PINNED - AGM & GEL battery info lead battery info

[expresso]

http://www.chargingchargers.com/charger ... c2024.html


this is the charger i got - this wont charge faster ? i guess i give up if this dosnt work - i got everything i need already and waiting for when the tech will bring me new batteries for him to make the connection -
i guess i will get a voltmeter this weekend to be safe and have in case the tech dosnt have one with him -

i would have to touch a POS with one end of the voltmeter and NEG with the other end - and it should read 24 volt ? or 25v etc but in that area - then those are the two posts i use ? is that correct -

or just touching one post at a time would work also ? like touch one POS post - and then touch one NEG - or do they both have to be touched at the same time


from what i read - its made for charging deep cell batteries - the specs of the charger fit right with the specs of the battery - its right in the Range of Gel batteries according to the Battery specs -

what the guy told me - i dont know - i would think he would know more about his product than me thats for sure - if this works great - if not - then i dont know - i asked before in some pervious posts - what chargers i can use - if anyone had links to some that i can use for this - but i never got any - this seemed to me to be the best combo - its not too small but compact enough to carry in backpack - i got the wires all done - SB50 connections the charger already is done with the SB50 also - simple plug and play type of thing - i guess i find out sooner or later if it does anything faster - it says 24 V 20 amp -

isnt that what i needed to get ? at least 20 amp - a little over double the rate - ?

[Burgerman]

It says: 28.8, 30.0 VDC charge at Absorption. That's CV. That would be perfect for AGM batteries, even Odyssey. It will also "charge" gel batteries.

But if you care how long they will last its wrong. MKs own technical spec sheet on their own gel batteries says 13.8v (x2 for 2 batteries) up to a max of 14.1v. It will charge them but it will shorten their lifespan markedly.

A volt meter cannot read anything at all with 1 wire connected.

AS STATED BY MK themselves in their own tech documents,

Here: http://www.wheelchairdriver.com/MK1.pdf

And

Here: http://www.wheelchairdriver.com/MK2.pdf

And there are more MK documents stating the same thing. There are a few documents that relate to mobility use that say that you can charge to a higher voltage. You can...
If you don't care how long they will last! They are after selling batteries, not putting users off buying them, they are not interested in a longer service life. They do not tell you that it will cost you money to replace them much sooner!

[expresso]

the 28.8 would be used - the 30.0 is for the flooded wet - i wont use that setting

the MK spec sheet i found shows this - which i based this on and looks to be right in line - closer to the higher end of the Range but not out of range -


http://www.mkbattery.com/images/M24SLDG.pdf


i followed these specs -

[Williamclark77]

Expresso, this is most likely the 24v connection going to the controller. Red arrow. I would ASSume so if I was doing it. Two seconds with a volt meter will tell you for sure.



To check for sure, touch the volt meter leads to it. One to positive. One to negative. Red and black respectively, but doesn't really matter. If you connect the meter backwards it won't hurt anything. It will just read negative. If it is your 24v connection it will read between 25.2 and 27.4 or so depending on how charged they are. You can't hook the charger up backwards though. Don't touch one lead of your meter to two wires at the same time. That will short and burn the lead.

I haven't had time to look at the charger you linked or looked for suitable automatic chargers. I use the Hyperion 1420i to charge mine. It's much easier to use a programmable hobby type charger and set it per the specs the battery manufacturer calls for than it is to find a good automatic charger, which is almost impossible for gels.

I much prefer charging my lead batteries separately at 12v in parallel (connect positive terminal to positive terminal and negative terminal to negative) than in series at 24v (connect positive terminal to negative of one battery). The reason being is for balancing. When charging in series at 24v, the charger looks at the combined voltage of both batteries and charges until the voltage equals the cut off point. If one battery is even slightly lower than the other, it overcharges one and undercharges the other, which shortens the lifespan of both.

The charging process is almost the same. You just flip the breaker on your 24v connection and hook up two batteries instead of one when charging.

