Urgent advice needed: 4 pole or 2 pole motors?

[Burgerman]

It's not that they read it on the internet, it's that with the same usage and the same mobility charger, they last less time. Like in the case of faico_26, for whatever reason, one of them got damaged even though it was new. Why?

Many reasons.

OK.
First of all you cannot just fit 2 new batteries and use them. You must use a 12V charger and charge each FULLY. First. Or you must at very least connect both together in parallel for 24 hours or longer to be sure both are at the same exact state of charge. Or on the very first charge, and the following dozen or so? You will overcharge one, and undercharge the other. That results is one battery becoming slightly sulfated, and the other becoming overcharged with shrinkage of gel, positive grid corrosion, and other issues.
The net result being that you have no range and a defective battery!

Then you cannot replace ONE battery to match the existing one. You must replace the pair or the same crap will happen all over again.

So I am not surprised at all!

You MUST ensure all batteries that are run in series are the same batch, same age, same state of charge, same number of and depth of cycles or they will likely die very soon.

And you must ensure that they are charged CORRECTLY! That does not normally include a mbility charger...

Its not possible. They are made in factories oveseas to mk's exact same standards and certification and measure exactly the same impedance and capacity. So theres literally no difference.

When you have tools to measure Ah to a couple of decimal places, (PL8v2 and software) and accurate 1000hz impedance tester (as shown in my Lithium cell pinned thread), its trivial to actually MEASURE this stuff. Then all the internet nonsense about US/China made MKs goes away!

It a story I keep on hearing for years. And I have tested and measured them. Exactly the same results.

What has really happened is this:
Cheap crappy generic one size fits all AGM,/Gel univesal chargers are now supplied for 5 to 10 years, and rehab chairs got much heavier and more common to have heavy powered functions. And generally have faster motors and more equipment today. And many chairs got narrower meaning smaller battery Ah.

So net result is deeper average DoD, higher current draw, which has a drastic effect on cycle life. Weight means less range as well as high daily discharge levels. And crappy "modern" chargers that charge at AGM voltages which damages gel, CV charge end too soon mean sulfation on top. So 3 things conspiring to kill gel batteries even if they were not smaller to begin with...

So horror stories appear on the internet looking for "reasons"... Its possible you had a bad one, one that wasnt actually new, or a pair that were not balanced and charged equally before installation. So over the next month of charges one got over, the other got undercharged. Causing permanant issues.

For what its worth the 40Ah ones at the 2 hour rate (6mph for 2 hours = 12 miles and dead batts) are around 25Ah batteries in reality. But because the voltage drops due to peukert you wont even get that before the chair stops moving. So maybe 18 to 22Ah usable. So it doesent take much to make you think they are defective! Way too small for a powerchair to begin with. And this soon means no range.

[Burgerman]

Thinking in NO damaging the AGM batteries of the new Q300R, making a full charge of 12 hours or so and then charging them every day would be enough?

Remember that everything you do right helps them some!

-On INITIAL installation both batts need to be from the same batch, same age, same state of charge, and fully charged for 16 hours before first use. If not they wont last whatever you do.

-Every time a lead battery is not sat at 101% full or on float at a CORRECT float voltage for storage it begins to age or deteriorate.
They like being full. They hate being discharged. They hate being overcharged too! They dont like heat, they dont like being stored at the wrong voltage. (13.2 to 13.3V)

-Every time a lead battery is used (cycled) you wear it out a little. If you charge it properly (not a mobility charger!) then you can help to minimise this deterioration. An AGM of decent quality will give 350 to 400 cycles in a lab. If those are DEEP cycles, thats maybe reduced to 20 cycles. If thats discharged lightly thats maybe many thousands of cycles. Tip. TOP IT UP SOME DURING THE DAY! It keeps the average discharge level (the Depth Of Discharge or DOD) lower. So you get thousands of cycles and not tens of cycles...

-Use correct charge algo, so 10 or 12A, CV at say 14.5V times two, and keep charging until current falls to 0.2 to 0.3A or 8 hours CV whichever occurs first. Then float for 4 to 6 hours (not critical) at 27.2V.

Think that I’m just an average user, with only some knowledge of Rc cars and Rc planes but I have no clue about how to make a charge/discharge cycle in the wheelchair batteries.

Buy a ZXD set as above! Its massive overkill but charges properly!
https://www.wheelchairdriver.com/board/ ... start=1920
Or anything that can do the same.

[Burgerman]

These...
Its a custom build, fully adjustable robust electrical telecoms power supply. A ZTE, ZXD 2500 converted to be a consumer supply.

