After reading more ill informed stuff elsewhere I did a page

[Burgerman]

http://www.wheelchairdriver.com/AGM-GEL.htm

Differences between AGM and GEL in use and in charging

[Burgerman]

Updated with a pretty diagram to show ANYONE how a multi stage charger works, and why one charger will not charge a Gel, or AGM properly.

[LROBBINS]

GREAT JOB! (But don't expect Mr. Smith to understand it.)

[g7pvs]

Hi,

The page looks good.

A similar page for LiPo and LiFePo4 would be interesting.

Best Regards

Trev

[Burgerman]

GREAT JOB! (But don't expect Mr. Smith to understand it.)

Well yes. But he will never look at it... Its not just him but the whole industry. Nobody cares or wants to know the details that matter.

Cheap cheerful AGM/GEL chargers "work" is more "modern" and the manufacturers are not stupid. Trouble it they are... And the industry believe their claims.

A Gel battery on a one size fits all charger will have its life shortened by around a a quarter to a third. The percieved cycle life advantage is simply thrown away. The Odyssey on the other hand charges much faster even on that generic 14.4v charger. So gets some real time on float before the chair gets unplugged. So it gets a more complete charge even on a lower voltage than ideal. The Gel however gets undercharged every time because it charges slower, and over voltage and so tortured at the same time... It loses out twice.

Net result is that Gels never see full service life due to too many volts and not enough time, and AGMs get closer to full. The actual service life is about equal in real world use due to the crappy chargers...

And you still see daft claims about batteries being "good" after 8 years use. Well ANY battery that isnt worked hard, cycled deeply, will do that even if charged badly! But most of these "good" 8 year old batteries are only good for their user.

To me they would be hopeless and tossed in the trash after one attempted trip! Been there and got the T shirt. I have a garden full of 12 month old descarded batteries tha would be great for 5 more years in a grandmas chair! She would never know.

[ex-Gooserider]

Maybe you should start a resale service... Get rid of your old used batteries at a discount, just for Grandmas and Junky Wheelchair readers...

Everybody wins - the WCJ types save money, and you make a bit while getting the junk out of your garden...

ex-Gooserider

[Burgerman]

I am going to use them as a big pile of excess solar power energy storage if the rain/snow/cloud ever stops!

[Burgerman]

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

MK above say: charge at 13.8 up to 14.1 MAXIMUM or service life is shortened, for CV 5 hours or 500thC.

Read the TEXT below CHARGING ...

Odyssey and most good AGM manufacturers state 14.4 to 14.7 volts to 1000thC for best cycle life and fastest charge.

http://www.odysseybattery.com/documents ... 11_000.pdf

Page 15 fig 6
Then read page 16!
HALF the service life if charged at 14.2v...

14.7V, MAX Amps scotty, 13.6V Float Room temp. 68f.

How then, can any one charger do both? Theres no way in hell it can know which type of battery or what size of battery is on the end of the cables!

I would love to hear Marks answer here! Because it cant actually do this...
No charger currently exists to satisfy this dual, without some user intervention or settings being changed, no matter what they claim. They just use 14.4v (28.8) as a good average...

I asked Ctek chargers the same question some years ago. Since they too claim gel compatibility and auto sensing etc. And they said "the standard 14.4v CV setting charges gels". Yes it does! And kills them off faster too. They had no further comment. And were not interested. Small part of their market.

[Step]

I saw these Exide Edge AFM batteries with 'SureLife Graphite Technology' ...
Sounds like excellent marketing

spec sheet here: http://www.exide.com/Media/files/Downloads/TransAmer/Products/Edge%204%20page%20booklet%20non%20spread.pdf

Can you tell if they have any advantages over the spiral ones?

These Exide batteries seem better available here in Belgium.

[Burgerman]

Lower cycle life than true deep cycle batteries, lower CCA and higher resistance than the odyssy, lower capacity in the same sized case, so cant see anything particularly good. Other than the marketing.

[Sully]

This makes agreat deal of truth; Quote; "Well yes. But he will never look at it... Its not just him but the whole industry. Nobody cares or wants to know the details that matter".