[expresso]

i called them again - to double check - also where i got the charger from - was told - a Good Quality battery like the MK spec sheet i posted will be fine - 38.8 - 14.6 is the range for MK24SLD G - now if any other Gel battery is used - or a cheaper quality battery - it may have lower specs maybe - but with the MK - it wont shorten its life or overcharge - i was also told the older ones were a lower range - but not anymore

only true test is to use it and find out the hard way if its ok or not - i made what i believed to be the best choice given this range - worst case is they bring me cheaper batteries with a different range or quality which i would then decide if i should change out the charger or not - if its MK - i give it a shot

[Blade Runner]

Will, don't make this more complicated for him. Expresso, dude your scaring me! Since you are not
knowledgeable, going with too many sources is confusing. I've been on this site for
several years, I do have a good understanding and I trust what Burgerman says.
Follow his instructions on how to do this. Your tech should know how to hook it up properly,
hopefully he will do it for you. Ask him to show you and explain what and why he is doing.

Good luck
Bob

[Burgerman]

i called them again - to double check - also where i got the charger from - was told - a Good Quality battery like the MK spec sheet i posted will be fine - 38.8 - 14.6 is the range for MK24SLD G - now if any other Gel battery is used - or a cheaper quality battery - it may have lower specs maybe - but with the MK - it wont shorten its life or overcharge - i was also told the older ones were a lower range - but not anymore

Yes it will be fine. It will charge them great. As long as you don't mind buying new ones more frequently...
And in fact voids the warranty!

28.80 volts is .6 volt above MKs spec for room temperature. See their own published spec sheets... That I linked to for your convenience.

To get the advertised cycle life you *must* charge withing the MK spec. That is 13.8v to 14.1v at room temperature. 13.8 will take almost 2 days to fully charge from dead. 14.1V - THE HIGHEST YOU CAN GO - will still take up to 16 hours.

Trust me! You are talking to an idiot or the receptionist. Or Mark over at the other site! Its something that those in the mobility industry "know" and its wrong. Bad information.

Second thoughts don't believe me, just READ THE CHARGE SPECS on the two MK TECHNICAL SHEETS. These were written by the guys at MK that know! Not some glorified receptionist. That's why I posted them.

READ THIS. ThIs isn't a dumbed down 1 page sheet specially for mobility use like you already saw, but the full spec sheet for AGM and GEL MK batteries. By MK...

http://www.wheelchairdriver.com/MK2.pdf

Which shows I am correct.
Yes you CAN charge at 28.8v or more if you want.
And MK GEL batteries can give 500 to 550 cycles. But not both at the same time! You can have lots of cycles, OR charge at a higher voltage...

If you want full service life you MUST stick to the specs.

[Burgerman]

http://www.mkbattery.com/documents/7175 ... 011-09.pdf

HERE is a 3rd spec sheet... A more simple spec and brochure for MK gel.

READ CAREFULLY AT THE TOP... Where it says CHARGING INSTRUCTIONS!!!

It says and I quote:

14.1V MAX or WARRANTY VOID!

These are all MK GEL batteries. Nothing changed, there are no different older or newer ones, its just that they know most cheap chargers charge at a higher voltage and it stops people like wheelchair users buying them So they quote a higher figure for mobility use. Because they prefer to sell batteries rather than confuse people. As they have you!

14.1v MAX if you want a decent service life. And look at the graph. The ONLY time its safe to charge them to 14.4v (28.8v) is if its around 6 degrees C below freezing. This is why we HAVE manufacturer technical spec sheets. So you don't have to rely on some numpty on a phone!

[paulgato]

Just following this discussion... The brochure/document that expresso is reading from has some weird info on it that seems to me to be misleading at best and just plain wrong at worst. It flatly contradicts the other, more detailed technical documents from MK that burgerman has linked to.

The chart on page 11 of the MK2 document clearly says that at 25 degrees C the optimum bulk charge voltage should ideally be 13.7v and the MAXIMUM should be 14.0v, and yet the 'brochure' document for the M24 SLD G says the bulk charge voltage at 25 degrees C can be up to 14.6v!

I can only conclude that the brochure is just that - a sales brochure, designed to tell people what they want to hear, and putting the best gloss on the actual facts, eg, telling you that you will get 1000 discharge cycles at 50% DOD, and at the same time saying you can charge at up to 14.6v. That brochure COULD have been written by an engineer, but only if they had a gun pointed at their head by the marketing manager. More likely it was written by someone in Sales who was told to write a brochure and picked some numbers and charts out of different technical documents without understanding them.

