Charging MK Wheelchair Battery

Power wheelchair board for REAL info!

POWERCHAIR MENU! www.wheelchairdriver.com/powerchair-stuff.htm

Charging MK Wheelchair Battery

Postby Rye » 22 Jun 2017, 21:43

I have an MK battery (from Permobil C300) that I need to charge separate from the chair. I have a wheeled shop-type charger. Is it safe to charge the battery with it? The charger has a "Jump 200a", "Boost 40a", and a "Maintain 6a<>2a" setting.
Permobil C350/C300, Quickie P-222, Magic Mobility V6 Off-Road
User avatar
Rye
 
Posts: 620
Joined: 04 Sep 2013, 16:30
Location: US

Re: Charging MK Wheelchair Battery

Postby Burgerman » 22 Jun 2017, 21:58

Its safe as in it wont hurt YOU. But if it charges above 14.1V (and it will) and if it gives an incomplete charge and it probably will, then it will hurt the battery.

But as a;ways more info or details needed. Can it do JUST maintain? And what does it mean by maintain? If its around 13.8V CONSTANT VOLTAGE that will charge the battery safely, but take 2 days for a full charge. But it sounds like a big old fashioned transformer/rectifier charger. And it will ruin a gel battery.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby Rye » 22 Jun 2017, 22:11

It does have a "Maintain" only selection (6a<>2a). It's a battery not used very often. The manual says "[the charger] maintains 12 volt batteries, keeping them at full charge." Whatever that means. I guess I should have asked will it hurt the battery anymore than charging with my 8a wheelchair charger?
Permobil C350/C300, Quickie P-222, Magic Mobility V6 Off-Road
User avatar
Rye
 
Posts: 620
Joined: 04 Sep 2013, 16:30
Location: US

Re: Charging MK Wheelchair Battery

Postby Burgerman » 22 Jun 2017, 22:22

Yes.

Dont do it. Its maintain may be a 2A trickle (current) if its got no electronics. That will ruin a sealed gel battery.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby Rye » 22 Jun 2017, 22:26

It's a computerized charger.
Permobil C350/C300, Quickie P-222, Magic Mobility V6 Off-Road
User avatar
Rye
 
Posts: 620
Joined: 04 Sep 2013, 16:30
Location: US

Re: Charging MK Wheelchair Battery

Postby Burgerman » 22 Jun 2017, 22:29

User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby Rye » 22 Jun 2017, 22:30

Permobil C350/C300, Quickie P-222, Magic Mobility V6 Off-Road
User avatar
Rye
 
Posts: 620
Joined: 04 Sep 2013, 16:30
Location: US

Re: Charging MK Wheelchair Battery

Postby Burgerman » 22 Jun 2017, 22:30

Does it have a spec sheet?
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby Burgerman » 22 Jun 2017, 22:32

As usual, not enough info...
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby Rye » 22 Jun 2017, 22:35

I'm gonna contact them to get more info.
Permobil C350/C300, Quickie P-222, Magic Mobility V6 Off-Road
User avatar
Rye
 
Posts: 620
Joined: 04 Sep 2013, 16:30
Location: US

Re: Charging MK Wheelchair Battery

Postby motoman » 23 Jun 2017, 14:13

Burgerman wrote:As usual, not enough info...


Its clearly has the length and width of the unit, what more do you want? :lol:
motoman
 
Posts: 297
Joined: 28 Feb 2012, 02:18
Location: Wisconsin USA

Re: Charging MK Wheelchair Battery

Postby Burgerman » 23 Jun 2017, 15:52

Quite. Why is it so difficult to find out what most chargers actually do (wrong)?
All the specs need include is charge amps, CV voltage, termination method or current/timer, float CV voltage level if any.
Then anyone that knows what they are doing can choose a charger.

It can be a simple line of data.
An example like this for AGM:
3 Stage. CC 8A, CV 14.40V, (Termination = 90mA or 8 hours whichever is sooner), CV Float = 13.50V. indefinite.


