Tips / Suggestions/ Advice

[markass530]

So I recently started helping out a guy who likes to tinker with Ebikes, with his batteries. I was an electronics tech in the navy, went through Nuke EM A School, which is roughly an AA Degree in Elec. Engineering, but that was a decade and a lot of beer ago. Anyways I've done a couple repairs for him, but now he's got this source for all these 4S 4 AH Batteries, all with their own little BMS In them. I've tested them and they work great, I've put some together and ran them on bikes and scooters. All great results. Thing is he wants me to build a battery for a Columbia ParCar Summit out of these things. It's normal battery is 8 225AH 6 Volt Lead acids. I'm admittedly a little over my head scaling up that big, My First game plan was to find out was much as possible about these battery packs, and how their internal BMS works (I've read a little about the various types, and what they do when they are still getting current thrown at them but they are fully charged. With these they shut down at 12 volts, and I cant get a reading with my multimeter even, but they charge up from there no problem. My Plan was to make it very modular, and have active cooling & lots of temperature sensors. Any help is appreciated

 

[spinningmagnets]

but now he's got this source for all these 4S 4-Ah Batteries, all with their own little BMS In them

Welcome to ES...would you happen to know the chemistry of these cells? Theres a good chance they might be the common LiFePO4, but theres a couple of other possibilities.

 

[markass530]

They are 4AH LiPoly, I've disambleded some down to the cell. They measure out a lot better then most Batteries I've ran through a Hyperion, that is at or above the 4AH rating. actually looking at one now it says 4100mAH,

 

[markass530]

First I'm putting a 2S 5P (Where 1S = 1 4S Pack) set up in his skateboard, so 20AH there, and then building a 4S 5P Set up for a Hannebrink bike, so I'll get some good intel on these things in action before starting on the car battery.

 

[markass530]

I was under the impression all lifep04 are Round 18650 style cells, is that not the case?

 

[wesnewell]

What's the rated voltage on each 4s pack? If it's lifepo4, it will be 12.8V. If it's rcl ipo (lico) it will be 14.8V.

 

[markass530]

Sorry I just re-read my original post, I thought I said the specs in it. It's 4S LiPoly, the Individual cells are labeled as 4100mAH, I've ran them through some B6, B8, & Hyperion chargers, they are pretty consistently on point with regards to capacity (and without having to run them down to 3 Volts, as seems to be the case with some other bike batteries I have)

 

[wesnewell]

There are all kinds of lithium polymer (lipoly) cells with nominal voltages from 3.2v to 3.7V. RC lipo (lico)will be 3.7V. And then there's lifepo4, which is 3.2V, or old lithium ion which is 3.6V iirc. So, I know you have lithium polymer cells, and there capacity is 4.1ah, but I still don't know what kind of lithium cells you have. I do know you want a 48V battery pack, so if it's lifepo4, then you want 16 cells in series. If it's lico or li-ion you can go with 12-14 cells in series. With 13s being the closest to a 48V SLA pack in voltage, but makes for an odd number of cells. Most use 12s for 48V systems and some use 14s. 12s is the safest if you're counting on the controller LVC to keep from over discharging the pack. Most 48V system controllers have an LVC of ~42V

 

[markass530]

here are all kinds of lithium polymer (lipoly) cells with nominal voltages from 3.2v to 3.7V. RC lipo (lico)will be 3.7V. And then there's lifepo4, which is 3.2V, or old lithium ion which is 3.6V iirc. So, I know you have lithium polymer cells, and there capacity is 4.1ah, but I still don't know what kind of lithium cells you have. I do know you want a 48V battery pack, so if it's lifepo4, then you want 16 cells in series. If it's lico or li-ion you can go with 12-14 cells in series. With 13s being the closest to a 48V SLA pack in voltage, but makes for an odd number of cells. Most use 12s for 48V systems and some use 14s. 12s is the safest if you're counting on the controller LVC to keep from over discharging the pack. Most 48V system controllers have an LVC of ~42V
NEXT 26" MTB bike $59, yescomusa.com 48V 1000W rear hub kit $276, Hua Tong 72V 40A controller $35, 10ah 2


I'm pretty sure LiPoly=LiPoly and never Lipoly=Lifep04, at least I've never seen or heard of that, and can't find any information about that, I think the accepted standard is if someone says Lipoly they mean 3.7 volt, LiPoly, same thing thats in my cell phone, and same thing thats inside the couple LiPoly bike batteries I've been inside 4.2 max voltage, I've cycled them between 14 & 16,8 volts several times. I'm stuck going with 12s, if thats not enough I can make a 1 cell booster to go with the thing. My Concern is on the design of the thing, and safety features. I'm leaning towards charging being done by 3 different charges for each 4S bank, just because getting something that will kick out 20+ amps is going to be a bitch.

 

[arkmundi]

I was under the impression all lifep04 are Round 18650 style cells, is that not the case?

Wikipedia is a great resource for these questions. See for instance: http://en.wikipedia.org/wiki/Lithium-ion_battery#Formats. The A123 AMP20 are the "prismatic" pouch format, which I and many others on this forum use and are very happy with. I'd advise that these are much simpler to use for building a battery pack than other formats in addition to their truly outstanding performance. Best.

