So my 850 has an ammeter hooked up to it and from what I understand the alternator is keeping up if the ammeter is >0. If it dips into negative amps then i'm relying on the battery; is this right?

I've been reading up on the two here and the general consensus is that a voltmeter is the way to go with the ammetere being a potential safety hazard. Now given that my dash is wooden i'm not too keen for that theory to ever be proven using my car as a testbed.

The ammeter in my car is a smiths and is hooked up properly, is it simply a matter of buying a smiths volt meter off someone and plugging it in the same way the ammeter is hooked up or does it require different connections. The ammeter is currently hooked up to the main battery line I think as the wires are thicker then anything else behind the dash and if you disc the ammeter nothing gets power.

Shard

The Voltmeter is hooked up ACROSS the battery terminals, NOT in series with it like your ammeter now is.
Easiest and one of the best ways to connect Voltmeter is run the <-> to a good earth on the body (under dash is OK) and the <+> down to the battery cable on the starter solenoid.
Light gauge cable is OK, it only carries very low current (mA).
Yes it will read all the time but it will read accurately, which it may not do if you stitch it into the ignition switch wiring.
No, it won't flatten the battery... for months, anyhow.

To unhook your ammeter, DISCONNECT the battery, then strip the whole lot of the ammeter cables out, and bin em.
Reconnect the cable wherever the ammeter feed came from.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Cool.

Off to find a voltmeter .

Shard

Brand doesn't really matter.
Marine ones are good, they are designed for a hard life.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

What the good Doctor said

However, if the cables supplying your ammeter have good insulation and the terminals on the back of the meter are well away from metal bits or earths (cover them with some heatshrink if you want to be sure)...then its just another guage.

If the engine is not running (or with sufficient revs) then the genny/alternator will not compensate for loads such as Stereos or those pathetic Lucas electric lights....so the Ammeter will read negative...which is good......danger Will Robinson

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"Show me the Mini!"