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MG Midget and Sprite General - AMP Gauge hook up... Will this work

On my AMP gauge, Is there any reason I cant just hook the positive side to positive side to the fuse box and the negitive side to the engine block or negitive side of the battry... like im doing with the volt gauge.

On the fuse box Id hook it up at an accessory connection where it gets power ONLY when the engine is running.

I just cant imagine why that wouldnt work on the midget, theres no relays and everything is 12 volt...the only down side I can imagine would it only read the amps for the one fuse box circuit and Im not sure thats an accurate guess... juice is juice

If my thinking does work and logical, would I still need to use the 8-10 gauge wire, or could I go with 12 to 16 gauge wire?


I do have a plan to do a proper amp gauge wire job if the above idea isnt a good idea but the above idea just seems more simple and not to mention Safer... (if it works)

Thanks guys

Prop
Prop

Prop
If I am reading your message correctly then DON'T hook up your ammeter that way!!!
The ONLY realistic way to hook it up is to (effectively) cut the big wire from the battery to the starter solenoid and put the ammeter in the break.
If you hook it up the way that I think that you described all you are measuring is how fast your battery (and/or alternator) can discharge directly to ground (read "arc welder!!).
A voltmeter is usually far safer,easier and as reliable as an ammeter.
BillM
Bill Masquelier

Prop,
I wouldn't cut the battery wire. Splice the ammeter into the large brown wire between the alternator and solenoid. Also keep in mind the ammeter is polarity sensitive. Hook it up backwards and it will show you battery dischrging. Not quite sure why you want to have both but go for it if you must. It certainly will make the wiring a little more complicated. HTH
Tim Michnay

Thanks guys.

I have a traditional path for its insultion but going to get a 2nd opinion, I was just woundering if this new idea I had would be a better idea... appeartly not.

Prop

God help us!

FRM
FR Millmore


Did a diagram for you Prop showing where it goes. Ammeter always in series as it measures flow through it. It has low internal resistance so as mentioned if just across the +ve and -ve the smoke will come out of it. :(

It needs to be the last thing before the battery which makes sure it measures everything going in and out. Don't put it on the output of the generator/alternator because it will always be +ve and just show generator output and if it stops charging go to zero. In the correct place it will show batery charge and discharge when not charging.

As mentioned a good voltmeter will also show if charging but like all gauges you need to look at them and when you have as many as the space shuttle it may be hard to know which one it is.

Greg H

god help us indeed mate (LOL)

Never has the term "a little knowledge is dangerous" been so evident!

So now not only is the engine f****d but shortly the car will be in flames or covered in acid residue as the battery explodes.
Robert (Bob) Midget Turbo

OMG

There was a recent thread on the MGB BBS about this subject...

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=thread&access=&subject=71&source=T&thread=2011020323130822041
Dave O'Neill 2

Prop,

If you wire your Ampmeter up as you suggest you will need several of these. They are in very short supply.

M J Pearson

HAHaha...

I think I still have some liquid lucas smoke in a box some where.

Im headed for the shop in a bit. Im certianly abandoning the 1st post idea I made... it was just a "Hmmm I WONDER moment"

Ill take a photo of what Ive got and let you guys see if Im correct on where Im going to do the hook up.

Thanks

Prop
Prop

Prop - if you even have to ask where to wire the ammeter then please just forget it. Add another exhaust pulse width modulation detection gauge or something. You are going to destroy your car.
Dean Smith ('73 RWA)

well I cant get the photos to work out vay well... vary over cast day, So Ill discribe the path I had orginally intended

I have a 71 usa spec midget with a single wire alt. conversion with built in regulator in the alt.

Here is how I have it currently wire!

The pos battry cable goes to the top selinoid post then a 2nd electrical cable goes from the top selinoid post to the ALT, on the bottom selinoid post goes to the starter...then the brown wire is attached to the top post (split, going in and comming out of the selinoid) and the white/red starter wire attaches on the side (stock set up... no mods)

SO AM I CORRECT for my orginal plan?
disconnect the alt wire at the top selinoid post and wire in the AMP gauge between the selinoid and the alt wire?

In a nut shell putting the AMP guage between the top post of the selinoid and the altnator connection for the single wire connection?

Does that work... that was always my plan.

Prop

Prop

I LIKE what Tim Michnay, was saying up above...

any reason I cant just splice into the big brown wire that goes into and comes out of the selinoid, not sure which side of the selinoid to do the splice on... but I like his idea, ALL electrical power moves thur the big brown wire.

whats your thoughts on that?


Prop
Prop

ONE brown wire delivers power from the Alt to the Batt cable connection on the solenoid. If you put the meter in this wire, it will show when the Alt is charging the Batt, but will never show a discharge except when you have blown up the Alt.
The REST of the brown wires deliver power from the battery cable connection to the car. If you put the meter in between the Batt cable connection and these wires as a group, it will show a discharge when anything in the car is drawing power, but will never show a charge.
If you connect ALL the brown wires together and wire the meter between this connection and the Batt cable connection, it will show Charge when the Alt is charging the Batt, Discharge when the Alt is not charging the Batt and the car is running off Batt power, but nothing if the Batt is charged and the car is running off Alt power.
Or you could leave it disconnected, in which case it will say nothing, but won't hurt anything, and it will be correct most of the time, since the damned car will never run anyway.

