With Dual House Batteries Do You Need 2 Monitors?

lonepeak · 02-12-2015, 06:34 PM

Forgive me in advance about this question. If I'm using 2 - 4d batteries in my house bank, do I need 2 use 2 battery monitors? I'm just now building my system and seem to have gotten lost on this point. Barry

mikracer · 02-12-2015, 06:52 PM

Assuming they're wired in "parallel" to create one large battery, you would only need one monitor.

Viva · 02-12-2015, 07:59 PM

That's it exactly. The monitors are typically capable of monitoring one "bank," and your house bank consists of two batteries. If you had four house batteries wired together that would be your house bank. So, one monitor for either of those scenarios.

(Some models can monitor some or all features on a second bank, but I'm speaking of the basic "one bank" type.)

lonepeak · 02-13-2015, 06:30 PM

Thanks...that's what I needed to know. Some stuff you read can really get confusing for an old guy. Barry

gcvt · 02-17-2015, 09:55 PM

Sounds like I just wasted money on a dual battery monitor, unless I hook one side to my battery bank and another to the starter battery. Learn something new here every day.

**daveb** · 02-18-2015, 01:58 PM

Quote:

Originally Posted by gcvt

Sounds like I just wasted money on a dual battery monitor, unless I hook one side to my battery bank and another to the stater battery. Learn something new here every day.

If you hook one side to the house and one side to the starting battery you'll be able to monitor both when the separator is open. Could be handy

gcvt · 02-18-2015, 11:26 PM

Quote:

Originally Posted by daveb

Quote:

Originally Posted by gcvt

Sounds like I just wasted money on a dual battery monitor, unless I hook one side to my battery bank and another to the stater battery. Learn something new here every day.

If you hook one side to the house and one side to the starting battery you'll be able to monitor both when the separator is open. Could be handy

If I'm doing that, I'll be running wires the entire length of the van.

If I'm doing that, I might as well wire it up so I can use the house batteries to jump the starter battery, if needed.

If I'm doing that, how do I do that?

Am I understanding correctly that it doesn't make sense to monitor two separate house batteries in parallel because if one loses power, it just steals power from the other one so they always end up with the same voltage?

edit: I'm not, and will never be, an electrician.

Scalf77 · 02-19-2015, 08:57 AM

You would be correct, that the two batteries in parallel will read as one, no need to monitor both.
What battery monitor do you have, and what other equipment such as Isolator. separator, etc. We can help you come up with a wiring plan. The wire sizes need to monitor a battery would be much smaller then what is needed to jump start from house to starter.

-greg

**daveb** · 02-19-2015, 11:32 AM

Sorry, I was guessing you had a battery separator. If you did, all you'd have to do is tap right off that. But Greg is correct, depending on the voltage gauge there are several options. You can even tap right off any (always hot) close 12v vehicle source to grab the starting battery voltage. If it's a volt/amp gauge you'll have to deal with the shunts. I'd think you really only need to measure amps on the house system though.
Isolators work OK but a separator is a better setup. Chances are the charge wire coming from an isolator is sized smaller because those are not designed to help jump start the vehicle. Being an isolator is basically a one way valve, you'd be spinning your wheels tapping off the charge wire and would have to run a wire up front to something like a fuse panel to measure vehicle battery voltage. You might have an always hot circuit in a trailer plug close by to tap into for starting battery voltage.

If you want to convert to a separator type system, it will be more of a job

gcvt · 02-20-2015, 12:29 AM

So this is the gauge I bought: http://www.dcjoules.com/apps/webstore/p ... ow/4092348

I'm going to wait on the battery jumping part of the plan and just concentrate on the battery monitor for now. Got other van things to deal with. Don't ask.

My setup is two group 27 house batteries - one behind each rear wheel.

The control panel for the old Onan, CO/Propane detector, etc. are all located above a closet in the left rear of the van, so that's the logical place to locate the battery monitor. So one + and one - wire from the nearby house battery and then one + from the starter battery with a 0.5 amp used on each + wire. Not sure on wire gauge yet?

In addition, the gauge's backlight runs off a jumper on the back which would be very hard to access. Plan there is to solder up a small toggle switch and mount that right next to the gauge so it draws less amps when it's sitting.

Am I headed in the right direction here? Am I missing anything?