Lead acid battery testers?

[ericmark]

At work the electrician has a battery tester which prints out a sheet showing what is wrong with the battery. In the main I simply did not question the results, however we use in the main AGM batteries for the carriage lights, which are used at the beer festival and Father Christmas trains, so no heavy load, and can easy be missed at to getting them recharged.

So I have put batteries on charge, and they have been good enough to start a generator, but have been previously shown as US with the battery tester. In the main I visit once a week, every Wednesday, so I have been using a small Lidi charger 3.8 amp, which will auto turn off once battery charged (14.4 volts), and back on should the battery voltage fall below 12.8 volt. And since only there once a week, either 1 or 2 weeks on charge, then charger moved to next battery.

But it seems we are scrapping good batteries, because of this fancy battery tester, except for an emergency, these batteries do not start engines, they are used only for lights.

 

[Harry Bloomfield]

I have yet to find a reliable way, to be sure of the state of batteries. This year alone, I've been well and truly fooled, by two LA batteries....

1. One of the pair of stair lift batteries, four years ago, totally went flat[1}, due to a discharge, and no charge. I replaced the single battery, with one from an older pair[2], which kept it going these past few years, whilst occasionally putting the removed dead battery on charge. [2] recently failed completely, so with little expectation, I replaced it with [1]. [1] has worked just fine, for several months now.

2. My tractor's starter battery, was totally flat, at the start of this years grass cutting season. Force charging it, by starting it with a good LA in parallel, it showed no sign of recovery. In desperation, and temporarily, I refitted it and it just managed to crank it over. Yet since then, it seems to have almost fully recovered - stands for weeks unused, and still cranks it over just fine.

Both batteries with a fancy tester, were shown as beyond redemption.

3. The caravan's battery gave out, when using the mover, a few weeks ago. Testing it with the fancy tester, it correctly indicated the need for a replacement, so that was replaced with new.

You type in the variety of battery, the capacity, then it tests it with a fairly low current draw. It can also check the alternator, displaying the output waveform, which you can check for potential problems - brushes, diodes etc., shows the batteries internal resistance, state of charge, capacity remaining, and state of health, but....

The only battery diagnostic I entirely trust, is an old fashioned, high current, volt drop, discharge tester. They make failing cells obvious.

 

[JohnW2]

I have yet to find a reliable way, to be sure of the state of batteries.

As both you and eric have said, I don't think that any of the "fancy testers" (at least, ones I have come across) are really 'fit for purpose' - and they probably result in a lot of usable batteries being chucked out (maybe they were designed by those who sell new batteries? ).

However, there is always the 'pragmatic bottom line' approach to determine the state of a battery - get it as fully charged as one can, and then see what one can get out of it during discharge?

 

[Harry Bloomfield]

However, there is always the 'pragmatic bottom line' approach to determine the state of a battery - get it as fully charged as one can, and then see what one can get out of it during discharge?

That would involve some design effort - a fixed load, a means to disconnect the load, and a mechanical, or recording timer. Alternatively, an incredible amount of patience, to sit and watch the discharge, time it, and calculate the result.

What my experience with batteries does demonstrate, is that the more you think you know about them, the less you actually know.

 

[ericmark]

About 6 months before my father-in-law died, he had in error unplugged his stair lift, unlike the Stenner, there was no option to manually wind it to a charging station, it was blocking the stairs, so new pair of batteries fitted, the old pair vanished, not to be found until his death, by that time well and truly discharged, and my Lidi smart charger will not charge a 12 volt battery if it is under 7.2 volts, as it sees it as a 6 volt battery.

So I put it in parallel with a good battery, a little nervous, as if there was a shorted cell, it could overcharge it, so plugged the Lidi battery charger into an energy monitor, so I could have a look as how it was doing on the PC.

It went 11 days, then as if someone had flicked a switch, it started to charge and went through the whole sequence, and seemed not the worse for wear. Repeated with other battery of the pair, and same result.

Since an apprentice, I had considered a battery with a voltage under 11 volt, as scrap, that was clearly wrong, however to commercially charge batteries needing over 24 hours to recover, was not really an option. But from the day of the first sealed for life battery, there has been a problem testing. Be it brown electrolyte, one cell bubbling, or wildly different sg readings across the cells, and you knew it was dud. But when sealed, does 11 volt mean shorted cell, or simply a discharged battery?

I remember the problem, returned battery as faulty, and if when it got back to Exide no fault found other than being discharged, then no warranty payment. So we had a second hand battery, which we could do nothing with, so a battery tester was required.

