Yet Another Laptop Battery Pack Build!

[stanz]

This is the "technical" post for my eBike battery pack build.

I purchased 60 NOS Thinkpad Li-ion batteries on ebay for $120. They're IBM 02K6646 Ultrabay 2000 Batteries. The specs on the web vary from 6-9 cells, I won't know for sure until they arrive.

Charging rate is quoted at 2amps but I know I shouldn't expect great power output since they were built for laptops, not tools.

My plan is to use 20-30 of the batteries for my eBike.

My commute is 2 miles and I do plan to pedal.

My hub motor will be an AmpedBikes 500-700W 36 volt unit.

I have an SLA pack to get started and plenty of time to work with these batteries.

This is my first venture into Lithium power so I plan on doing loads of research both here and on the net.

My first design thought is to charge them as a pack but to also wire them with an ATX power connector to allow for individual cell group charging. I'm a computer guy so I have ATX cables laying around.

 

[stanz]

I just purchased some balancers per one of the threads.

I'm guessing the batteries already have some sort of protection built in, I'll see once they arrive.

 

[aaronski]

This seems like a really cheap way to build a big pack. I'm going to watch this thread. I have new lipo for power/weight, and am thinking old li ion for range.

60x6 cells is what? 240 cells, 2 ah each would yield a 48v, 40ah pack.

 

[stanz]

This seems like a really cheap way to build a big pack. I'm going to watch this thread. I have new lipo for power/weight, and am thinking old li ion for range.

60x6 cells is what? 240 cells, 2 ah each would yield a 48v, 40ah pack.

That's why I'm doing it, Li-ion pack for under $100!

I only need 36 volts.

 

[kZs0lt]

60x6 cells is what? 240 cells, 2 ah each would yield a 48v, 40ah pack.

60x6 would make a 360 cell battery , and at 2Ah each would yield a 36v 72Ah battery.
But the sizes are all weired. I've took a quick search on these batteries and get different configurations and sizes. Some refer to a 3.6Ah 9 cell battery. The weight of a regular 18650 LiIon is somewhere around 45g. Some sources say 0.59lb battery, that would make only a 6 cell battery. At 10.8 it can be a 6 or a 9 cell battery, it may not be a 8 cell.
But yet again some are pretty slim, no way to enclose 18650's in there. Is it possible it is not using 18650 format cells?

Do you know more information about size(WxDxH) and weight so we can estimate cell format, count, configuration, and capacity?

 

[stanz]

MOST sites list it as 9 cells, so 3s3p. The most consistent figures are 10.8V 3200mAh

Dimensions from two sites:

H: .51" or 13mm
W: 5.12" or 130mm
D: 5.71 or 145mm

10 batteries should net me 36V at 9.6Ah

To insure "full" capacity if the cells are weak I could use 30 batteries for a net of 28.8Ahr. Even if the batteries have degraded by sitting around in boxes that should be at least 10Ahr. of lithium capacity for $60!!

That's cheaper than SLA.

 

[aaronski]

Yea, but if you have to use 28 ah to get 10 usable, than it's about the same weight as lead acid as well...

 

[stanz]

Yea, but if you have to use 28 ah to get 10 usable, than it's about the same weight as lead acid as well...

I'm just being pessimistic. I haven't done any sort of testing on load capacity of the cells yet.

 

[stanz]

Here's the label showing these batteries were NEVER opened!

Label from the battery pack

I just took a pack apart. It has six cells, three pairs I guess, and some sort of battery management board. Each cell is 1.34" wide by 1.944" long by .417" thick (34mm X 49mm x 10.6mm).

Here's the interior view

Each cell has HF4PH6 etched into them.

Anyone out there seen these cells before?

 

[stanz]

For those of you without Li-ion laptop battery experience I should shed some light on the "issues":

1) Li-ion laptop batteries (LLB) self-discharge due to the cell design AND the drain of BMS circuits.
They ALL should have BMS integrated in the pack since without it ... they explode!

2) LLBs do NOT like to be kept at full charge when warm.
We used to sell LOADS of replacement batteries when I work in the PC industry in FL.

3) Cell discharge rate can be is 5-10% per month if disconnected.

4) No memory effect!

5) Loose pouch type cells have the highest energy density but require containment. (or boom!)

Luckily my cells are "virgin" having never been cycled in a laptop and each cell is encapsulated. I'm going to charge up 10 of them before breaking them up into a 36V battery pack. Hopefully I'll have my watt meter by then and can do some load testing/conditioning.

If they perform per spec I'll have a 10.8 ah pack. I'll double the pack size for my eBike to keep the load around 1C. That would be a $40 cost for the pack.

 

[SamTexas]

This is the first time I've seen prismatic lithium cell in a laptop pack. Do you know what chemistry it is? Li-Cobalt, Li-Phosphate or Li-Manganese. Or may be something else?

 

[stanz]

This is the first time I've seen prismatic lithium cell in a laptop pack. Do you know what chemistry it is? Li-Cobalt, Li-Phosphate or Li-Manganese. Or may be something else?

I have no idea how to tell, I figured the letters on the cells might mean something to somebody "HF4PH6". I googled it but came up empty. (I can't believe I just typed "googled it", I hate it when a noun becomes a verb. Text me, fax me, argh!)

 

[stanz]

So, we highjacked another thread and did some talking. Sorta like a bad Monty Python ripoff "I'm not dead yet! I'm feeling much better!"

