Battery Light Showing

My battery light just came on

The alternator is new. Any suggestions?

Check your wiring at the alt ,belt tension ,alt retaining bracket bolts etc .You might not have done them up tight enough .

Jon, also worth checking the charging voltage at the battery. The light will come on if the voltage is too high as well as too low.

Could be a dodgy regulator - I had 16.6volts at the battery with my old alternator. Enough to boil the battery - I could smell it when driving - nasty acidic smell.

Someone will correct me if wrong but I believe the correct charging voltage is approx 13.8 volts. Max 14.2 volts. Higher than this could damage the battery and electrics, lower means starting problems

I believe the correct charging voltage is approx 13.8 volts. Max 14.2 volts. (

Charging info I have states that 13.9v will totally avoid gassing in extended periods of use, as when a charger is left permanently connected to a battery, which is classed as "permanent float". A useful voltage if left connected to a car battery over the winter say. However 14.5v will quickly provide a full 100% charge while still giving negligible gassing.
However in the Alp, the chances of getting 14.5v at the battery is slim due to the long length of cable from altenator to battery, plus the not so good earth path in these cars, as Juzzblack I am sure would confirm. To this end when I reinstalled the gearbox, I fitted an extra earth strap on the opposite side of the box to the existing one, and two more straps across the two rear engin mounts. It helps but still not perfect. I have often thought to route a heavy extra earth cable from the battery earth anchor spot, running alongside the 12v one, connecting directly to the engin block. But have I got around to it...............................................No

re the cable from front to rear, been there and done that john!

i had an atmo with battery light problems, removed alternator and had it refurbished, refitted and the battery light would still come on if you held the electric window switch up when the window was closed.

spark said 'poor earths'

ran a lenght of heavy battery earth cable from the battery to the sub frame, replaced the gearbox strap and ran a cable from the engine to the subframe. replaced earth from battery to the car frame at the front.

i also stripped back the two front foot well kick panels and cleaned and retightened the earth points in there.

started up the engine and held the button up again and the light still came on!

i asked the alternator to come off by its self as it had been off soooo many times, back to the sparks and asked for everything to be replaced.

guess what.... no problems after that!

crap parts fitted the first time!

all the extra cabling did not change the charge voltage back to the battery and cranking speed remained unchanged, so i trailed all the new cabling back out and left it as standard. no problems for the next two years of my ownership.

i think if the standard cables and earth points are clean, tight and have no corrosion then leave it that way!

battery light would still come on if you held the electric window switch up when the window was closed.!

Simon,
You raise some very interesting points re the light/windows scenario. I have to say mine has always done that. But I have accepted it, because in this instance we are moving into the area of the "locked rotor" syndrome. I could spend hours on this one but I am sure I would bore the pants off you all, if I havent already done so ( I thought I would get that one in first before someone else does )
Anyway beiefly In most cars with electric windows.their motors are fitted with enertia switches which detect a sudden rise in current, and switch the power off to the motor. This sudden rise in current is caused by mechanically the stopping the motor whilst the power is still applied. Looking at it from another angle, when you apply power weither AC or DC, to any motor, for the minutest fraction of a second the motor looks like virtually a dead short to the supply. The moment it starts to rotate the current drops to a normal current for the power of the motor. As a quick example, at the moment of power applied to a starter motor the current demanded by the motor can be anywhere around 200 to 300 amps. However once the motor starts to move, it drops down to around 30 to 40 amps. Now apply this principle to the window motors on the Alp, the motor is running at normal current consumption, the window hits the stop, motor stops "locked rotor", it now appears as a virtual short across the 12v supply, you keep your finger on the switch, I suspect the wires are starting to get hot now, voltage drops below the level that keeps the ign light off, hey presto the light comes on. If you held long enough you will blow the fuse, however the length of cable and earth path will delay this from happening.
As this light problem does not happen to Simon, a new altenator and possibly a new battery just might negate this, but I suspect it will come back as the battery gets older, and the altenator gets older.
I would be interested to hear other owners experiences of this.
John

none of my gta's (3) or the road worthy one's that i work put the light on?!

none of my gta's (3) or the road worthy one's that i work put the light on?!

