Wheelchair with Handcycle

Aloha, I have run my 72v Lipo 8800mah pack through a couple of charges and found a problem

ONe of the BMS's was heating up (I have 2 x 37volt running in series = 74 Volts) and I found one of the modules that should be 7.4 volts (2cells) is only at 4.5 volts.

What is inside the cell pack? I am wondering if there is a disconnect in the series of first cell to second cell or do you thing the 2 cell pack as a whole is toast?

Anyone taken them apart? Here is a link to the cell. http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=16783

francis
 
Sounds like you might have a bad cell in your pack. If you open it up you will find a group of pouch cells and the connections / wiring. Are you not able to test the cells individually using your balance wires?

Also, take a look at this thread and consider the compression method threads scattered around ES. You might want to re-think your pack a little bit.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=52244

:D
 
Your motor should be fine for 15 amps @ 80 volts. You Need a torque arm or two for that motor Now. Disconnect cruise control so it doesn't get stuck on full throttle. How do you charge your setup ? Do you have a cellog to check cells ? You said 36volt pack with BMS ? Pics please. Yes a little more rack. More ? Dont know.
 
Aloha, yes there was one dead cell in my 2 cell pack (zippy 5000). I have an extra cell to replace it.

1) is the shrink-wrap good enough to compress the 10s 5000 mah pack that I already have, as I only pull out about 3c from the pack and only use up to 30-50% before I opportunity charge?

2) I got my pack free from a friend and learning Lipo, but I do notice the pack is slightly puffy, (not hard puffy but cushiony as if there is gas between the cell and outer layer. is this normal?) or is this what compression method is all about?
thanks
Francis
 
spdas said:
....... or is this what compression method is all about?
thanks
Francis
Click to expand...

It is (probably) what the compression method is all about. Depends on how puffy is your puffer. Yours doesn't sound bad....Plastic shrink wrap is not generally considered stiff enough to keep the cells from puffing.

:D
 
Aloha all. Maybe a STUPID question, and I have a 2 cell Lipo pack and trying to replace a defective cell.

**** BUT ****

how do you get the solder to stick on the tabs + to the - to make the 2 series pack?

I tried cleaning the tabs off well, tried a 40 watt and got a 140 gun type solder iron.
Tried rosen core and tried acid core.
When I warmed the tab that had a bit of solder on it, the solder balled up and fell off.

Anyone changed Lipo "Hershy bar" cells?
What is going on?
thanks francis
 
Aloha, all. I bought a 48v 12ah lithium pack, see pix. It came testing at 40v only and I found the BMS had a burned area,
So time for a new BMS for the 13s. I searched Ebay and cannot find the correct size (65mmx65mm) to fit into the pack. Any ideas?
20160124_115116.jpg
thanks
Francis
 
http://bestekpower.com/481v13spcmbmspcbforli-ionli-polymerbatterypack/PCB-D132.html
 
Aloha, I am also putting together a new 60v pack.

1) does it matter if i use 4x4s bms's and not 1 x 16s BMS?

2) Amp rating of the BMS, If I am using a continuous 10amp to the motor, what size bms should I get? Does it depend on what current you draw or what current you charge at?

3) A bit unrelated question. I am putting together a "hard case" LIpo battery. Does the "hard case" provide enough compression? ebay cells I bought:
http://www.ebay.com/itm/131473796790?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


thanks for your replies

francis
 
1. For a 16s pack, you want a 16s bms unless you want to charge each 4s section separately.
2. Motor amps mean nothing the bms should output the same or more amps as the controllers max amp draw. All bms's have a max output and max charge rate. you need to stay within those4 limits.
3. I've been using a 24s2p pack made with those same hardcase packs for almost 4 years and 13K miles. It would be a real pita to to remove them from their case. Don't worry about it.
 
Thanks for the help. soooo-

I guess it is ok to charge a 8s pack using a 13s bms or does it need to be exact?

And the does the hard case give enough compression? (the packs I currently got from a friend are swollen 1 1/2 times their size with what seems to be air, so I want to be sure I treat the new packs nicely)

thanks again
francis
 
Aloha,
Looking at my battery pack and the aluminium part, I would like to replace it with a square plastic piece and put the black plastic end pieces on top and bottom. In order to make it shorter to fit my new lipos. or longer if I add more lipos. Anyone done this and knows an applicaiton? I am thinking to find a 3"x4" vinyl fence post or some such that fits nicely. Or some other square tube.......do you know what comes close to working?

francis
 
Puffy packs are not just air. Hydrogen, I believe and very flammable. Be careful with those.

I like hardcase because they have their own protection and they pack nicely together.

For soft pouch cells, fence post sometimes works? Sometimes gutter downspout, Mailbox posts, reshaping various plastic pipe, etc?
 
I like these hard cases too and 4 fit nicely into the case, but only fill up 2/3 of the case. Rather than cutting down the case and regretting it later, just wondering if anyone found the "perfect tube" to swap out. I will cruise around home depot tomorrow and see what fits nicely. I have some "carbon fiber" vinyl covering to wrap it to make it it look nice.

francis
 
Aloha, I got my 4x4s @5 ah and they seem to have a real thick shell and should make a nice compact pack.

