A friend has just been given an invalid chair. I suspect the battery is at fault as it appears not to be working after a 3 hour charge.I have the usual DIY meters for measuring voltage, continuity etc., is it possible to do a basic test to see if the battery is OK with these, if not what do I need.
Invalid Chair Battery Testing
- Thread starter yottie
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Three hours isn't very long if it was flat.
Measure the voltage of the battery. What is it compared with the nominal voltage?
If it is above the nominal voltage, measure it when you switch on the chair. What does it go down to?
Measure the voltage of the battery. What is it compared with the nominal voltage?
If it is above the nominal voltage, measure it when you switch on the chair. What does it go down to?
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I would assume if given it, not used for some time, I have found it can take 11 days to recharge if left flat for an extended time, and still recover it seems fully.
I am assuming lead acid, the sulphur from the acid can go hard over time, and only way to get the sulphur back into the electrolyte is a long charge. The worry is if one cell goes short circuit then other cells will over charge, if this happens then you get a bad egg smell, hydrogen sulphide, with a dedicated charger you can't connect it wrong way around, but with a standard smart charger to stop you connecting wrong way around it measures the voltage so if the battery is over discharged it will not charge.
So if the charger is a standard charger with a dedicated plug it may fail to charge.
If they fail to charge there are two methods, well in essence they do the same, a power supply or a good battery in parallel, either way we are putting a voltage on the battery for an extended time. The voltage does not need raising, it just takes time.
I seem to remember there was a problem with my mothers caused by lack of use, and the firm looking after it simply swapped the batteries, but I would guess they then put them on charge using a power supply or similar.
The mobility scooter fried a battery due to a cell failing in the other battery of the pair. This
was the result, however likely would have needed a pair anyway can't really put a new and old battery together.
I am assuming lead acid, the sulphur from the acid can go hard over time, and only way to get the sulphur back into the electrolyte is a long charge. The worry is if one cell goes short circuit then other cells will over charge, if this happens then you get a bad egg smell, hydrogen sulphide, with a dedicated charger you can't connect it wrong way around, but with a standard smart charger to stop you connecting wrong way around it measures the voltage so if the battery is over discharged it will not charge.
So if the charger is a standard charger with a dedicated plug it may fail to charge.
If they fail to charge there are two methods, well in essence they do the same, a power supply or a good battery in parallel, either way we are putting a voltage on the battery for an extended time. The voltage does not need raising, it just takes time.
I seem to remember there was a problem with my mothers caused by lack of use, and the firm looking after it simply swapped the batteries, but I would guess they then put them on charge using a power supply or similar.
The mobility scooter fried a battery due to a cell failing in the other battery of the pair. This
was the result, however likely would have needed a pair anyway can't really put a new and old battery together.Sponsored Links
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With a smart charger that is one which is designed to work with valve regulated lead acid or absorbed glass mat, (VRLA, AGM) the power in is a reflection of the power out, so a energy meter on the socket will show what the charger is doing. An example 
this shows a 12 volt battery being charged with a Lidi smart charger where it starts at 3.8 amp, then 3 amp, then a long time at 0.8 amp, it will in fullness of time drop to 0.1 amp. With the use of a energy meter wifi connected to my PC, I can see without going to the charger how it is doing, at the moment my wife's Jaguar is on charge and I can check it from my bedroom.
This was an eye opener for me, over the years as an auto electrician I have worked with many batteries, and have tried to revive them, with some success, however I now realise it was not all the work I did trying to get them to come up, it was simply time, I would say two weeks on a power supply or smart charger before you say battery is US.
But the problem is if there is a shorted cell, when the battery recovers a large charger can over charge the battery, the blown battery shown was on a 4 amp 24 volt charger, and it is a 36 Ah AGM battery. Smell would have alerted there was a problem, but on charge in a garage seldom used. And in the outer case as fitted on the mobility scooter could not see the damage.
The computer showed the sulphated battery recovered as if a switch had been clicked, it sat for 11 days doing nothing, I had a good battery and sulphated battery in parallel to get charger to work, so it showed the charging of good battery when first put on charge, then nothing, and then within an hour after 11 days went to full charge rate 0.8 amp, stayed there for around AH/0.8 hours, then down to 0.1 amp and using it seems OK, they worked a stair lift. Same done again with a caravan leisure battery.
The beauty of the Lidi charger is once it has gone through the 3.8A and 3A stage, it will not auto return, so maximum charge rate 0.8 amp, so even if there was a bad cell, it would not charge at too high a rate.
A 12 volt battery should show over 12 volt, after charge it will quickly drop to 12.8 volt, at 12.4 volt time to put back on charge, the charge voltage depends on the charger, for a VRLA or AGM the voltage is normally limited to 14.4 volt at which point smart chargers will drop charge rate. Most wheel chair and mobility scooter chargers are stage chargers, the idea is to bang in the charge when flat, but reduce the charge rate as the battery approaches the 80% charged point. So with a fully charged 12 volt battery left on charge, it will sit at around 12.8 to 12.9 volt, as it drops to 12.7 volt the charger will auto switch on, the battery will hit 14.4 volt very quickly, and then charger will switch off again. Typical patten
.
this shows a 12 volt battery being charged with a Lidi smart charger where it starts at 3.8 amp, then 3 amp, then a long time at 0.8 amp, it will in fullness of time drop to 0.1 amp. With the use of a energy meter wifi connected to my PC, I can see without going to the charger how it is doing, at the moment my wife's Jaguar is on charge and I can check it from my bedroom.This was an eye opener for me, over the years as an auto electrician I have worked with many batteries, and have tried to revive them, with some success, however I now realise it was not all the work I did trying to get them to come up, it was simply time, I would say two weeks on a power supply or smart charger before you say battery is US.
But the problem is if there is a shorted cell, when the battery recovers a large charger can over charge the battery, the blown battery shown was on a 4 amp 24 volt charger, and it is a 36 Ah AGM battery. Smell would have alerted there was a problem, but on charge in a garage seldom used. And in the outer case as fitted on the mobility scooter could not see the damage.
The computer showed the sulphated battery recovered as if a switch had been clicked, it sat for 11 days doing nothing, I had a good battery and sulphated battery in parallel to get charger to work, so it showed the charging of good battery when first put on charge, then nothing, and then within an hour after 11 days went to full charge rate 0.8 amp, stayed there for around AH/0.8 hours, then down to 0.1 amp and using it seems OK, they worked a stair lift. Same done again with a caravan leisure battery.
The beauty of the Lidi charger is once it has gone through the 3.8A and 3A stage, it will not auto return, so maximum charge rate 0.8 amp, so even if there was a bad cell, it would not charge at too high a rate.
A 12 volt battery should show over 12 volt, after charge it will quickly drop to 12.8 volt, at 12.4 volt time to put back on charge, the charge voltage depends on the charger, for a VRLA or AGM the voltage is normally limited to 14.4 volt at which point smart chargers will drop charge rate. Most wheel chair and mobility scooter chargers are stage chargers, the idea is to bang in the charge when flat, but reduce the charge rate as the battery approaches the 80% charged point. So with a fully charged 12 volt battery left on charge, it will sit at around 12.8 to 12.9 volt, as it drops to 12.7 volt the charger will auto switch on, the battery will hit 14.4 volt very quickly, and then charger will switch off again. Typical patten
.