What reason is there, for the industry to admit, or desire to comply with their own rules? That doesn't sell more batteries, and that is what they are in business to do! They aren't completely lying with the propaganda sheets, but they aren't actually writing the absolute truth either. The premise is we are just a herd of sheep. Y'all get the rest.

[Burgerman]

MARK just posted this misinformation over at the other place:

Tony, mobility-specific chargers are engineered to meet the charging voltage of mobility-specific batteries.

The CTE charger (and those like it), is designed to charge both AGM and Gel batteries by delivering a voltage within the correct range (and, per battery manufacturers, there is a tolerance to charging, not an exact number). Here's an example:

MK 22 Gel pair (cycle) = charge between 27.6v – 29.2v
MK 22 AGM pair (cycle) = charge between 28.8v – 29.16v

The CTE charger delivers 28.8v in its “constant current, bulk stage,” then drops to 27V once 80% capacity is reached, charging the batteries to completion, so you can see that the 28.8V rate of the charger hits both Gel and AGM lead acid batteries, and the multiple stages helps optimize both the charging cycle and battery life. For the consumer, he or she should rest assured that mobility-specific batteries and chargers are engineered to offer optimal performance in working together. Thank you.

Sources:
http://mkbattery.com/images/M22NF%20SLD%20G.pdf
http://mkbattery.com/images/M22NF%20SLD%20A.pdf
MK Charger Reference: http://mkbattery.com/images/charger0603.pdf

27.6 is OK for gel. Right up to 28.2. (14.1v single battery) Above that at room temperature 68f or 20c shortens life and voids warranty... Marks range of figures are over a wide temperature range - not your bedroom... If its cold enough you can use 16 volts. Take a look at the correct charge voltage on the temp/charge volts graph in the link below:

See the MK recommendation HERE: http://www.mkbattery.com/documents/7175 ... 011-09.pdf

Specifically this part here about charging MK gels at room temp!!! Doesent get any clearer. Or look at the charge voltage and temperature at 20c. 13.8 to 14.1 volts...

I also have to add that the charger doesent deliver "constant current bulk stage" as he says at any voltage in particular. Its just chargers max amps output as volts climb up TO this figure... The charger then reaches Constant Voltage stage (Absorption) at a specific set voltage and then holds it there until amps fall away and then it says "done". So hes wrong again. And then it drops to a float stage after that. He doesent get any of this stuff.

See this page here http://www.wheelchairdriver.com/AGM-GEL.htm

[justahack]

Don't most common mobility chargers put out about 14.4v ? If so, would it not be advantageous to use standard AGM batteries since those are most suited to the majority of chargers? ( I.E. for folks who just want to get in and drive and are not going to bother with specs and chargers etc.) Thanks,

[Burgerman]

Yes.

IF most AGM batteries were any good.

But most are not. The Odyssey can be charged at 14.4v up to 14.7 too though, and it IS good! So a stock nasty charge anything charger actually suits an odyssey better than the gel it was supplied to charge! But you have to watch the cut off CV point. If its too soon then it will be undercharged and live half its full life. 200 rather than 400 cycles. Needs to keep going at CV stage for around 5 hours for full charge (to 1000thC) or cut off at 100thC and have a high float value for around 8 for a complete charge. This doesent need to be every time but at least once a week FULLY charged.

Theres another way to do this too. 1 amp, for 1 hour after a typical 3 or 4 hour CV stage ends. Ignoring the volts. It will go high! Dont watch. This is called "accelerated finish" instead of a long wait. Its not as kind!

[woodygb]

B.M.. ..I found this in one of the MK pdf's ..you may have seen it...but I thought it was worth a post.

percent.png (91.51 KiB) Viewed 4883 times

[woodygb]

Here's MK's recommendations.

agm-gel volts.gif (131.49 KiB) Viewed 4884 times

[Blade Runner]

Woody, you sure got Mark E. riled up.

Bob

[Burgerman]

Well as usual he was wrong while preaching! He doesent like being corrected.

[woodygb]

Bob,

He has little reason to be riled ..I've only used his data source... MK ... and not mentioned B.M.!

Perhaps it's his ego or Pride that's being pricked?