ALL chargers should include this info. Or how can you know if its suitable?
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby Sully » 24 Jun 2017, 15:59

Very few buyers of these chargers give a hoot. All they want to do is see if the customer's vehicle will take a charge, or sell them a new battery. They rarely have much if any understanding of a Deep cycle battery, gel, cell etc. etc. It simply is not important to them and what they do. :|
Sully
 
Posts: 2223
Joined: 04 Dec 2010, 18:44
Location: Hampstead, North Carolina, USA

Re: Charging MK Wheelchair Battery

Postby Burgerman » 24 Jun 2017, 19:35

Yes but I mean all chargers. You cannot buy one easily as almost all have inadequate info.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby LROBBINS » 24 Jun 2017, 19:59

Maybe they don't publish specs because they know that any two units of the same model are likely to have noticeably different charging characteristics. There seems to be a bit of QC lacking in these.
LROBBINS
 
Posts: 5543
Joined: 27 Aug 2010, 09:36
Location: Siena, Italy

Re: Charging MK Wheelchair Battery

Postby Burgerman » 24 Jun 2017, 20:50

Maybe. But is it not possible to have a reference voltage chip cheaply of some kind? And many chargers charge at CV and then stop charging at anything from say 3A down to 1A. Even supposed mobility chargers. That really should be around 1000thC based on capacity, so a 73Ah MK would be about 73mA termination. Or 8 hours for thermal runaway safety on old or warm batteries that never drop low enough.

I have 3 invacare branded upright chargers here. They (two of them) charge at 8A and have a CV of halfway between AGM and Gel. So too high for MK, too low for AGM. They are supplied with their own MK equipped chairs. The long loom, and bus cables on the chair, mean the battery sees an ever increasing CV voltage... its too low straight after CC stage, while at 8A, and too high while sat for hours at 2amps downwards. Which I may add is where the green comes on. They remain charging at CV for about 12 Hours though, long after the green. At about 28.66V. And then drop to float after this of 13.7V. So ok for completing charge but too high for storage... The 3rd charger looks the same, has a timer for CV stage, is 28.8V and no float.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Charging MK Wheelchair Battery

Postby LROBBINS » 24 Jun 2017, 22:00

Of course they could be either engineered or trimmed to have a precise profile. After all, your hobby charger does. It's just that the manufacturers of run-of-the-mill chargers don't care because their customers don't know to care. And it isn't all that hard these days to be precise. I have two simple voltage dividers for measuring voltage drop across the contactor - to check for stuck open or fused. Without even trying to match the resistors, there's all of a 1 mV difference between the two when the contacts are closed. SMD film resistors are that close.

The original switching charger patent was held by an Italian manufacturer who still makes a pretty wide range of chargers from small to humongous. They are all programmable for any profile one would want, but only at the factory. They sell to distributors who sell to re-sellers (generally separate ones for sales to businesses - wholesalers - and sales to individuals - retailers) who sell to end users. If the distributor who supplies the fork lift market specifies a profile for say 1000, 100 or 200 Amp units, he'll get it. At any level in the chain below that, not a chance. The retail sellers, of course, can not tell you anything whatsoever about the specs of the ones they sell.
LROBBINS
 
Posts: 5543
Joined: 27 Aug 2010, 09:36
Location: Siena, Italy

Re: Charging MK Wheelchair Battery

Postby Burgerman » 25 Jun 2017, 17:27

One thing the hobby chargers (At least the PL8 and the Hyperion) does is to monitor real battery voltage rather than the voltage at the charger as it charges. It does this at high frequency during some short breaks, many times a during the charge. So it knows the difference between the actual battery voltage while not shoving 40A in, and the loaded (on charge) voltage at the charger. So it can adjust the chargers CV charge voltage to give the correct voltage at the battery as it charges rather than at the the charger. It has 3 voltages. ON charge. Off charge. and Displayed voltage. All 3 are different! The displayed voltage is the chargers averaged battery voltage while on charge I think.

As far as I can tell no mobility chargers do this so the voltage climbs in a curve during CC and CV stages. Rather than holding a steady value at the battery.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom


Return to Everything Powerchair

Who is online

Users browsing this forum: Gregg and 95 guests

 

  eXTReMe Tracker