Its a 3kw capable, 0-60V and 0-50A power supply. For many purposes. Its also a completely user configurable 3 stage lead acid or Lithium battery charger!

You set all the parameters and then set it to be plug and play (locked) in its menus if you want.

Anything can charge a lead battery. Badly! This can do it properly. If you tell it to...

Again its all about knowledge. Its a tool. It requires you to make the right choices it isnt magic. Its always about knowledge.
It can charge at any curent. So an XLR safe 12A or less if you wish.
But fit an anderson connector, so that you can put a lot back fast at higher power during the day as you eat or check your mail and that reduces average DOD and extends battery service life as well as imediate range. The batteries will love you. An essential overnight charge is then EASIER to achieve in a complete fashion too. As the CC stage time is reduced.

Its all a matter of choice. And knowledge.
Lead batteries are still crap! But this gives them the best chance!

[faico_26]

Nice tutorial, thanks!
In have been using the Invacare Mirage since 2006 almost 20 year, 1 chair every 5 or 6 years, never a problem with the batteries. But this time everything went wrong and now I understand why. I got the 2 new batteries, 1 was almost dead but I was on holidays for 1 month out of my country. So I spent about 1 month using 2 batteries when 1 was dead. The result is that when I got the dead battery replaced probably the other one had suffered a lot. Bear in mind that during my holiday time I took the batteries to extreme discharge several times. Terrible.
One thing that I’ve learnt is that I will never buy batteries in online shops anymore. You cannot even imagine the problems the store put against me to reject replacing the dead battery. When they should have replaced both!!

[Burgerman]

Had you had a PL8 you could have properly tested the remaining battery and it would have shown that it too was damaged.

Theres really not much that ever goes wrong with a battery. They can have a manufacturing fault. Such as a bad electrolyte mix, or contaminated metals. But in the vast majority of cases a battery isnt faulty. Its murdered. By the user. Who normally thinks that they didnt do anything wrong...

Ever time a battery came back under warranty I would cut them in half longways to decide if it was a manufacturing fault of killed by misuse.

Almost all were white inside, across all cells. Thats lead sulfate. Caused by undercharging. Some were dry, short of water, dried out gel, gel with bubbles in it or AGM materiial with no electrolyte left. And blue or light grey positive grid corrosion. This is caused by too high charge voltage or too warm battery, or by charging at too high float voltage in storage.

If we ever cut one apart and ONE cell showed a difference, and the other cells looked healthy, grey, black inside, no electrolyte missing, then that was a defective cell. A manufacturing defect.

I had a EV battery, a haze AGM EV 12V one fail completely and suddenly. That had an internal cell joining strap burn through. So no go! Again that was a manufacturing issue.

But these things are almost always user problems. Charger problems. Too deep discharge (active material expanded out from the grids) and sulfated etc) or left in a less than fully charged state for long periods.

Batteries dont die, they are murdered by ignorance.

[Burgerman]

Also... A great way to very quickly destroy a battery is to use it in a very warm country like spain. Then while its not 100% charged, it is sulfating really fast!

Lead battery lifespan is reduced massively by a few degree extra.


a lead-acid battery that is expected to last for 10 years at 20C, will only last 5 years if it is operated at 30, and just a year and a bit if kept in a desert climate at a temperature of 40C.
Heat destroys lead batteies.
Incorrect charging does the same only faster. At 30 and at 40C you need to lower charge voltage respectively.
Deep cycling, and especially regular deep cycling (too small battery) also rapidly kills them.
In the heat leaving them not fully charged even for short periods is highly damaging as the permanant sulfation happens much faster.

You are in spain right?

[faico_26]

Yes, I’m in Spain and it was July. Then I used the batteries for 1 month in Costa Rica, but it was not extreme heat, 20 degrees on average but very humid.
The batteries were brand new and from the first day one of the batteries was not ok. I had a voltage sensor conected and the bad battery fell super fast while the other one remained on 12v or more.

[Burgerman]

In a chair, while not moving plus say 5 mins wait any battery that isnt above around 12.3V is either dead, knackered, or discharged, bad cell, or something...

[faico_26]

Exactly, I knew from the first moment that the battery was dead, but the problems I found with the shop trying to replace it were incredible. Eventually they accepted to replace it but like a favour to me they said.
When I asked before purchasing the 2 batteries, the guy in the shop told me (by phone) that I must buy only the MK because he said my charger would only charge correctly the MK batteries (which obviously were more expensive). I don’t know if that is true or I could just have bought another batteries cheaper. The result with these MK has been terrible. The first battery was dead and I probably damaged the good one.