Interesting Simon,
I was hopeing there would be more comments on this, as I feel it is a common occurance. But you have got me thinking, why would a small window winder motor, cause the batt light ot come on when held like you say, but light does not come on when driving with all lights/wipers/fan/radio/heater fan/cruise control.......oops/ (yes I have fitted one) are all on together drawing some 35 plus amps worth. When I get back I am going to do some checks, as I have a little job to do on the car with a lazy opening door actuator anyway. If I draw any conclusions I,ll come back to this subject.But it would be interesting if others have come across this occurance.
Cheers John.

JohnC
Window winder motors will draw about 100w (about 8 amps) during normal operation, but will peak at about twice this draw on start up (momenterly) and again the same peak when the mechanical stops are reached (fully open or closed)
If your windows are less than perfect then you might see normal draw increase by 50%.
To understand why your battery light comes on when operating the windows but not other 'power draw' ancillaries is a little more difficult as I am not aufait with the GTA wiring, but at a guess, it is where in the loom the power draw occurs, rather than the Battery and Alternator voltage being dropped by the current being drawn. Put it down to good old 'French Car electical design', as we all know Dieppe employed the best leccy designers!!

Hi Turbo 5,
You have got some good points there. When I have some time I,ll have a look through the cct,s. to see where the feeds are taken from.
Just had a quick check, found that each window is seperately fused at 30amps. There,s a message there, is,nt there. Interesting
Anyway I wonder how jon_viola got on with his problem. Did,nt he post the first question
I hope he hasnt fallen asleep with boredom.

Wakey wakey jon, Have you fixed your problem?

Hello,

Not asleep just not got out to put a meter on the battery. Will let you know asap, sounds to me though like the new alternator might have knocked out the regulator, typical!

The GTA alternator is a 2-pin type and is has an ignition fed 12v supply which it uses to regulate itself. The battery light feed is actually used only as an "error" light, unlike single wire alts that use the battery light bulb as a series resistor to the battery, used to regulate the charge (which is messed up if you change the bulb for a different one!).

I've been fitting GTA alts to DeLoreans for some time and the D is also blessed with a voltage gauge. I've had one which worked perfectly, charged and regulated correctly on load changes, but the light was permanently on. A service exchange one from Renault and the problem was gone.

Hi Martin,
Thanks for that info, so to help the understanding, here,s the cct Martin is on about:-



The cct shows Martins explanation perfectly:-
Pin 1 of the two pin plug by the altenator, goes to the ign switch, which will sense the battery voltage, and any drop in voltage, as different things are switched on, and tell the regulator accordingly.
Pin 2 goes to the batt light, and operates as Martin says.
The main output from the alt, goes to the starter, then on to a little black junction box in front of the engin, on the bulkhead, and then on up to the battery.
If you ever suspect a low charge to the battery, Remove each of these connections, clean them and put them back with little smear of vaseline, just enough to keep air off the bare connectors. One word of warning, disconnect the battery first or you will get some big flashes In fact I can virtually guarantee that if you do it the next time you have the engin open, you will get a bit of a turn on each nut from alt to batt. One worrying thought occures, the regulator sensing voltage passes through two large connectors R5 and R17, and we all know how good these French connectors are.
Now I really must go and start packing
Cheers John

Managed to get round to looking at the car today.

Alternator's dead

It's a new Renault one at that must have done max 700 miles now to find out what could have blown it......

Er... "being a new Renault alternator" could have blown it... Mr Smith arrived at mine courtesy of the AA this afternoon thanks to a "new" alternator.

Edit: I realised today that I haven't been fitting GTA alts - I've been fitting a late 25 turbo alt. I thought they were the same but it seems the +ve terminal on the 25 alt is in a much more sensible and accessible place at the bottom.