Relay for a volt meter

I've searched the posts for installing a Datel volt meter and they seem to involve a relay. I'm terrible at electrical probems/installs, so can someone explain to me just why I need a relay. Why is that better than just hooking the positive side to, say the running light in the front turn signal or some other switched positive wire and then grounding the negative wire some where? I realize the voltage might be a little less, than at the battery, but I'm just looking for a voltage drop, am I not? Maybe an inline fuse (in case the wire developes a short), but why the relay, since the volt meter draws so little juice?

I have grown to not like the "Worry Meter"

I bought the accessory fuse box attachment for the VFRness and am using one of the four blocks for the meter. Very easy.

The reason for the relay is to get an accurate reading at the battery. It eliminates variables and gives a better picture of what the charging system is doing. For those who know how to do basic wiring it is cheap and easy to do. I had hooked mine to the license plate light circuit for a while about a 1v drop but it was not always consistent so I went to a relay for accuracy and I have had several electrical issues in the past. It works either way, relay is better but more work.

Aaa, I knew I should have bought the fuse box when I bought the VFRness (damn). Will have to invest in one when I get the funds. I used a relay for my heated grips, but just hooked the power wire to the + battery post and have no more room there. Could I run it off that power wire, where it hooks on to the relay?
I placed that relay for the grips under the dash (for lack of the proper term) on the left side. I've mounted the meter about 2" forward of the rocker switch for my heated grips and it would be a short distance to hook the meter to that same post on the relay (same with the ground wire). Would it be advised to put a small inline fuse in the meter line? I'll have to do that for now and then measure my voltages with a multi-meter, and then watch for variations while driving.
Thanks to all for your help. (Sorry no pics, I'm at work)

I've searched the posts for installing a Datel volt meter and they seem to involve a relay. I'm terrible at electrical probems/installs, so can someone explain to me just why I need a relay. Why is that better than just hooking the positive side to, say the running light in the front turn signal or some other switched positive wire and then grounding the negative wire some where? I realize the voltage might be a little less, than at the battery, but I'm just looking for a voltage drop, am I not? Maybe an inline fuse (in case the wire developes a short), but why the relay, since the volt meter draws so little juice?

On mine I first hooked up a relay powered by the rear tailight. It was ok, worked fine with the key on and off switch. Ended up deciding I didnt like it, I wanted to check the battery before I fired up the bike. --- Ez solution, just extend a togle switch and fuse holder off the positive lead from the battery, and add a lead from the negative side to the meter neg side. (20 bucks of parts from the auto parts store tops.) - Run the wires up the left side of the bike by the harness. No relay required. - Now I can see if I am in deep do even before I hit the key on. The meter is such a low amp draw (3 milliamps), that most of the time I just leave the switch on.
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On mine I first hooked up a relay powered by the rear tailight. It was ok, worked fine with the key on and off switch. Ended up deciding I didnt like it, I wanted to check the battery before I fired up the bike. --- Ez solution, just extend a togle switch and fuse holder off the positive lead from the battery, and add a lead from the negative side to the meter neg side. (20 bucks of parts from the auto parts store tops.) - Run the wires up the left side of the bike by the harness. No relay required. - Now I can see if I am in deep do even before I hit the key on. The meter is such a low amp draw (3 milliamps), that most of the time I just leave the switch on.

Any discernible voltage drop through the toggle switch?

On mine I first hooked up a relay powered by the rear tailight. It was ok, worked fine with the key on and off switch. Ended up deciding I didnt like it, I wanted to check the battery before I fired up the bike. --- Ez solution, just extend a togle switch and fuse holder off the positive lead from the battery, and add a lead from the negative side to the meter neg side. (20 bucks of parts from the auto parts store tops.) - Run the wires up the left side of the bike by the harness. No relay required. - Now I can see if I am in deep do even before I hit the key on. The meter is such a low amp draw (3 milliamps), that most of the time I just leave the switch on.

Any discernible voltage drop through the toggle switch?

None --- I get 1/10 of a volt difference (or less) lower at the meter up front vs checking battery voltage direct at the battery. Not enough to be concerned about.
meter pic
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Splicing the meter in at the your existing relay Should work fine. You can check but the voltage should be very close to the battery voltage.

A fuse between the battery and the meter would protect the wiring in case of a short.

I am thinking about adding a accesory power outlet and vot meter to mr we to me 6th gen. What is the fuse box people all about?
Thanks in advance,
Mike