[Burgerman]

Almost every mobility charger in the last decade isnt any good for gel... Some might be? Only measuring them will tell you! But I never found one.

They are generaly a one size fits all, claim to be AGM/gel compatible which isnt actually possible.
14.4 to 14.7V (28.8 to 29,4) CV, at 8A, normally and they end that CV stage WAY too soon. After maybe 2 to 4 hours. And give a green light. Then as long as the green light is on you get a float stage. Sometimes...

They think that its close enough to charge AGM and gel. And say so on the label... They do non of that above accurately.
Its a closer match for AGM as long as it is allowed to stay on charge for a full day and ignore the green light.

And its true. Anything CAN charge a AGM or a Gel battery.
But not if you hope to get even half of its useful service life...

Remember that we are charging gel now at too high voltage, even before warmer summer temperatures. And remember the battery is warmer than the room after use and while charging. So a 20C day means mabe a 23C battery.

So MK specify 13.8 to 14.1V max. For best cycle life. And a warranty!
Best voltage for max service life then, would be 13.95V. (x2 so 27.9V at 25C).

Heres what MK say about using a higher voltage...

[Burgerman]

So not only did your battery expert have it wrong, it is the exact opposite. Dont listen to "experts"...

And its really worse. Because not only does a one size fits all AGM/Gel charger, charge at too high voltage, it UNDECHARGES the battery. So the overvoltage part damages the gel, causes shrinkage and voids.
And then the UNDERCHARGING caused by it ending charge far too soon, allows the battery to remain less than 100% charged.

That means the lead sulfate that now still coats the plates, hardens over time and turns into much larger crystals that do not conduct. This is why rapid recharging is important! This means that any subsequent FULL charges, (when left on a float charge long enough for e.g) never fully remove the lead sulfate back into the electrolyte. As these crystals are non conductive. Once enough of this exists, the capacity is diminished, and internal resistance increased, then the battery is junk.

And no all the snake oil "desulfators", pulse chargers, high frequency chargers, reverse wave pulse chargers, etc in the world cannot do anything more than a proper charge cycle can. Because permanant sulfation is permanant because IT DOESENT CONDUCT!!!

Lead sulfate is formed on the cell plates naturally as part if the discharge reaction. The electrolyte acid gratually turns towards water during discharge. The plated are coated in lead dioxide and lead sulfate. When charged FULLY all of it is returned back to the electrolyte. Making the acid high specific gravity again. Unless only 99% of it gets returned by inadequate time on charge. That means maybe 1% gets left behind every charge. This hardens and turns to non conductive crystals over time, and does this much faster in warm conditions... And you live in spain!

[faico_26]

Thanks Burgerman. When I pick up the Q300R I will check the charger but for sure it will be a moibility charger, I hope it will charge AGM decently. We’ll see.

[Burgerman]

I thought that sunrise used gel batteries in all new chairs. At least here in the UK they do.
They are normally the exact same battery as the Haze Gel EV ones you can buy in many places (good quality) but with different branding. Called the ETERNITY Technologies, GEL G04. I dont know if Haze or Eternity or some other supplier is the actual manufacturer but they are identical with different stickers on the sides! They are both 80Ah in grp24 size, same impedance etc.

The Dietz chairs also use gel batteries. It that case their grp24 one is 76Ah, MOVE branded. Also good quality.

Some brands use A500 Sonenschein branded batteries, also gel. And the original designer of the gel battery system that the others use under licence.

Others use 74Ah (73.6) MK gel as grp 24 size.

Any of these 5 are great for normal use in a chair. Gel is better for almost all purposes in a powerchair.
Only odyssey AGM beats them in high current/sport/fast charge situations (like my silly programming, wheelies, power soccer, etc).

Here is MK gel v MK AGM.

[faico_26]

In Spain with the Q300R the only available option is 64ah AGM Battery.

[Burgerman]

Do we know which one? Is there a spec sheet?

[Burgerman]

Batteries Q300R
QML160016 Battery, 50 Ah, Gel, Maintenance-Free 0
QML160013 Battery, 56 Ah, Gel, Maintenance-Free £130
QML160030 Battery, 64 Ah, Gel, Maintenance-Free (3) £130

(3) not available with ISM6-L

So you cant have the bigger battery if you have more than one powered option, (the R-Net 90 POWER MODULE can do 1 seating channel without a seating module added) and more needs a ISM6-L

But it says they are all gel?
https://www.sunrisedice.com/asset-bank/ ... /78875.pdf

For what its worth, a 64Ah battery in that GRP22 size will mean very high impedance. OR/ AND less cycle life. So the smaller Ah battery is a better bet.