(14.6v just happens to be the maximum voltage given in the MK2 document for AGM batteries at 25 degrees C. Coincidence?)

But I have to say - and no disrespect intended at all - that I share the concern expressed by bladerunner (?). For the sake of safety, someone who does not already know that you need to touch both leads of a multimeter to something to measure a voltage should probably not be messing with large 24v lead acid battery packs. Of course you need to make a decision about which charger to get, etc. but maybe, just for now, leave someone else to do the actual testing or connecting up.

[Burgerman]

The chart on page 11 of the MK2 document clearly says that at 25 degrees C the optimum bulk charge voltage should ideally be 13.7v and the MAXIMUM should be 14.0v, and yet the 'brochure' document for the M24 SLD G says the bulk charge voltage at 25 degrees C can be up to 14.6v!

Its because in the world of powerchairs we have a problem. Huge ignorance of batteries and chargers by almost all involved. Originally MKs were sold and used as OEM batteries with many powerchairs, and these were all supplied with a new fangled charger. It was a 2 stage charger that stands upright. It wasn't the same as the 3 stage common chargers that we see everywhere for the last 15 years (in Europe). It charged at 28.2v and its CV stage had a timer as it wasn't great at sensing the current fall to a low level. So they charged at full power till 28.8v and then charged until about 1 amp was reached, plus a time period. They worked great for the MK gel. They have no 3rd float stage.

These looked like this:

MK sell AGM batteries too. So some of these chargers had a switch...
And some charge at 14.4 (28.8) volts. They just have different firmware... Depending on if sold with a chair that had gel batteries or AGM.

Well most chairs have 14.4v 28.8v chargers now, and its very hard to find chargers for gel batteries, other than marine chargers. So in an effort to simplify things, and sell more batteries, they added a special mobility use leaflet. That incudes a wider voltage range so they can be used with any chair or charger. Its a marketing choice, not an engineering one... You LOSE service life.

And many chairs came out using generic 3 stage chargers, that included a float stage. So as to not "opt out" of the market place, they needed to reassure mobility users that their existing charger will be OK. And it is. If you don't mind shortening the cycle life, or ending up with high resistance batteries. Rather embarrassingly, the sales brochure is at odds with the 3 or more GEL technical PDFs that are still floating around.

The problem is this. At 14.4v and when charged a battery "gasses" lightly. A pure lead AGM like Odyssey does this at 14.7v. An AGM is quite capable of recombining the gasses into water. These are known as recombinant batteries. No electrolyte is lost. The GEL blows bubbles or voids in the gel instead, that never recover if bad enough. To prevent it they charge at a slower and lower voltage.

[expresso]

First let me say - i have learned alot from this site - and i feel you guys and Burgerman are very knowledgeable for sure - i dont know nothing really about all batteries and connections etc, - and just got interested in all these chargers - etc, in the past few years since i been on this site - which is great -

and no i dont plan on making the connections myself - i am not going to guess anything i dont know enough about - the Tech will be connecting it for me - i just wanted to know for myself - i am curious and like to understand it rather than just hand it to someone to do for me - and still not understand -

in the event its not connected correctly - can anything go wrong with the chair etc, - or would just my direct connection not work - or if connected wrong and i tried to charge it that way without knowing of course - could it be dangerous ?


about the charging specs - i guess i am just as confused as i was at the beginning - i went with the specs i found - maybe my charger i just got is a bit over the top for a True Gel - maybe it will shorten its life - i wont know for sure till i use it and see how long it lasts - now since i am not paying for the batteries - i guess its ok for me to do it and see - but i understand that if i were paying for them myself - it would be in my best interest to get it just right and make it last -

i usually get new batteries each summer - i rarely went two summers with the same set of batteries - and if it does shorten its life - the tech would come - check it - fails load test - i get new batteries - now if i had to pay for them - knowing what i know - i could always buy the AGM style and use the charger for them -