 

[dogman dan]

The big problem would be safety of a pack big enough to run a car. The small probobility of one cell going off, setting off other cells, x a lot more cells. The key thing would be really intense sorting of the cells for bad ones, plus really close monitoring.

The issue is the size of the fireball if the pack should go off. You'd need to be really cautious about the main hazard, a dead short, which can devastate any EV, any chemistry.

Just my fraidy cat 2 cents, but maybe your buddy would be better off with lifepo4, like some thunderskies or whatever in big prismatic format for the huge battery.

Money for the big lifepo4 blocks could be raised by selling off these avaliable lithium polymer cells for a profit though. 8) They sound good for small EV's to me.

 

[arkmundi]

I'm pretty sure LiPoly=LiPoly and never Lipoly=Lifep04, at least I've never seen or heard of that, and can't find any information about that, I think the accepted standard is if someone says Lipoly they mean 3.7 volt....

I'm pretty sure all lithium-ion batteries encountered on this forum are considered part of the class known as lipo or lipoly, though there is much confusion on terminology. Its better to be specific about chemistry and format to describe a cell, as lipo is so generic as to be meaningless.

 

[markass530]

I'm stuck with what I got as far as supplies. I Plan on doing some failure tests with at least one pack , so will see how bad they fail, as of yet it seems The BMS does a pretty good job of shutting them down if things get to crazy

 

[Punx0r]

If charging to 4.2V this sounds like RC lipo, but they don't have any kind of BMS...

Li-ion (phone battery etc) should only be charged to 4.1V

It might help if you post a photo of one of the batteries? If it's a lipo it'll be instantly recognisable.

 

[spinningmagnets]

I was under the impression all LiFePO4 are round 18650 style cells, is that not the case?

cell_man (Paul) sells LiFePO4 packs from both cylindrical cells and foil pouches.

http://www.emissions-free.com/id31.html

 

[markass530]

Ill work on some pics, each 4S Pack has it's own BMS, that as far as I can tell shuts it down when It gets run to low (around 12.5 volts) at this point I cant read anything off it with my meter , but they charge right up. I've ran a bank of 5 as 5P for a couple weeks, then checked each one out and they were all within .1 volts of each other. . As far as what they Are, I'd bet my life on the fact they are Lipo, just like the kind in Thin & Light Laptops, Portable USB Chargers & A Polaroid tablet my friend broke.

 

[markass530]

Found it! The Tech page for the BMS in these things


http://export.chinaexcite.com/ProductDetails/2889983169/Protection_Circuit_Module_For_14.8V_Li-ion/Li-polymer_Battery_Pack.html

 

[Punx0r]

2C continuous discharge

4.35V hvc?

 

[Tommy L]

Hello.....

your posts say: lipo lipo lipo and I bet my life they are lipo. Sure, what is the chemistry?

Polymer cells use a porous separator that, when exposed to the electrolyte, turns to a gel.
Other chemistry do not use this porous separator.

So the chemistry and the cell specifications are really needed if you are asking for help.

Sounds like an awesome project!

Tommy L sends... \\m//

 

[markass530]

They are pouch style LiPoly, I Dunno how I can find out any more then that, they look exactly like most other lipoly's i've seen in Ipods & Tablets & ba-pk24-330 Currie bike battery, and Newer Sony Vaio Laptop batteries. (the only ones ive seen that were different were older Prismatic style cells in old apple batteries and this external laptop battery from 2004, those were hard, these are soft) the pouches are very susceptible to damage if frocked with at all. Client just did first road test on his electric skateboard with 8S 20AH set up i built and he was frocking elated. gave me some Currie 24 volt 10AH LiIONs I sold to him last month back to me as a bonus . I'm doing some tests charging some packs in parrell, with one or two of the packs being 1 or 2 volts off from the others in voltage at start to see how they will behave

 

[markass530]

they look exactly like these things:

http://www.karlssonrobotics.com/shop/polymer-lithium-ion-battery-6ah/?gclid=CIPQ3Nvty7ICFSiCQgodfl8Adw

 

[Punx0r]

3.7V nominal ought to make them lipo? Properly called LiCo IIRC...

Then again, I just checked my phone battery, and that's stated as 3.7V nominal, despite being a different chemistry.

 

[Tommy L]

3.7V nominal ought to make them lipo? Properly called LiCo IIRC...

Then again, I just checked my phone battery, and that's stated as 3.7V nominal, despite being a different chemistry.

I'm not the one to make a call on that one.... sorry

If you have a 3 pack like that at 3.7v and it's 6ah, stacking many of these in parallel then in series could make for a
light duty pack. But $40.00 for 6ah at 3.7v isn't a good deal these days.

Sorry I couldn't be more help....

Tommy L sends... \\m//

 

[markass530]

They Just Look like those (The Individual Pouch Cells) , They are still the same packs I Described in my original post, they are 3.7 so I Guess LiCo, whatever is the standard nowadays

 

[markass530]

They Just Look like those (The Individual Pouch Cells) , They are still the same packs I Described in my original post, they are 3.7 so I Guess LiCo, whatever is the standard nowadays