Ammeters are wonderful tools, when wired properly and understood by the viewer as to what they are seeing.
If one has one only from solar controller to battery bank, then there is no reason to have one which can read both + and - amperage
But if one has only a ammeter inline on solar controller to battery bank, then any loads on that battery are not read. 6 amps from the solar but a 5 amp load means only one amp is available to recharge the battery.
Now having a ammeter wired to read amps into or out of the battery is better, in my opinion, as one in the case above, would read only one amp, but the newbie might not realize that 5 amps are going to power loads and think something is wrong with their solar.
A shunted Ammeter is also easy to miswire, as ALL loads must pass through the Shunt. nothing can be connected directly to the battery (-) that does not pass through the shunt, otherwise the current will not be measured and if frame grounds are used then a lot of current can bypass the shunt leading to inaccurate display readings
I enjoy having these RC type watt meters, but they are limited to 25 amps continuous, if that, and can only count upto 64AH before flipping back to zero, and only count current flowing in one direction:
http://www.amazon.com/GT-Power-Analyzer-Consumption-Performance/dp/B00C1BZSYO
They are also not very accurate at loads under 0.8 amps, but this varies model to model/ brand to brand as I had one, which did very well measuring small currents accurately.
I have modified my GTpower 'wattmeters' with 8awg wiring and 45 amp powerpoles and will pass 40 amps through them continuously, but some good soldering skills/tools are required for this.
I have also employed one of the following devices on a project for a friend. While these come in 10/50/100/200 amp versions, I was much less than impressed with the low current accuracy of the 100 amp model:
http://www.amazon.com/DROK-Multimet...4307&sr=8-12&keywords=100+amp+digital+ammeter
This one can only read current in one direction and would not register currents below 0.78 amps but was fairly accurate from 1 to 100 amps.
They can be calibrated but doing so required a fine touch and still would not read currents below 0.78amps.
The Analog meters, well usually one cannot easily discern the difference between 1.5 and 2 amps. I'd much prefer Digital in Van dwelling usage.
If one only wants to occasionally satisfy their curiosity as to the amps flowing, then a DC Clamp on Meter is a Very useful tool to have, as one can just hook it over any Single wire, + or - in any circuit and see the current flowing through it. As it is also a full function digital multimeter they are quite useful to a dweller trying to figure out how much any single device, or multiple devices are drawing from the battery.
This is not a specific product recommendation, just an example:
http://www.amazon.com/Uni-T-UT210E-..._UL160_SR160,160_&refRID=0GGVGAJBW81CS5N98WEP
Please note that any clamp on meter less than ~35 dollars will likely measure AC current only. The description might say AC and DC but this is for voltage only, so double check to make sure it can measure DC current.
I have the craftsman model:
http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P
Which I like and use regularly, but have no real experience with other models to make a comparison.
My battery monitor ( Blus Sky IPN pro remote) reads alternator current into or out of the batteries. This requires a 500 amp shunt which can pass starter current, and requires moving the vehicle stock grounds to the load side of the shunt and the only wires which go directly to the battery (-) come from the battery side of the shunt.
I've seen it register 120+ amps cranking my engine, but the actual current is likely higher due to a fairly slow refresh rate, and i've seen my alternator produce close to 110 amps into a depleted battery bank.
So where and what you want to measure is important as to what product you decide upon.
