Rev's drop / Alternator

[WIMPUS]

Hi,

When i put my lights on my rev's drop very much, read somewhere it could be from to much load on the alternator ..
I've still got the original one, but i've got halogen headlights & other bits.
And because it's all taking more amps then original i think it's maybe this ..

I've looked into upgrading my alternator a while ago, wanting to do this i the future (maybe the future is now  >:( )  :)

Wim

[Rich_s]

It could be, i have an 18acr on mine and will happily tickover on main beam (with halogen lights), heater on full and wipers going.

have you got a volt meter in the car or can you temporarily fit one and watch it as you turn the lights on and see what happens.

first thing i would try is cleaning the alternator and all the contacts inside as could just be in need of a clean?

rich

[WIMPUS]

932 wrote:

It could be, i have an 18acr on mine and will happily tickover on main beam (with halogen lights), heater on full and wipers going.

have you got a volt meter in the car or can you temporarily fit one and watch it as you turn the lights on and see what happens.

first thing i would try is cleaning the alternator and all the contacts inside as could just be in need of a clean?

rich

I've got a Volt gauge in the car (connected to the voltage stabilizer)
And without the lights on its 14 volts .
When i put on the lights it drops to i guess around 13volts ..

That 18acr one, that 45amps then ?  :)

[WIMPUS]

Just been looking into my 'Spitfire Owners Workshop Manual' (Very good book!!)
And seen that from 173 on it was a 16ACR and was giving around 34 amps ..
So not that much  :-/

[Rich_s]

i think the 16acr is std, when mine failed i upgraded to the 18acr although even on the 16 mine was always ok.

14volts sounds a bit high for normal running, mines is normally only that high when battery is a bit flat, once charged it is about 13 at most.

is your battery ok and holding enough charge? terminals nice and clean and tight?

rich

[Rich_s]

on a different note, which bit of the door handle did you need as found a few more bits so may have what you want? if got a pic i can check to see if i have the right bit.

rich

[WIMPUS]

932 wrote:

i think the 16acr is std, when mine failed i upgraded to the 18acr although even on the 16 mine was always ok.

14volts sounds a bit high for normal running, mines is normally only that high when battery is a bit flat, once charged it is about 13 at most.

is your battery ok and holding enough charge? terminals nice and clean and tight?

rich

Well think it's actually around 13,6volts (gauge is a bit optimistic).
Battery is a year old and one with the most amp i could fit in the battery box  :P

[WIMPUS]

932 wrote:

on a different note, which bit of the door handle did you need as found a few more bits so may have what you want? if got a pic i can check to see if i have the right bit.

rich

Well i need a inner door handle chrome bezel (if i say it right!).
Someone cut a bit in the chrome with a dremel or something :-/
You can't see it straight away, but i see it and don't want to buy a new one.
But if i found one that wasn't to expensive i'm always interested !   ;)
(Need to build a bigger shed in a few years i think, off all the spare parts i'm going to have for spitfire's  ;D )

[Rich_s]

that sounds a bit more like it :D think my gauge is wired into same connection as the stereo so not a true reading either.

hahahaahah my battery is std tiny one but works ok if i keep all brushes on starter and alternator nice and clean.  

sounds like the alternator is working fine then if getting enough volts, are all earth points from headlights back to battery all clean and corrosion free and tight?

[Rich_s]

if you mean the bit that sits behind the handle thats a sod to get off without damaging it then i do have them, will get a pic and send them over to see what you think and if any use you can have them.

[junkuser]

If the battery is fully charged Wim, the output of the alternator will attempt to just match the drain occurring at the time from whatever is drawing power.
As long as the alternator has sufficient output to match the drain, the load on the engine will be the same no matter what size the alternator is (Ignoring efficiencies of design).
At idle, the engine will slow in response to the load and as the alternator will be running at below its optimal output speed, the voltage will drop.

There can also be voltage drop in the car wiring which can cause the volt meter to show low readings under different circumstances.

[WIMPUS]

932 wrote:

that sounds a bit more like it :D think my gauge is wired into same connection as the stereo so not a true reading either.

hahahaahah my battery is std tiny one but works ok if i keep all brushes on starter and alternator nice and clean.  

sounds like the alternator is working fine then if getting enough volts, are all earth points from headlights back to battery all clean and corrosion free and tight?

Normally all the earth's are good, but going to see the next few days  ;)

[WIMPUS]

932 wrote:

if you mean the bit that sits behind the handle thats a sod to get off without damaging it then i do have them, will get a pic and send them over to see what you think and if any use you can have them.

