PINNED - Lithium battery conversion/info

[steves1977uk]

Just to add I charge the pack at 30 amps and it does this for 60-90 minutes before dropping away down to 1 amp after about an hour.

Steve

[Burgerman]

http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm

That's fine. Updated page here!

[JoJo7]

I get it. Thanks.
Referring to your photo part way down this page:
http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm
I expected to see n+1 balance connector wires for n cells in series. In this case 13 cells-> 14 balance connector wires. But it looks like you only have 4 balance connector wires. Can you explain?

[Burgerman]

There are 14.

[stevelawiw]

Just to add I charge the pack at 30 amps and it does this for 60-90 minutes before dropping away down to 1 amp after about an hour.

Hi Steve what psu do you use to charge at 30 amps?

[Burgerman]

You will need about 1000 to 1100 watts for that.

I use one of these. I have 2 now in fact. http://www.ebay.co.uk/sch/i.html?_odkw= ... acat=58288

http://www.ebay.co.uk/itm/USED-digimess ... 2a4a592f59

Actually do 44A and 31V maxed out or about 1350 watts.

[stevelawiw]

Bah! I bought the wrong one

http://www.amazon.co.uk/Heavy-Regulated-Supply-Adjustable-Current/dp/B00FG62NGW/ref=sr_1_1?s=diy&ie=UTF8&qid=1414584456&sr=1-1&keywords=bench+power+supply+20a

I thought it would pair up nicely with the hyperion, but if you try and use it with the hyperion trying to pull 20a the psu trips out and interrupts the power supply stopping the charge, so I have the hyperion set to charge at 15a. It works but it's far from perfect

[Burgerman]

hyperion 550 watts output. 85 percent efficient? So about 700 watts in.

So a 24v 700 to 800 watt supply is required.
I run 2 hyperions at full power from 1 power supply when charging hobby stuff.

I cant afford amazons prices!
http://www.amazon.co.uk/PSU-BENCH-40A-Q ... ds=sm+3040

I buy the "used" ones on ebay. They are actually brand new demo ones, never a mark. Used to be 199 now 214.

[steves1977uk]

Just to add I charge the pack at 30 amps and it does this for 60-90 minutes before dropping away down to 1 amp after about an hour.

Hi Steve what psu do you use to charge at 30 amps?

Hi Steve,

I use the same PSU as BM has shown the ebay links for the digimess. I would charge at 40 amps but since 4mm banana plugs are only rated up to 30 amps, I don't want to risk any higher.

Steve

[Burgerman]

Theres some heavy connectors at the rear that I connect to an Anderson.

[Burgerman]

50A http://www.skyrc.com/index.php?route=pr ... uct_id=180

Another https://www.youtube.com/watch?v=9WRv4qu1THI

Theres these too.

60A https://www.youtube.com/watch?v=XHS6hklR3ic
Another 1200 watt one https://www.youtube.com/watch?v=kiAbAHXWpuY

When it comes to power (and everything else) the hobby guys are way ahead!

Note the charge rate on the tiny hobby batteries. I do this daily for 10 years.

Yet mark over at the other site thinks we wouldn't benefit from better charging, batteries etc in a recent thread. He is like all the chair manufacturers on a different wavelength to the rest of the world. Just in the process of ordering another lithium 108Ah LiFe pack for another chair here!

Tempted to get one of these too... https://www.youtube.com/watch?v=bmpzwfk8u6E Charge at 50A or 2000 watts...

[steves1977uk]

Tried using one of those EFUEl psu's, the only problem I've found with the one I have is when you try to draw a high current under load, the voltage drops and the charger cuts out.

They might be ok for the Hyperion but definately not the PL8 unless charging small LiPo packs.

Steve

[Burgerman]

50 or 60A?

[steves1977uk]

it's rated 60a at 20v or below, or 50a at 24v. The newer 30v one might be better.

Steve

[Burgerman]

I just acquired a pair of powerlab PL8v2 chargers. Or I have when they arrive on Monday. But am looking at the instructions and software.

For my hobby stuff. I will likely keep the Hyperion's for charging the 13S 45V stuff only now as I only have 2 working ones left and these go to the cell count and voltages that I need.

My first impression of these is that they are pretty good. At least as good as the Hyperion's, and probably better for 8Cell lithium batteries. As used in a powerchair.

But they have a few issues.
1. Software is really difficult and clunky. And you cant set charger up for your specific needs as its pre-set menu driven. Its like big brother!

