This is interesting for those of a geeky disposition

[wildebus]

I've watched this guys videos in the past and then he disappeared off youtube for a few years - https://www.youtube.com/channel/UCVktNhxFTBnrLfeIe1tdgSQ
He does some interesting tests and experiments and can be well worth a watch if you fancy something a bit different and technical.

He is back again and has a couple of new videos on Battery Desulfation which I found a little intriging, especially putting in 30V into a 12V battery (not something that is often done as far as I am aware and I certainly have not done so before).
Now before posting the link, I am going to make the following statement...

I am not recommending anyone repeat or copy what is shown in this video.
Anyone deciding to do a similar thing is responsible for their own actions.​

So this is the video and the results he got are pretty impressive

In my motorhome I replaced the original pair of 100Ah AGM Batteries with 3 x 100Ah Lead Carbon Batteries. I would have done this anyway for greater capacity, but the two original batteries also had very little usable capacity, probably due to sulfation.
As these two batteries were originally high quality batteries of a respected make, I am wondering maybe if I should out of interest try and resurrect them in a similar was to the video above? Might be an interesting thing to try over the winter as the only other thing I can do with the batteries is weigh them in for a few quid at the scrappers - but if they can be resurrected, they would be worth a couple of hundred quid at least by saving me the need to get some batteries for my general testing setup.

 

[jez]

Four and a half years break from YouTube? Must of got six months of his sentence for good behaviour.

 

[trevskoda]

Problem is mainly the plates start to break up and fall to bottom of battery shorting the cells out, no fix for this as such.

 

[wildebus]

Problem is mainly the plates start to break up and fall to bottom of battery shorting the cells out, no fix for this as such.

yup. this is why checking the temps is useful along the battery. Only one way to find out is that is a problem on it .....

 

[wildebus]

Put one of my 100Ah AGMs I got with the Motorhome into a battery box and stuck a SOC monitor on the setup to monitor it.
I would have liked to try sticking in a high voltage into the battery like in the video above but I don't have a variable 30A PSU like that guy does (I was actually thinking of getting one to test Solar Controllers but ones with a decent current are very pricey!)

So what I did was connect up my 20A Victron IP22 Blue Smart Mains Charger. This is by default a 14.4/14.7V mains charger, but Victron have recently (not sure when exactly) updated this unit (applied by bluetooth when you connect to it) to add more flexibility.
So while I couldn't put in a 30V level charge, I could whack in a 17.5V one! As you can see from the screenshot below, putting in a 16.7A @17.27V which is a fair charge (288W) into the battery (I think this is the maximum current the 20A charger can put out at the high voltage. 288W = 20A at 14.4V, which is the default voltage).
Will be interesting to see if this has any effect. If it ends up drying out the battery I woukldn't have lose anything other then the cost of the electricty to run the charger (I did try charging it with the Charger on the normal settings before I replaced them and it made no difference to the capacity).

 

[wildebus]

went to the shed and checked on the battery ....
Definately a bit of gassing (no surprise) and the battery was getting quite warm, but had taken in 54Ah in the time, so a fair old charge in. Turned off the charger now until tomorrow. Bit more charge and then do a discharge test to see what kind of capacity it is holding.

 

[trevskoda]

went to the shed and checked on the battery ....
Definately a bit of gassing (no surprise) and the battery was getting quite warm, but had taken in 54Ah in the time, so a fair old charge in. Turned off the charger now until tomorrow. Bit more charge and then do a discharge test to see what kind of capacity it is holding.

Are you not using a smart charger. or just doing tests.

 

[wildebus]

Are you not using a smart charger. or just doing tests.

For this process, a smart charger configured as standard would be pointless. You really need a dumb old thing to give the battery a good licking.

I am actually using a very good smart charger however - the Victron IP22 - but have configured it to push out a very high voltage.
(I don't have a dumb charger)

 

[Nabsim]

Is a dumb charger used by dumb waiters?

Sorry, couldn't resist. I will get my coat ha ha

 

[wildebus]

When the pair of these batteries were in the motorhome, I was seeing maybe 10Ah of available power from them? maybe 15Ah at a push until the system shut down due to low voltage (and low voltage on a Sargent system is something like 10V - so VERY low).

Working on just one of the batteries currently to see if I can revitalise it ....
Fair bit of time at a pretty high (for a 12V battery) voltage of 17V or so. Made the battery nice and warm and bit of gassing, but had to try it as standard charging didn't get me any more capacity back

Set up the SOC monitor for the battery to be 100Ah (that is what it is meant to be, so as good a starting point as any).
Took a photo of the monitor just after I started a discharge test ... so a few Ahs taken out as I was faffing around

Then left it running the discharge test - which was basically an inverter that fed the battery charger that was connected to the other battery, and left that until basically the inverter would either cut out due to low input voltage or the other battery took so little charge the draw would be too small for it to be a concern. (I'm expecting a voltage cutout to happen)

The monitor this morning shows the following - 35.88Ah remaining (supposedly - the monitor assumed a 100Ah battery remember) and a voltage of 11.94V.

