Ammeter

[djp852795]

I am replacing my original ammeter with a new one but I find that there are only two ‘blades’ to connect to at the back - whereas there are four on the original -(Two brown and white off the same terminal)
 

Can I connect the two brown and white cables together ‘before’ they get to the new ammeter? - or rather how should I proceed connecting the wires as I can’t attach both the brown and white wires.  
 

I’m conscious there is potentially a big current and I want to make sure all is well behind the dash before I put the Rev counter back.

Advice would be appreciated. Thanks. 

[rcreweread]

Hi (Do you have a name?) - if you still have the old one, can you not take the terminals off and refit to the new one. Failing that, you can get some "piggy back" terminals ( don't know their official term!) which push onto a single flat spade and convert it to a double - personally I would try and avoid cutting your existing loom about 

Cheers Rich 

[RobH]

There are doublers available which make it unnecessary to cut wires as you would need for a wired piggy-back type, but you would need to insulate it well when installed.

https://www.autosparks.co.uk/electrical-components/terminals/1-4-6mm-male-to-male-piggy-back-spade-terminal-up-to-28-30-cable-diameter

Edited April 24, 2023 by RobH

[djp852795]

Thanks - the original “bolted” connectors look entirely different from the single blades coming through the back of the new ammeter - but I suppose I could try soldering one on an extra blade. Just seems strange that there isn’t a special heavy duty connector available for the purpose.
 

i did look for a piggyback connector but they all seemed so small/thin compared to the thick brown/white female 10mm wide connector on the wire at the moment - i thought they would restrict current too much.  Rob, will the ones you linked be heavy duty enough for this then? If so,I’ll go that route. 

Many thanks

Derek

[RobH]

Thinking about this I'm not clear now on what you had on the original ammeter Derek.  Was it screw-down terminals as on the earlier cars, or 9.5mm spade connectors? 

Unless the replacement ammeter has the same, surely it is just the wrong type ?

What size are the spade connectors on the new ammeter ?   It is difficult to find real information on current ratings for them but a  6.3mm spade is only quoted as up to 25A which is really too small for the alternator cable, not only the current rating but also to support the physical weight and stiffness of the wire.  After all, that is why the alternator is provided with two 9.5mm terminals.  

 

[Mike C]

18 hours ago, djp852795 said:

I am replacing my original ammeter with a new one but I find that there are only two ‘blades’ to connect to at the back - whereas there are four on the original -(Two brown and white off the same terminal)
 

Can I connect the two brown and white cables together ‘before’ they get to the new ammeter? - or rather how should I proceed connecting the wires as I can’t attach both the brown and white wires.  
 

I’m conscious there is potentially a big current and I want to make sure all is well behind the dash before I put the Rev counter back.

Advice would be appreciated. Thanks. 

I increased the charging capacity of my alternator and had to install a +/- 60 amp  ammeter. You might consider doing the same if your ammeter's going off scale just after starting.

[Charlie D]

If you decide to unscrew the terminals at the back on the ammeter do them one at a time. ( i.e. undo one. Fit whatever you choose to put there. Refit the nut tight.)

Then do the other.

I have a feeling that if you do them both at once you may end up with the ammeter innards in free flight and they could fall inside the case. I’m pretty sure this happens with the other small instruments so it may well be the case with the ammeter.

I was thinking you could fit this sort of thing, but the bigger version.

https://www.autoelectricalspares.co.uk/spade-terminal-63-mm-male-non-insulated-double-flat-earth-tag-tin-plated-x-100-4295-p.asp

Charlie.

[RobH]

 

8 minutes ago, Mike C said:

had to install a +/- 60 amp  ammeter

Not really necessary Mike.

Just because you increase the capacity of the alternator doesn't mean that capacity will be used - that is determined by the load not by the generator.  If the ammeter is pegging for a short while after starting, it means the battery is very low and you are probably revving the engine.  It does no real harm to the meter - they are pretty simple and robust devices - and it won't happen if you refrain from revving for few seconds. 

[Charlie D]

Or maybe get 4 of these.

Right spade size, but not sure about the hole.

https://www.amazon.co.uk/Other-9-5mm-MALE-spade-connector/dp/B006T1SOFW

 

Charlie.

