Gav Diamond

iTrader: (6)

Been out today and had the charging system checked on the Cossie.

Reason i had this done was on the AIM dash the voltage seemed quite low to me as this reads info from the ECU.

I have spoken to James from Motorsport Developments who said to change the lead from the Alternator to the battery.

I went to a local auto electrics place today who seem to think that changing this cable will be of no benefit so i had a charging system test done to see what its doing at the minute.

These are the results:



Bearing in mind this is what there machine is reading not what my ecu is getting so do these seem ok as have conflicting information now with regards to changing the lead from alternator etc

Thank you

RONNIE AMIS

iTrader: (17)

13.67, is that what it's charging at with all electrics on?

thats pretty good to be honest mate

Graceland

Open voltage - that should be a minimum of 13.1 volts ideally - change the cable from the alternator to the starter and then check the feeds from the battery. Also rewire the fuel pump if you havn't already done so and add an aditional earth bond from the engine to the chassis (I have added my earth bond from the front lifting point next to the inlet manifold and then sent this to the earthing point infront of the battery on the tray itself)

Just for reference, on my Cossie, at warm (925 rpm) idle with nothing switched on I have 14.6 to 14.7 volts accross the battery and then with everything switched on (all exterior lights, interior lights, heated screens front+rear and heater fan) and the radiator fans running this drops to 12.6 to 12.7 volts, then when the rpm is raised with everything switched on to 1500rpm I get 14.6 volts

Bearing in mind I have rewired the alternator main feed, engine earth, chassis earth, fuel pump and all auxilliary feeds from the battery too for optimum reliability

jammy86

The ECU voltage is missleading really as that is not the voltage coming from the alternator. Voltage drops when there is a load, so the load of the ECU and anything else wired up to the same source will cause the voltage to be less than across the battery.

It sounds fine to me....

JAmes.

martysmartie

iTrader: (1)

Seems fine to me, do you have standard alternator as your one made 110A when the standard alternator is 90A (Assuming it's a Saff).

It is possible as with most Cosworth wiring looms for them to deteriate and not be up to to the job especially circuits dealing with high current, but I should think this would be unlikely.

If theres nothing wrong apart from the reading I woulden't worry.

What reading are you getting on AIM then?

Martin

Gav Diamond

iTrader: (6)

The guy said it was tested with the lights etc turned on.
The current draw at the time shows 66.6A


Hi mate
Open voltage is tested with engine turned off, have spoken to the old man who says the batteries straight off the production line will only do 12.8-12.9 so getting 13.1 you are doing well there.

My car doesn't have a wire from starter to alternator
My fuel ppump has been re-wired as its an Aeromotive one in the boot.


Thanks mate

Gav Diamond

iTrader: (6)

Sorry mate missed your post

Its a 3dr cossie

Forgot to put my reading, the AIM is showing 13.6v with the lights off but with them on is showing 12.9v
These are when cruising at about 2000-2500rpm

tabetha

There's absolutely nothing wrong with those readings, unlike gracelands, over charging.
tabetha

jammy86

Standard wet cell lead acid batteries are 100% charged at 12.85V (typical). When just off the charger they may show slightly higher but this will settle once the surface charge is taken off/settles.

Optima Yellow, Red and Blue tops, aswell as other AGM and gel type batteries can have a 100% charged Open Circuit Voltage of 13.1-13.2V.

A standard battery showing 13.1V as normally is likely to be damaged. When overcharged batteries will gas, which isn't too good and can be explosive. At worst they might spit out some acid, but provided that the battery is in an area open to atmosphere or has a vent tube fitted it shouldn't be too big a problem provided that its not being over charged all the time.

Don't measure the battery voltage just after turning the car off. You need to remove the surface charge to get a good idea of what the level of charge is. Google battery care, or surface charge and there is lots of info out there.

JAmes.

Its Dave

iTrader: (4)

Gav

On my Aim im getting with light on ect ect 12.8- 12.9 some time it will just full under that tripping the warning low battery light on Aim dash, my battery is a red top optima

Gav Diamond

iTrader: (6)

Tabetha/Jammy86

Thanks guys

Dave

Nice one for that mate, just me worrying for nothing then as there must be a slight volt drop to the ecu but must be ok if we are getting similar readings

RONNIE AMIS

iTrader: (17)

sorry to hijack your post mate, your battery has been moved to the back hasn't it? what did you do with the earths? bolt them straight to the body work and then earth the battery to the chassis?

just asking as this is what i have done and am a bit paranoid, some body said to run a earth straight from the engine to battery aswell as chaccis earth,

cheers mate

tabetha

So long as you have clean solid connection points to the body, with no rust between the panel it is on and the panel it may be spot welded to, it will be fine.
Rust always builds up between two panels that are spot welded, as gives a high resistance.
As the body carries much more conductive material(in mass) to the body is fine.
Most battery makers will not warrant a battery above a certain point, and all must be capped at 14.4, otherwise super venting occurs which is HYDROGEN GAS, as in used in Hydrogen bomb!!
Calcium batteries can run up to 15v quiet happily, this is why it is vital to put a calcium battery in a car that had one at manufacture due to higher charging rate.
tabetha

RONNIE AMIS

iTrader: (17)

Would their be any tell tale signs that the earths aren't good enough? I made sure all surfaces were clean, I have started the car since and it runs fine And is charging fine, just paranoid when it comes to electrics lol

Gav Diamond

iTrader: (6)

All earths are to the body mate and yes battery is in the boot.

tabetha

So long as voltage is still there when under load, ie from starter it is fine.
I have seen cars turn up at the rollers, put together by some people who really should know better that have bolted through the body for the earth connection onto painted metal.
It was hit and miss whether it played up, till the paint was scraped off his newly painted shell!!
tabetha