Installing ammeter 1200 Herald

[Tom]

Hello, after 30years of slowly collecting all the bits a pieces required to install an ammeter, temp and oil pressure gauge I’m almost there! I even managed to find a period gauge holder! It’s all mildly scruffy but all so fits nicely with my mildly scruffy Herald.

Everything is going well, the only thing I’m checking in on is the ammeter, I’m thinking the cars entire electrical system other than the starter motor needs to pass through it so is that the thick brown wire on the solenoid, through the ammeter and then back to the solenoid? Obviously good connections and very good insulation is the order of the day here!

looking forward to driving down the road knowing that my oil pressue/engine temp and charging system are working rather than hoping👍🏼

[johny]

Looking at the manual wiring diagram the brown wire on the solenoid is the battery supply so connected in this your ammeter would show battery discharge with engine stopped/ignition on and battery charge current only when running. In the latter case the cars electrical system is supplied directly from the dynamo via the regulator so you wouldnt see that on the ammeter reading. I think thats probably what you want so if at anytime when running you see -ve on the ammeter you know the battery is discharging...

Youre right about insulation especially on the ammeter terminals themselves!

[Tom]

Cheers Johny, ok , yes what I want to know is wether the battery is being discharged or not. So would connecting it in series with the regulator be better?

[johny]

I think youre better off as youve suggested knowing about the battery charge rather than the electrical system consumption👍

[Pete Lewis]

far easier and safer simpler is to use a volt meter to show battery condition

doenst need any heavy wiring just link into the ignition 

Pete

[johny]

Ammeter much more period Pete😃

[dougbgt6]

Here's mine, as was, I broke down and had to pull the car on the starter motor onto the grass verge. The ammeter wiring got VERY hot, started to melt and the fumes were most unpleasant. I replaced the ammeter with a volt meter, not as informative, by the time you notice something is wrong, it's too late! But, better that than going up in flames.

Doug

[Tom]

True but I have all this stuff, pretty much collected it all for free too👍🏼
 

Haven’t connected the ammeter yet, I need to source some big spade connectors first. Went for a spin to, oil pressure seems good but the temp gauge only got just off its stop so I think I might need a different sensor, with the engine at operating temp the sensor measured 68ohms, I’ve no idea what car the gauge was originally fitted too? I suppose I could experiment with some resistors to find what valve equals normal temp on the gauge and then find a sensor to suit?

Does anyone know any suppliers for these things?

[dougbgt6]

Does your car have a voltage stabiliser? This works on the voltage supply to the Temperature gauge and fuel gauge, if kaput it will give dodgy readings on both.

Suppliers are the usual suspects, Canley Classics, Rimmer Bros, James Paddock.

Doug

 

Edited June 15 by dougbgt6

[Tom]

Yes I’ve fitted a solid state stabiliser, it’s 10v bang on👍🏼
 

I don’t think the ammeter came from a Triumph so not sure Triumph specialists would know, wondered if anyone knew of a gauge/sensor specialist?

[johny]

1 hour ago, dougbgt6 said:

Here's mine, as was, I broke down and had to pull the car on the starter motor onto the grass verge. The ammeter wiring got VERY hot, started to melt and the fumes were most unpleasant. I replaced the ammeter with a volt meter, not as informative, by the time you notice something is wrong, it's too late! But, better that than going up in flames.

Doug

What was the problem Doug? Difficult to think if what can go wrong with an ammeter to overheat wiring. Internal short to earth?

[johny]

1 hour ago, Tom said:

True but I have all this stuff, pretty much collected it all for free too👍🏼
 

Haven’t connected the ammeter yet, I need to source some big spade connectors first. Went for a spin to, oil pressure seems good but the temp gauge only got just off its stop so I think I might need a different sensor, with the engine at operating temp the sensor measured 68ohms, I’ve no idea what car the gauge was originally fitted too? I suppose I could experiment with some resistors to find what valve equals normal temp on the gauge and then find a sensor to suit?

Does anyone know any suppliers for these things?

I take it the engine does get to full temperature? The gauges arent linear so a few degrees low and the gauge can be a long way off normal....

[Colin Lindsay]

I was always a big fan of the Smiths Battery condition gauge, simple and effective. I avoided fitting an ammeter once I saw the gauge of wire that was required to take the current; big chicken I know but in a car with no fuses that's a lot of power going round the dashboard. In the photo the ignition has just been switched on so the needle is moving up to the green section, and it drops quite a bit when lights and heater blower are on.