Looking over the spec sheets of those links - and its different from the one i had and different from the battery sticker itself - in that case - yes your right - to keep it at those charge levels - - in my case i am fucked then i cant win no matter what i do - i tried at least -

but i do get it - and it is very confusing when you hear so many different arguments on the same subject - do i trust the industry - NO - i would take the info from this site first as the correct info over others when i dont know it for a fact myself -
i looked on the battery itself which says the same as the spec sheet i found from MK - 13.8 - 14.6 at 77 degrees F - thats the sticker on the battery itself - again - i followed those specs and ended up with the charger i got - what you are saying makes sense to me and i believe it - they rather you over charge all the time and just buy new batteries - and in the event i had to buy my own batteries for what ever reason - i would just get a MK AGM type or some other good AGM instead of Gel and not worry about it then -

you live and learn the batteries i am using now are going on the second year and they are not great but also not that bad either - in the summer time - my trips range about 10 to 14 miles - which get me down to the Red each trip - before i am able to charge fully again - so instead of 1000 cycles - or what ever they say - its more like 500 good cycles i would say -

[paulgato]

Just a thought, and shoot me down in flames if this is crazy, but what if a person were to put a high current diode in series with a smart charger? Say a Schottky diode with a forward voltage drop of about 0.6v for a 12v charger, or a non-Schottly diode with a forward voltage drop of about a volt for a 24v charger. Would that totally confuse the smart charger, or would it gracefully drop the charge voltage by the required amount and make these readily-available so-called 'universal' chargers charge gel batteries just nicely...?

[expresso]

i was looking over the different specs coming from MK for the same type of batteries - and maybe i found the reason behind the different numbers

what i noticed is one spec sheet says 13.8 - 14.1 at 68 degrees - while the other says 13.8 - 14.6 at 77 degrees - maybe just maybe that might have something to do with the different numbers - the different degrees ??

if thats true - i be fine since my apt is very hot all the time also at the very worst - i seen the chart showing how much you loose if overcharging all the time - at worst case i would be at 0.3 volt over charging -- and if thats true -

instead of 100% - it would be 90% - if you go to 0.7 over - then you really get a hit at 50% - that would be noticeable very easily - in the end i may just be at the 0.3 % over charge - i guess it depends which spec sheet i am looking at

[paulgato]

Nice thinking expresso, but no, the charge voltage required goes DOWN as temperature goes up, (...not up as temperature goes up.) A hot environment will require slightly lower voltage charging, but the difference is small at any kind of normal room temperature. Look at the chart on page 11 of the MK2 document burgerman linked to.

As for your idea of sticking with the high(ish) voltage charger and accepting the shortened battery life (since you are not paying for the batteries!) ...and then if you do start paying for the batteries start using AGM's instead, well that sounds like a very workable plan to me. I'm sure someone else more knowledgeable can tell you more, but to me that sounds like it will work just fine for you.

[Burgerman]

Most of the mobility industry are using gel batteries with 14.4v chargers through plain ignorance - inc the manufacturers - and it "works". But batteries never reach full service life.

If its 25 degrees, you need to be charging at 14v... Or a bit less.

Batteries age through a variety of causes.
Not FULLY charging. Most mobility chargers are guilty of this as it takes more than overnight to FULLY recharge. And that means a wait. So they gradually sulfate.

Natural depletion of active plate material. This happens faster the deeper they are cycled.

Water loss through overcharging voltage (gassing) leaving dried out gel in gel batteries, with cracks and fissures and voids. These batteries do not lose much if any capacity or range, but get weak and high resistance instead. So they feel crap in use, chair lacks torque, and this can start after a few hundred cycles.

[Burgerman]

Just a thought, and shoot me down in flames if this is crazy, but what if a person were to put a high current diode in series with a smart charger? Say a Schottky diode with a forward voltage drop of about 0.6v for a 12v charger, or a non-Schottly diode with a forward voltage drop of about a volt for a 24v charger. Would that totally confuse the smart charger, or would it gracefully drop the charge voltage by the required amount and make these readily-available so-called 'universal' chargers charge gel batteries just nicely...?

It may. But then float will be too low. And float (after charge ends) is the thing that really tops up the battery to 100 percent and returns the last traces of Lead Sulfate back to the acid. And that would effectively stop it almost completely.

