best gel charger and how to test a used one?

[yeshelp]

HI
concerning the gel batteries, i could get an invacare metal box pretty heavy used.
do those break easily ?
is there a way to test that the chargeur works well including its intelligent charger ability ?

and finally wich one of those 2 would be best to MAXIMISE THE HEALTH of the battery so that it lasts many years?and why .
i noticed that the metal invacare in the picture is much much more heavier that the other one.

https://imgur.com/U4ht3Em
https://imgur.com/7vPo2d1

ps , even if i click notifyme by mail i dont receive the email and they are not in spam folder do you know how to fix this?

tx have a great day

[Burgerman]

How to fix? Get a real email address. Not a webmail provider like google/microsoft etc that YOU can control. They all get sent every time automatically. Your email system removes them as spam.

Gel. Its very hard to recommend a charger. Almost non give the actual charge specs. Or are too short on detail. Some marine chargers do a good job. Theres also a couple of others that I cannot remamber the name of that people will post here. But they WILL require configuration.


BOTH of those chargers in your links are junk. And will give you a terrible service life. They "work" (anything does)... Thats about it. I binned all mine. ESPECIALLY the heavy one... Its very old tech and really crap. I mean even more crap!

I use:
a) one of my many bench power supplies, set to exactly 14.1V per battery or for a powerchair with a pair 28.20V and measured with a GOOD multimeter (I dont trust most of their displays). I set charge amps to 1/3rd the battery Ah. So on a 74Ah MK gel set to anywhere from 20 to 30Amps. If the battery is only a little discharged I charge for around 6 hours, and or until the current falls to around 300mA. If its heavily discharged I leave it sat at 28.20V for 8 to 12 hours. NOT longer. If I have the time, and this isnt an overnight charge then I will leave it for anything up to a week at a lower float voltage of 13.5V (27.00V) as this will ensure its 100% charged and so as desulfated as its possible to be and this helps service life.

b) my PL8 and set to charge at the same as the above. 14.1V, 20 to 30A. But limit to 8 hours CV voltage, no float. Or 750th of Capacity in charge current termination whichever comes first.

c) A 30A leisure charger that sits near my bed. It has adjustment pots on the inside, so I adjusted it to do a sensible job. Again 14.1V (28.2) and 30A. It stops charging after 8 hours or around .5A in current which is too soon. And reverts to a 27.6V float indefinitely. Thats a fraction high, but since it stops too soon it helps complete charge. I would not leave this connected for more than 1 to 2 days.

ANY of these will melt the chairs puny XLR connector and wiring loom. So are all connected via Anderson connectors. And ANY of these allow a fast boost charge at high amps during the day. So connect for an hour while you eat or go online during the day, and you will put a huge amount back fast. That is highly beneficial to battery service life, and allows you to go out in the evening and know you will get bacl. But the main advantage is that you will be lowering the average daily DOD and your battery will last one hell of a lot longer. An overnight FULL charge is still essential at least every 2 days.

Via an XLR connector the chair can only be charged at 12A max. Thats a hell of a lot better than a typical 5 or 8A mobility charger. And these power supplies/chargers can also be set to 12A MAX. But thats far less good as the initial charge stage (CC Bulk) take longer. Leaving inadequate time for a complete charge overnight regardless of what the lights on your mobility charger may tell you. You will easily get 98% or 99% and it will say "full". On charger and chair. But thats not enough if you want your battery to last. That last tiny bit is super slow. Maybe 4 to 6 hours. And its important.

I suggest you check out the shirley charger (ZXD conversions) as its a power supply. AND a 3 stage automatic PROGRAMMABLE charger. And can be used for many things. It does 0 to 60V and 0 to 50A. Its not intuitive and will give you a headache at first. Theres a thread here somewhere. I have 2.
https://www.wheelchairdriver.com/board/ ... start=1440
It will do everything. But to be safe, it depends on YOU setting it correctly and understanding a few things.