The CTE charger Pride seems to supply puts out 28.8v Charging Voltage(DC) and 27.6v Floating Voltage(DC) ... that's 14.4v per battery ...the recommended optimal on a gel is 13.85v @ 60-69F ...It would appear to be supplying .55v over the optimal...the block graph suggests that this will reduce life by 30%.

[Burgerman]

ABSOLUTELY correct according to MKs own freely available data.

Whats more is its actually worse than it appears, because in order to return all the Lead Sulphate that coats the plates back into the acid before it becomes hard and permenant, charging at CV stage must end after a much longer period on a gel battery than we have available on an overniight charge. So most cheapy mobility chargers tell you the battery is "ready" long before it actually is...

So Lead Sulphate builds up faster on the plates over time and never gets removed by a regular full charge... So we have OVER VOLTAGE as well as an INCOMPLETE charge leading to a) water loss over time and voids in the gel, and b) long term sulphation rapidly decreasing capacity/increasing impedance...

Meaning your expensive new gel batteries will never see their potential full service life. Expect around 300 cycles at 80 percent DOD instead of the 500 you should get
So marks claimed advantage over the nominally cheaper (but faster charging and perfectly voltage matched) AGM batteries is simply lost/wasted.

So you may as well buy the 400 cycle Odyssey AGM instead and gain some high amp performance gain as at least the 14.4v (28.8) mobility charger matches this quite well! Because you will get around the same real world cycle life PROVIDED you leave them on float as long as possible after charging (faster) every day. But this happens naturally since they charge lots faster.

[Burgerman]

http://www.wheelchairjunkie.com/forums/ ... 4&page=all

You got to love it. He will say that this doesent apply to mobility use or some such crap.

Or, whats the betting he will not reply?

[woodygb]

I'd go with ignore.

[ex-Gooserider]

Didn't ignore, but definitely blew you off and dodged the issue.... Don't know where he gets his (Unidentified) engineers from, but they don't seem to work for MK, or any of the other quoted battery tech manual writers, nor do they seem to have ever read that information...

I've poked at it some more...

ex-Gooserider

[Burgerman]

Yes I saw his latest reply. He now blames everyone in the industry and thinks its a newly identified but minor thing that woody should sort out with the battery and charger manufacturers...

Except that his company are the ones supplying the wrong charger and wrong charge algo for the very batteries they fit... Which he thinks is OK.

Honestly its not worth the bother. Best to educate yourself, and charge them your own (MKs) correct way. As always - knowledge is power. Those that make the effort to learn and understand the world around them benefit from longer battery life (in this case) and less expence, much as with everything else in life.

But I love the way he claims "inside knowledge" all kinds of "tech" powerchair industry stuff, while calling people like us "hobbyists or enthusiasts" in a derogatory way, as if he knows better while misinforming his readers. When its actually him as usual thats not got a clue!

But this seems typical of most mobility manufacturers. The good engineers that know anything useful, all seem to not be atracted to the mobility industry. Its full of useless jobsworths that plainly do not get it. We are therefore still 20 years behind - using heavy iron chairs with solid tyres or tubes, with wildly inneficient brushed motors, weedy/weak badly programmed controllers all fed with ultra heavy pre-historic lead batteries that they still dont even understand! Even though the marine/solar/every other manufacturer does. The rest of the cheaper non mobility EV world moved on years ago.

[Burgerman]

His reply (mark) copied and posted here:

Woody states conjecture: Mobility chargers may be reducing battery life by 30%.
Ex-Gooser immediately then restates it as a fact: Mobility chargers are reducing battery life by 30%.
Then, SweetBearCub reads Woody's conjecture, turned into fact by Ex-Gooser, and is now alarmed by the problem (which was literally fabricated from fallacies of logic).

What we have, therefore, is not a technical discussion, but a tabloid discussion, with no credibility, based in fallacy, not fact.

Funny then, that woodys "conjecture" (caused by a "fallacy of his logic apparently") was lifted DIRECTLY from the very manufacturers info sheets on charging in several places in several different MK documents about MK Gel Battery! So it is in fact, FACT!!!

And in fact well known by myself, and most people that deal with batteries in all other industries.