I put a few of the batteries on an old AC/DC brick I had laying around 12V 1A. I figured that would be safe since the batteries have built in BMS. So far so good, no explosions!

I still don't have my watt meter from Hobby World and I don't expect it until maybe next week. I ordered it last Friday.

Until then I can't do any accurate load tests on the batteries. I tried a 100W 110V incandescent light bulb thinking that the 11W resistance would mean a 1A draw. Well light bulbs don't play that way, it may only be a 1/4A draw. Anyway, I left it hooked up for 5 hours and the battery never dipped below 11V, it started out at 11.6V I think. Hey, it's been years since I've done any "science" give me a break.

If someone out there has a multimeter with an amp range or a watt meter I would REALLY appreciate it if you could tell me what the current draw of one or two 100W light bulbs is at 12V DC. My goal is to get a one amp load for the first test and then ramp up from there.

My goal is to see if I can revive these packs to 1/2 capacity. I would be happy with that since I only paid $2 per battery, including shipping.

Anything more than that would be gravy, anything less would be a lesson learned.

As far as I can tell nobody on FS has tried to do this with NOS laptop batteries. All previous efforts have been with known bad used batteries.

These batteries have NEVER been used, they just sat there on a shelf after they were shipped from Japan 8 years ago.

If this effort pans out the packs will be referred to as "undead" from now on since I'm trying to bring them from beyond the brink.

 

[snellemin]

I've been using those same cells in my little RC cars and remote controls. I harvest them for Compaq/HP laptop packs.

cells are labeled Moli ICP-103450CA 2000 mAh

 

[stanz]

I've been trolling the Internet trying to find out the exact chemistry of the batteries and found this quote:

"Power Manager reports the UltraBay battery chemistry to be Li-Polymer, while Li-Ion is printed on the battery"

That would explain the pouch I guess.

 

[SamTexas]

I've been using those same cells in my little RC cars and remote controls. I harvest them for Compaq/HP laptop packs.

cells are labeled Moli ICP-103450CA 2000 mAh

So they are Lithium Cobalt just like most other laptop batteries, just different format.

http://www.molicel.com/ca/pdf/ICP103450CA.pdf

 

[SamTexas]

I've been trolling the Internet trying to find out the exact chemistry of the batteries and found this quote:

"Power Manager reports the UltraBay battery chemistry to be Li-Polymer, while Li-Ion is printed on the battery"

That would explain the pouch I guess.

No, not LiPo. Not according to the above data sheet.

I find it irritating whenever I see "Li-Ion" stamped on a battery. It's basically useless. When will manufacturers begin to explicitly say the battery chemistry? Sounds almost like they have something to hide.

 

[SamTexas]

If this effort pans out the packs will be referred to as "undead" from now on since I'm trying to bring them from beyond the brink.

Again, I wish you success. But keep in mind it not just a matter of "undead"ing them, it's also an issue of how much capacity is left and how many cycles are left after resurrection.

 

[stanz]

Oh, never mind, I think I found the cells at the Panasonic:
http://www.panasonic.com/industrial/batteries-oem/oem/lithium-ion.aspx

I would assume that Panasonic makes them for IBM since it looks like Molicel started making them in Taiwan after 2003

Both company part numbers end in 103450CA.

Same dimensions and ratings. I got lead there from a Thinkpad site, it took some doing.

Constant current discharge rating is 1C so I need a 20ahr pack to get 20 amps to my bike.

 

[kZs0lt]

So these are Lithium Polymer cells.
When you say pack was dead at 0 volts, you mean that the pack reads 0.0v through the connectors, or that upon open-up all the cells were individually down at 0.0v. Could you take apart a pack that reads 0 volts and wasn't charged up, and measure cell voltage at the cell tabs, beyond the BMS pcb and report back your readings on individual cells?

 

[stanz]

So these are Lithium Polymer cells.
When you say pack was dead at 0 volts, you mean that the pack reads 0.0v through the connectors, or that upon open-up all the cells were individually down at 0.0v. Could you take apart a pack that reads 0 volts and wasn't charged up, and measure cell voltage at the cell tabs, beyond the BMS pcb and report back your readings on individual cells?

No, they're not Lipo, I found the cells on the Panasonic commercial website.

Yes, I only checked them at the connectors before I charged them. I crack another open tomorrow, they're at work.

That's a good idea since the BMS may have taken them offline.

 

[stanz]

Rather than wait for my watt meter I went over to the Harbor Freight store and purchased a multimeter with an amperage tester! ..... The 100W bulb pulls .25 amps, so far that load has been on the first pack for 5 hours, I hooked it back up and will check it later.


I tore open another pack to check cell voltages, zero volts.

More later

 

[aaronski]

great info. keep it coming.

 

[stanz]

I'm done for a while so I'm disconnecting the load

7 hours at .25a, battery voltage is now 10.72, lowest cell is 3.55V

Pretty close to my goal of 1.8aHr I'm not going to let the cells go much below 3.5 for the first charge/discharge cycle.

Next cycle I'll charge to a higher voltage if the IBM BMS will allow it.

 

[stanz]

First discharge cycle is done, the battery is down to 9.99V the last drop was fast.

7.5 hours at .25 amp draw = 1.875 aH. for the first cycle.

The battery is charging now. I'm off tomorrow so I won't do another cycle until Friday.