...or, a new one that sells cheap:
https://www.harborfreight.com/cpi/cta...emnumber=95778
https://www.harborfreight.com/cpi/pho...5799/95778.gif

$4.99 (a dollar less in the store during the current sale).

Actually, voltage and resistance are the driving forces behind amperage. The battery supplies voltage and the electrolite creates the resistance, which in turn ups the amps ;)

The amount of gas produced is a direct function of the current flowing. Keep the solution in the cell as conductive as possible without disolving the plate material is very desirable and increases efficency of the generator and reduces heat per volume of gas produced. Simply applying 12 volts and varying the concentration is going to result in a lot of the voltage being used to produce heat = Volts x Amps = heat in watts. Since only the amps make the gas you want to make the cell drop as little voltage across the cells as possible. One way to do this is to use several cells in series each one dropping some of the 12 volts total and the gas produced is Amps x Number of cells. Another way is to use a chopper circuit with an Inductor and Capacitor and a "flyback" diode to switch regulate the battery 12 volts down to what a single cells wants to see for voltage and in the process you keep the current to the cell high but reduce the battery current by an amount equal to the cell voltage divided by 12 volts i.e. if the cell voltage was 1.2 volts you would draw 10 amps from the battery and conduct 100 amps in the cell - (1/10th) - if you had switching components that could handle that much current . . . like I have.

there is a relationship between current, voltage, and overall resistance.

good old ohm's law.

https://en.wikipedia.org/wiki/Ohm's_law

for those who don't know.

the theory is simple, the application can sometimes be a bear

my two cents
 

What I have seen is that a PWM is used for the single cell units. The amount of electrolyte is a factor as well. A lot of the devices may look like a college project but some of us don't even have the training or experience in electronics to build one. This is probably bad because we don't really understand how it works.

I have been looking for a way to hook up a amp meter with a LCD that I can install in the cab and not have the 10-25 amps running in the cab. A malfunction /overheat of the wire could mean fire under the dash. If any one can build a unit or has details on what I need then please help.

Figured I need a shunt under hood. The ones I found were not cheap. Not sure about how to size it. and what I need to make it read on a LCD . Want mili amps in the cab

Infrared thermometer for steam traps.... We just got a new ultrasonic device at work. You can test bearings, find air leaks, test steam traps(has temp reading) plus you can hear it without sticking a screw driver on it and detect electrical leaks by sound on high power lines(can't remember the technical term for it right now). It selects the frequency automatically and the one we have interfaces with a computer so you can log the data and history. Believe it's made by Emerson

How do common OEM amp meters do the job?

You could just make sure to use a fuse that's rated appropriately for the wire you're using.

You could use a clamp-on meter with the jaws cut off and relocated remotely using extra wire. I'm not sure how they work but this could cause the reading to be inaccurate (due to the extra resistance of the longer wire).

You could relocate the LCD remotely and leave the whole meter under the hood (whether clamp-on or not). You don't need to know anything about electronics, just basic soldering skills.

you could possibly put a freakin huge resistor (wattage rating) in line with it and read the voltage drop across it from the cab. that way you don't have high current lines under the dash.

maybe buy a 1 or 2 ohm resistor that can handle a couple of hundred watts (it will be physically big). mount it under the hood and use a radio shack volt meter to read the voltage drop. you would have to come up with a chart that tells you what the voltage drop will be at different amperages.

after writing this, it is probably more trouble than it is worth. it will work but there are probably easier ways to do it.

you could gut a multimeter and relocate the display near or on the dash. I think this was alread discussed.

PWM and amps
 

Got a bit carried away with the Arm & Hammer and my amps got too high. Pegged the 30A meter and blew the fuse, but wondered if a PWM would allow the same cell output with lower amps and heat?

PWM works great with motors that have inductance in the windings but not so good in this application. If you really want to regulate the energy into the HHO generator use a PWM circuit with a high frequency and a series inductor between it and the HHO generator.