This means that the battery actually provided 64Ah of power - which is quite remarkable compared to what I had seen it do in actual use - and a final voltage of 11.94V - which again is quite remarkable.
This is not a very scientific test, but for a new 100Ah Battery to have discharged 64Ah with a final voltage of 11.94V would be perfectly acceptable and I would be happy with that. So for THIS battery to have apparently done that is remarkable (reusing that word again, but it really is!)
( I said I was expecting a voltage cutout for the inverter, but it could well have been the other battery was as charged as it could be - say 30% losses in charger and inverter ... maybe 45Ah or so in the other battery? With the condition of these batteries, that is more than likely as much as it would take at the moment).

Makes me actually wonder if the monitor is reading correctly as the results are so remarkable surprising Think I will put a clamp meter on the cable and see if that agrees with the current the monitor is saying.

Put battery back on charge again, and again at a high (17V) intially. Maybe reduce in a few hours time depending on heat/smell? The battery is certainly getting warm but there are no specific hot spots I could detect.

Will do another discharge test after that and see what I get....

 

[Nabsim]

wouldn't (or shouldn't) the desulphate stage on a smart charger do this though Dave?

 

[wildebus]

wouldn't (or shouldn't) the desulphate stage on a smart charger do this though Dave?

It might - but would take ages, as those stages are usually limited to around 16V and for a 1 hour duration maximum.
Doing it this way is kind of doing that on steroids


Also checked the currents and the Monitor is reporting the right current (and voltage) so the Ahs (V x I) reported are correct

 

[wildebus]

This is a bit strange ....

162Ah into the 100Ah Battery!

There is the Columb efficiency that means around 1Ah for every 10Ah put in is wasted. Battery was getting pretty warm, so more energy lost through heat, but still seems much too high a charge figure?

Next stage will be to put the charger back into normal smart charger mode and see how the battery completes the charge, then put a load onto see what it can deliver.

 

[trevskoda]

I think some do this but use a timmer with off on to let the battery cool between high voltage bursts.

 

[wildebus]

I think some do this but use a timmer with off on to let the battery cool between high voltage bursts.

yup. I think I might try that with the second battery

On the discharge test I want to get a steady 5A load (so discharge at the C20 rate) and get an idea of what the battery can do.
I don't know how much it will really recover, but will just be handy to have in the shed to let me mess around with solar chargers and the like.

 

[wildebus]

Had the battery sitting not connected to anything other than the SOC meter for a few days and it was showing a decent voltage level still, which is the first basic test.

Connected the little 300W inverter and put a 240V 7W CFL light on it yesterday (those two added up to 0.9A, so close to a C100 type discharge level.
This should have meant - if the battery was perfect - by the time we have discharged 50Ah after around 50 hours it would have gone down to around 12.05V.
Checked this morning and after around 21 hours, battery is down by 20Ah - so pretty well as expected - but the voltage is down to 12.07V, which is lower than I would have liked, but on the other hand is a significantly better performance than before I did the high-voltage charging, so it has had some effect

Stopped the discharge test and put the charger back on (at 17.5V again) and will see what happens next time round ....

 

[trevskoda]

The big problem with standard batteries is that the plate frame inside starts to break up and crumble falling to the bottom of the casing causing internal leakage, hence i always tell folk to buy a varta or bosch silver battery as this will not happen to at least 5 years old.

 

[wildebus]

I'd want a battery to last more than 5 years! the ones I am working on are 12 years old. The ones I have installed now I expect to give full service for at least a decade.

 

[xsilvergs]

In the 70's I was using equipment very similar to this for charging lead acid and alkaline batteries in aircraft, great for recovering batteries, just wind up the voltage until they started to pass current .

No girls to share with just a odd chap called Vic who supposedly lived in a cardboard box in his down stairs flat. He'd probably breathed to many lead fumes.

 

[wildebus]

Not done anything with the second battery yet, but the first one does seem to have recovered pretty well
I don't think it is back to full capacity by any means but it has been sitting without a charge for coming on for maybe 3 weeks and the voltage is still very acceptable.
So all in all, a worthwhile exercise to get batteries back to having some purpose and while it wouldn't really have been a feasible option to reuse these particular ones in the Motorhome (bearing in mind they have given over 10 years of all-year round service already), maybe younger batteries could be resurrected even further?