[faico_26]

On the order form there is only 1 option which just says 64ah, nothing about gel or AGM. But in the instructions manual says that 64ah is AGM.

[Burgerman]

I see contradiction is their paperwork. Almost like they dont know what they are doing. That couldnt possibly be right though.

So its a lottery!

[faico_26]

Today I’m picking up the chair. I will ask confirmation to know whether it is AGM or Gel.

[faico_26]

To sum up: Did I choose right? I chose 4 pole 163RPM. Or maybe should I had chosen 2 pole 175RPM?

[Burgerman]

2 pole motors are crap. Regardless of any microscopic speed advantage on paper. Because the load compensation works badly, Less torque which is more important than speed, and they slow more under load so likely slower anyway. And because they are technically more efficient theoretically, in practice because of the way a controller works, they are the opposite.

If speed is that important get 4 pole 13kph motors.
Remember that speed = much more Amps at every speed even slower ones. So needs bigger power module and bigger batteries too. Or problems...

2 pole?

[faico_26]

Thanks man, that is the answer I really needed!!!

[Burgerman]

Why are 2 pole more efficient in theory?
Because the 2 magnetic poles are twice as wide. Less magnetic overlap inside the motor.
So small gain in efficiency theoretically.

less efficient in practice?

Because a 2 pole is NORMALLY much higher impedance. Lets call it double. Which it normally is.
That means that it draws less current. And current = torque in direct proportion at any given voltage.
So that if we need X torque to propel a chair at 2 mph, for e.g; then it takes double the motor voltage to = the same torque.
And so instead of say 10V it takes 5V from the controller to get the same current and same torque.

So with the 2 pole we get 10V and say 5A. = 5 X 8V = 50 WATTS FROM THE BATTERY.
With the 4 pole, we get 5V from the controller and the same 5A (x 4V) = 25 WATTS... So double the range... But slightly lower intrinsic efficiency so not quite 2x better. But still much better. Lower impedance always better.

[faico_26]

Why are 2 pole more efficient in theory?
Because the 2 magnetic poles are twice as wide. Less magnetic overlap inside the motor.
So small gain in efficiency theoretically.

less efficient in practice?

Because a 2 pole is NORMALLY much higher impedance. Lets call it double. Which it normally is.
That means that it draws less current. And current = torque in direct proportion at any given voltage.
So that if we need X torque to propel a chair at 2 mph, for e.g; then it takes double the motor voltage to = the same torque.
And so instead of say 10V it takes 5V from the controller to get the same current and same torque.

So with the 2 pole we get 10V and say 5A. = 5 X 8V = 50 WATTS FROM THE BATTERY.
With the 4 pole, we get 5V from the controller and the same 5A (x 4V) = 25 WATTS... So double the range... But slightly lower intrinsic efficiency so not quite 2x better. But still much better. Lower impedance always better.

This is the only web where I could find such precise information, thanks!!!

[Burgerman]

Physics.

[faico_26]

I already have the chair. Quite fast actually.
What I don’t like are the noisy motors. Very powerful but very noisy.

[Burgerman]

Well. I am used to an angry superbike with open exhaust. So all chairs seem very very quiet to me! But I know what you mean.

Are you sure that theres no fault? They shouldnt be loud. If they are then maybe theres a problem. Are both the same? A whine (slight) is normal.

Turn up sound and listen to these!
This sounds like a motorcycle...
At 1.25 mins.
https://www.wheelchairdriver.com/gopro/RC-BM3.mp4

[faico_26]

Hi,
There is no fault, it’s just the buzz when revs up. I guess it’s normal, I’m quite sensitive to these little details. My Invacare Mirage is super quiet.
By the way, your chair is really impressive.

[Burgerman]

Its a bit overpowered.
And its broke.
And I now need tilt/recline/legs etc for ongoing pressure sore prevention and cure reasons so its an ornamant.

[faico_26]

Yesterday I asked the guy at the store to increase joystick sensitivity but the only thing he could is increase acceleration. So the chair it’s a bit lazy in the first moment but it accelerates super fast, too much I would say. He put it at 85%. It’s like a turbo.
What I don’t like though is that when I’m running on a straight line at top speed and I make small corrections of direction the chair slows down every time I just move a little bit the joystick to right or left.