How To Read Vehicle Battery Condition

[sahan84]

I have a question of how to read the battery condition.In my car it has (EX*D ) NS 40 ZL and on the top it says if it is Green - Good

Red - Need replace/charge like wise (I cannot remember all what was there)

There is condition tester also with 2 small green and red color balls inside it.But how can I decide whether the condition of the battery?

[Nishan.dj]

For what I know;

Green : Good

White : Recharge

Red : Replace

But I don't think you should trust 100% of what that inbuilt meter says. To see the actual condition, you need a volt meter basically to test.

If your battery is in 12V-14V range, at low load, it is good. When load comes, it is normal to reduce voltage but it should not be below 12V. Test with AC, Stereo and Lights on in your vehicle.

Also plug the volt meter and see how much it drops by the time you start the engine. That will give you an idea of how good or bad your battery is.

Hope this helps.

[sahan84]

Thanks..Nishan

[Rumesh88]

What Nishan.dj has given above is correct except that the indication Red does not necessarily mean to Replace but may indicate a low acid level. If it is a Ex*de battery easiest thing to do is taking your vehicle to one of their service centers like the one near Thimbirigasyaya traffic lights and they will simply do the needful for free (unless of course your battery needs replacing).

[sathyajithj99]

and also ex#de has battmobile that would reach to you

[luckey007]

The "Magic eye" is just a compact and specified hydrometer. There is a neck in transparent glass tube, the color in it reflects to the top. when you look from the top you can see the color. Then small two differently colored and weighted [of course density] small balls placed and they go up and down according to the electrolyte level[red] or the concentration[green]. So it is not a silver bullet.

And the second fact, it only measures one cell. So we assume other cells also in the same condition. But sometimes it may be not so.

For proper assessment you need a voltmeter/multimeter and a hydrometer.

[zaradiyel]

For what I know;

Green : Good

White : Recharge

Red : Replace

But I don't think you should trust 100% of what that inbuilt meter says. To see the actual condition, you need a volt meter basically to test.

If your battery is in 12V-14V range, at low load, it is good. When load comes, it is normal to reduce voltage but it should not be below 12V. Test with AC, Stereo and Lights on in your vehicle.

Also plug the volt meter and see how much it drops by the time you start the engine. That will give you an idea of how good or bad your battery is.

Hope this helps.

Hi,

To add a few, voltmeter testing won't give the best idea.Sometimes it may give satisfactory voltage but still would fail to crank.[personal experience].

Best to check with a Load Tester.However before connecting the Load Tester the battery should be fully charged .

This is what we do for ships' lifeboats to check for any battery drain issues.Hopefully this will enhance your knowledge along with the others' opinions.

Plus use the Hydrometer to measure the Specific Gravity of the Electrolyte.On the meter the correct value should be in the Green range.[This test is not applicalble for fully sealed batteries].All cells to be checked.The electrolyte level should be well visible when you see from top after removing the knob.The knob for each cell is with an opening to let out gasses [Hydrogen] produced.

If the value is above the green zone you can add Distilled water to bring it down,if its low you should take it to a battery shop.

Good luck

Edited March 29, 2015 by zaradiyel

[Nishan.dj]

Hi,

To add a few, voltmeter testing won't give the best idea.Sometimes it may give satisfactory voltage but still would fail to crank.[personal experience].

Best to check with a Load Tester.However before connecting the Load Tester the battery should be fully charged .

This is what we do for ships' lifeboats to check for any battery drain issues.Hopefully this will enhance your knowledge along with the others' opinions.

Plus use the Hydrometer to measure the Specific Gravity of the Electrolyte.On the meter the correct value should be in the Green range.[This test is not applicalble for fully sealed batteries].All cells to be checked.The electrolyte level should be well visible when you see from top after removing the knob.The knob for each cell is with an opening to let out gasses [Hydrogen] produced.

If the value is above the green zone you can add Distilled water to bring it down,if its low you should take it to a battery shop.

Good luck

Very valuable information.

Even if a battery shows the correct voltage doesn't mean that it has the full capacity.