But we are just internet idiots aparently that dont know as much as him? And its all "hyperbole". Maybe he should tell that to MK who produced the charts and data for their own batteries? Cant he read? Or understand logic?

Hes right though. Best to ignore him and educate yourself.

[White Lightnin']

I stopped reading Mark's website long ago because the usable information I got from reading it wasn't worth the time it required. The attitude exhibited toward those contributing to the cite hasn't changed.

The laughs I got from reading through this thread and the thread referred to in Mark's website made the time it required well worthwhile.

[woodygb]

I really felt like quoting Mark and posting this...

The views on these threads skyrocket, so keeping them going actually increases the readership.

Marvelous .. my "conjecture" is being read!!

Ignoring me is far more detrimental to me because if I have no readership

They're not just reading YOU ...JEEZ !!!

However.. it is his site and he has a following/family that I have no wish to upset... so he'll need to read it here.

On B.M's site I can put my view point and get a proper reasoned and factual discussion / argument / debate .... it may not end in agreement .... but more often than not enriches knowledge.

[Burgerman]

The difference is that here we all seem to run on fact and logic. Over there half the posts are handholding, or religion, or some kind of ill informed missinformation that nobody is allowed to question...

Its all a bit pointless really. He doesent want reasoned debate or the correct answers. He want HIS answer. Just like all the rest of the mobility industry. Which is the very reason we have:

Lead batteries, iron frames, tubed or rock hard tyres, crappy programming and no access to the tools to fix it, and so on.

The rest of the world moved on 10 years ago. My RC helis have astounding performance that the Nitro burning piston engines cannot match, and wouldnt fly at all with lead brick batteries...

The hobby people ALWAYS lead the way. Not only with hobby stuff, but even cars! Low profile car tyres, alloy wheels, aerodynamic spoilers, electronic ignition, shaved door handles, clean low lines were custom car/racers only in the 70s. The rest of us inc the manufacturers all thought it was crazy boy racer stuff.

Try and buy a car WITHOUT these things today. Its just that the Wheelchair industry are even slower to evolve. Their knowledge of batteries, motors, materials etc is many years behind every other industry.

I have here 3 lithium powered brushless planes (some 7 or 8 years old and all brushless), 22 loose lithium batteries aquired over years of flying, 2 lithium powered laptops, a lithium powered mouse and keyboard, lithium LED ultra bright torches, lithium garden strimmer, lithium powered razor, 2 lithium powered helicopters and one of these is 9 years old, and a lithium powered lawnmower. And about 6 old phones and a smart phone. I also have a lithium powered chair, and one of my carers has a lithium powered bycycle... And all my cameras have used lithium for at least 8 years. Including my GoPro video camera. And the hedge trimmer. And the 2 RC transmitters. There are also plenty of lithium powered scooters (non mobility) and cars too.

So why lead with hugely innefficient brushed motors that waste HALF the power in our massively overweight oversized iron wheelchairs?

Ask the expert...

[Burgerman]

To elaborate a little here - one reason is "presumed" cost.

Well its cheaper! Do the math. Because they have a higher C rate, no peukert affect you can use a pack of just over half the Ah of the lead you replace = SAME cost as premium lead batteries.

But wait! Its now 1/4 of the weight, and half the size! So you gain more, because the CHAIR can be smaller, lighter, and the battery can be smaller again, because the total mass is massively lower than the old iron chair. So better materials (carbon, kevlar, titanium, alloys) can now be used saving even more mass.

Then we could gain literally another 30 to 40 percent in range with BRUSHLESS MOTORS. So our lighter smaller chair, with a SAME COST battery of half the original Ah will give greater range than before by a large margin. So you could keep this range, or increase speed or reduce battery size/cost/weight again...

And this doesent factor in the 2000 cycles, or 10 to 20 year expected battery life either! Compared to about 3 to 5 hundred with huge lead bricks!

Translated = idiots. This is why the rest of the world moved on from lead for EVs ten years ago.

[woodygb]

The main reason is.. IMO ...they have no financial incentive to do so.... it might be in the interest of the end user to make a chair using the tech you suggest .. but perhaps not in terms of profit for the chair company.