WheelchairDriver

by **Burgerman** » 04 Apr 2018, 14:20

I bought 2 spares. 7 years ago. I still have them.

by **expresso** » 04 Apr 2018, 17:04

i had a few spares also - i still have them - but i did end up using one spare after the first year - just my bad luck maybe - but glad i had the spares - i had extra spares and made a 12V pack for another item i use it for - its great to have spares - never know - you dont want to wait around if you ever needed one -

i got extra spares with the intention of using 4 of them for something else also if i didnt use them for the chair - i still have 2 spares which i hope i wont have to use - been going good for close to 3 summers now - this summer will be the third with lithium :clap:

by **garriew** » 04 Apr 2018, 18:04

Do I need a power supply w/ the Cellpro PowerLab 8 v2?

by **Burgerman** » 04 Apr 2018, 18:22

A battery in a car, anything from 12 to 30V works fine. You need a 35 A or more and 24V up to 30V to get maximum power which is a lot. But you can also run it from a smaller supply.

by **garriew** » 05 Apr 2018, 04:14

Burgerman wrote:A battery in a car, anything from 12 to 30V works fine. You need a 35 A or more and 24V up to 30V to get maximum power which is a lot. But you can also run it from a smaller supply.

Would this be a good PS?

http://lipoconnectionsolutions.com/HP-2 ... 241500.htm

If yes, what would you chose for the charger type? and other options?

by **Mind The Gap** » 05 Apr 2018, 09:25

Update

Hello Paul,
We have received your order online. Thanks for your business.
For the reason that Headway facotory temparily stop their plan to produce more 38140S 12Ah model since Jan(they said the demand is much lower than their other models), right now we only have some stock for this model. They don't produce it and may no longer produce this model even we order a lot.
So we are sorry for the inconvenience, and we suggest you to think about if you can use 38120S 10Ah model or 40152S 15Ah model which we can ship immediately.

Sorry for the inconvenience. And please kindly let us know your advice and we will work on it accordingly.

Have updated order to 58 40125s with 4 hole connecting plates, waiting for repy.

Paul

by **Gnomatic** » 05 Apr 2018, 15:47

garriew wrote:
Burgerman wrote:A battery in a car, anything from 12 to 30V works fine. You need a 35 A or more and 24V up to 30V to get maximum power which is a lot. But you can also run it from a smaller supply.

Would this be a good PS?

http://lipoconnectionsolutions.com/HP-2 ... 241500.htm

If yes, what would you chose for the charger type? and other options?

I have that PSU with an EC5 connector. It works well enough with my PL8.

by **expresso** » 05 Apr 2018, 16:03

Mind The Gap wrote:Update

Hello Paul,
We have received your order online. Thanks for your business.
For the reason that Headway facotory temparily stop their plan to produce more 38140S 12Ah model since Jan(they said the demand is much lower than their other models), right now we only have some stock for this model. They don't produce it and may no longer produce this model even we order a lot.
So we are sorry for the inconvenience, and we suggest you to think about if you can use 38120S 10Ah model or 40152S 15Ah model which we can ship immediately.

Sorry for the inconvenience. And please kindly let us know your advice and we will work on it accordingly.

Have updated order to 58 40125s with 4 hole connecting plates, waiting for repy.

Paul

If you can fit those 15Ah - you be better off anyway - more juice

since you ordered them i am guessing they will fit -

by **garriew** » 05 Apr 2018, 16:21

Gnomatic wrote:I have that PSU with an EC5 connector. It works well enough with my PL8.

Did you order it w/ bullet connectors?

by **garriew** » 05 Apr 2018, 16:43

garriew wrote:
Gnomatic wrote:I have that PSU with an EC5 connector. It works well enough with my PL8.
Did you order it w/ bullet connectors?

I figured it out.

by **Gnomatic** » 05 Apr 2018, 23:52

Mine works fine so far. Its a no frills supply. But it gets the job done.

by **Mind The Gap** » 19 Apr 2018, 10:09

Hi all
Batteries out for delivery today, nice weather and I'm stuck in hospital.☹️

by **Burgerman** » 19 Apr 2018, 12:58

by **robert97** » 21 Apr 2018, 16:53

this is a typical charging one of my two 7S5P headway 38140S packs.