Edited April 25, 2023 by Charlie D

[michaelfinnis]

25 minutes ago, Mike C said:

I increased the charging capacity of my alternator and had to install a +/- 60 amp  ammeter. You might consider doing the same if your ammeter's going off scale just after starting.

You could connect a shunt (resistor) across the ammeter terminals to change the range of it.You need to ensure the wiring is capable of taking whatever current you are passing though.

[RobH]

6 minutes ago, michaelfinnis said:

You could connect a shunt (resistor) across the ammeter terminals to change the range of it.

Again - really not necessary. See my post above. 

[mrehke]

Do not forget to isolate the battery before working on the rear of your Ammeter and the wiring loom...black smoke and fire / new hairdo time, or worse if not...

[Waldi]

I have a Bosch 55A generator and the standard Amp-meter behaves normal. The alternator will only deliver as much as the battery asks.

Make sure the connectors slide firmly (stiff?) on the terminals, otherwise the electrical connection is not ok, leading to high resistance, heat development.

Waldi 

[greasemonkey]

I think Derek's ammeter connections are probably like this one. Two spades, a big & a small, on each post. 

Phil.

[djp852795]

Firstly cheers for feedback: mine is similar to your pic, grease monkey.

My old red/white ammeter doesn’t seem to work (no current when applied across posts) so I got a new replacement - and beefed it up to 60amp just in case taking on board “potential safety” issues. One had two blades.  Tried to jerry rig a cross piece - to act as a double blade - onto the new one, but you can see how the plastic burned with the heat needed to solder the whole thing.   (It has come off since as it fractured)

So now I have to decide whether to piggy back off the numbered ammeter or get the old red/white repaired - can’t be that difficult surely?! They’re simple enough aren’t they and I don’t really expect it to draw more than 30 amps - but more the shunt option.

Whilst I can probably get the numbered type to work using a form of  piggy backing (not now worrying about smaller size connector) I would really preferred to keep the old red/black - but don’t want a massive repair bill. Think I’m talking myself round to repairing the original but temporarily installing the number one until it’s done.  Any recommendations for a quality, reasonable specialist?
 

Really  appreciate the feedback. It’s wierd that there isn’t a simple “heavy amp” piggy back connector produced by someone - I can’t be the only 6 who’ve had this “three into one” issue. 

Derek

[RobH]

If your old one has gone open circuit it will most likely be the internal current loop of heavy wire having come adrift from one of the terminals. ( It probably wont be exactly like this one but generally similar.)

Edited April 26, 2023 by RobH

[djp852795]

Rob thanks -  So I might be ok to solder the break if I can find it?

[RobH]

Yes but you will need a big soldering iron, the usual electronics one will be too weedy .

[greasemonkey]

Derek - Quality specialist = Speedy Cables in S Wales. Coincidentally I enquired only last week regarding upgrading standard ammeter to a 60A jobbie... answer was £140 plus vat plus carriage.... So £180 ish.... yikes !!!

Oh, and 6 week lead time.

Think I'll stick with what I've got having read comments here!!

Phil.

[djp852795]

Ditto greasemonkey - Cheers! 

[djp852795]

Close out for those interested: Located and opened the original non working ammeter to find that the 30amp wire behind the face had ‘blown’ (or rather “evaporated” - must have been a heck of a short). That’s why it didn’t work! I have been running round with a 60amp replacement for the last couple of years.

Because I preferred the original white red C/D face, I decided to replace the damaged 30amp wire loop in the original unit, with the 60amp ‘bar’ from the 60amp ammeter. 

Behind the dial, I had to make sure that the ‘live’ bar was neatly placed behind the face, and clear of the pivoting indicator. It involved a lot of careful cutting, filing, and sanding to make it fit properly so nothing touched anything else.

I was super careful here, making sure that the inner terminals were bolted together really strongly, the insulator washers applied, and the blades cleaned off and the wires well insulated. 

Turned ignition on ready to remove battery connector - but all good, and no need to play around with the original loom/connectors at all.

Thanks to all. Appreciate the feedback - esp RobH & Phil.