This part i mean  :)

[WIMPUS]

I've been talking to a guy with a spitfire mkIV from the uk and he took a picture from me on idle speed and then with the lights on..
Only dropped 200 rpm  :o


Tested my car this morning ..
Idle around 900/1000rpm.
When i put on the lights (but not the H4 headlights) then the rev's don't go down really (also the radio played, heater on .. )
When i put the headlights on .. Drops more then 300 rpm , nearly stalling then  :o

Someone i know that works on cars said it maybe is tired also..
And i can believe that, think it's still the original one .
And months ago my starter was broken also, opened it up and every wire inside was coming loose..
It was just so tired..
So i guess the alternator has been  working hard in all those years  :-/

Now for a 45amp one, do you need to put a extra wire because of the more amps or not ?  :)
And where to you get the cheapest one ?

[Rich_s]

Hi Wim,

I have the 18acr and no extra wiring at all, just unbolted one and bolted on new one, been fine since, cant remember where i got it from though.

i have had a look and i do have that door handle bit but its a bit rusty and not very good i'm afraid :(

rich

[GT6 M]

Wim,revs can drop if its running weak at tick over.
As for another feed, just run a  3 or 4mm wire to the batt +
butt, put on a diff terminal, the Lucas,ns have 2 big spades, both the same connection inside

there a good chance that yer OE terminal frae,t alternator is black with heat,
both the connector and the wires.
And, at its age, will moer than likely have corroded wires at the end too.

Note, just cos ye got a bigger out put charger, dont mean ye need bigger wires.
this only applies if ye actually using extra power for things.
If no power used,then charger will be putting oot next to nothing .

M

[sparky_spit]

I've got one or two of those door handle bits in the shed.  I'll have a look and see.  If Rich's don't work out you can have what I have. I can either post them or send out with one of the UK entrants in the Dutch night rally, which would get them closer to you maybe.

[Sheepy]

sparky_spit wrote:

I've got one or two of those door handle bits in the shed.  I'll have a look and see.  If Rich's don't work out you can have what I have. I can either post them or send out with one of the UK entrants in the Dutch night rally, which would get them closer to you maybe.

Are you going to stonleigh? If so I can pick it up for Wim, or I can also look for one while I'm there if yours is no good.  :)

[drofgum]

796 wrote:

Wim,revs can drop if its running weak at tick over.
As for another feed, just run a  3 or 4mm wire to the batt +
butt, put on a diff terminal, the Lucas,ns have 2 big spades, both the same connection inside

there a good chance that yer OE terminal frae,t alternator is black with heat,
both the connector and the wires.
And, at its age, will moer than likely have corroded wires at the end too.

Note, just cos ye got a bigger out put charger, dont mean ye need bigger wires.
this only applies if ye actually using extra power for things.
If no power used,then charger will be putting oot next to nothing .

M

Marcus,
Always remember that once started with a truly dead battery the alternator will charge at its full rated output. So a wire rated for that output is only wise.
                                                                                 Cheers,
                                                                                 Paul

[sparky_spit]

4058 wrote:

Are you going to stonleigh? If so I can pick it up for Wim, or I can also look for one while I'm there if yours is no good.  :)

I can't this year but thescrapman will be going, who lives very close by. I'll find them in the shed and see what they are like and get back to you and Wim.

[WIMPUS]

Well tonight i got out in the car again..
When it was warmed up a bit , choke off and on idle it was around 700-850rpm, sometimes hitting 650 (with lights, radio on).

Gone for a good long drive and after an hour of driving i looked at it again
And then it was around 850 rpm, with the halogens off it goes back to 900 ish and with everything off around 1000 rpm..

I know the mixture is still a bit lean (but drives very well ! ), Can it be that ?
Or should it be the alternator that is getting a bit tired or dirty inside ?  :)

[WIMPUS]

892 wrote:

Hi Wimpus,
Your engine RPM is dropping as you are loading the engine when you request electrical power when switching electrical loads on.
The more electrical power you demand the more load the alternator puts on your engine, ie the mechanical load on your engine increases.

If you changed your alternator to a more modern (higher current rating) and efficient one, it might decrease your RPM droop. but it would substantial droop your engine RPM when your battery was discharged!

it sounds like your engine, while idling has insufficient power as the electrical load is stalling your engine..
Check you fuel or timing settings as this is the cause of your problem. The alternator is not the cause.

Cheers,
Iain.

ok, thanks for that !

Last week it seemed ok, but i already  knew i needed to get the mixture a bit more rich..
But still not looked at it  :B
Going to try tomorrow if i got time  ;)

Before my carb problems the car was always running a bit to rich and got the same problem back then also ..

[sparky_spit]

sparky_spit wrote:

I can't this year but thescrapman will be going, who lives very close by. I'll find them in the shed and see what they are like and get back to you and Wim.

PM sent to Wimpus, Sheepy and TheScrapman

[Velocita Rosso]

sparky_spit wrote:

PM sent to Wimpus, Sheepy and TheScrapman

I`m sure there was a film entitled such...... :)

[sparky_spit]

michael_charlton wrote:

I`m sure there was a film entitled such...... :)

A Cohen brothers film maybe?

The Good, the Bad and the Ugly?   I'm not saying any more.....  :)