: a good balanced charge

as you can see, the pack took 41917 mAh and was perfectly balanced.
given

" Lithium batteries hate being fully charged, ... "
Re: Vienna aka Viennese
Postby Burgerman \xbb 24 Mar 2018, 10:23

and

"To get good cycle life tesla/volt ... and a max charge of 80%. "
Re: PINNED - Lithium battery conversion/info
Postby Burgerman \xbb 08 Mar 2018, 21:37

does it make sense to stop charging early most times? and fully
balance/charge occasionaly?

by **expresso** » 21 Apr 2018, 18:14

From the looks of that Graph - You are already not fully charging - i mean its already being stopped - at 3.55V your good and you should balance them all the time - i believe this to be correct way - BM will correct me for sure - its looking good

by **Burgerman** » 21 Apr 2018, 21:30

I charge at 3.550V per cell. The manufacturer says 3.650. Why? Because that much overcharge allows a degree of natural balance as the full cells cant charge more. and energy is wasted as heat. So they get less cells back as damaged due to use of unbalanced cells. They do that because the typical charger is a 2 wire dumb charger and relies of a typical BMS which has too low balance current and lets the cells go over and under the target voltage for many hours while attempting to balance...

You can reduce it to 3.525 or 3.500V if you want as a minimum, but charge time will be slower, longer at CV before true balance is achieved.

Your CV time is already too long though. Whatever the termination point mA is on tha PL8 now, increase it by 50% at a time until you get a termination at about 1 to 2 hours after it attains a balanced CV top voltage. On your graph around 3.6 hours point.

You only need longer at CV if the pack is slow to balance. If its good, as yours is, set termination Ma higher, CV timeout to say 2 hours, too.

by **Burgerman** » 21 Apr 2018, 23:08

Remember that tesla cars cells are typically 500 full discharge cycles only as they are just lico cells as used in a laptop. Thats 4.2v to 2.5V to use full capacity. But teslas battery management never allows the cells to be fully charged. So they do not deteriorate fast. It says 100% at a lower approx 4.1V per cell. And the car says its dead when about 25% remains, and then stops.

Dont run them low, or high, and dont take massive currents or fast charge them, and they last way longer than the 500 cycle limit suggests. Much the same applies to the 2000 cycle LiFePO4 chemistry we use too. Except it starts off with 4x the expected life and does not burn.

Lithium lasts as long as you plan it to last. With correct treatment they will go on almost forever. With wrong treatment you get 1 cycle. With "full" rated capacity used and recharged, they dont last.

Fitting a BIG pack and only using say, 20 to 70 percent of it most days means it should last practically forever. Because of lower average % discharge daily and lower current on charge and discharge per cell. Fitting a lot of Ah is the correct way to go lithium. It pays back massively. Charging to just 70% or 80%is hard to do with our LiFePO4 packs, since the voltage cant tell us this. So charging to 3.500 or 3.525 and keeping CV level down to as long as it takes to balance, and then to top up slowly with a low current (typically an hour of CV) is the kindest thing for them. But thats still 98% full. But its volts they dont like. Keep away from the manufacturers 3.365V!!

Teslas LICO cells, are never full, even when the car SAYS they are. He uses a 140KWH rated pack and uses 100KWH from it. Allowing 20 percent unused at the top and bottom of the capacity. For service life reasons. And some say to only charge to 70% for even better lifespan. https://electrek.co/2018/04/14/tesla-ba ... tion-data/

by **shirley_hkg** » 24 Apr 2018, 08:58

Cool connector. What's it called ? :dance

by **Burgerman** » 24 Apr 2018, 10:57

Dunno. But its huge! Unless thats a photo trick. :problem:

by **Gnomatic** » 27 Apr 2018, 17:18

Doing a bit of maintenance on my chair getting it ready for warm weather. In the process I pulled out my battery pack and decided to see what kind of shape its in after one year of use. I fully discharged my 90Ah pack till one cell hit 2.9v, then charged it back up.

