amp/amp hour meter

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mike1245

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Does  anyone use and amp/amp hour meter to keep track of the of the amounts left in the batteries.  It measures amp hours used and the amp hours put back when charging.
Thus you always know how much you need to run the Gen to replace the amp hours used.  Much more accurate than the idiot lights on the control panel. Especially useful when boon docking.
Mike
 

Tom

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A number of us have that function, either in a standalone monitor, or integrated with an inverter hooked to house batteries.
 

John Canfield

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Years ago we 'boondocked' for 16 months on our sailboat in the Caribbean, we spend a grand total of three or four weeks at a marina.  Battery bank management was a very inexact science on our boat and the best I could do was to carefully monitor voltage of the off-line battery and get a feeling for how long and how often to charge.  We had an inefficient solar panel, a wind generator and traditional gen set so battery management was not ideal like it can be now.

If we ever have to ditch our Xantrex RS2000 inverter, I'll go with Magnum and their battery monitor add-on.  Our RS2000 gives up a lot of info now, but not amp/hrs in or out.
 

Jim Godward

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John,

I put a Trace 500 in the MH to  monitor the batteries way back in 2001 and have never regretted it.  Lots of information and you can adjust things to the way you use your particular set.  The various monitors available really help in monitoring the batteries and I think help prolong the life too.
 

Just Lou

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I use a meter/monitor system called Trimetric.  You can Google it and learn more about it than I care to iterate here.  There are others, both add-ons and integrated systems proprietary to specific manufacturers

All quality battery monitors assume that you have a basic understanding of your own battery systems capacities, specifications, operating environment and the expectations of performance that you place on them. 

Most, if not all, monitor systems will record current voltage measurements and amp drain/charge rates, and calculate amp hours needed to restore to a fully charged condition, but I know of none that will tell you "how long your generator must run to replace amps used".

It's like any other tool.  If you understand how your system works and interacts, you know what you want measured and reported.  If you don't, then the best monitor system is a waste of money.
 

Jim Godward

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Lou,

Very true.  I can do a fairly good estimate if needed run time with the number of amp hours left or used and the way the charger works, bulk to float.  I usually only take the batteries back to about 90% when boon docking as it takes too long to get that last 10%.

I am way out of practice as the last time we were boon docking was a couple of years ago.

Of course having 2 large solar panels helps a lot too.
 

bukzin

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How tricky might it be to install one of these meters as an add-on?

I understand sometimes (maybe all the time) a shunt must also be added to get accurate readings?
Is that correct?


I would like to boondock a lot more in our 2006 Monaco Diplomat, also will be adding solar.

Thanks!
 

Gary RV_Wizard

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I would expect that a 2006 Diplomat already has afairly accurate ammeter as part of its inverter/charger display panel. In most motorhome electrical designs, all the battery amps pass through the inverter/charger and it measures the amps on its internal bus. Look at the manual for your remote display - good chance there is one that shows a battery amps. Also battery voltage and several other parameters.  If not sure, post the make & model of inverter and its remote display panel. For example, the Xantrex RV series inverter uses a Xantrex RC7 remote display panel.
 

Just Lou

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Gary RV Roamer said:
..... In most motorhome electrical designs, all the battery amps pass through the inverter/charger and it measures the amps on its internal bus. Look at the manual for your remote display - good chance there is one that shows a battery amps. Also battery voltage and several other parameters.  If not sure, post the make & model of inverter and its remote display panel. .......

Not necessarily true.

The I/C cannot measure amps added to the battery via the alternator and isolator solenoid if the I/C has an internal shunt.  Likewise, the I/C does not measure the amps used by the various sensors, lights and DC loads.

The only way to measure all current going through the batteries is to put the meter shunt in-line with the battery (usually installed in the negative path to frame ground).
 

Jim Godward

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Lou,

To continue along the line of your comments, the I/C also has no information about what the solar adds either.  I suspect your system that you mentioned in another thread covers *ALL* amps added to the battery from whatever source as does the Trace system in my MH.  I have a large shunt in the ground line that is used by the metering circuit to keep track of the adds, outs and net remaining.