[paulgato]

Ah yes. True, true. I did the maths wrong on that one. The charger expresso found has an absorption voltage which could benefit from being reduced by half a volt from 14.4v to 13.9v (or from 28.8v to 27.8v) but the float voltage on it is about right already at 13.5v (27.0v) so a simple diode wouldn't work. Ah well.

The other option perhaps is to use a closely-regulated, single-voltage power supply set to 13.7v (x2 = 27.4v). The MK spec (on page 11 of the MK2 doc) says at 25 degrees C that the IDEAL absorption voltage is 13.7v and the MAXIMUM float voltage is also 13.7v.

[expresso]

all this is great knowledge to know - but it has been driving me crazy and everyone around me who i am trying to explain it to also - in the end - like you said - everyone just uses what they get and dont even waste a moment thinking about the correct charge etc, - i dont know anyone who actually is concerned about charging and taking care of the batteries etc, as everyone on here does - and now me also - every so often i get obsessed with this - i like to know the reason and now i do from this site and all the facts from everyone here -

sometimes not knowing or understanding may be better but thanks to everyone here - i understand better now - i will use what i got - in the event i need to buy my own for some reason or another - i just buy the AGM not before asking here which i need or are best for my use - and be 100% then on those batteries -

till then - i been charging this way for past 15 years - so i am not doing anything any worse than before - i just know now it can be that bit better - looking it over - there is another charger which goes right up to 28 V for gel - which falls just right i guess - reason for not getting that one - was a few - one it had to have different leads made and i had to connect them each time - may not be a big deal but when you have other people doing this over and over - who know less than me - i have to always double check - and second was it was 15amp charger - and my goal was to charge as fast as i can outside if ever needed to -

now are those two factors a big enough deal to avoid it - maybe not - but i did now - this one i got less likely to be used incorrectly - just flip the switch to Gel and flip it on - it came with the connections i needed already - its a plug and play

[Burgerman]

A little knowledge pays over and over though.
I used to go through a set of MK gel batteries every 10 to 16 months, depending on how pissed off with a lack of performance I got.

So I did a few things a little different.
1. DO NOT discharge deeply unless you have to. That kills lead batteries fast.
2. Bang as much back, as often as practical as you can. If you get 5 mins while you eat, sit at computer, drive, etc.
3. Use bigger chargers that pile some back in fast. I use heavy bench power supplies directly (44Amps at 29.4v), a 30A 24V Leisure charger, my van as I drive, at up to 100 Amps, and FULLY CHARGE over night at 12v and about 18 Amps as I sleep. This keeps them as full as possible during their lifetime. Which is now 3 to 4 years.
4. USE CORRECT CHARGE ALGO!
5. Use Odyssey PURE LEAD batteries, as they have lower resistance (better performance) and charge much faster and at 14.7v. The fact that they charge fast, means they get a COMPLETE charge overnight where MK do not.

Because of 5, the lower 400 deep cycle life ODYSSEY actually outlasts the 500 cycle MK gel in the real world anyway. And performs better too. The chjair I am sat in has totally abused, 4 year old Odyssey batteries in it. And I still cant see a problem with them. Whereas in the past this would have needed 4 sets!

[expresso]

thats very nice - you have it all set up for charging correctly fully all the time - i am impressed if you have your batteries 3 or 4 years with heavy use - which brand model Oddessy would you recommend in the event i would buy them at some point -
can you link me to the right one - to replace group 24 batteries -

i see a few problems for me the way i use the chair as compared to you do and charge etc, - I do deeply discharge my batteries each day during the summer months - i get down to the Red - or very close - Orange almost gone - -

i ride the whole time - now i dont charge during this - so in my case - i will discharge them much deeper than you do in between charges - i can manage two summers maybe with the MK Gel they give - if they tested it - it may not fail load test and they wont change them - depends on the Tech - mines is cool and it just happens to fail all the time and i have been lucky getting new sets each year -

but besides that - what do you think is best for me the way i use the chair and charge - i mean now that i know - i will be aware and charge more often to keep it full as much as i can -

lets say i were to get the same batteries you have which lasted you 4 years - but if i get them and use my chair the same way - deeply drain and then fully charge most likely when i get home - not charging thru out the day like you in the Van etc,