[Burgerman]

If you want an easy answer then there really isnt one. You said you wanted to know why. And you wanted to maximise lifespan. That isnt possible to answer in a simplistic way.

At best you would just use a charger that someone recommends. But that may or may not be any use. It would need to be programmed correctly for gel and used correctly. For e.g you want batteries to last a long time. The best way to do this is to charge opportunistically when you have time a few times during the day. And fully charge at night. But with a correctly configured charger. The only way that opportunistic charging works is to charge at high Amps. So not a mobility charger as that is far too slow. You would be tied to a charger for hours every day.

[steves1977uk]

Was it this one BM?... https://ringautomotive.com/en/product/RSCPR824

Steve

[Burgerman]

rsCPr824

This one at least is safe for gel powerchair use but its only a low power charger. And when set for gel. Does it properly charge it? Its hard to know as I dont have one to measure. As usual theseres little info about cv times or termination currents. But its a best guess till then. So the answer is that probably! But I would like to see exactly what it does. The devil is in the details. Theres also a blue one I cant remember the name of... I would say that it should be OK but will take at least 16 to 20 hours for a complete charge.

[steves1977uk]

That would be this one... https://www.victronenergy.com/chargers/ ... 65-charger

Steve

[Burgerman]

Whats important here isnt "what charger do I need". Because you can buy 2 identical appearing ones and both may have different firmware and do different things. What matters is that YOU as a user understands what the battery needs, for best service life. And ensuring by measuring or monitoring any new charger to see if it actually does this.

That as usual needs some knowedge. As always knowledge is power. Those that have this will have batteries that last. Those that dismiss the details, simply wont!

The tools needed to FIND OUT are a GOOD multimeter. A clock. And a means of measuring current accurately.
I use a fancy digital multimeter, a "clamp" ammeter, and the computers or wall clock.

And I understand batteries. So I make sure that they are charged correctly.
MK for e.g have a tech charge specification here: http://www.wheelchairdriver.com/MK1.pdf

And that basicaly boils down to this:
Charge at room temperature 68F/20C at 14.1V Max (13.8V is OK but will take WAY longer and we dont have the time) at around 20 to 30A. Keep going until the current falls to a very low level around 1000 of capacity, or falls by less that 0.1A over an hour. This typically takes 8 hours once the CV voltage is reached. Then its full. Float is not required if this is done properly and is the fastest way to charge in the limited time we have to do this. Total CC and CV charge time 12 to 16 hours. (8 to12h at CV)

[expresso]

https://www.batterystuff.com/battery-ch ... 415ul.html

i have used this one long ago before i really knew much about charging profiles etc, - but it seems to be pretty close in specs at 28v for gel and 28.8 for AGM -

havnt used it in years - never knew it says it can be used as a Power supply also - maybe its worth a look again - to understand how to use it that way - since i have one sitting here - hardly used - went to lithium not longer after

i got it to faster charge the lead at the time - not super fast but 15A not too bad either - most important was the charge profiles for gel

[Burgerman]

Stage 3 - Constant Voltage , Float
or Maintenance Charging Stage
As explained above, as the charging cur-
rent drops below the preset threshold
(1.5 to 2 amps for SEC-1215UL / SEC-2415UL
and 2.5 A to 3 A for SEC-1230UL), it signals
that the battery is 100% charged.

At the point this charger decides the battery is 100% it is nowhere near full. It therfore NEEDS the 3rd stage, float, for at least another 8 hours before you actually disconnect the battery. Because it terminates the carge at either 2A or 3A! Instead of around 100 to 150mA.

[expresso]

yes but its correct settings for Gel

you have to let it charge and leave it going to float -

takes times as they all do - but gets it done correctly -

would be nice if it charged longer before going to float - only the PL8 can do it the same way and faster maybe -

its better than any other Gel charger they give you generic kinds

or the Schauer model - you can call them and ask to have it set your way at your specs - i found that out later on - i still have one 20A of those - gave to a friend for her to use with lead -

[LROBBINS]

I had also gotten a Schauer charger from Expresso and it was reasonably good for my Odyssey AGM, far better than the several mobility chargers I'd tried over the years, but nowhere as good as the ZDS from Shirley. Yes, getting the ZDS programmed the first time takes some navigation of less than obvious settings, but that's basically a one-time task. I do adjust voltage for temperature changes, but that's just a matter of turning the knob. For the new chair, with 200 AHr LiFePO4, I have my second ZDS set up just as a power supply feeding a PL8.