So 89Ah returned. With the charger not violating the laws of thermodynamics, that means the actual amount of power returned to my pack is a bit less than that. So in a year on I've had a bit of degradation. I'm not surprised by that. A big heavy chair and a big heavy me, with a fairly small pack. I'm off pavement quite a bit, so I'm working the cells hard.

Still though, not bad. It might be good for me to build a 30Ah add on pack at some point. 90Ah has proved to be plenty of range for me. But with the add on, it would lighten the load on the cells a bit. Especially when I know I'll be going on hiking excursions etc.

With the PL8 saying 89Ah returned, what's the best guess of the actual capacity of my 1yr old pack now?

by **Burgerman** » 27 Apr 2018, 19:54

So what Ah was REMOVED from the pack, when the first cell hit 2.9V?
THAT is the all important figure and deadly accurate.
With the following provisos:

Never test to full capacity, unless a spare cell, since its very bad for the cells and you can finish up with a cell that has increased self discharged rate very easily. To test and measure FULL capacity you must discharge at around 0.1C to 2.50V. Or use a higher rate and a CV discharge to 2.50V.

So unless looking for ultimate capacity measurement at 100% discharged never really try to go lower than your 2.9v (or 2.8v at the very lowest). But that wont measure full capacity. Theres also a false drop off at around 90 percent discharged that looks like thats it. But that flattens out again for a while if you keep going. But best not to try that unless you are desperate to make it home... So you will measure about 11Ah this way from a true 12Ah cell if you discharged it fully at a low rate.

You cannot measure Ah back in with any level of accuracy.

So 89Ah returned. With the charger not violating the laws of thermodynamics, that means the actual amount of power returned to my pack is a bit less than that. So in a year on I've had a bit of degradation. I'm not surprised by that. A big heavy chair and a big heavy me, with a fairly small pack. I'm off pavement quite a bit, so I'm working the cells hard.

I would be surprised if theres more than 3 to 5% loss of actual capacity. You cannot measure Ah back, to determin capacity that way. For these reasons.

You do not know how much was left after you stopped discharging. So you might get only 90Ah back into a 100Ah battery to be 99% full because it wasnt empty. And the last 1Ah to 3Ah may take 6 or 8 Ah to complete due to thermal losses and balance losses (1A dumped to a resistor begining as soon as CV is reached, which all add up.
These losses depend on balance settings, and termination current as much as anything. But also in cell internal losses at 3.600V. And on resistance in the whole system. The loom, cells, and the charger all have internal resistance and get warm. Its quite normal to be 97 to 99% efficient at the early part of the charge. And much less as charge starts to reach CV.

With the PL8 saying 89Ah returned, what's the best guess of the actual capacity of my 1yr old pack now?

I dont think it is very helpful. What did it take out? Add to that say 5 to 7% remaining that you didnt remove. Thats more realistic.
But at a guess I would say about 3% less than when new. Going by my own packs. Unless theres a fault.

by **Gnomatic** » 27 Apr 2018, 20:28

Thanks for the reply.

I don't know how much I took out Without a supply with adjustable voltage, I'm not able to use my load dump and the PL8 to do a regen discharge the way you do, with the PL8 controlling the whole thing, measuring how much power its taking out of the pack etc.. And w/o regen discharge with load dump, the PL8 is very slow by itself when discharging.

So I just connected my ~20A load dump to my pack. Used the PL8 to monitor, and when cells hit about 3.1v, I disconnected the load dump, and used the PL8 to finish discharging. Then charge the pack up.

So your 3% best guess is all I was asking for. My intention was not extreme precision. So all in all my pack seems in decent shape after a year of use. No returning to lead bricks.

by **Burgerman** » 27 Apr 2018, 21:03

With well maintained lithium, on a relatively large pack, we seem to get around 3 to 4 percen capacity loss initially, then it seems to stop deteriorating any more unless abused in some way. At least the caacity loss seems to slow greatly.

