The thing you are calling a voltmeter is actually a multimeter (voltage-current-resistance) unit. It can measure any of the three. The 10-amp range measures current, not voltage, and in most multimeters, it has a separate set of inputs where you plug the probes into it. I think you have a minor typo in your description of where you hooked the probes into the battery circuit, but assuming you got the probes in the correct holes in the meter, and are trying to put the meter in series with the battery to see if any current is flowing, and you are seeing none, there are several things to consider.
1. What is the battery voltage? A zero current reading would mean the battery is completely flat, so I don't think that is the issue.
2. Is the 30-amp main fuse in the positive battery wire blown? If so, no current will flow.
3. If everything in the TM is turned off, there may still be a small current flowing (we have spoken of parasitic loads), but it is so small that it doesn't show on the 10-amp range.
4. Some multimeters will measure only AC current, but not DC current. Does your meter label say "10A DC"?
5. The negative terminal of the battery usually has two wires connected to it - a white one and a bare (or possibily green) wire. If you are looking to measure battery current, you can measure in the white wire (as I think you are doing), but you must disconnect the bare or green wire.
6. I think that the converter has a main 12-volt fuse somewhere inside it I don't have a schematic to be sure where it is. If this fuse is blown, the battery will not receive any charge current, or show any discharge current.
Let us know what you try next. May I ask the make/model of the meter you are using?
Bill
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