Electrical puzzle

My Microvision engine monitor shows that my alternator is charging the battery (indicates 14,1 volts) but my amps periodically shows zero (flashes a warning) even when radios, Xponder, strobes are powered. Increasing the load by turning on landing lights or the fuel pump seems to "fix" the problem. I'm thinking loose wire/connections. Thoughts?

Is you ammeter set up to read the electrical load of the system or the current going in or out of the battery?

Easy check

Scott is right. I built both my planes to show current in/out of the battery. As such, when the battery is fully charged and the alternator is performing correctly there is very little current shown (1-2 amps). If you can see the shunt you can tell the arrangement but there is an easier way.

With the engine off, turn on each of your systems. You should get a negative number on your ammeter corresponding to the amount of current required to run each. Voltage will start at 12.8V and drop a tiny bit when a load is added. It is not a bad idea to do these individually and make note of the draw of each to help determine ways to shed load if you ever have an alternator failure airborne. Now, start the engine, turn on the alternator and repeat the process. If the load stays very close to zero and the voltage remains at about the 14.1V you mentioned your system is wired to measure current in/out the battery and is performing normally.

It seems the OP's question is answered, but here is my logic for installing the current shunt differently.

There are several acceptable positions to install the current shunt. I installed mine to measure load demand to the battery/alternator. This means that I do not measure the full current draw of the alternator, so I do not know the charging+usage amps, just usage. I figure that as long as the voltage is 14.0+ 0.2 volts, then the battery is getting it's charge and not a worry. If the alternator goes out then I know the amperage draw on the battery as measured by the shunt and can reduce loads while monitoring the voltage. The back up battery(s) can be added to reduce the starting battery load.

This is my logic, and yours can be the opposite and still be "right".

BillL said:

It seems the OP's question is answered, but here is my logic for installing the current shunt differently.

There are several acceptable positions to install the current shunt. I installed mine to measure load demand to the battery/alternator. This means that I do not measure the full current draw of the alternator, so I do not know the charging+usage amps, just usage. I figure that as long as the voltage is 14.0+ 0.2 volts, then the battery is getting it's charge and not a worry. If the alternator goes out then I know the amperage draw on the battery as measured by the shunt and can reduce loads while monitoring the voltage. The back up battery(s) can be added to reduce the starting battery load.

This is my logic, and yours can be the opposite and still be "right".

Click to expand...

Your logic is sound except that in the "charge meter" configuration, if the alternator goes out, you will see the full load, just like you do with a "load meter". There is no difference if the alternator quits. I like the "charge meter" configuration as it shows me battery condition to some degree, which the "load meter" can not.
They both work.

Thanks for info; I will troubleshoot next weekend and hopefully let everyone know what I found. (if anything)