[Burgerman]

Heres the problem with the majority of chargers. And the Schauer. Even if they charge at the correct CV voltage. They end the CV stage at a figure like 1.5A or even 3A. They then display a green "ready light". And stop charging at the 14.1 or 28.2V. At this point you get up, unplug the charger and go about your day. And it is far from charged.

Now look at this graph of a set of MK bateries charged correctly at 12A and 28.2v and by the XLR connector. This is the Amps scale. Take a look at the 3A or 1.5 Amp point where the charger expresso and lenny both have stops and terminates charge.

It does so LONG before the charge is really completed. That takes many more hours. That leaves lead sulfate on the plates which destroys the battery charge after charge by adding more and more. Until it becomes permanant.

Now if its configured to have a 3rd stage too, at a safe but lower float voltage, this extra part of the charge will eventually catch up. But at a typical float voltage level, that can take another 16 to 20 hours. As very little current flows. Thats not great if you only have overnight to charge the chair. And the same applies to the odyssey. That needs to have 8 hours at CV minimum, and or to 1000thC or down to 65mA on the PC1500 we use.

Remember you cannot speed this up. Its the rate that a battery accepts the charge.

Here its still charging at a third of an amp after 10 hours. And not done yet! It will take at least another 2 to 3 hours.

[expresso]

there is a 3rd charging - float on both the chargers - the one lenny has and the other one i have also

now how long it takes to keep going and get it full - that i dont know - but the float it there safely can be left connected for as long as you like - you just leave it connected till you are in need of using the chair -


in the past - early on before i knew about anything with chargers etc, - i would normally unplug it also when the green light comes on - most times - wasnt helpful for sure now that i know

[Burgerman]

Yes but that means you cannot recharge fully overnight.

And again you can only leave it connected for as long as you want if the float is set to a low figure like 12.35V. To complete the charge on most chargers that cut of the charge too soon you need the float to be around 13.7V or it will literally take a week to reach a fully saturated desulfated state. And then you cannot leave it connected indefinitely as thats too high for long term float.

So again the devil is in the details. And I dont know what those are. You can measure it.

The reason we charge at 14.1V until a very low current or less than 0.1A drop per hour is so that we finish a complete charge without need of any float stage quickly for cyclic use. Ie overnight chargeing. It also demonstrates why a slow 8, 10 or even 12A charge via XLR is simply too slow. It wastes time and doesent allow a full charge to be achieved overnight.

[LROBBINS]

Yes, the Schauer stops CV too soon so I often gave the chair a long soaking float. The ZDS can be set to end CV at low current, but it doesn't have a timer (wish it did) so there's a risk in setting that too low; with these old tired batteries I've got it at about 0.01C rather than 0.001C after having a runaway once when set lower.

[Burgerman]

Exactly. Thats why you need to understand whats going on.
And adjust for every battery and scenario. And thats why theres no buy it and plug it in one size fits all charger thats any good...

Whats needed to make batteries last, as was the posters original question is basically knowledge. And adjustability. And opportunistic top ups during the day. Etc. Theres no perfect dumb charger. The closest to that is usually a dual bank 40A marine charger correctly set up for gel. But dont expect a green light meeting you in the morning!

Or a simple power supply. And you choose what to do. As usual knowledge is power. Way more important than "what charger".

P.S. If you get the thermal runaway thing lower the voltage. Try 14.4. Or less. (Odyssey) Or buy a new battery. Old batteries may never reach 1000thC. Some new ones dont. Dont worry about that after 8 hours at CV they are full anyway. This stuff is why commercial one size fits all charger cut off too soon and rely on a slow long float to complete the charge. But we dont have that long! Plus they dont know what additional loads are already connected. So they choose a "safe" Amp point.