If you want to manage the batteries one of the add on systems is required in my opinion.
 

Just Lou

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Thanks Jim,  I appreciate you posting your understanding of the different methods and points of current measurements.  I don't have the benefit of solar, so didn't think to include it in my description of the difference between actually measuring ALL charging/expended battery currents and only those sources/loads attributable to the I/C.
 

Gary RV_Wizard

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The I/C cannot measure amps added to the battery via the alternator and isolator solenoid if the I/C has an internal shunt.  Likewise, the I/C does not measure the amps used by the various sensors, lights and DC loads.

Maybe, maybe not. In many such systems, the I/C is the only path to the house batteries, so all current in and out flows through its internal bus. The isolator solenoid may or may not have its own cables direct to the battery bank. I know mine does not, but I would hesitate to generalize.
 

Just Lou

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Gary RV Roamer said:
Maybe, maybe not. In many such systems, the I/C is the only path to the house batteries, so all current in and out flows through its internal bus. The isolator solenoid may or may not have its own cables direct to the battery bank. I know mine does not, but I would hesitate to generalize.

I agree that MOST properly installed I/Cs are cabled directly to the house batteries (through a large fuse, of course), but they are NEVER the only path from most DC loads, or external charging sources, to the batteries.  The entire DC distribution panel being a prime example.  LP detectors, luggage lights, radio and  power awnings, via the disconnect switch solenoid, being others.

The isolator solenoid must have large current carrying capability, and is always wired electrically between the house and chassis batteries, usually via bus bars or battery cables.  Your particular isolator solenoid is cabled directly to your BCC where the cables are attached to each battery bank.  The isolator is closed any time a sufficient charge voltage is present or the aux start button is depressed.  This may not be a direct battery connection in your eyes, but you can't get any closer electrically.

JMHO and tendency to generalize.
 

Gary RV_Wizard

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but they are NEVER the only path from most DC loads, or external charging sources, to the batteries.  The entire DC distribution panel being a prime example.  LP detectors, luggage lights, radio and  power awnings, via the disconnect switch solenoid, being others.

Ya gotta admire a man who is never in doubt!  ::)
 

Just Lou

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Gary RV Roamer said:
Ya gotta admire a man who is never in doubt!  ::)

Prove me wrong..........  and you have my permission to officially rename this forum to "ASK GARY.COM".
 

Tom

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OK guys, time to quit trying to prove who's right and who's wrong, or who has more or less knowledge.
 

Tom

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I've been sent to my room by forum staff more times than I care to admit  :-[
 

hes4all

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Tom said:
OK guys, time to quit trying to prove who's right and who's wrong, or who has more or less knowledge.

Hi Tom, well I am man enough to admit that I have very little knowledge of anything, so that is why I went to AM Solar and had a TriStar-60 MPPT by Morningstar controller installed along with 900 watts of solar panels. This controller gives you more options than a person like me will ever used.

To be honest, the system is awesome. With the shunt installed I can see amps used, amps available, charge rates and alot more. Was it all worth the cost? I can't say forsure yet, but I was just at the races in Vegas and I never ran the generator, in the past it would run at least two hours each day. Pretty awesome I would say. Thanks


This is what the Tri Star meter gives you.
~ Battery Voltage
~ Solar Input Voltage
~ Charging Current
~ Battery Sense Voltage
~ Battery Temperature
~ Battery Min/Max Voltage
~ Daily Charge in Watt Hours
~ Heatsink Temperature
 

Jammer

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bukzin said:
How tricky might it be to install one of these meters as an add-on?

I understand sometimes (maybe all the time) a shunt must also be added to get accurate readings?
Is that correct?


I would like to boondock a lot more in our 2006 Monaco Diplomat, also will be adding solar.

Thanks!

In addition to the Trimetric there is also a stand-alone meter from Xantrex, and a product called the Clipper BM-1.  I like the design of the xantrex, but have heard reports that all of them work.

In general a shunt is required when adding one of these.  It's not a trivial job, but it's not difficult for someone with experience with battery wiring.

 
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