how much better can they be compared to the MK Gel now ? i am not looking to buy them myself just yet - but i may be curious to try it one day when i get my other chair - i will have 3 chairs then - i would have to pay myself for the 3 chair - they will cover two chairs - primary and back up - so at that point - i may get new batteries Gel they give - and i may put them in my 3 chair i use just for the home now - and get my own for one of the chairs i ride with - at which point i now have a choice to get either a Gel or AGM since i am buying it - thats what i am looking at for the future - and in that case i can then use the charger for the AGM ones i may end up trying in one of the chair i ride with just to see if in fact i get a few years more out of them - in the meantime - i want to get the wires connected on a new set of batteries and use the fast charger i got -

i mean i can if i really wanted maybe return it and exchange it - but its a process and i will pay shipping for sure back - then have to wait for another - have new leads made etc, - and it would be 15 amp instead of 20 - not sure i want to do the return thing unless its not working for some reason -

let me ask you - i didnt even turn it on yet - if i plug it in and just turn it on with out the charger being connected to anything - is that ok - just to see if it turns on ? or does it have to be connected to give me any indication that its working

thanks

[Burgerman]

As usual, it depends...

I can tell I have gel batteries in my own chairs even if new, healthy, and fully charged. They give no "power" to lift the wheels easily or steer sharply in difficult situations. If your chair was programmed to respond fast, and was maxed out, with everything set to GO with 100 percent acceleration and turn acceleration then you would feel this too. This is due to peukert and resistance making the voltage drop under load. You may never feel this. 99 percent of users never do... As they age, and as they discharge, this gets worse.

Most AGM batteries are frankly crap. Wouldn't want one as a gift. Unless you start looking at Odyssey PURE LEAD batteries. These can start a truck in Siberia, and be deep cycled too. They do BOTH things well.

So for me these 68Ah batteries, that are lighter than the MK gel are already the winner. And they both can charge faster, and they do charge faster even on the same charger, because of the IR being lower.

Will you get the same range as your 73Ah grp 24Mks? Well you will if you use them heavily, maybe more. If you use them like my gran, no. They are better at high loads. They charge faster. So in reality they end up more charged, which makes them last as long as the MK.

The ones I use and that will replace a grp 24 are PC1500 group 34/78.

[expresso]

Ok so the PC1500 is the only AGM to get if going to AGM - they will handle deep drains and charge up even faster - response better under loads etc.

given the way i drain them daily in the summer and then fully charge - they will be just as good or better than the GEL i use now ?

in my case - i am about 160lbs - not sure how many stones that is - my chair is actually very light also - and its Center of Gravity is such that it has a tendency to wheelie easy - i never saw any other model chair do wheelies like my chair - invacare - pride etc, - even from a stand still i can make it wheelie easily

now because of that - i had to actually slow down the take off so i wont wheelie everytime i touch the joystick - but i do feel the difference from a new battery and as it ages the wheelies are not as much during a stand still - i cant say if the AGM would be better in the respect of things - i never used any thing but what they give us which has been MK Gel only -

maybe one day i may just give it a try - are these any good at all ?

http://www.ebay.com/itm/271486770825?ss ... 1423.l2649

[Burgerman]

Without seeing proper specs, and as usual there are non, nobody can say.

But its easy to build a lead calcium AGM battery, there are hundreds of different ones, and most are really crap. Is there a proper spec sheet anywhere? EG:

Cycle life at 80 percent discharge?
Peukert values?
CCA figures?
CA figure?
Internal resistance figures? (Around 2.2mOhm is good for an 80Ah battery). Where 4mOhm is TWICE as bad.

Some group 24 batteries are 5 or even as much as 7mOhm. Which means they are usually crap.
The smaller group 34 Odyssey is 2.5mOhm for eg and its called a PC1500 as that's the Amps it can provide short term.

[expresso]

looking at the 1500 you use - i can see why you would want to keep them in good shape for many years of use - they cost alot !!! -

not sure if was looking at the correct one - but i see prices from $280 to $305 each battery or $345 - thats about $700 a pair -

[Burgerman]

You get what you pay for with batteries. They are better because instead of using pure expensive lead, and very careful manufacturing with close flat smooth plates/acid soaked glass mat as a tight sandwich, other manufacturers cheap out.