2. There's no way to set up a float charge for lead... You can set charge rate/ Amps and the default end point is about 2/3rds charged! And no float. And there are a lot of safety inspired things that get in the way. Like length of time at CV or charge. Top work around it you have to set a manual cut off at say 200thC point to 500thC point, and say 30 mins at 1 amp at a "trickle" then off... Default CV time is a joke and this can take much longer that they allow from the drop down menu. But its about workable if you set it correctly and know what you are doing.

3. LiFePO4 (or as they incorrectly call it A123!). This wants to start balancing at one of 4 settings. 3.0, 3.1, 3.2, 3.3v It is too soon. The actual balance depending on charger calibration, and on actual cell voltages may SEEM 10 or 15mv out, at these lower voltages when in fact cell balance based on Ah is actually perfect. And because discharge "curve" is actually almost a perfect horizontal line trying to balance them at this voltage can end up unbalancing them significantly. Because the real balance once the voltages start to rise near charge end may bear no significance to this 3.3v point. So it doesn't allow you to set this high enough. On a small pack, it would have little affect because the charger easily rebalances as charge ends. On as huge 108Ah pack for eg it may take a long time. So while it will work its not a great idea. It does allow 2 options however. a) you can choose balance at CV only. That will work. And is what the hyperion does. Or you can choose to charge on a lipo "pre-set" and charge to 3.600v instead of 4.2, and set every single setting manually. And start balance at 3.4v or 3.5v. Which is I think what I will do eventually if I charge my 13S battery as a split pack. Which I might do since I can charge at 40A mps with 2 chargers. That means 2 hours to charge from 5% to 100% percent...

When I get these chargers and analyse what it does, what is possible I will update this thread. This is exactly why I ended up sorting out the hyperion charge issues years ago! Only that started out with more issues than this charger.

[steves1977uk]

Will be interested to hear how you set up the PL8 for headways BM

I took the A123 high power preset and customised it. The only thing that irks me is that there needs to be higher balancing voltages.

My PL8 managed to blow the 15A fuse in my digimess PSU What happened was I had upped the DC Power input to 40A (normally I use 35A at 28v), but I had left the charge amps at 30A. When I started the PL8 charging it normally draws about 32-35As and never any higher, only this time it started to draw more than that after it had put about 15A back into the pack. I'm hoping the digimess PSU will be ok if I get my Brother to put a new fuse in it.

Steve

[Burgerman]

That surprises me. I regularly have my 2 Digimess 30V 40A power supplies charging lead batteries at 29.4v (or a bit more because of wiring losses) and at max amps. Like 43 to 44 Amps...

For years. The only time I upset one was connecting 2 series batteries in reverse polarity. Funny noises, huge bang, and some smoke. Sent it back for repair. Cost me 100 quid to get it fixed... And I did that a few times in the past and just blew lumps out of the andersons!

[Burgerman]

I am setting up my new Revolectrix PL8v2 (two off) charging station next to my PC.
This has 2x linked 1344 Watt (40A, 8 cell) chargers, and 2x 40V x 40Amp bench Digimess power supplies...

They are 1600 watts input each, so when charging at full power I can charge at 3.2kw from the wall... Slight overkill and these are a stupid price but no more Hyperion's so decent single 14S chargers are no longer possible.

2 of these http://www.revolectrix.com/pl8_description_tab.htm allow them to run as one big charger and that can charge one big 16Cell battery provided you use 2 ISOLATED power supplies. (Check yours by measuring resistance between the NEG output terminals - they should be disconnected or isolated from ground and each other when everything is plugged in!) And they have PC software to drive them and log data. And they are reliable and the company seem to be very solid. And a big 2 amp balance current means faster charge. They have a couple of issues, but nothing we cant work around.

These are preferred over the iCharger by me http://www.progressiverc.com/icharger-4010duo.html alternative because of the isolated supply/one big battery issue, PC software, and one or two reliability issues. For most users the fancy coloured screen and ease of use would make the iCharger preferable I think. But I always used PC control and data logging / graphs.

[shirley_hkg]

What's the pros to charge at 20--30A, when you have time to spare ?

[Burgerman]

None. I never have time to spare. I charge lead chairs directly from the power supplies while sat at my PC on my lead powered chairs at 40Amps every day.

But the BM3 chair has 3x the watt hours to put back. That takes a lot of recharging. So more amps / watts = faster.
But that wasn't really the point. I was quite happy using the Hyperion's at 550 watts each. But they are no longer in production. And only have 2 working ones left. And one of those is in my van for hobby use at the field. If the indoor one fails, then I have no charger than can charge my lithium chair. And I am about to do another 108Ah lithium battery for my older chairs. Those are being rebuilt. So I will change the BM3 45V chair to split charge, and use a single 8S charger on the 24v 108Ah older chairs. And a higher balance current is also helpful.