[expresso]

you would get the green light before morning easy - the problem is how much time you have left before you need to use the chair again - it may not be on float long enough

unless you can ajust it like the PL 8 term. point - they will all stop too soon - they cant know how old a battery is - if they made them to charger lower and stop lower - then when a battery is old - as it ages - it will try to get lower and lower and it cant -

its the best comprise - if you have no choice but to use a plug and play charger

the only part of the charger i have and lenny - is the end stage - they both float and can leave connected to get it fully charged - it comes down to how much time you have to leave it on charge - before needing the chair

i have not seen any charger better than the one i have and lenny in a plug and play dumb charger - thats not adjustment by the end user - its as close as you can get -

[Burgerman]

you would get the green light before morning easy - the problem is how much time you have left before you need to use the chair again - it may not be on float long enough

From a 3A cutoff point you would need around a week at a float of 13.35V and around a further 8 to 12 hours at 13.8V.

And thats why I use a simple power supply, (plug in at 12pm and unplug at 10am to get up). Or a shirly ZXD or a PL8 to charge. This is essential for cyclic use if you dont want short battery life. Which was the original posters question.

[expresso]

yes yes yes - but without the PL8 or anything else for that matter


Just among plug and play dumb chargers - thats how they are all going to be - if you had to choose among them - those are the closest i found -

if anyone can find a Better one thats not adjustment and just plug it in and go to sleep - then post it here so others know about it - apples to apples -

its apple picking season lets go

[Burgerman]

You cant do that because the SAME charger can have different firmware, or badly calibrated votage etc. I have 3 of those invacare upright chargers supplied with chairs using gel batteries. When I monitor what they do all 3 are very different. One would be OK for AGM The other two are so wildly erratic that I am not sure what the hell they are even meant to be doing. Those are marked with an X and kept only for components. The first one I keep to occasionally lend out to those using AGM if they need it.

So whatever you buy you must TEST it. And only then decide if its any use and for what... Thats if you care. The original poster does. Most people do not and just use any old charger and those also "work"... Sort of if you dont much care.

The only way to get any real consistency is with more expensive chargers that mobility providers dont supply. Marine gel for e.g.

[LROBBINS]

I will get new batteries, but they will not be Pb! Rachi's new chair with its novel lift and tilt mechanism is now functioning as intended so after a bit of real-world experience to see if there are any further changes needed (at a minimum I will probably want to do some more tuning of the PID gains for keeping seat angle constant during up and down) I will be ordering some more 200 AHr cells for the old chair. That chair is really pretty sad after 23 years and many mods (the mods are OK, it's the few remaining original pieces that are on last legs), but it will do OK as a backup.

[Burgerman]

How old are those odyssey ones?
To attemp to rejuvanate them, to desulfate them, you can discharge fully (to 10.5V). Then charge at say 1A for around 75Ah returned Constant Current - no CV. You can do this by charging at 1A for 75 hours. (3 days). Set the max voltage to around 15.6V on the zxd limited to 1A.

Dont do it more than once or maybe twice in the life of the battery.

If you measure Ah counted out as you discharge it, with PL8 then after this, the capacity should be restored somewhat.

[LROBBINS]

A month shy of 6 years old. Not quite as bad as it sounds given that Rachi weighs all of 35 kg. and neither of her chairs is one of the current heavy monsters, but they are nevertheless at end of life.

[Burgerman]

See above. Edited as you posted. I say this as your charger ends too soon. Your battery may be sulfated. A long very slow cc charge to beyond original capacity can reverse some of that. At .5 to 1A the recombination can just about cope. Better to do it 6 days at .5A if time allows. Must start empty. Or you do not give the internal sulfation inside the lead pasted plates a chance to be recovered as it takes time. Dont do this with gel!

The reason this works on an odyssey is that the plates are very thin. So the sulfates inside these pasted plates has a better chance of seeing some action!

