6 replies to this topic

[Stimpy]

A stab in the dark here!

Has anyone ever fitted a Revotec Fuel gauge to their mini?

And if so was it just plug-and-play or was there any hassle (at the tank end)

Thanks in advance folks!

Steve

[dklawson]

Using the search feature I found something like 6 previous threads about Revotec products but most of them were focused on cooling systems. None appeared to mention the Revotec fuel gauge.

I looked at their site. They don't provide a lot of information. If you have not already bought the gauge, I suggest contacting them. Explain that you would like to use your existing sending unit if possible so you'd like to know the resistance range that their fuel gauge requires. Their web site did not provide this information on the fuel gauge page, nor was it on the sending unit page.

There sending unit appears to be the "common" aftermarket design to mount to the top of a tank using a flange with 5 bolts. You may be able to fit that to the Mini tank but I don't think it will be easy and you'll have to be careful that the sending unit terminals don't touch the rear parcel shelf.

If you can use the standard Mini sending unit, that would be a lot easier. For reference (and these values are nominal) the Mini sending units after 1965 operate with an approximate, nominal range of 270 Ohms = Empty, to about 30 Ohms = Full. This is "almost" equivalent to one of the industry standard ranges that goes from about 240 Ohms-Empty to 33 Ohms-Full. If that's the range the Revotec gauge works with, the Mini sending unit is probably close enough to use.

[Stimpy]

I did contact them. Twice. (Via email). No response!

You've provided some fantastic info though - and I've ended up being educated (again). I should be able to make some inroads with that info.

My reason for revotec - by the way - is due to 2 other dials being made by them (so keeping it the same to look right).

I haven't bought the gauge yet and I'm keen to make sure it'll work first.

[Stimpy]

I did contact them. Twice. (Via email). No response!

You've provided some fantastic info though - and I've ended up being educated (again). I should be able to make some inroads with that info.

My reason for revotec - by the way - is due to 2 other dials being made by them (so keeping it the same to look right).

I haven't bought the gauge yet and I'm keen to make sure it'll work first.

Well - I thought there must be a way of making it work even if the sender sends the wrong current or wotnot.

So - of course - it does not work!

I have wired it straight to the tank's sender just to test it and the needle moves very slightly but well under 'Empty' on a full tank.

Is there anything I can wire on the way to the gauge that converts or boosts the signal so I can make the gauge accurate?

[dklawson]

So now you have the gauge? Did you buy their fuel sending unit also?

Sending units don't really "Send" anything. They are variable resistors. Current flows from the gauge, down the sending unit wire, through the resistance of the sending unit, and on to earth. The variable resistance of the sending unit "throttles" the amount of current flowing and thus changes the gauge's reading.

If you have bought the Revotec sending unit let us know. Also let us know if you have a multimeter to measure the sending unit's resistance.

[Stimpy]

So now you have the gauge? Did you buy their fuel sending unit also?

Sending units don't really "Send" anything. They are variable resistors. Current flows from the gauge, down the sending unit wire, through the resistance of the sending unit, and on to earth. The variable resistance of the sending unit "throttles" the amount of current flowing and thus changes the gauge's reading.

If you have bought the Revotec sending unit let us know. Also let us know if you have a multimeter to measure the sending unit's resistance.

Ok - I bought the revotec petrol gauge but not the sender. I thought I'd try it out on the mini sender first.
I don't have a multimeter but I will see if I can borrow one and investigate.

I was just wondering if that resistance could be altered in-situ somehow so that the gauge works with the mini sender.

Perhaps I was a bit naive

[dklawson]

No... you're not naive, just optimistic.

If the Revotec gauge uses a sending unit with a "narrower" resistance range (full to empty) than the Smiths sending unit AND if the resistance changes in the same direction (full to empty), then it may be possible to put a parallel resistor in the circuit to match the Smiths sender to the Revotec gauge.

If the Revotec gauge is expecting more total resistance OR if it expects the resistance to change in the opposite direction than the Smiths sender provides... then it will not be possible to match the two.

Until you know the resistance specifications of the Revotec sender I don't think there is much point in trying anything. That said... you COULD find a local electronics shop (an older one preferably) and inquire if they have high-wattage variable resistors (potentiometers). You'll be looking for wire-wound units capable of handling a fair number of Watts and preferably adjustable between 0 and at least 100 Ohms (250 or 500 Ohms being preferable). If you can locate such a potentiometer and a multimeter, let us know and we can walk you though how to determine what the Revotec is expecting for a resistance input.

The link below is for a picture of a wire-wound potentiometer. This will give you a general idea of what I'm talking about above. It's just a variable resistor where you turn the shaft to alter the resistance of the device. In your case, it could be temporarily installed in the Revotec wiring to act as a sending unit. Combined with the multimeter it would allow you to determine the resistance range the Revotec expects.
http://i00.i.aliimg....ometer.summ.jpg