(I searched the archive for the term "amp/hour monitor" and came up completely empty -- am I asking the wrong question?? But there are quite a few for sale out there, so this item does exist. Please forgive me if this question has been asked and answered many times, but I could not find a prior discussion on point.)Anyway, I understand that monitoring the voltage gives me the state of charge, which can roughly tell me how many amp/hours I still have in the battery. The problem, of course, is that the voltage reading varies for a lot of reasons -- temperature, how much load there was on the battery a few minutes ago, etc. I am hoping that someone can recommend an after-market device that will indicate remaining amp/hours. Thanks in advance for your suggestions.

That's a tough search.. if you searched that exact phrase. In Advanced, I tried 'amp hour' (exact) first, followed by Search within results= 'monitor.' (It's not amp/hr..it's amp-hour). Or it could be amp-hour, or meter, or monitor.. yikes!These posts in Tech might help.

Bogart trimetric. Easy to use. If you go solar their sc2030 30 amp controller works works well and communicates with the trimetric for full adjutment. You dont have to pay mppt prices for good performance. OR you could do the geometric and a morningstar controller without their monitor. You'd think I was breaking bread with handybob today. ;)

discussion of battery monitorsi started at the above information. i ordered a victron 700 unit (not yet installed).there is other information on that web site to explore in addition to the above.the smart gauge looked interesting but even more money.time will tell next summer on how well the victron works.the search term is typically 'ah meter'

Dan,I don't have an amp-hour meter in our rig, but I do have a meter that I consider as more basic - but about as valuable. I have a permanently mounted ammeter in our RV ... in addition to a permanently mounted voltmeter.I monitor the voltmeter for a pretty good estimate of the state of charge of the batteries. I monitor the ammeter to indicate how much amperage every appliance is drawing to make improvements or for maintenance, plus I check the ammeter periodically when charging the batteries to indicate when they're fully charged. The ammeter shows near zero amps flowing when the battery bank is fully charged. The two meters together make up a very simple system for me to keep track of our RV battery bank's condition. Since the highest priority appliance draw-down situation to keep an eye when drycamping on is the propane furnace's battery draw-down, during the furnace's OFF cycle I check the voltmeter after the short "rebound" of battery voltage back to a steady state reading. When these readings are kindof average around 2 volts, I begin to recharge with the generator or idling main engine's alternator.

Recommendation for amp/hour monitors? | Good Sam Community

time2roll
Nomad
Nov 28, 2015
Ivylog wrote:
chuckbear wrote:
Ivylog wrote:
I'd spend the $150+ difference in my suggestion on another battery and not worry about how many AH used.
It doesn't matter how many batteries you have if you don't know the state of charge and if the batteries are being recharged adequately. You'll wind up with lots of batteries that live a very short life. Chuck
I've been able to figure that out with a $5 volt meter for the last 10 years.
+1 for just using a voltmeter and a little thought.
More solar, better converter, more battery would provide more actual power.
Can't imagine having a monitor system that costs as much as the batteries. Maybe 10% of the battery cost is the value point to me.
JMHO
CA_Traveler
Explorer III
Nov 28, 2015
Ivylog wrote:
chuckbear wrote:
Ivylog wrote:
I'd spend the $150+ difference in my suggestion on another battery and not worry about how many AH used.

It doesn't matter how many batteries you have if you don't know the state of charge and if the batteries are being recharged adequately. You'll wind up with lots of batteries that live a very short life. Chuck

I've been able to figure that out with a $5 volt meter for the last 10 years.
I did that for many years because I developed a seat of the pants idea of SOC with various loads. Morning with minimum loads was predictable.

But with thoughts of solar I wanted to know more and I got that. Not only battery information but accurate load information just by turning a light on/off and noticing the amp difference. So I was on my way to determining a bunch of things - like why did my 100A Magnum inverter only produce 80A (yes I accounted for house loads). So I called Magnum for an appointment for them to fix it - turns out no fix needed as with 117V AC input 80A is good. One of about 6 "cost design trade offs" I was to learn about - And another one is that while charging 80A the display (non BMK) shows 100A, just by coincidence of course. :h

And now with solar it's a even more valuable tool. If only they would upgrade to predict how much solar power I'll get that day...:B
MEXICOWANDERER
Explorer
Nov 28, 2015
chuckbear wrote:
Ivylog wrote:
I'd spend the $150+ difference in my suggestion on another battery and not worry about how many AH used.

It doesn't matter how many batteries you have if you don't know the state of charge and if the batteries are being recharged adequately. You'll wind up with lots of batteries that live a very short life. Chuck

"Bounced?"

"Are You Nuts? I still Have Checks Left"!
Ivylog
Explorer III
Nov 28, 2015
chuckbear wrote:
Ivylog wrote:
I'd spend the $150+ difference in my suggestion on another battery and not worry about how many AH used.

It doesn't matter how many batteries you have if you don't know the state of charge and if the batteries are being recharged adequately. You'll wind up with lots of batteries that live a very short life. Chuck

I've been able to figure that out with a $5 volt meter for the last 10 years.
chuckbear
Explorer
Nov 28, 2015
Ivylog wrote:
I'd spend the $150+ difference in my suggestion on another battery and not worry about how many AH used.

It doesn't matter how many batteries you have if you don't know the state of charge and if the batteries are being recharged adequately. You'll wind up with lots of batteries that live a very short life. Chuck
CA_Traveler
Explorer III
Nov 28, 2015
Golden_HVAC wrote:
Click on the link above for Bogart Engineering and Trimetric meter. That is the best one for reading how many amp hours are leaving your battery. I think they sell a dual battery bank model too, if you happen to want to watch your engine battery as well.
One extra wire is connected to the engine/aux battery to display engine battery volts only. The shunt is on the house battery and uses 4 wires to display amps, volts, AH, etc.
Ivylog
Explorer III
Nov 28, 2015
I'd spend the $150+ difference in my suggestion on another battery and not worry about how many AH used.
EsoxLucius
Explorer
Nov 27, 2015
If using a compatible Blue Sky controller, the Blue Sky IPN ProRemote works. As does the Magnum BMK with Magnum inverter/chargers.
CA_Traveler
Explorer III
Nov 27, 2015
chuckbear wrote:
I've been using Victron battery monitor for years and it's the only unit I consider. It will give you all the information you need and then some. It's an easy install but the unit must be calibrated. The instructions come with it and it isn't difficult. Chuck
Ditto for the Trimetric.

Installation and setup may/may not be easy for these units. Running the wire to the controller may be involved depending upon your rig. Plus the shunts which are precision calibrated brass/copper resistors should not be mounted near flooded batteries due to corrosion - so there may be some battery cable work. Or your battery cable clamps may not fit the shunt and require some work. Here’s mine:
Matt_Colie
Explorer II
Nov 27, 2015
Before the depression, I did a lot of work on long distance cruising boats. I was asked about these things a lot and finally figured out a simple answer:
A Volt Meter will tell you if your batteries are in trouble right now.
An Ammeter may tell you if you will be in trouble sometime soon.
Both require significant attention to be any value at all.

The true battery monitors do a cumulative watch on the bank status. They can report percent of remaining capacity with reasonable accuracy.

If you are going to count on your house bank for anything important, you want a monitor. They are not inexpensive or simple to install, but they are very worthwhile.

Matt