WheelchairDriver

-Hi I have 1 set of MK AGM that was still good but dropped to 2 or 3v each that I would like to revive. I also received 2 used set(unknowed history) of mk Gel that are not as low voltage but was too low for a charger to begin charging apparently. I read Burger 's writing saying that it has to be an operation done one battery at the time.

It is usefull to have at least an extra pair of battery to use for a chair we want to repair (to avoid constant battery transfers)and I hope out of the 3 pairs I will have one that allows to roll around the block .

-If the tool can also maintain or top up(bring to 100pourcent) a disconnected battery detached from a wheelchair every 2 or 3 month to prevent sulfatation, i would like that since I need that too.

-I wish it won't cost an arm and a leg but if there is a tool that would proove usefull for the future scenarios and is not that more expensive I might be interested.

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What do I look for in bring back to life tool? Correct me if I am wrong but we want low amps(how many) and user defined voltage since MK batteries 's voltage are not standard. Maybe force- repair feature or stuff like that?

I guess if the tool can AUTO Stop when it has to, or be forgotten a bit it would be usefull to know to help me choose since memory can forget to do a task and if constant baby-sitting can be reduced if feels better. but I'm open.

-So noco charger would not be a good choice.

-Would ip65 12 v be a good choice ? it seems to come in 1.1amp 5 amp(low curent mode of 2 an 4amps) 7amp 10 amp with low current option that is unclearly defined...They say it can revive dead batteries but I have not found the how it does it.

-would a power supply do both revive and top-up tasks ? would it be a better futur proof machine?
I read that some member like zxd2400 and een? if they are good solution which versions, models should I look into ?


I have ip65 24V13amp but the voltage only goes down to 26.5v

Thanks

Best for you would be a cheap lab PSU. You leave it around 26v forever.

Or if you want a ZXD, that's the best. You can charge any battery you want as long as you understand what you're doing. You have to DM Shirley here if you want one. They're around $375CAD shipped.
This one would work: https://www.amazon.ca/NICE-POWER-Variab ... 0DP2FL2J2/
That's a lab PSU. You need to understand what you're doing. It has no protection whatsoever. It will let you overcharge your batteries and blow your house up! But as long as you set proper voltage it's fine.

What do I look for in bring back to life tool? Correct me if I am wrong but we want low amps(how many) and user defined voltage since MK batteries 's voltage are not standard. Maybe force- repair feature or stuff like that?

A charger CANNOT repair a battery once it's sulfated. If your batteries are under 10v you NEED to charge them ASAP. Every minute left at low voltage is damaging for a lead and it's permanent.

Its all too late.

Even if they seem to charge, and they might. They will have reduced CAPACITY. And increased RESISTANCE.

Batteries dont die. They are MURDERED by ignorance.

***************
So after a charge, instead of being a 73.6Ah battery each one may be a 50, 30, 10Ah or whatever. Worse, insead of being around 4mOhm they may be 8, 12, 20mOhm. And the chair will perform as if it has a flat battery even when charged. Or it wont move...

Death of a battery is all a matter of degree.
How do you KNOW if they are any good once charged? You MEASURE them.

Personally I use the hobby charger, PL8 to MEASURE the Ah out. That takes 20 hours, and has to be carefully measured. Temperature, discharge rate, and a way to automatically stop the discharge at the correct voltage point. The hobby charger does all that for me.

Here is what that LOOKS like.

FIRST correct CHARGE.



SECOND you MEASURE capacity over the 20 hours during a slow discharge and then see how many Ah you got back in Mah on the graph/in text on the left.
Here I got 74Ah back, when testing a set of healthy MKs...



Then I would MEASURE the battery resistance as an AC impedance.



Unless you do ALL THREE of these things you are guessing. And cannot ever know.

You dont have that PL8 charger/tester.
You dont have the ZXD power supply/3 stage charger either.
You dont have the IMPEDANCE tester.
You also dont have the required knowledge or experience either.

So in your case all you REALLY need is that cheap eBay 2A gadget for £8 to charge those MK batteries. That I already posted pictures of in the other thread.

