Current

[davidj]

Hi,

My early +2 has had an alterator conversion, but retained the ammeter (upgraded to +-60Amps). Everything appears to be OK, I *think* the battery is charging and the charging light on the dash goes out. However, the ammeter needle hardly ever moves! With the lights on and the engine not running, it moves slightly negitive, while with the engine running it might move to +3/4 amps but no more.

Is this correct? I originally replaced the +-30 unit with the +-60 because I read an Ammeter can kick out a lot more power and blow the original unit, but I am bearly seeing any current. My concern is it is not charging the battery sufficiently, which will run out of juice a long way from home

Thanks in advance. David

[GrUmPyBoDgEr]

The physical movement on your 60A Ammeter will be half of that of the 30A one you replaced.
With the headlights on drawing say 55W each they will draw approx. 9A which will only represent a small Needle deflection over a Scale of 60A = 15% of total Scale, with the 30A Ammeter it would have been 30% of total Scale.
Does that match what you're seeing maybe?

Cheers
John

[Frank Howard]

David,

When I installed my 45 amp alternator, as Elans (+0) don't come equipped with ammeters, I deliberately chose a 30 amp ammeter because I wanted to be able to see movement more clearly. Sure when the alternator is charging an almost dead battery the ammeter will peg, but that doesn't do it any harm. You might want to consider "downgrading" to the original 30 amp ammeter.

[bob_rich]

Hi

Depending upon how the ammeter is wired it may should only indicate the charging current , which after starting may be quite high initially but quickly fall back to a steady modest level ( a few amps perhaps probably less that around 5A). This connection is I believe quite normal. If the alternator fails then the ammeter would read a discharge and would indicate the full electrical load so if you were drawing 45A ( full lamps , screen heater, heater fan motor etc ) without the alternator running it would read 45 A discharge. When engine running the electrical load of 45 A is supplied by the alternator provided it is adaquately rated. If it runs out of chuff at say 35A then the ammeter would show a discharge of say 10A as the balance of the 45 A load would come from the battery.

If the ammeter ever indicated a charging current up at high current (>15A for any length of time after starting it would suggest that the charging circuit is not in control or the battery has one or more shorted cells.

hope this helps best of luck

regards

Bob

[msd1107]

A couple of people have mentioned the benefits of an ammeter reading to a smaller full scale figure. This should always be done, as it increases the precision in reading the gauge at fractional levels. So use a 0-50 psi oil gauge, not 0-100. Use a -30-+30 ammeter, not a -60-+60 (you can find ammeters with full scale of 30, 40, 50, and 60 but the 30 is the most common.

Size the ammeter at no more than 40 amps max. These came in some of the '80s small Japanese sedans and are quite inexpensive in the breakers yard. Keep in mind the original Elans functioned with the 23 amp generator which put out much less in stop and go traffic (well, people would drive in traffic with main headlights down, heater motor off, use RainX instead of wipers, etc) to cope.

All lights are available in much higher efficiency versions than the original bulbs, which decreases current draw.

David
1968 36/7988

[Frank Howard]

Size the ammeter at no more than 40 amps max.

David,

I think you meant alternator.

[Frank Howard]

original Elans functioned with the 23 amp generator

I heard it was actually 22 amps!

[msd1107]

Hi Frank,

I think you are correct!

David
1968 36/7988

[neilsjuke]

There is no gain from fitting a alternator with a output much higher than the current used by the car you should check with a amp meter with every thing turned on + approx 5amps for charge.
As the amp meter fitted would be of a range suited to the current drain and the alt will regulate to what being drawn no need to change its more important to get the output wiring right and of correct size.
Neil

[davidj]

Hi,

Thanks for all your replies. I think (hope) Bob explained the situation. As I understand it, the ammeter is reading the current which the alternator is providing over the battery, which is normally only a few amps. Not the total output of the alternator. So providing it is always showing positive everything is OK.

Unfortunately when I brought the car, it was wired incorrectly, so I cannot compare the original ammeter with the new one.


Cheers,

David