In general, how much faith can be put in these indicators?
I have a 'maintance free' battery which performs fine but the 'Green' indicator does not appear. The window appears dark indicatiing that the battery needs charging according to the legend, but after driving around 40miles this indication shows no change?
I am concerned that come winter the battery will not cope.
How do these indicators work?
What battery tests should be done to get its real state.
I have just acquired the car and am wondering wether to demand a replacement battery or not?
All comments, especially those based on experience are welcome.
Regards
WBD
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From memory the "green" is a float that goes higher up a tube depending on the state of charge. I've never seen a battery with an indicator that didn't eventually go green - even a dying one that was about to give up had the green showing. My experience is limited to about 5 Delco Freedom batteries over the years. You may have very low battery fluid so the float can't get high enough to show the green although the battery will normally show white if it is very low. Most Quick Fit tyre places can test a battery for you.
With regard to driving it to charge it up - a very discharged battery once took me 3 solid days of careful trickle charging with a battery charger to go back to green so 40 miles probably won't charge it enough.
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wbd
Leave it a bit and see if it changes after a week's running. If it's been sitting before sale, the battery likely will be a bit down and will need up to 40 hours of driving to reach a reasonably-charged level. For something that costs a few pence; [the indicator is just a little floating ball of precise SG plastic] they're fairly accurate at showing the charge-state of the acid - nothing more.
Despite wild claims; there's no currently-available product that can quickly and reliably assess the actual condition of a battery. If the indicator re-floats after a while; your battery then has the same chance as any other of lasting five more years - or five more minutes.
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the glass window is dirty
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TourVanMan TM < Ex RF >
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Take what the built in hydrometer says with a pinch of salt. They only measure one cell anyway, and a 12 volt battery has 6 of them.
To test your battery yourself do the following first thing in the morning BEFORE the engine has been run:
1. Make sure all electrical loads are switched off and measure initial battery voltage. It should be around 12.6V. If it's less than 12.2V the battery is in a discharged state and you may be looking at replacing it.
2. Disconnect engine speed sensor, fuel injectors or make other arrangements so that the engine will not start. It's not a good idea to disconnect the ignition coil as fuel will still be injected and exit via the exhaust unburned.
3. Crank engine without it starting for at least 10 seconds and observe battery voltage during cranking, which should not fall below 10 volts on a petrol engine, and 9.5 volts on a diesel. More importantly the voltage should not vary by more than 0.3 volt during the time the engine is cranking and voltage has stabilised. ie. If you start cranking and measure 10.4 volts it must not fall below 10.1 volts during the 10 seconds of cranking. If it does the battery is not up to the job.
If you do this test when everything is cold, and it tests OK you can be assured the battery is in perfectly good condition. If it doesn't meet all the above it needs replacing.
It's also a good idea to check the engine earth and starter motor connections while you have a voltmeter handy. The best way to do this is by volt-drop testing them.
Connect the voltmeter between battery negative and a suitable clean point on the engine block. Crank the engine and observe voltage which must be less than 0.5 volt. If it reads more the engine earth connection is poor. Do the same test between battery positive and the starter main connection. Again you're looking for a maximum of 0.5 volt drop. Any more and you have a bad connection there. If you find problems here correct them and test the battery again.....
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Thank you all for your interest and observations.
So the green indicator is a green ball that requires a certain specific gravity of electrolyte to float in the window. albeit only for one cell. If the specific gravity is low then the ball sinks leaving the liquid surface in the window = dark?
A White appears when the electrolyte level becomes low?
I suppose that more charging may bring up the green indication, surely the vendor should have done this before delivery?.
I must admit I use this on my weekly check of the battery condition, when everything appears to be OK.
As for battery testing, the hand device provided at Central tyre (Alpha battery tester) said the battery was OK, but I was not filled with confidence.
I remember a battery tester as big flat plate and a meter between two spikes applied to the battery terminals?
Regards
WBD
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The modern battery tester takes a series of very high current pulses from the battery to assertain the internal resistance and current capability thus it's condition and indicated state of charge. I hated the old type as they used to burn a mark in the lead terminals
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The old type in practised hands could be used to prove a bad battery was good and vice versa.
It should only be used as 1 method of testing a battery.
There is no way of testing any battery correctly unless it has been fully charged, rested and topped up if needed.
A battery is a storage device and all that can be tested is how well it can store! Any test by a fast fit type operation, or even anywhere else that doesnt stablise a battery voltage first, charge it as needed, stand it, then test it, with readings at all points is only a guideline to the amount of charge it holds. No more, no less.
i would expect a proper battery test to take a minimum of 4 hours, possibly as much as 24.
if in doubt, replace it is the best advice as it is probably cheaper than a proper test!
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The batery in my vectra has one of these indicators on the battery. In all the time I've owned it I've never seen the indicator bright green. It's always been a dark green -- come winter or summer. Always starts on the button though.
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I have one of these indicators on my deep-charge liesure battery. Indicators are green-white-clear. The indicators work just fine although they can be difficult to see at times.
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