They use lead that isn't very pure but is cheaper. Then they add zinc, calcium, tin, and other things for physical strength instead of thick solid lead. These mixed metals mean they can use thinner plates and still get the strength to prevent distortion. So then there's no need for super accurately made even thickness super pure lead plates like the odyssey. And odyssey also use super thin separators to allow these accurate plates to be sandwiched very close together. Meaning low resistance.

The downside to adding impurities for strength is increased resistance from the non pure lead/other metal mix, meaning slower charging, greater peukert affect, lower CCA figures etc. And the battery gasses at a lower voltage on charge. It does this at 14.4v typically, rather than 14.7v for odyssey/optima and the rest. So We get slower charging too. And a shorter life from unwanted reaction taking place from the extra metals present.

As I say, you get what you pay for with batteries. Now weather YOU will see a benefit depends on a lot of variables. That I do not know. So the answer is I cannot tell you. They are MUCH better for high rate discharge, and fast charging, and for any user that routinely drives along a beach, wheelies 100s of times a day etc. Or wants to get some battery power back in fast!

[expresso]

i see what you mean - your right - you get what you pay for - wish it wasnt so much more - hard for me to justify a purchase when i get them free - not the same ones but they do work for me for the most part - i have to keep it in mind - one day i may give it a shot - maybe on my new chair -

of if need arises that i have to buy a set - sound great to have the power you mention - i do feel the power only when they are brand new - it changes fast but like i said - for my chair and me - its pretty good - wheelies enough - i end up scratching the bottom of my battery box when i go up -

going up any hill - or curb cut etc, - i can easily wheelie - i have to see how my new chair feels - if i get it 646 model quickie that ones a bit different

seems like more chair is involved - may feel heavier - even though on paper - it isnt much difference - my 222se is very nimble light

the new chair i can get to my batteries easier also - this one i have to take chair apart which isnt hard if you can do it yourself -

[Burgerman]

If I got them free I would use them.

[expresso]

Yes i agree - now i am going to the process to get a backup chair - and they will take care of both chairs - so its hard to justisfy buying spending $700 for batteries when i get them free - MK Gel so far its all they been using - i cant complain -
they are getting a bit more strict in making sure it fails the load test before changing - the tech from my vendor which i picked because of this Tech guy - hes great - works with you and goes extra mile - if i say i need new ones - and its at least a year old - he puts it down as fails load test - then i wait for the process to work and hopefully in a few weeks - i will keep my old batteries and make a little backup power for the house - will connect them as one large 12 volt - get a inverter and can then use it to power my lamp in the event i lose power -

so back to the chair - a while back i posted about my large big box lester charger which i sweared works good for me - i still think its ok - i found out it charges at 2.38 V per cell - which makes it about 14.28 V as compared to 2.4 at 14.4V

i am not disagreeing with you - i understand what your saying and you prove it with your batteries lasting 3 or 4 years and going - i got another picture of the battery pack in a friends chair - its a better picture - shows how its connected and its clearer as to where to connect my wires this way - and also the label on the battery showing the charging range which is fine for the battery - but yes like you say - and i do believe also - they dont care too much if you overcharge a bit and slowly wear it out faster but not as fast so it wont be considered a Bad Battery - they know it will last many years during normal wheelchair use that 99% of users do really -

its only a handful like US who really use our chairs alot and harder than most - and last but not least - we will end up getting new batteries either way - if they dont care about - why should i go crazy about it - i like to know the facts for myself to know - never know when or if i may need to get a set or i want to get a set of batteries for myself and would not want to kill them in 6 months - if i spend that much - i want many years of use out of them -

here are the pictures

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heres the connection on a invacare chair tourgue 3 model

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from that picture - the battery on the right - connect the wire to POS and then the other wire to NEG on the battery on the left side of the picture - that would be the correct way to make the direct connection to charge - ?

i am just double checking that i understand it - the Tech will be doing the work and connection either way - i will take pictures of mines when it gets done to see if its the same way - which most likely it would be -