Although it is not the best way, I get the battery's ability to provide the load simply by monitoring how much volt it drops by the time it crank.

Ebay has pluggable volt meters for very cheaper price and anyone using it can get a general idea of the battery.

Though it is not advised as a good practice, I practically have seen fixing batteries by flushing and adding new acid into it. And had gained extra 1 to 2 years of life span extended.

[Rumesh88]

Use of a hydrometer and load tester could be beyond the means of an average user. Moreover, if you have a sealed battery then a hydrometer is of no use at all. However, in addition what others have mentioned above there is another simple test that you can do to monitor the health of your battery (and part of the alternator) with a simple digital voltmeter having 2V AC measurement range. Get the engine running at 2000 RPM with headlights and AC switched on, and measure the ripple AC voltage between the battery terminals. Although the measurements vary between different set ups, generally you should get a reading of less than 100mv AC ripple voltage. Lower the value better the set up (unless of course your alternator is totally busted and fail to produce any charging current at all in which case the ripple will be zero!). If you benchmark the ripple voltage value after installing a new battery and keep monitoring it over the life of the battery you will notice a gradual increase in the ripple voltage. Any sudden jump like to 500mV may indicate a fault with the alternator - most common being a open circuit diode, or a battery gone beyond its serviceable life. While the values are not absolute (may vary between the meters, particularly if you use a more expensive true RMS meter) and given for guidance only, this method provides a another means of monitoring to supplement the methods discussed above.

[Nishan.dj]

Use of a hydrometer and load tester could be beyond the means of an average user. Moreover, if you have a sealed battery then a hydrometer is of no use at all. However, in addition what others have mentioned above there is another simple test that you can do to monitor the health of your battery (and part of the alternator) with a simple digital voltmeter having 2V AC measurement range. Get the engine running at 2000 RPM with headlights and AC switched on, and measure the ripple AC voltage between the battery terminals. Although the measurements vary between different set ups, generally you should get a reading of less than 100mv AC ripple voltage. Lower the value better the set up (unless of course your alternator is totally busted and fail to produce any charging current at all in which case the ripple will be zero!). If you benchmark the ripple voltage value after installing a new battery and keep monitoring it over the life of the battery you will notice a gradual increase in the ripple voltage. Any sudden jump like to 500mV may indicate a fault with the alternator - most common being a open circuit diode, or a battery gone beyond its serviceable life. While the values are not absolute (may vary between the meters, particularly if you use a more expensive true RMS meter) and given for guidance only, this method provides a another means of monitoring to supplement the methods discussed above.

Thanks for such a great detailed reply.

Question:

"Get the engine running at 2000 RPM with headlights and AC switched on, and measure the ripple AC voltage between the battery terminals."

Why is that particular RPM?

Is if for both petrol and diesel engines?

Thanks.

[Rumesh88]

Thanks for such a great detailed reply.

Question:

"Get the engine running at 2000 RPM with headlights and AC switched on, and measure the ripple AC voltage between the battery terminals."

Why is that particular RPM?

Is if for both petrol and diesel engines?

Thanks.

That is the RPM given in most repair manuals to check the charging system. At this speed the alternator should provide enough charging power to keep the battery charged while supplying the maximum steady load (that is why we have to have the headlights and AC on). It is applicable to both petrol and diesel engine. In case if you don't have a RPM meter you may just rev up and keep it steady until the meter reading becomes stable.

[Nishan.dj]

That is the RPM given in most repair manuals to check the charging system. At this speed the alternator should provide enough charging power to keep the battery charged while supplying the maximum steady load (that is why we have to have the headlights and AC on). It is applicable to both petrol and diesel engine. In case if you don't have a RPM meter you may just rev up and keep it steady until the meter reading becomes stable.

Isn't the alternator providing enough charging power at idle speed? Normally diesels it is 600-700RPM (Correct me if wrong)

If the alternator doesn't provide the load it needs at engine idle time, We will have an issue in case if we keep the AC and Headlights on for some time when the engine is idle. Isn't it?

