Gel vs Lithium Batteries

Power wheelchair board for REAL info!

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

Re: Gel vs Lithium Batteries

Postby Burgerman » 07 Apr 2021, 10:10

15 years in one case. But then my BM2 lithium battery is about 10 years old and as good as new. So its expected if the current levels (C rate) and upper and lower voltages are carefully controlled. They are very careful about using only around 70% of the battery capacity avoiding being full or empty if humanly possible. Sometimes it isnt due to mars seasons and dust build up. But mostly they can. And so extending the life of the cells. And just like the PL8 everything is very controlled and balanced in the same way. Albeit built into their on board computers and controlled and monitored on earth by radio signal. A bit like our BT modded pl8's! So yes they dont have a PL8 obviously, but do have its equivelent as a built in computer controlled system able to control the charge rate as they balance. Just as most EV like tesla do.

But with laptop style lithium ion cells that your phone and laptop, teslas. and mars rovers use you can determine state of charge by voltage quite easily. And so a simple BMS can control charge much more easily than it can with lifepo4 cells. The reason we are avoiding those is because each one is a very angry firework. And the dissabled cannot get off and run away. Or push it outside rapidly so it doesent set your house on fire.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Gel vs Lithium Batteries

Postby Burgerman » 07 Apr 2021, 11:09

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

Re: Gel vs Lithium Batteries

Postby ex-Gooserider » 13 Apr 2021, 02:08

Of course there are no details about what kind of batteries were in that thing - or the charger being used.. US scooters that looked like that would probably be lead powered, but who knows what they were using in China...

Of course if it was lithium, probably also had a BMS in it...

ex-Gooserider
T-5, ASIA-B
Jazzy 1100
Jazzy Select 6
Quickie Q-7
Invacare Mariner
Want to make / get a better chair, ideally one that stands.
User avatar
ex-Gooserider
 
Posts: 5962
Joined: 15 Feb 2011, 06:17
Location: Billerica, MA. USA

Re: Gel vs Lithium Batteries

Postby Burgerman » 13 Apr 2021, 02:11

I know what they are. 18650 cells. lithium ion cobalt. And not many. Same as used in a laptop. Yes BMS. All those tiny scooters from china use them.

They can be reasonably safe until they are not!
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Gel vs Lithium Batteries

Postby wes4dbt » 15 Apr 2021, 17:19

I got a portable chair, KD Smart Chair. been just sitting in the garage, haven't used it in 4yrs. It has some type of lithium batteries, don't know if the batteries are even any good anymore. Been worried about how safe they are. Hate the chair, don't plan on using it again. Probably should figure out how to dispose of it.
wes4dbt
 
Posts: 134
Joined: 21 Sep 2017, 20:04
Location: Modesto, Ca

Re: Gel vs Lithium Batteries

Postby Burgerman » 15 Apr 2021, 19:07

The batteries will maybe discharged. When below a certain point they are ruined and probably safe ish.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Gel vs Lithium Batteries

Postby robintheplumber » 16 Apr 2021, 12:09

wes4dbt wrote:
If you do what most mobility chargers do, and discharge them heavily as you were doing, you will get a few months use and crap range. I tell people this for 23 years and nobody listens!


Oh, I think most people listen, maybe they don't understand but they listen. I asked a second time because the sell sheet, which I mistook for a spec sheet, seem to be saying something different. Sometimes it takes hearing things more than once before you understand.

Thanks for the information

btw - I'm still interested in information on this question,

If your chair comes with a 5a charger is it safe to use a 8a or higher??? I've always worried that you might burn out the wiring or it might ruin the batteries. If I could use a 8a charger that probably would help.


If I buy a new charger, I want it to do the best job.


In the same place as you wes4dbt but determined to get to Lithium. So if I've got it right.... If you fancy lithium you'll need the charger 1st because without it, it seems charging requires Burgerman's understanding of batteries, power supplies and the universe in general. The only one BM recommends is this one:
http://www.store.revolectrix.com/Produc ... Lab-8_3299
And it'll do wonders for your lead, Gel etc.. apparently. They fly off the shelves (probably because of this forum) every time a new batch is produced. A new batch are due for release shortly (so they say) and you can pre-order. They'll supply people in the order they ordered!!
robintheplumber
 
Posts: 42
Joined: 05 Nov 2019, 19:18
Location: Southampton U.K.

Re: Gel vs Lithium Batteries

Postby Burgerman » 16 Apr 2021, 12:29

If your chair comes with a 5a charger is it safe to use a 8a or higher??? I've always worried that you might burn out the wiring or it might ruin the batteries. If I could use a 8a charger that probably would help.


Most proper mobility systems, like Pilot Plus / R-Net, or Dynamics DX / DX2 or the newer LiNX stuff, etc all state 12Amps RMS Maximum.

So in almost every case you can charge at 12A safely. I have done 13 and 14A at times when in a hurry and nothing bad happened!

LEAD batteries are better charged at the higher rate, 12A or more with a different type of connector such as Andersons, as I use. For e.g. I have a 24V 30A charger next to my bed. A 40A one next to my computer. And regularly see 60 to 70A charge in my van. Why is it better?

Because the faster you can load the initial BULK part of the charge on a deeply discharged battery the longer it allows you during the brief overnight period to get a more complete charge. And that means lower sulfation levels, longer service life.

Remember that it actually takes around 16 minimum, to 24 hours to FULLY charge (fully saturate) a lead acid/gel/AGM battery.

A battery can if deeply discharged pull 100A or more from a charger if it can supply that much. And it then rapidly recharges at first. Then the current (Amps) soon starts to drop. After say 1 hour it will have fallen to maybe 2 or 3 amps. And will take another 16 hours to fully charge.