I ordered 4 more to make 10ah (as that was the last of them, at least for now) and that should give me the range I want.
5.0ah.jpg
4x4s packs in series and parallel 2 making 10.ah and 60volts

Questions,
1: Are the plastic shells strong enough to avoid swelling?
2: Should I be able to use one bms for each pack that is in parallel, using the same charger?

thanks
Francis
 
1. No.
2. You just need one bms per pack, regardless of how many packs you put in parallel. 16s1p or 16s6p only needs one bms.
 
Hey spdas, perhaps this can help illustrate one way to assemble 16S2P w/BMS using Turnigy hardcase packs.
FullSizeRender-2.jpg
I never molest the Hobby King packs so that I can still claim warranty if needed within the 1st couple months.
FullSizeRender-1.jpg
My method uses 4S silicone wire JST parallel extensions and merely move the female contacts to whatever housing’s needed for my BMS cell channel connection. No cutting or soldering. The supplied 4mm bullets handle series power connections up to my custom APP adapters. Parallel cell level is accomplished through the 4S balance wire extension cable.

As you series main power connections you’ll discover redundant balance wires from the 4S packs. That’s for you to figure out and keep it all straight. I wouldn’t wish my methods on my worst enemies.

It’s a learning process, go slow, test for polarity often. Always lightly touch connections in a way which allows for you to pull away without full plasma flash/destruction.

As far as swelling - don’t worry much about that. If the cells are contaminated from manufacture and/or abuse (over discharge) they’re gonna puff. Trying to stop that is somewhat futile in my experience. If you notice some swelling get it out of the full pack - it’s bad, defective, etc.
 
Aloha, Going without a BMS. Am I wrong?

I have two battery packs.

One, the bms (or something) went bad, burned the board, and seems to have taken some cells with it.

the second was my inherited battery system...... the BMS is OK, but for some reason it "zero'ed out" a cell and also killed the new cell I bought. I had to charge the cells individually to balance them and now they seem to be OK

SOOOO. I put together another pack of 5000mah 4s hard cases x4 in series to make 59volts and plan to NOT use a BMS and NOT drain them under 20% or charge them over 90%. Every so often I will plug in my cellog to see how each 4s pack is doing and if needed use a small balance charger to bring them all together. I also bought a balance board that will charge up to 6 packs of 2s-6s to even things out.

What do you think?

francis
 
BMS didn’t get the nickname “Battery Murdering System” for nothing. Yeah, I’ve had those kinda problems, ‘get frustrated and say “screw it, I’ll just run naked”.

De-rate capacity a bit, leave yourself some headroom and keep a close eye on things, running naked can work. Keep CellLog handy for quick checks. (you do know how to disable the splash screen so it pops right on?)

Here's one of my 16S1P (4qty x 4S hardcase) naked setups -

My BMS equipped packs are more for my own curiosity and knowledge than anything I really need. I’m always a BMS so it tends to be redundant in practice. Although, BMS did alert me to a suddenly degraded cell once or twice.

But a couple of those times it was needed is/was when a bleed balance circuit malfunctioned and sucked the charge out of a cell group. The irony is that it wouldn’t have needed the BMS protection if the BMS hadn’t frocked up and drained the cell group?

I suppose someday when I move on to 18650 can cell pack BMS will likely be more of a “permanent” installation. So it should be good to understand how they work and connect? As well as how they can “fail”.
 
Aloha, all. I FINALLY got my wheelchair trike going BUT:

I hooked up my 36/48/60 350 watt ebay special controller and it works but is limiting to 11.5 mph, regardless of the watts used. Motor seems to want to lurch faster, but it cuts back to 11.5 mph

1) do I need to play around with the "self study"? What is that anyway?

2) there also is a single "speed signal wire" where does that go?

here is the controller.

http://www.ebay.com/itm/371239291127?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

thanks Francis
 
Aloha, All. Still trying to find what to do with the single wire "speed sensor"?

Where does it go?

Is it for hi and lo speed?

do I ground it to change speed?
or apply 5v
or apply battery voltage?


HELP!

thanks
Francis
 
Speed sensor is for speedometer. It measures speed through a separate sensor module and magnet attached to wheel. In some controllers (S12S for one) it needs to be active for the controller to work.
otherDoc
 
Aloha, OK that speed wire does not explain why the controller is cutting back at 11.5 mph. The controller seems to lurch to 12mph then cuts to 11 then 12 mph. etc. The controller is listed as 36v-48v @350watts. I am running it at 45 volts. Could it be trying to switch and figure out if it should be running at 36 or 48v internally?

thanks
Francis
 
spdas said:
The controller is listed as 36v-48v @350watts. I am running it at 45 volts. Could it be trying to switch and figure out if it should be running at 36 or 48v internally?
Click to expand...

Does it since automatically? If so, you might be on to something. Or maybe it thinks it is on a 48v low voltage cutoff point......just a thought.

Can you reduce to 36v for a test? Or up to 48v+ for a test?

:D
 
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