevinM60]

The batteries are tied together effectively making them one battery.

From what I'm understanding from Shadowspapa's post is that they are separated during an ESS event. I gather that is to save the main battery power for restarting.
If that's true, a voltmeter connected separately to each battery will give you the individual battery level but only during an ESS event. Aside from those events both meters would show the same value regardless of individual battery condition.

 

[Jteakus]

Truth

 

[Wolf Island Diver]

Why do you want to know the voltage of the two batteries separately? As Shadow Papa said, it’s only relevant during an ESS event. If it’s about battery health concerns, then I’d either just get rid of the Aux or replace it with a better unit than the OEM one and keep the truck on a tender.

To me, the Aux battery is like my appendix. It’s not really needed but it’s there. It has only two states I care about: unhealthy/failing AND Okay. I don’t monitor my appendix because the information wouldn’t help me. If it goes bad, I’ll have it taken out and stored in the garage in a jar next to my Aux battery. I don’t think monitoring the Aux voltage would tell you anything helpful. If it’s low, maybe it needs to charge. It’s a small battery, maybe there’s been a lot of ESS events. Voltage drop over time with no load might be a useful metric but you can’t test that the way it’s connected. If I have a thing that I don’t really need and I’m thinking about fabricating stuff for it, then I’m thinking about getting rid of it.

Sponsored