[68vitesse]

In my Vitesse I have an adaptor for USB output, it plugs into a cigarette lighter socket, which has a display that cycles between ambient temperature, voltage and load on the usb sockets.

Surprising how low the voltage gets when cranking the engine even with a geared starter motor.

Never liked the idea of all power, except starter, going through an ammeter.

Regards

Paul.

[dougbgt6]

13 hours ago, johny said:

What was the problem Doug? Difficult to think if what can go wrong with an ammeter to overheat wiring. Internal short to earth?

There was nothing wrong with the ammeter, however all the current from the battery goes through the ammeter wiring. I blew the head gasket in a traffic jam coming off the M4. To get to safety, on the grass verge on the roundabout below the motorway, I held the ignition on and pulled the car on the starter motor. The starter motor normally turns only briefly, but an extended period tends to get the wiring VERY hot.

Doug

[johny]

wow you had the starter wired through the ammeter! That was very brave😲

[Tom]

No way I’m putting the starter through the ammeter!!

I’m guessing worst case scenario for the ammeter would be directly after starting with the lights and heater on? Would this be maybe 140w? So maybe 11.5A until the battery is topped up? The cables I have a pretty hefty but maybe I’ll look into voltmeters.

looking back at sensors, it looks like the ones fitted to minis seem to have lower resistance values, I wonder if my gauge came from a mini?

[johny]

The dynamos/regulators fitted were either 22 or 25 amp rated so this should be the max theoretical charge that could flow into the battery. Of course if upgraded to an alternator this could be higher...

[Wagger]

I am surprised that nobody ever made a centre zero millivoltmeter for cars. Simply fitting one at the two ends of the battery to chassis cable would sense the current by using the voltage drop across it. I  measure the resistance of the earth strap (using an old earth bond tester) and use a millivoltmeter (Voltmeter set to millivolts) to check if my vehicle is charging. I also use a DC current clamp.

I blew two AVO meters up as an apprentice trying to measure high current, so I avoid using ammeters whenever possible. Fellow apprentices blew up really expensive Wattmeters too.

[Jon J 1250]

Bit late to the party but here's mine, I recently improved on the original owners connection using choccy block connectors.

Brown wire to solenoid is cut and bullet connectors soldered on with loop out (yellow/red) run out through ammeter gauge.
It works pretty well show battery charging and gradual decrease in charge current, and of course you can see the effect of lights and accessories quite clearly.
Never had any issues with it, even before with the previous old AC branded gauge and choc connectors.

Regards
Jon

[johny]

Red/yellow wires look a bit smaller than the the original brown so might tend to warm up a bit if you start the car with a pretty flat battery and then drive off. Even more so if they are run together wrapped to the ammeter but hopefully never be a problem. Have you got a dynamo or alternator fitted?

[GFL]

1 hour ago, johny said:

Red/yellow wires look a bit smaller than the the original brown so might tend to warm up a bit if you start the car with a pretty flat battery and then drive off. Even more so if they are run together wrapped to the ammeter but hopefully never be a problem. Have you got a dynamo or alternator fitted?

Yes, be careful of overheating wiring, the full charge/discharge current will go through that wiring and the Ammeter, 20 to 28 amps if you have a dynamo, more possibly if you have an alternator.

I've heard horror stories about the connections coming loose or getting corroded on the actual ammeter too, so make sure all connections are clean, tight and secure.

Gary

Edited June 19 by Gary Flinn

[Jon J 1250]

1 hour ago, johny said:

Red/yellow wires look a bit smaller than the the original brown so might tend to warm up a bit if you start the car with a pretty flat battery and then drive off. Even more so if they are run together wrapped to the ammeter but hopefully never be a problem. Have you got a dynamo or alternator fitted?

Good spot, not planning to ever fit an alternator but yes would have to consider that, also if I fit any auxiliary lights, which I may well do.
The Red/yellow wire is what the original owner fitted 50-60 years ago, it is in very good condition so reused it on the assumption it has been fine for decades.

[johny]

Yes if its been ok for that long cant be too much wrong but you can always feel or smell for any warmth in the wires and connections. After a jump start of your flat battery would be about the most arduous conditions you could have of the whole charging system...