This is a ONE OFF!

The USUAL recommendation by odyssey is this:

If the charger has a timer, then it can switch from absorption mode to float mode when the current drops to 0.001C at the 10h rate capacity. In amps. If the current fails to drop to 0.001C amps, then the timer will force the transition to a float charge after no more than 8 hours CV. Another option is to let the battery stay in the absorption phase (14.7V or 2.45 VPC) for a fixed time, such as 6-8 hours, then switch to the continuous float charge.

That means 62mA or 8 hours at CV for termination whichever is soonest. Float is only needed to complete the charge if this happens sooner. And/or to store the battery. And 14.7V is prefered. At room temp. Not in siena!

[LROBBINS]

I have a table of temp vs V glued to the supply.
Vcv --- Vfloat
20o: 29.4 - 27.3
25o: 29.1 - 27.1
30o: 28.9 - 26.9
>30o: 28.5 - 26.5
Transition to float is at 0.7 A (after about 5 hours after a typical day) and it continues to charge reaching ca. 20 mA by 8 AM

[Burgerman]

Dont know how you stand all that heat! Would cause me all kinds of problems...

[LROBBINS]

This year was record hot with the highest high being right around body temperature - it was awful. Right now, in full sun, we're at about 24o and I'm happy at that. Most summers, except for an occasional hot August day, mid 20's has been about the norm, and in the winter it's been ocassionally below 0. Serious snowfalls are only once every few years, and we're totally unprepared for that, and drivers havn't the foggiest idea how to drive safely with even a dusting on the road. We're lucky to have a ground floor apartment with large windows. Hence, on all but those miserable days, if we open up at night and shutter during the day, it stays comfortable inside all day. I do pity our neighbors on the floor above (which is the top floor) who are under the slate roof!

[yeshelp]

How old are those odyssey ones?
To attemp to rejuvanate them, to desulfate them, you can discharge fully (to 10.5V). Then charge at say 1A for around 75Ah returned Constant Current - no CV. You can do this by charging at 1A for 75 hours. (3 days). Set the max voltage to around 15.6V on the zxd limited to 1A.

Dont do it more than once or maybe twice in the life of the battery.

If you measure Ah counted out as you discharge it, with PL8 then after this, the capacity should be restored somewhat.

hi do you mean restored to close to new?
that is very important since my batteries now last half a day. if i can someone bring them back to life i would try it even if it takes 3 days.
Maybe it is better for me too invest in a good adjstable charger rather than 2 new batteries.
but before to decide could you tell us more about this rejuvenation and the equipment needed ? tx

[yeshelp]

See above. Edited as you posted. I say this as your charger ends too soon. Your battery may be sulfated. A long very slow cc charge to beyond original capacity can reverse some of that. At .5 to 1A the recombination can just about cope. Better to do it 6 days at .5A if time allows. Must start empty. Or you do not give the internal sulfation inside the lead pasted plates a chance to be recovered as it takes time. Dont do this with gel!

The reason this works on an odyssey is that the plates are very thin. So the sulfates inside these pasted plates has a better chance of seeing some action!

This is a ONE OFF!

The USUAL recommendation by odyssey is this:

If the charger has a timer, then it can switch from absorption mode to float mode when the current drops to 0.001C at the 10h rate capacity. In amps. If the current fails to drop to 0.001C amps, then the timer will force the transition to a float charge after no more than 8 hours CV. Another option is to let the battery stay in the absorption phase (14.7V or 2.45 VPC) for a fixed time, such as 6-8 hours, then switch to the continuous float charge.

That means 62mA or 8 hours at CV for termination whichever is soonest. Float is only needed to complete the charge if this happens sooner. And/or to store the battery. And 14.7V is prefered. At room temp. Not in siena!

Hi burger man are you saying that rejuvenating can not be done or that it is not safe? is is the same fore amg and gel batteries?
tx

[Burgerman]

No just a tempory unknown capacity gain. A reprieve whie you look for replacements maybe a month or so.