If you try the same with a 5A charger, it may sit at the maximum 5A for 10 hours on a 70Ah battery, BEFORE it drops to that 2 or 3 amps. And then takes another 16 hours on float to get to the same fully saturated point...

So the faster you complete the CC stage, the faster you load the bulk of the charge back in, the longer it gives you to start topping off that last bit. So the battery ends up more full when you have to use it. It also means you can wack a lot of power back in in a short time as a mid day top up, as you eat or sit at a computer/TV. That too loweres the average depth of discharge, meaning much longer battery life, and less to put back at night, so more complete charge happens in the limited time availabe.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Gel vs Lithium Batteries

Postby Burgerman » 16 Apr 2021, 12:42

With lithium, the opposite is true. They dont like big currents, dont like being left full for long periods, or being discharged at high rates. Or being discharged deeply.

So here the obvious solution to prevent ALL of those things is to fit a big Ah lithium pack!
So currently that means a 200Ah pack in a grp 24 sized space.

By doing this, you can use the PL8 at 40A charge and it will continue to charge at 40A for 95% of the charge. So you can put back a full 200Ah if you want in 5 hours with 15 mins top off/balance. But you then have charged the lithium at a very low rate compared to what they are capable of. So they like that. You can also not charge full. Theres nothing to sulfate. So theres no need to do a 3.65V per cell charge. You can do a 1 hour charge top up. That will add the same amount of range as a fully charged set of 70Ah lead batteries! Because they only give 40Ah best case. So a ONE HOUR charge will allow most people to do more than needed in a day. And you can do a full charge weekly.

Of charge to a lower voltage of 3.550V with some benefit. And if the pack is fully charged to this voltage you will get at least 5x the range of lead. So you do not need to heavily discharge either. Again this makes the battery last a long time. Only go 4x as far!
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Gel vs Lithium Batteries

Postby wes4dbt » 23 Jul 2022, 01:53

I resurrected this thread because my question is related to the Victron charger we discussed earlier in the thread.

The charger has been doing a great job on my 40 ah MK Gels. Over a year and they're going strong. I got another chair, this one has 52ah MK Gels.

My question is, would I use the same charging profile that I use on my 40's. It seem like I would but I thought I'd check.
wes4dbt
 
Posts: 134
Joined: 21 Sep 2017, 20:04
Location: Modesto, Ca

Re: Gel vs Lithium Batteries

Postby Burgerman » 23 Jul 2022, 02:13

Yes.

Its amazing that MKs last a lot longer when charged correctly isnt it...

All these people that tell us MKs are no longer as good, etc is nonsense. THEY are killing them with incorrect charging via a typical mobility charger. The difference is huge.

Esp if you give them a quick charge during the day AS WELL whenever you get chance. E.G sat at a PC or meal times. That makes them last at least twice as long.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Gel vs Lithium Batteries

Postby fishinjunky » 23 Jul 2022, 13:31

Burgerman wrote:Yes.

Its amazing that MKs last a lot longer when charged correctly isnt it...

All these people that tell us MKs are no longer as good, etc is nonsense. THEY are killing them with incorrect charging via a typical mobility charger. The difference is huge.

Esp if you give them a quick charge during the day AS WELL whenever you get chance. E.G sat at a PC or meal times. That makes them last at least twice as long.



i thought about getting this charger for the mk gels i took out of my chair but they were a year old an already murdered went from 8 miles range down to 6miles (4 miles offroad) so i decided to just scrap them. I was going to donate them to local nursing home like bm mentioned but they told me they werent allowed to take them.

i do have a 12 year old tdx sp with group 22nf batteries. This chair is just a indoor backup. Would this charger extend the 22nf lead acid batteries life? I could use my icharger but i want to use it just for the lithium. This chair is very very lightly used only in winter indoors
Invacare tdx sp
Bounder 300M 200ah lifepo4
fishinjunky
 
Posts: 1041
Joined: 11 May 2021, 02:28
Location: West Virginia United States

Re: Gel vs Lithium Batteries

Postby Seajays » 23 Jul 2022, 16:57

I think my 10 amp charger that came with the chair killed my MK's
Seajays
 
Posts: 1201
Joined: 13 Apr 2010, 18:25
Location: Edmonton,Alberta,Canada

Re: Gel vs Lithium Batteries

Postby Burgerman » 23 Jul 2022, 17:47

Batteries age naturally (umnwanted chemical reactions from the acid/impurities) over time even if kept at the perfect float voltage. It only helps to keep them healthy for longer. You lose 20% of capacity on a 10 year quality battery even if only used for standby purposes.

You lose capacity if discharged/recharged. And you lose it faster the deeper they are discharged. So dont discharge them deeply every day. To do this add a top up charge for an hour during the day. That will make a huge difference to lifespan.

Dont charge at the wrong voltage. Dont STOP charging until they are fully filled, and saturated. Overnight (8 hours) is inadequate to do this. And so at least on gel, you need 10 to 12 hours CV at least! And possibly another few hours at a lower float voltage to fully return the sulfates back to the electrolyte.

This will help give a longer life. As will charging at a higher rate. To allow a longer CV stage. So 20A via an Anderson connector.

BAD THINGS
Charge wrong CV voltage.
Charge too short time. Takes around 16 hours.
Too deep daily average discharge (too small battery for the job)
Fitting before both batts are charged INDIVIDUALLY to 100% or at least connected together in parallel overnight.
Stored too warm temp.

Gels are much more voltage sensitive than AGMs. And most chargers that the mobility industry uses charge a)too slowly at 5, 8 or 10A, b) at AGM 14.4V, c) give a green light far too soon. So undercharge.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Previous

Return to Everything Powerchair

Who is online

Users browsing this forum: LROBBINS and 144 guests

 

  eXTReMe Tracker