[Rumesh88]

Isn't the alternator providing enough charging power at idle speed? Normally diesels it is 600-700RPM (Correct me if wrong)

If the alternator doesn't provide the load it needs at engine idle time, We will have an issue in case if we keep the AC and Headlights on for some time when the engine is idle. Isn't it?

At idle speed with full electrical loads you would not get enough power from the alternator to charge the battery. However, in vehicles with speed compensation for headlights and/or AC, this could be marginally achieved. But as a general practice you need to bring the revs up to 2,000 before taking measurements. If you read the charging voltage (let's say 14.0V) at this RPM with full load, then compare with the value at idle (something like 13.6 V) you will always see a difference.

[Nishan.dj]

At idle speed with full electrical loads you would not get enough power from the alternator to charge the battery. However, in vehicles with speed compensation for headlights and/or AC, this could be marginally achieved. But as a general practice you need to bring the revs up to 2,000 before taking measurements. If you read the charging voltage (let's say 14.0V) at this RPM with full load, then compare with the value at idle (something like 13.6 V) you will always see a difference.

It means that if the full load is needed at idle it gets from the battery? In such cases for a longer time (Assuming the engine is idle for some time while the vehicle is not in motion) the battery will get discharged and will have problems. Is it so?

[Rumesh88]

It means that if the full load is needed at idle it gets from the battery? In such cases for a longer time (Assuming the engine is idle for some time while the vehicle is not in motion) the battery will get discharged and will have problems. Is it so?

To be very precise the load gets a portion of the current from the battery and the rest from alternator. Regardless of the size of the portion, the battery will discharge to the point when all of the current is supplied by the alternator (Remember, these two are electrical sources connected in parallel) . This point can be anything from, for example, 13.6V(may be 10% discharged) to 10.5V (may be 70% discharged) or even beyond. The point depends on many factors such as the design and idle RPM but the fact is that if you leave vehicle with all electrical loads switched on while engine on idle your battery will not be fully charged at any given time.

[Nishan.dj]

To be very precise the load gets a portion of the current from the battery and the rest from alternator. Regardless of the size of the portion, the battery will discharge to the point when all of the current is supplied by the alternator (Remember, these two are electrical sources connected in parallel) . This point can be anything from, for example, 13.6V(may be 10% discharged) to 10.5V (may be 70% discharged) or even beyond. The point depends on many factors such as the design and idle RPM but the fact is that if you leave vehicle with all electrical loads switched on while engine on idle your battery will not be fully charged at any given time.

If we can increase the alternator RPM related to the engine idle (Ex: pulley conversion - http://gadi.agric.za/software/renting/pulley_calc.php), is it possible to keep the batteries fully charged? If so what would be the common (regardless of the engine model or any fact) RPM which the alternator should meet?

[Rumesh88]

If we can increase the alternator RPM related to the engine idle (Ex: pulley conversion - http://gadi.agric.za/software/renting/pulley_calc.php), is it possible to keep the batteries fully charged? If so what would be the common (regardless of the engine model or any fact) RPM which the alternator should meet?

Feasibility depends on the vehicle in question. You cannot find a ballpark RPM figure common to all. What you can do is when the battery in fully charged condition measure the battery voltage at 2000 RPM at full load (let's say it is 14.0V). Then bring the revs down to 1500 and see if it still retains 14.0V. Go on reducing the RPM by 100 each time and get the minimum value that can hold 14.0V steady. If that is 1300 RPM and your idle speed is 1000 then you need a pulley conversion to boost the RPM by 30%. What it means is that you must change the dimension of the pulley by 30% which may not be practically possible. Even when you do that it would not charge the battery but simply keep the existing charge as it is.

BTW out of curiosity, may I ask the why you need to keep a vehicle in idle for an extended period of time with both headlights and AC switched on?

