Connecting a Digital Ammeter-Voltmeter to a Rectifier: Step-by-Step Guide

Hello all. I would like to follow the topic and ask how to connect a digital ammeter-voltmeter in such a rectifier.

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Here you have material about this module. The bypass, if it is not in the module you plug into the minus wire of the battery charging cable.
The diagram is on the last page.

And all on the subject quick, simple and to the point and not like the ramblings of other pseudo electricians who write a poem half a page long not at all on the subject I am asking about. Thanks for your help. One more question. What if the shunt is built into the ammeter? Is it enough to solder into the - wire?

I am under the impression that there is a shunt in the picture of the meter (the last one in #1). And in any case, you connect so that the current flows through the shunt (i.e. you cut the wire, and connect the ends to the shunt, or - if the shunt were built into the ammeter - to the ammeter). If you have a separate shunt: it should have separate current and voltage terminals, you connect the current to the current shunt, connect the voltage shunt to the module, and make sure that the current and voltage wires do not touch. They are only supposed to be connected via the terminals of the shunt, if they come into contact, the readings will be overestimated, because the resistance of the contacts will be added to the resistance of the shunt.

Added after 6 [hours] 8 [minutes]:

piotrekwnaw1 wrote:

can I connect instead of the old ammeter ? It is soldered with 2 wires from the diodes to the fuse. Do I have to plug in the black wire coming out of the fuse

If the ammeter does not require power, it can be plugged in anywhere in the path of the current; if it does, then in such a place that it has power (in this, on the appropriate wire - e.g. on the minus).

If there is a fuse on the wire where you want to place the ammeter, and the ammeter requires power supply, then you have to think: what happens to the ammeter and its power supply if the fuse blows? Because then it is not indifferent on which side of the fuse this ammeter will be.

Aha, if a module uses a power supply (because it has electronics, not an electromechanical system), it is worth thinking: what happens if you accidentally connect the battery in reverse? Because electronics are unlikely to like a reverse-connected supply voltage - maybe power the module via a diode?

This module in the photo is a voltmeter and ammeter in one and has electronics in it. If it has a shunt on the outside, it should be connected as in the diagram, on the last page of the attachment that I posted in #2. The shunt must be plugged into the minus wire, and when the shunt is already in the module, the wires from the module (thicker - black and yellow in the diagram, black and red in the author's photo) are plugged into the minus wire.
If it is certain, the voltage of the module supply (thin red and black wires) will not exceed 30V in the peak, then the thin red wire can be incorporated directly into the plus wire, and the thin black wire can be left nowhere connected (this is what they recommend).
In the schematic, the voltage measurement wire is red next to black and yellow, and in the author's photo it is thin yellow.

If the module on the minus lead is switched on between the fuse and the rectifying diodes, then if the fuse blows, the module will get power from the transformer via these diodes; if it is switched on outside the fuse (the fuse will be between the module and the diodes), then if the fuse blows, the module will get power from the battery, which will maybe be connected in reverse (and maybe the fuse will blow from this).... Probably worth thinking about.