Battery indicator

budgel, Oct 3, 3:42pm
2004 Ford Courier 2.5TD.
How reliable is the little battery indicator window in the top of a battery?
Mine shows green all the time, but after sitting unused for several days the voltage is lower than it should be, and the ute only just starts first time. For the rest of the day it's fine. The glowplugs have been replaced and are fine, there is no corrosion on the terminals. The alternator charges at 14.4V and the battery sits at 13.8V after a run.

I'm going to charge it to full, then disconnect the battery overnight and measure it in the morning to ensure there is no parasitic loss.

Any thoughts?
tweake, Oct 3, 4:24pm
the problem with the "magic eye" is it only indicates on one cell. so if you have a fault in any of the other cells you can have a dead battery and it still shows green.

sit it on a battery charger overnight, check fluid level (if possible).
apollo11, Oct 3, 9:00pm
Doesn't the red dot in the middle have to be showing as well? If it's just the green ring I think it means the battery is starting to get tired.
franc123, Oct 3, 9:21pm
Doing a proper battery load test, either with an electronic simulator or carbon pile tester has always been more reliable than those indicator eyes. Any problems with car batteries are going to be exposed when it's under load, in your case if you dont have access to one of these you could give it a good overnight charge and then stick a multimeter across it and see how low the voltage is going after a 10 second crank. Disconnect the fuel cutoff wire on the injector pump so it wont fire up and watch the reading, if it struggles and /or the voltage is going below 9 volts the battery is on the way out.
gpg58, Oct 3, 9:32pm
If its a calcium blend battery, you have to use a suitable charger, or you will only get it surface charged. Had one that showed green, yet was always too flat to start car when cold, so took it back to shop as i believed it was faulty(it had been let get dead flat, before attempting to recharge it though -spare car over winter, now my spares usually have battery isolators fitted to stop that happening).
He put it on a higher voltage charger for 24 hours, and gave it back. It was then fine until i sold the car a year+ later.
Ps, have also had calcium's on a standard charger cook themselves, when 12 amp charger was left on overnight(stinking hot and case bulging).
budgel, Oct 4, 1:08pm
Thanks for the input. Last night I checked the voltage when I parked it.
13.04V I then disconnected the earth strap overnight.
. 1.00pm today it is 12.87V. Not a huge amount, but I think a steady decline like that over several days equates with my problem.
Time for a new battery I think.
Franc 123, I will try that . I suspect it will confirm that it needs replacing.
GPG58, It's a normal lead acid battery.
budgel, Oct 4, 1:33pm
Apollo11. you are correct. It's been so long since I had anything to do with these I completely forgot about the red dot. I just had a look at my battery and there on a sticker in clear sight is a diagram showing that. Doh!

No red dot, bugger!
franc123, Oct 4, 8:54pm
Even in a good battery the open voltage wont stay at those levels for very long even if its disconnected, it's entirely normal for it to stabilise around 12.55-12 70V and maintain that level after charging. If it was dropping below 12.4V after say a week with no load then that would be more of a concern.
marte, Oct 4, 9:44pm
If it's just a low acid level in the one cell that the indicators on.
What's a good method to level up the acid levels in all of the cells?

( Tipping it upside down & then back up could be problematic since it's going to generate gas, then pressurise it, then squirt out acid out of the vent tube. Obviously )
elect70, Oct 9, 9:37pm
Ive learnt the hard way that soon as battery starts giving problems replace it esp if its over 3 years old . Century worst
s_nz, Oct 9, 10:16pm
Only top up lead acid batteries with distilled / de-ionised water.

Never tilt or poor out the acid.

The only circumstance you should add acid to a battery cell is if acid has been split from the battery. Of course it is quite hard to get your hands on small quantities of Sulphuric acid, and it's kinda dangerous, so might be best left to the Pro's.
ronaldo8, Nov 8, 5:46pm
A 0.17 volt drop is nothing. Even a small drop in temperature will do that. When you parked it it was still warm. Im suprised it only dropped that much.