Ammeter/ Volt meter adjustment

He may be right.

The Trimetric does not really show "net amps" but only the amps in or out of the battery. If there is a load running while you charge, the load will get its amps from the charger as long as its voltage is higher than that of the battery. Same with solar charging.

So the amps out of the charger or controller can be higher than the amps into the battery, which is what the meter shows, so you need to disconnect all loads to be sure both amps should be the same.

In that case, my worry about one-way amps is wrong, does not apply.

CA Traveler wrote:
The shunt is intended to measure the battery amps and NOT the charger amps. The amps supplied by the charger FIRST feed any house loads and then any remaining charger amps go to the battery.

I don't understand how the charger feeds the house loads? I am using a car charger with my converter/charger unplug.

CA Traveler wrote:

Gjac wrote:
I am charging my house batteries now at 15.4 v and 7.3 a according to my B&D 40 amp charger. The meter in question reads 15.2 v and 1.3 amps. My HF meter reads 15.3 v. Once it stabilizes I will try to adjust the pot to read the same as the B&D charger reading.

Alternate approach: Disconnect the frame ground wire from the shunt. Connect the charger to the positive battery post and the shunt side away from the - post. Now the shunt and charger should read the same since there are no longer any house loads. The shunt electronics need to be connected so that they work.

I think with the one way amps reading this meter has, you don't get that "net effect" like you do with the Trimetric amps.

Gjac wrote:
I am charging my house batteries now at 15.4 v and 7.3 a according to my B&D 40 amp charger. The meter in question reads 15.2 v and 1.3 amps. My HF meter reads 15.3 v. Once it stabilizes I will try to adjust the pot to read the same as the B&D charger reading.

Alternate approach: Disconnect the frame ground wire from the shunt. Connect the charger to the positive battery post and the shunt side away from the - post. Now the shunt and charger should read the same since there are no longer any house loads. The shunt electronics need to be connected so that they work.

The shunt is intended to measure the battery amps and NOT the charger amps. The amps supplied by the charger FIRST feed any house loads and then any remaining charger amps go to the battery.

By "outer end" I mean the end away from the battery that all the neg wires go to. By "inner end" I mean the end that is attached to the neg battery post.

I would get the voltage right and let the amps fall where they may. It might be the amps adjustment amount varies with the range of amps so maybe adjust the amps when amps are closer to 100 (midway for the 200a shunt) or for whatever would be the average amount of amps you usually would be running.

My adjustment is not going any better. My B&D reads 6.4 a but the most that I can get the amps to read by turning the pot clockwise is 3.8 a. The problem the volts go to 64 volts. So I readjusted the volt pot back to 15.4 v. but could not get move then 3.8 a or less than .1 amps. Maybe Richard was right or I am missing something. I am not sure by what you mean by the "outer edge of the shunt". My shunt has a large cable going to the frame and grounded by a bolt the other cable goes to the neg post of the second 6V GC battery wired in series.

The inverter neg would go to the outer end too but only if you are using the ammeter to measure draws not charging inputs, with the one way meter.

I just tried to calibrate my ammeter part and the same little screwdriver that turned the voltage pot easily would not turn the ammeter pot so I pushed harder and the pot screw head came off!!! Drat, very flimsy. So now there is nothing to grab onto to turn it and it is stuck. Also I must have done something because it was reading 3 amps (with 12 amps worth of lights on) and after I broke it, it read 234 amps. Phooey. So now I have a $12 voltmeter and don't need the shunt. I think the shunt will make a good buss bar for another job though.

Hope your meter project goes better than mine did! :)

I am charging my house batteries now at 15.4 v and 7.3 a according to my B&D 40 amp charger. The meter in question reads 15.2 v and 1.3 amps. My HF meter reads 15.3 v. Once it stabilizes I will try to adjust the pot to read the same as the B&D charger reading.

MrWizard wrote:
Are you trying to read chassis/engine batteries or house batteries
Any measuring device (the shunt)
Must go in between ALL CURRENT FLOW in and out of the batteries
Is the negative from ALL your charging systems connected to the chassis and not to the battery negative

I am trying to measure the house batteries. My shunt is connected between the frame and the neg post of my house batteries.