Trouble with amp gauge

I just installed an amp gauge with my hho system and I don't get any reading on it.
I ran my power wire from my relay to my PWM then the + wire going to the cell I cut and put the half of the wire coming from the PMW to the + terminal on the amp gauge the other half runs on to the fuel cell. I'm not getting any reading at all. I originally made the splice with the ground wire going to the fuel cell and that got the same results. I am getting voltage to the PMW and coming out at a reduced amount appx. 13v--app 3v out. why am I not getting any reading?

make sure it isn't connected backwards, otherwise its a defective amp gauge. they are pretty simple

I have the positive wire coming out from the PWM going to the Pos terminal on amp gauge and then a wire going to the pos terminal on the cell. I have 2 cells wired the same way for my v-8 and I already broke one amp gauge so I had to replace one with an amp gauge from the auto parts store. So I doubt both from different stores are both broke. It must be how I wired it. Does the amp gauge need to be before the PWM?

it shoulnt matter. current flow will be equal in all parts of the circuit. either you have too little current to show up on gauge or too much and it blows it as soon as you turn it on for the first time. could also be a bad pwm, maybe switch it out with one you works. also never underestimate chinese made parts. sometimes we have to buy 3 or 4 before we get a good part depending on the manufacturer.

Amp gauge should be installed pre-PWM and should be on the ground. If you connected the positive to one side, then that could be the issue or perhaps you simply connected the gauge backwards.

Quote:

---

Originally Posted by motocross1550

it shoulnt matter. current flow will be equal in all parts of the circuit.

---

Not true. The PWM will consume power itself, so amperage will be slightly different before the PWM than after. Just try checking the voltage drop post PWM.

Quote:

---

Originally Posted by Stevo

Not true. The PWM will consume power itself, so amperage will be slightly different before the PWM than after. Just try checking the voltage drop post PWM.

---

Motocross was simply stating an accepted fact about electrical theory. The current through the meter - Cell bank - battery, loop will be the same. The PWM is an external control and if it uses FETs, the control current is essentially external to the controlled current. If power transistors are used, the control current will be only in the Milli-ampere range if the transistors are biased to saturation. The power consumed by the Pulse Width Modulation (PWM) unit will be seen in it's voltage drop not it's current drop.

I stand corrected. Yes that theory is obviously correct and what I have seen in the past must have been a set of anomalies. Voltage drop is indeed how consumption is measured.

I was aware of this rule, but seeing some anomalies with the current carrier sensor I like to use. I asked my EE friend and he suggested checking the caps on the PWM unit as well as the current carrier. Apparently what I have seen could be the result of not decoupling or insufficiently doing so then reading the current average. Hope that clears it up.

Is it a full current amp gauge or fractional (shunt style)? If shunt style then it's probable that you toasted both gauges innards the second you ran any current through them.