After a year on heavily used lead mine are generally declining ever faster. The opposite to what we see with lithium. And usually down to less than 80% remaining capacity. But because the IR also goes up markedly as they deteriorate you actually get much less than the 80% range you would expect. It becomes very noticible fast! This can be largely avoided and last about 3 year+ if you regularly whack about 40A, 29.40V back in (odyssey) for an hour or so every time you sit near your computer, or drive anywhere. So they dont actually ever get low! It keeps them full/younger!

by **ex-Gooserider** » 01 May 2018, 02:40

shirley_hkg wrote:Cool connector. What's it called ?

It looks like some sort of Anderson variant, but that doesn't help much. I tried looking at http://www.ddclm.com/ based on the name in the photos, but the site is in Chinese or similar ideographic language, and I don't see any buttons for getting English, so you are probably better off checking it out than I am... cheers

I'd say the nicest thing about it is that little lever setup to ensure positive hookup and locking - might be really good for our members that have trouble manipulating regular Andersons...

ex-Gooserider

by **crypmanii** » 02 May 2018, 03:07

Has anyone on here converted an Omegatrac to Lithium batteries? I've been reading through this thread but with 174 pages of information its a little overwhelming. HaHa. I know its not a quick "plug & play" process to make the conversion. Is there a kind of walkthrough for making the conversion? Something like this may have already been posted, and if so I apologize for asking, but I just haven't seen it yet within the pages I've already looked at.

Any guidance would be greatly appreciated.

Thanks all.

by **expresso** » 02 May 2018, 03:20

If you like you can start here

viewtopic.php?f=2&t=6873

this is an ADD ON pack which you can add to the lead in the chair - you can just look here to get an idea on a much smaller pack -

you can see its just two rows of cells - - but its the same if you make one large pack for the chair - just keep adding more rows of cells -

i started this way with help from others here - my intention was just to make an ADD ON to see how it works out - two weeks after that - i realized how great it will be and since then i have done a full chair lithium with an ADD ON - this one actually and use a 36ah ADD ON with lead on another chair -

its addictive and soon will be doing another chair -

this section is fairly easy to to understand and view pictures etc, - if you can make this ADD ON - you can make the whole chair also -

there are other types of Cells now which may be easier also - instead of these headways -

take your time and figure it out what can fit etc, - you wont go back to lead after lithium

by **ex-Gooserider** » 08 May 2018, 02:57

Not an expert on Omegatrac, but I don't know of any reason why it would be any more of a challenge or more difficult than it would be on any other chair...
The process is not THAT difficult, (

unless you're Expresso...

) but it does require a good understanding of basic electrical concepts, and a reasonable level of ability to do basic mechanical and electronic build tasks - which is often the biggest issue for those of us in chairs...

It has also gotten a bit more complex lately in that we are getting more choices about what cells to use, but this may be a good thing as it lets us make even better packs than used to be possible...

The basic approach is still the same =
1. Figure out how much space you have available
2. Pick a combination of cells that will fit in that space, ideally the one that will give you the highest Ah capacity.
3. Get an appropriate charger (currently the PL-8) and power supply
4. Get the cells, and test them to find the right arrangement to get a pack that will balance readily,
5. Build the pack and install....

ex-Gooserider

crypmanii wrote:Has anyone on here converted an Omegatrac to Lithium batteries? I've been reading through this thread but with 174 pages of information its a little overwhelming. HaHa. I know its not a quick "plug & play" process to make the conversion. Is there a kind of walkthrough for making the conversion? Something like this may have already been posted, and if so I apologize for asking, but I just haven't seen it yet within the pages I've already looked at.

Any guidance would be greatly appreciated.

Thanks all.

by **Schultz5905** » 18 May 2018, 04:20

Does anyone have a diagram of a 5 x 8 cell pack.

by **Mind The Gap** » 18 May 2018, 07:57

Hi BM

Any chance of a preset for a 8s7p 105ah Lifepo4 pack for pl8.

Cheers Paul

by **Burgerman** » 18 May 2018, 08:47

Will do, but expresso has one, and may post before I can as I am stuck on bed with wrong computer at this moment!

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