You set to 13.60V. Not more. One at a time. Charge for two weeks each. Disconnect.
Wait 48 hours.
Then MEASURE voltage. If 12.90V (or above) they are 100% fully charged. That does NOT mean they are any good! Just safely fully charged.
They may still have very little range, or be very high resistance.

If they read less than 12.80V, they are LIKELY permanantly damaged, but try again. If they still will not read 12.90V upwards after a further 2 weeks @ 13.6V + 48 HOURS WAIT then disconnected, just then throw them away.

HI everyone

You seem to have a nice way to test them Burgerman,

Even though it would be nice to mesure the life left in them more precisely, I think I will go simply to revive them and well, test them in a wheelchair in the appartement and a bit outside by the amount of time distance it can do with them.


- On aliexpress I have the choice of 1amp 2 am 3 amp In versions of 9-24v and 3-24v.
From what I understand the number of amp indicated is the max current it will shot. So in the case of a battery revival, should I go with the smallest so 1 amp?

-What advantage would Ihave from taking the 3 amps?

- I would have to cut the end of the wire and solder something. At first view crocodile clamps (overkill but would grab the battery well)would be convenient. There are used car booster cable in my neigborhood for 15 dollars. Do I have other options that make sens?

-Did anyone test if their display of voltage is reliable or if it is better without display and using a mutlimeter to turn the potentiometer wheel?

-Am I correct saying that it all comes from china anyway so i might as well buy it where is the cheapest so aliexpress?

THanks
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Here is the page where we see choice 1 to 3 amp.

https://www.aliexpress.com/item/1005009732031412.html?spm=a2g0o.detail.pcDetailTopMoreOtherSeller.6.1600mr1Smr1SGa&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40050.354490.0&scm_id=1007.40050.354490.0&scm-url=1007.40050.354490.0&pvid=6717b465-d3f0-44cc-bb6c-cec289ba5c57&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40050.354490.0,pvid:6717b465-d3f0-44cc-bb6c-cec289ba5c57,tpp_buckets:668%232846%238115%232000&pdp_ext_f=%7B%22order%22%3A%22359%22%2C%22eval%22%3A%221%22%2C%22sceneId%22%3A%2230050%22%2C%22fromPage%22%3A%22recommend%22%7D&pdp_npi=6%40dis%21CAD%219.27%218.89%21%21%216.63%216.36%21%4021033d9d17725846876403962ef6e5%2112000050081368108%21rec%21CA%21%21ABXZ%211%210%21n_tag%3A-29910%3Bd%3A3da78dad%3Bm03_new_user%3A-29895&utparam-url=scene%3ApcDetailTopMoreOtherSeller%7Cquery_from%3A%7Cx_object_id%3A1005009732031412%7C_p_origin_prod%3A

24v isn't enough. You need the 36v version because float is around 26v. BUT are we talking about maintaining them? If so, 1A is fine. You fully charge them using a charger then you plug this in and it'll keep them charged.

24v isn't enough. You need the 36v version because float is around 26v. BUT are we talking about maintaining them? If so, 1A is fine. You fully charge them using a charger then you plug this in and it'll keep them charged.

No.
The point was to try and desulfate a very discharged battery. And to maintain it at a float voltage for a very long time in order to restore as much capacity as possible.

A typical charger will refuse to charge a fully discharged battery. Then it will try and charge a sulfated battery fast which doesent help much as you want a long slow 1 or 2A curent over a long time. While voltage climbs. Becuse otherwise gassing and smells and internal pressures.

So just set any power supply to 1 or 2 Amps max. Set to the correct voltage. Since we are doing one at a time then anything that goes above say 15 volts will work.

As for voltage accuracy you can check with voltmeter. But most cheap voltmeters are not very accurate anyway...
As for soldering then you have 2 options.
To do one battery at a time then fit croc clips or ring terminals. To do two in series for long term maintainance then you do then need a 30V version and set the voltage to a suitable long term maintainance voltage. Like 26.4V. And a XLR connector...

o in your case all you REALLY need is that cheap eBay 2A gadget for £8 to charge those MK batteries. That I already posted pictures of in the other thread.