[Nishan.dj]

Feasibility depends on the vehicle in question. You cannot find a ballpark RPM figure common to all. What you can do is when the battery in fully charged condition measure the battery voltage at 2000 RPM at full load (let's say it is 14.0V). Then bring the revs down to 1500 and see if it still retains 14.0V. Go on reducing the RPM by 100 each time and get the minimum value that can hold 14.0V steady. If that is 1300 RPM and your idle speed is 1000 then you need a pulley conversion to boost the RPM by 30%. What it means is that you must change the dimension of the pulley by 30% which may not be practically possible. Even when you do that it would not charge the battery but simply keep the existing charge as it is.

BTW out of curiosity, may I ask the why you need to keep a vehicle in idle for an extended period of time with both headlights and AC switched on?

Your explanation is highly appreciated. (Probably the best answer I had for this matter so far)

The story is this.

It's a 1974 j44 jeep that I restored to the best possible. I mean not as an extremely off road but somewhat in between.

So I fixed a dual air conditioning (not myself but I got it done) and found that the power it needs is more than the alternator can produce. So the stator was changed and an IC regulator was added. Also changed the pully so that it gets high RPM. I know that this is not the best way but somewhat successful. Also I fixed an idle up switch (again not by myself but got it done). It gives a bit more high RPM and avoid vibration which comes with the high load at idle.

The only problem having is that the insufficient production of the current at idle speed.

Solution was to fix a new high capacity alternator which I discussed on this forum as well but didn't get time to spend for that.

So I have seen higher capacity custom made alternators and also recondition ones such as 4HF1 engines alternators.

Thinking of doing it when I get time.

The reason I asked about idle time production is clear to I think.

It is also an interesting topic.

[Rumesh88]

Your explanation is highly appreciated. (Probably the best answer I had for this matter so far) The story is this. It's a 1974 j44 jeep that I restored to the best possible. I mean not as an extremely off road but somewhat in between. So I fixed a dual air conditioning (not myself but I got it done) and found that the power it needs is more than the alternator can produce. So the stator was changed and an IC regulator was added. Also changed the pully so that it gets high RPM. I know that this is not the best way but somewhat successful. Also I fixed an idle up switch (again not by myself but got it done). It gives a bit more high RPM and avoid vibration which comes with the high load at idle. The only problem having is that the insufficient production of the current at idle speed. Solution was to fix a new high capacity alternator which I discussed on this forum as well but didn't get time to spend for that. So I have seen higher capacity custom made alternators and also recondition ones such as 4HF1 engines alternators. Thinking of doing it when I get time. The reason I asked about idle time production is clear to I think. It is also an interesting topic.

I get it now. http://forum.autolanka.com/topic/15819-getting-more-power-from-alternator/

Although the system is 24V still the same theory applies with figure multiplied by two. In your case I do not think you have many options except going for an upgrade. If you can get hold of a clip-on DC ammeter, get the load measurements for AC unit and headlights to confirm that your intended upgrade is capable of handling the load.

[Nishan.dj]

I get it now. http://forum.autolanka.com/topic/15819-getting-more-power-from-alternator/

Although the system is 24V still the same theory applies with figure multiplied by two. In your case I do not think you have many options except going for an upgrade. If you can get hold of a clip-on DC ammeter, get the load measurements for AC unit and headlights to confirm that your intended upgrade is capable of handling the load.

Could you comment on the following text please?

Min. Alternator Continuous Duty Output Amps

(At your planned operating speed)

=

Maximum Vehicle Electrical Load

(for vehicles, typically, 40% of max stock alternator output amps.)

+

50% of Total Battery Bank Capacity

(in Amp-Hours -- NOT cold cranking amps)

+

Average Current Required to Supply Non-Stock Loads

(http://www.zena.net/htdocs/alternators/alt_inf2.shtml)

Is it practical to use this formula to measure the alternator?

Edited March 31, 2015 by Nishan.dj

[Rumesh88]

@Nishan.dj - You can use the formula but the Maximum Vehicle Electrical Load is an unknown in your case. This is why I advised you to get it measured. For 50% of Battery Capacity parameter you can take 35A (Assuming you have two 70Ah batteries). For the last parameter you can leave a headroom like 10-20A unless you have some kind of exotic audio set up.