Battery light on dash staying on

My red battery light stays on until I rev engine to 1500rpm. Does this mean battery or alternator are on way out?
Thankyou

Could just be shitty terminals. What have you checked so far?

Cheers. Lol checked nothing, but coincidently got a service a few days earlier

Mine dose the same, but mine has been doing it for months. It has come now where I have to jump start it every morning and then its fine if it dosent sit for 4-6 hours. There is nothing running when the key comes out. I'm nearly ready to buy a battery but I'm a bit hesitant because I'm not shore if I need one.

I'd try replacing the alternator brushes first. If that doesn't fix it its time for either a new alternator, battery or both...

mine does it too,i have 2 month old battery and new terminals,1 terminal might be loose,will check when i get my car back on mon or tues.

Battery could be rooted.

More then likely the alternator is rooted though.

Put a GU Patrol ZD30 alternator in, there 90 amps.

All of you should first check your charge rate before doing anything. Start your car and place a multi-meter over your battery terminals. You should be getting a reading of between 13.8 vdc to 14.2 vdc if your getting below this reading at idle rev the engine up to 1500 rpm. As sometimes it needs a quick kick to get it charging. U can buy yourself a cheap multi-meter at buntings for around $20

Matty450 said:

All of you should first check your charge rate before doing anything. Start your car and place a multi-meter over your battery terminals. You should be getting a reading of between 13.8 vdc to 14.2 vdc if your getting below this reading at idle rev the engine up to 1500 rpm. As sometimes it needs a quick kick to get it charging. U can buy yourself a cheap multi-meter at buntings for around $20

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And if this is the case matty, then what? A new alternator or battery?

Are you still having issues? If so what have you checked?

I have checked terminals, unscrewed battery cap, indicator was green. I put about 10ml of water in too. Dunno what else to check..?

Well you would have to tell me what voltage u are getting. The way your charge light works is it is connected to your battery and earths itself through the alternator that way when you get in your car and turn your key to accessories without starting it u see your battery light come up, then once you start the car and the drive belt spins the alternator it starts feeding back a voltage along the same circuit as the battery light. then because you have your 12 volts coming from the battery and your 12 volts coming from your alternator your charge light goes out as there is no potential difference in the voltages. If your charge/battery light is dim after the car is running that might mean that there is a slight potential difference in which case you would have to test to see if it is your alternator or battery that's causing the difference.
To be honest though it sounds like it isn't a major issue it might be the brushes in your alternator that are slowly on their way out but until the day comes that your charge light stays on constantly u shouldn't have any major dramas. When that charge light is off it is telling you that your alternator is doing its job.

with mine all the terminals are good,not the battery as its new and ive also tried 3 others.mine sits at 11.5 when i start it on idle,then give it a little rev and light turns off and it jumps to 12.5 and climbs up to 14 once started to drive.id say its deffently the alternator slowly dying

if you have a charge rate of 13.8 to 14.2 volts dc and if 4 to 6 hours after you turn it off it won't start, then you need to check current draw.
to check current draw get your multimeters and set it to 10A range (change the test probes around if necessary). turn the key off. disconnect the negative battery terninal from the battery.
put one probe on the negative terminal of the battery and the other probe on the terminal that would go on it so that the multimeter is in series with the battery and the battery termial.
if you get a reading higher than 0.05 Amps then something is still on. see how you go
Cheers

Yeah what placey said raises a good point for you Craig. If your battery is as new as u say it is, provided that your alternator is charging correctly once u are driving it and giving the battery a good charge it should be sitting above 12 volts before you go to start it in the morning, you said it was 11.5 which is pretty low so there could be something drawing power while you have your car off.

it sits well above 12 when turned off,nothing is drawing power,i should of explained clearer.
its well above 12 before i start but the power draw when i start it drops it to 11.5,it will sit on 11.5 until i bring the revs up to 1500rpm then everything goes normal and does what its meant to do.
the alternator just need a kick in the arse to get it going so theres something going on there like the brushes or the alternator itself is packing up shop.

it could still be the battery. i've seen lots of batteries that were bought a couple of days previously, and they load test no good. some alternators need a couple of seconds to create the potential difference. what happens if you start the engine and let it idle. does the voltage stay the same? is the alt light still on? what turns on when the ignition turns on? ie. radio, aftermarket lights, chargers. that sort of stuff. also note that when the ignition turns on the glow plugs are on and that will cause a bit of a drain as well. and when the engine starts, the glow plugs are on intermitantly. as in they flash on and off to help the engine run nicely for a few seconds (about 10 to 20 seconds normally. called afterglow).

Placey001 said:

it could still be the battery. i've seen lots of batteries that were bought a couple of days previously, and they load test no good. some alternators need a couple of seconds to create the potential difference. what happens if you start the engine and let it idle. does the voltage stay the same? is the alt light still on? what turns on when the ignition turns on? ie. radio, aftermarket lights, chargers. that sort of stuff. also note that when the ignition turns on the glow plugs are on and that will cause a bit of a drain as well. and when the engine starts, the glow plugs are on intermitantly. as in they flash on and off to help the engine run nicely for a few seconds (about 10 to 20 seconds normally. called afterglow).

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i tried 3 batterys as i was curious,all same thing.it will stay on 11.5 all day if i dont up the revs.doesnt bother me until the alternator stops chargeing completely then ill just replace it.

Craig09 said:

i tried 3 batterys as i was curious,all same thing.it will stay on 11.5 all day if i dont up the revs.doesnt bother me until the alternator stops chargeing completely then ill just replace it.

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Your alternator is stuffed then. Get it reconditioned.

if thats the case, either one or two of the exiter diodes are stuffed or the regulator is stuffed. take it to an auto elec and get them to check it out and find out exactally what is wrong with it and how much its gonna cost to fix. find out how much it costs to get a new alternator as a comparison. another option is to get a zd30 patrol alternator as it has a higher amperage (90 amps i think). food for thought