You set to 13.60V. Not more. One at a time. Charge for two weeks each. Disconnect.
Wait 48 hours.
Then MEASURE voltage. If 12.90V (or above) they are 100% fully charged. That does NOT mean they are any good! Just safely fully charged.
They may still have very little range, or be very high resistance.

If they read less than 12.80V, they are LIKELY permanantly damaged, but try again. If they still will not read 12.90V upwards after a further 2 weeks @ 13.6V + 48 HOURS WAIT then disconnected, just then throw them away.

Thanks
ordered 2 of them :1 amp for 3 to 24v with display

https://www.aliexpress.com/item/1005009 ... 211%210%21

The more you wait the more you damage them. You know that right? If I were you I'd charge them as soon as possible. Not wait a few weeks for Aliexpress to ship them.

emilevirus wrote:The more you wait the more you damage them. You know that right? If I were you I'd charge them as soon as possible. Not wait a few weeks for Aliexpress to ship them.

Yes I know, aliex says 1 to 2 weeks.

HI
I received the tools and soldered them. They( I build 2) are ready. 1 amp.

The set of battery that is very low voltage is MK agm. Are the mesurement previously mentionned(and in the quote ) for agm or for gel?

I remember gel and agm dont have the same optimal voltage to be charged at.

Since also have 2 pairs of gel of unknowed past life but around 12.something volt at least, Could you tell me what are the voltages number that would be in A) B) C) for GEL MK?
thanks

Burgerman wrote:
You set to A)13.60V. Not more. One at a time. Charge for two weeks each. Disconnect.
Wait 48 hours.
Then MEASURE voltage. IfB) 12.90V (or above) they are 100% fully charged. That does NOT mean they are any good! Just safely fully charged.
They may still have very little range, or be very high resistance.

If they read less than C)12.80V, they are LIKELY permanantly damaged, but try again. If they still will not read B)12.90V upwards after a further 2 weeks @ A)13.6V + 48 HOURS WAIT then disconnected, just then throw them away.

You set to A)13.60V. Not more. One at a time. Charge for two weeks each. Disconnect.
Wait 48 hours.
Then MEASURE voltage. IfB) 12.90V (or above) they are 100% fully charged. That does NOT mean they are any good! Just safely fully charged.
They may still have very little range, or be very high resistance.

If they read less than C)12.80V, they are LIKELY permanantly damaged, but try again. If they still will not read B)12.90V upwards after a further 2 weeks @ A)13.6V + 48 HOURS WAIT then disconnected, just then throw them away.

Do that with all of them...

oh Iam surprised I will use the same voltage for both agm and gel then.

If you have the will to explain the following , it could be nice to know . I like to understand stuff. When I was in the process of selecting a charger for the gel batteries I remember the agm charger was not appropriate since gel and agm had different voltage ideal. Now i would be charging both agm and gel to 13.6v.

You dont charge a battery TO any specific voltage. You charge it to a 100% state of charge. That happens faster (and is more damaging and more time critical at a higher voltage. At a lower voltage, it still end up just as full. But can take MUCH longer. And with less damage due to gassing, corrosion, etc. And now it becomes very hard to know exactly when to stop.

You charge AT (not to) a specific voltage for a bunch of different reasons.

Because you are not charging in cyclic use and want to recover a set of sulfated batteries a slow long overcharge is needed. So you are slow float charging them. Not rapid cyclic charging. Same for both.

CYCLIC charge (over 8 hours) from daily use use:
14.1 @ 20C gel. With 8h max at CV normally.
14.4 to 14.7 depending on battery for AGM.

Float charge from a discharged state in 18 hours to 48 to full, time not critical and so no harm even for a week @ 13.8V gel.
Same on AGM.

2 weeks at 13.55 to 13.6V in an attempt to desulfate and fix a set of damaged batteries...

LONG TERM months on float to prevent self discharge up to a decade in standby use at 13.25 to 13.35 V.