In the main, wanted something where we could show the punter the results, and say sorry this battery is showing as simply discharged, we can't change it under warranty. And we had a Bosch battery tester that looked more like a battery charger, and its computer measured how fast the volts recovered after putting it under load. It had a pair of jump lead like cables, and the load was applied by pressing a button, so no sparks to ignite hydrogen gas. The old Durite battery tester, was banned as they could cause an explosion, seems HSE would no longer allow their use, but the new testers became smaller and smaller, but I had no reason to question what they reported, if it said battery needs charging, then that's what needed to happen, it was a pain explaining that if the machine said battery simply discharged, then we could not replace under warrantee, this was not a problem if it came still in the car, if the car was charging, and battery showed as discharged, we assumed it was faulty, the problem in the main was the leisure battery from a caravan, which could be either simply discharge, or baked with a faulty battery charger, but the latter would be a faulty battery, so we were not worried.

I found my mothers Stenner stair lift was over charging batteries, if used 4 times a day or more, then no problem, but the charger was rather basic, and if the lift was not used, it would overcharge the batteries, I measured over 30 volt across the pair, used every day, batteries would last about 4 years, used once in a blue moon, and batteries failed within 2 years.

These look the part, and not cheap, but not sure I trust them any more?

 

[Harry Bloomfield]

About 6 months before my father-in-law died, he had in error unplugged his stair lift, unlike the Stenner, there was no option to manually wind it to a charging station, it was blocking the stairs, so new pair of batteries fitted, the old pair vanished, not to be found until his death, by that time well and truly discharged, and my Lidi smart charger will not charge a 12 volt battery if it is under 7.2 volts, as it sees it as a 6 volt battery.

Mine is a Stannah. It has the charger at the top, and some sort of low voltage track, built into the back of the track, so no matter where stopped, it can charge. The charger is nowhere near adequate to supply the running current of the lift, in use the batteries provide the current, then when not in use they recharge.

In wrecking one battery, what I found was that part of the control system uses the 24v, of the two 12v batteries in series, but part of it uses just 12v from one of the batteries - basically unbalanced load.. Rather poor design, for best battery life.

 

[SUNRAY]

I have yet to find a reliable way, to be sure of the state of batteries. This year alone, I've been well and truly fooled, by two LA batteries....

1. One of the pair of stair lift batteries, four years ago, totally went flat[1}, due to a discharge, and no charge. I replaced the single battery, with one from an older pair[2], which kept it going these past few years, whilst occasionally putting the removed dead battery on charge. [2] recently failed completely, so with little expectation, I replaced it with [1]. [1] has worked just fine, for several months now.

2. My tractor's starter battery, was totally flat, at the start of this years grass cutting season. Force charging it, by starting it with a good LA in parallel, it showed no sign of recovery. In desperation, and temporarily, I refitted it and it just managed to crank it over. Yet since then, it seems to have almost fully recovered - stands for weeks unused, and still cranks it over just fine.

Both batteries with a fancy tester, were shown as beyond redemption.

3. The caravan's battery gave out, when using the mover, a few weeks ago. Testing it with the fancy tester, it correctly indicated the need for a replacement, so that was replaced with new.

You type in the variety of battery, the capacity, then it tests it with a fairly low current draw. It can also check the alternator, displaying the output waveform, which you can check for potential problems - brushes, diodes etc., shows the batteries internal resistance, state of charge, capacity remaining, and state of health, but....

The only battery diagnostic I entirely trust, is an old fashioned, high current, volt drop, discharge tester. They make failing cells obvious.

And of course the only tester which gives very obvious reliable results are now not permitted.

I use LA batteries for portable public address and radios uses. Initially standard car batteries as we had an unused second hand source. (I had 16 95Ah at one time). When that source dried up I started buying leisure batteries 2 80Ah followed by 2 115Ah have kept me going for around a decade. Initially I only used 6 cheap simple chargers (which took a fair amount of planning during the summer months). I have always used an ACT battery tester which indicates the state of charge with an Ah reading... very misleading results but useful as a guide. I currently leave those 4 batteries on permanent charge with LIDL 'smart' chargers but I'm not convinced they keep the batteries in ideal condition. The batteries current ly return condition as 30-40Ah but in reality I occasionally a pair of 10W LED floodlights overnight for camping on a dusk to dawn sensor and a battery will run for a full week. (I guess around7-8 hours per night for 8 nights so around 84Ah but bear in mind the LEDs will happily run at sub 12V levels).
Recently 2 of the batteries have shown as 'volts too low' and appear to be 5 cells using DMM but a quick 1hr charge with a basic charger brings it up enough for the smart charger to take over again.

Historically I used to use 200W of lights (4xMR16 50W) and monitor the voltage every 15 minutes until reaching 12V which was usually around 4-6 hrs (~32-40Ah) but I haven't done that for years... perhaps I should start again?