Plus I really need 2 in here. I am charging my camera, (lithium) and my flash (4x AA Eneloops) as I type.
Quadcopter + spare pack are 16.8v 5200mAh and can charge at 8C (40A each...) and RC transmitter is next in line and there's a few more.

Once done the chair will get 30 mins at full power then dog walk! There's quite often a queue for charger or power supplies here!

[stevelawiw]

Hi BM so does this mean that there's not going to be a replacement for the 1420i in the Hyperion range? If so you must be slightly miffed that the charger you spent some time on helping with the development shall be no more?

I feel in a bit of a quandary on which direction to take on my next project which is to up the voltage on my outdoor/indoor chair. From what I've learnt from you and others on this site the higher the voltage the better, so I was going to buy a Roboteq HBL2372 (available in about a month according to Roboteq) and reconfigure my 7p8s LiFePO4 into 3p20s to give me 64v. I was planning to have this split into 2 10s packs for charging purposes and use two 1420is to charge.

I'm not looking to be doing 20mph everywhere but I'm attracted by the greater efficiency (and more speed on tap is never a bad thing in my book).

I'm going to have a go at modifying the GB motors by installing my own Hall sensors like this http://endless-sphere.com/forums/viewtopic.php?f=30&t=32838&hilit=invacare&start=25

As I say I'm in a bit of a quandary if there's not going to be a replacement 10-14s Hyperion as I'll be stuck for a charger for my 10s packs (I guess I could stock up with Hyperions!)

[Burgerman]

You can charge any pack up to any cell count if you use multiple 6S or 8S chargers. They can connect together and work as one. As l
The only proviso is that you either:

Have a connecting link you can remove between the battery segments. Much as I do now when charging 12v/24v for lead.
OR
You use a FLOATING or ISOLATED power supply such as the ones I am using to charge each half or third.

So for e.g. you could quite easily have 3 of my new 8S chargers, and have a 24 cell pack. But it starts to get more complicated.

The other thing is that when you get beyond around 50V then electric shock and other issues start to become a problem. As well as granularity of control at slow speeds. At least if you use the usual 24V intended motors.

[steves1977uk]

Mum helped me to replace the fuse in my digimess PSU, turned it on and.... Bang!!!

Do you send them to the address on their website for repair BM?

Steve

[Burgerman]

That's not good! Those things are bomb proof. What did you do?

Yes email them. They have a fixed not very cheap price. Come back looking and working as new.

First take a look, may be something simple.

Also here http://www.tercalibration.com/Make.aspx ... 9&tid=7347 no idea of price or competence but they repair these too.

[steves1977uk]

All I did was up the DC Power input on the PL8 to 40A (up from 35A). The digimess PSU was set to max amps and volts (40a at 31v). There was always a red led lit under the volts but never on the amps. So no idea how it managed to take it out.

Steve

[Burgerman]

I suspect that it was just a coincidence. They are protected against over current, the voltage just falls when the current is maxed out. Eventually if it falls far enough it considers it is a short, and cuts off power. You can link the outputs and turn it on, no problem.

The charger cant be the issue.

[Burgerman]

Tested my two PL8 chargers and my power supplies today. At 27v and almost 43 Amps. They didn't seem to care.

They do seem to have 1001 things the slap your wrists for though. It wont let me do lots of things I want it to do...

How do you get access to the OEM password I wonder... That should allow me to make a few settings it thinks I shouldn't.

[steves1977uk]

No idea about the OEM firmware password, although this would allow you to fine tune the settings from what I've read.

I've also managed to get the PL8 working with the EFUEL 1200W 60A PSU I have as I have had the digimess sent away for repair.

What settings do you use on the DC Power input BM? I used 28v at 35a before I changed it to 40a and blew the PSU. I now use 18v at 45a on the EFUEL, since this hovers around 22v when unloaded and goes up to 24v or slightly above when under load.

Steve

[Burgerman]

I use 40A on the charger. Low voltage cut-off at 10V, and tried it at 42, without problem.

I actually set the power supply at 29.4v and max amps because I use this to charge my lead powerchair directly at full power daily. It sits at 41 to 43A for about 30 mins before it drops away.

[steves1977uk]

Ah I had mine set at 31v at 40a and the low power limit set to 28v, although this shouldn't of caused the PSU to blow. Have asked digimess if they could upgrade my PSU to 50a if it would be possible for them to do so. They also sent me the circuit diagrams for the PSU.

Steve