FRM
FR Millmore


Perhaps take a pic of your engine bay and we can get our Paintbrush skills out and all have a go at drawing on the pic and sending it back? Although you never know what you may get :)

With an ammeter the connectins need to be done well e.g. spliced in and soldered and proper crimps at the other end for the gauge, 5mm-6mm wire because all the power goes through it.

If you really want to do it perhaps a job for your local Auto Elec?

A working fire extinguisher is always a good idea too in a workshop, you never know when you may need it!
Greg H

This BBS always brightens up your day!

Seriously, does anyone make a shunt so you don't have all that current going up into the dashboard and you can wire up the ammeter using thin wires? I like the idea of seeing what the charging system is doing (charging or discharging) rather than what it has done (battery charged or flat) but I'm not too keen on loads of amps going to and from the dash for no really good reason.

Mike
Mike

Normal thing in industry but not sure about automotive.

If you buy a shunt it must be matched to the impeadance of the gauge (including wires to it from shunt) otherwise it will not be accurate. Normally bought as a pair but I think ammeters in cars are really a thing of the past. Only there these days because you've restored your old British clunker and you want it in there or have a rally car with 500 watts of spotties and want to keep and eye on things. So might not be that easy to get a nice looking automotive gauge designed for a shunt, just a bloody great big 4" panel meter.
Greg H

>>does anyone make a shunt so you don't have all that current going up into the dashboard and you can wire up the ammeter using thin wires?

You could dismantle the ammeter, extract the shunt and position it near the battery; then the 'ammeter' reads the voltage across the shunt (as normal) - but the long wires carry only a few mA (could still fuse the +ve side).

Car ammeters normally measure current in/out of the battery, except the supply to the starter-motor (some 100s of amps); if you were to include the s-m in your requirement, the FSD of say 300A would mean the normal current range for lights etc would hardly make the needle move. And the ammeter itself (or the shunt) would become hot during cranking!

Normally disconnect the fat brown alternator wire and brown to loom from the solenoid; connect them together. Ammeter goes between this join and the solenoid. Bit more complicated to dynamos, but same principle.

A
Anthony Cutler

<<A working fire extinguisher is always a good idea too in a workshop, you never know when you may need it! >>

It probably doesn't work since his last fire!
Dave O'Neill 2

FRM - Prop's alternator is a single wire. This method will work. But Prop.... KISS!!!!! A single voltmeter will let you know all you need to know. Kind of reminds me of a race car I work on that the owner decided he had to have a thermocouple in each cylinder bank. Lots of stuf to look at but not useful at all. Especially when you are going down a straight at about 140...We now have 2 air-fuel gages instead.
Tim Michnay

Prop,
Simply put, DO NOT USE AN AMMETER. If you have an alternator, the ammeter no longer serves a useful purpose except for occasional diagnostics when something is very wrong. At that point, you need a different (and more sensitive) ammeter. With an alternator, a voltmeter provides much more useful information.

As seen above, in order for the ammeter to work, it needs to be in series. This means that ALL of the power generated by your alternator and used by your battery both need to run through the gauge. Is it a good idea to run that through your firewall twice??? (no.)
David "don't look, Ethel!" Lieb
David Lieb

AMP guage UPDATE...""Another""... new plan!

Sometimes the voice of resson does manage to slip into the ol brain noodle from time to time, So I got a new CRAZY plan for the amp meter...

Instead of getting rid of this cool looking gauge, which appeartly has little importance unless your using a generator/dynomo. Ive decide to KEEP the gauge in place as is for all to see and admire!

After all my primary objective of the 10 gauge consel IS Total cool factor, (Bling bling!!) and real funtionality a close second. SO Im thinking leave it as is and not just hook it up. If anyone ask, Ill just have to do a politicians kind of white lie about its TRUE funtionality..lol

Bottom line Im on my 5th attempt to make some scene of the birds nest wiring ive got in my 10 gauge concel, and I think hooking this thing up is not really (safely do-able) as its just more high energy ELEctifing wires to the mix.

So what do you guys think about that cool idea ???

Thanks guys

Prop
Prop

Cool Prop -

One question, what kind of interior will you put in your car after this one goes up in flames?
Also, will this be covered on your insurance, if so you could go all leather, that would be awesome!!

J/K - I think your console is going to be ultra cool and I'm just jealous...
Rick Bastedo

Rick,

Im thinking that lambs leather from prestige auto trim might be nice this time around....Your right, I do need to make sure my insurance will cover the "Occasional" auto fire, After all I am over-due for another ...LOL


Prop
Prop

Prop,
Don't do it. Once you start down the road of poser-hood, there is no rehabilitation possible.
David "Find a clock to fit there" Lieb
David Lieb

Im afraid that moment has come and past my friend. Its too late for me, save yourselfs!!!

Check out this really cool chrome hood emblem Ive got my eye on... If it looked good for the pre-war midgets its got to look awsome for the post war midgets


Ebay # 370488335206

Now i just got to figure out how to pay for it.

LOL ... Bling Bling!!

Prop
Prop

Fixed you amp gauge problem. Stick this on the face of it. I even gave it a few amps charge to be sure your battery never runs flat. It'll be the only car that keeps charging when it's just sitting in the shed.

Greg H

I was thinking just wire it into the indicator circuit so it could be used to tell when a bulb has gone, other than the fast flash of modern flashers or the slower flash of older hot wire flashers.
David Billington

Greg,

Thats a great solution ... free non expiring energy!

I could hook the AMP gauge up to the condensor to Identify when it goes bad...LOL


Prop
Prop

This thread was discussed between 27/02/2011 and 01/03/2011

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