 

[JohnW2]

That would involve some design effort - a fixed load, a means to disconnect the load, and a mechanical, or recording timer. Alternatively, an incredible amount of patience, to sit and watch the discharge, time it, and calculate the result.

It was the latter I was thinking about, and there is not necessarily any 'calculation' to do - as I wrote,it's a 'pragmatic' approach, and one will often merely need to know whether it can do what one wants it to do. For example, if (per Sunray) one wanted it to be able to supply 200W for 4-6 hours, one could simply go away and come back 4 hours later and see whether the light (or whatever) was still working, and what the voltage was.

.... Historically I used to use 200W of lights (4xMR16 50W) and monitor the voltage every 15 minutes until reaching 12V which was usually around 4-6 hrs (~32-40Ah) but I haven't done that for years... perhaps I should start again?

Maybe you should - and it would be far from beyond the wit of man (or you, Sunray or myself) to 'automate' that (precluding need for looking every 15 mins), such that the time taken for the voltage to fall to 12V (or whatever) was recorded.

 

[Harry Bloomfield]

I use LA batteries for portable public address and radios uses. Initially standard car batteries as we had an unused second hand source. (I had 16 95Ah at one time).

The modern replacement, less abuse sensitive, seems to be Lithium, or safer/heavier LiFePo4.

My best life for LA, seems to be achieved by just giving them a regular, short boost charge. 20 minutes per day, for the car, once every month or two for the caravan's 120ah battery.

I found my mothers Stenner stair lift was over charging batteries, if used 4 times a day or more, then no problem, but the charger was rather basic, and if the lift was not used, it would overcharge the batteries, I measured over 30 volt across the pair, used every day, batteries would last about 4 years, used once in a blue moon, and batteries failed within 2 years.

The modern ones have much better, more controlled chargers.

 

[ericmark]

The Lidi Smart charger seems to have evolved, early one no display 3.8 amp, then came with a volt meter, also 3.8 amp, and then a 5 amp version.

The early versions would not return to 3.8 amp or even 3 amp, think from memory would flit between 0.8 amp and 0.1 amp for high AH range and to zero with low AH range so it would charge to 14.4 volt (14.8 in cold mode) then drop to 0.1 amp until voltage dropped to 12.8 volt. The problem was if the battery would not reach 14.4 volt at 0.8 amp, when it could hold the battery at a high voltage for an extended time.

The 5 amp version would return to a higher amps, so unlikely to hold at a high volts in the same way. But they were cheap, around £14 I seem to remember.

 

[SUNRAY]

The Lidi Smart charger seems to have evolved, early one no display 3.8 amp, then came with a volt meter, also 3.8 amp, and then a 5 amp version.

The early versions would not return to 3.8 amp or even 3 amp, think from memory would flit between 0.8 amp and 0.1 amp for high AH range and to zero with low AH range so it would charge to 14.4 volt (14.8 in cold mode) then drop to 0.1 amp until voltage dropped to 12.8 volt. The problem was if the battery would not reach 14.4 volt at 0.8 amp, when it could hold the battery at a high voltage for an extended time.

The 5 amp version would return to a higher amps, so unlikely to hold at a high volts in the same way. But they were cheap, around £14 I seem to remember.

Ah (Not Ampere/hour) that may be a point, these 4

are certainly of different ages and the screens do display differently, I have another unused pair too, must have a look at the instructions.

 

[chivers67]

I use a Hioki at work to test the battery impedance(s). If the batteries are over 7.5mohm we replace them as they can't always produce enough current for the UPS to run for very long.

 

[SUNRAY]

I use a Hioki at work to test the battery impedance(s). If the batteries are over 7.5mohm we replace them as they can't always produce enough current for the UPS to run for very long.

Let me have the batteries when you reject them

 

[morqthana]

But they were cheap, around £14 I seem to remember.

Bit cheaper than a CTek!

 

[ericmark]

Ctek do a whole range of chargers, up to 25 amp designed for caravans and boats. In the main they will return to full output if the battery becomes discharged, this is a duel edged sword, as although it means used in a caravan it can replace the built in battery charger, on the other hand, if a cell goes short circuit it can over charge the battery, where the Lidi 3.8 amp would only go to 0.8 amp charge.

The main point with the Lidi charger was connect and forget. It also auto detects 6 or 12 volt, so unlike the Ctek where a battery can show 3 volt and still charge, a 12 volt battery must be around 7.5 volt to charge. Also you have to press a button on the Lidi, if there is a power cut, it will not resume once power is returned. But it does display the volts of the battery.