11 replies to this topic

[Joe555]

I have been given a TIM Ammeter, it's in the box and I think it's unused but has no instructions. What I am asking is how to wire it in.  I have looked in the Moss catalogue and they have two listed, one for a dynamo and one for a alternator, what is the difference? My car has an alternator.

[tiger99]

it is very difficult in a Mini, because you have to join all the brown wires together that were originally on the battery terminal of the starter solenoid, into one thick wire, and run that to one ammeter terminal, the other ammeter terminal goes back to where you removed all the wires from. All of this extra wiring is unfused, and therefore a major fire hazard. And, there will be extra voltage drop, which will affect the battery charging.

 

It is common practice on alternator-equipped cars to never have an ammeter, but instead have a battery condition meter, which is a voltmeter with expanded scale, reading only the useful range, maybe 10 to 15V.

 

Remote sensing ammeters exist, and if you had one of these you would pass all the brown wires through the hole in the hall sensor. The ammeter itself would need 12V power from the ignition-controlled circuit via an in-line fuse.

[tiger99]

Here is a typical current sensor. Note that it needs to be provided with _ and - 15V, and will need some kind of instrument to read its output of up to 50mA remotely.

 

http://www.farnell.c...eets/797312.pdf

[Rog46]

Ammeters for cars usually read -30 to +30 Amps that is fine for a dynamo which charges at a reasonably low rate, however alternators can push out MUCH more current than this so it is difficult to run thick enough cables to and from the alternator, and larger scale ammeters are rare. All in all I would suggest you sell it on eBay and get a voltmeter instead!

[Joe555]

Thanks for the replies. I have decided not to fit the ammeter and not to sell it for two reasons, as it was given to me I don’t think I should make money out of it and also it may be dangerous for someone who buys it . But I thought to keep it as a test tool. This leads to the next question, I temporary connected it, switched the lights on and it showed a discharge of 10 – 15 amps started the engine and it only showed a very slight charge, is that normal? My car has an alternator.

[Dan]

How did you have it connected?

[Joe555]

I took all the brown wires that were on the same terminal as the big black cable from the battery and
connected them to one side of the ammeter and connected the other side of the ammeter in their place.

[KernowCooper]

This should show a discharge of the total current draw which it apears you have with the lights on, when the engine is running at 2000-2500rpm this should bring the amp to a plus charge and then slowly decrease back to 0, this is if the meters accurate? I would put a voltmeter on the battery and with the engine running at 2000rpm with everything off you should see 13.7-14.3v across the battery which confirms it is charging correctly, if you dont see this voltage then carry out tests on the alternator to see why.

[Joe555]

Thanks,
I am sure it's all ok it's just that I expected to see more charge.

[KernowCooper]

It should if the amp meter is working bring the meter back to 0, i would do the test with the volt meter on the battery and if thtas ok bin the Tim

[Dan]

  If the battery is healthy and full and the engine starts well then a single start might not take a huge amount out of the battery.  It could conceivably only put it into a low current charge rate.  You said the gauge registered a small charge but you didn't say how much.

[Mr Joshua]

As mentioned above having to run that much extra cable does lead to electrical/current load handling issues. Having fitted one and running it for some years now I would advise the following everything in your electrical system from switches to ignition barrel switch to fuses must be in tip top condition to reduce resistance. Otherwise as I found out you will run into major charging issues. Best advice don't fit it if you you don't want to start replacing things like your ignition barrel loom.