Homemade Battery Packs
- Thread starter DrkAngel
- Start date
Hwy89
10 kW
I got tired of buying used laptop batteries on ebay. I bought a lot of crap before I finally accumulated enough good matched cells to build two batteries for our bikes. When I spotted an auction for a lot of 444 new, two cell, 7.4 V packs I couldn't stop myself from buying them. I took 96 of them apart and built a great 12s 16p pack that gives me over 100 miles of range.
My efforts to re-sell the remaining packs failed so I have been finding uses for them for LED lights and repowering a battery drill. I'm thinking about using 100 of them to put together a 4s 50p, 14.8V storage battery that would run my RC charger and could also be used for camping and possibly run my trolling motor.
Each of the two cell packs has a bms that blocks charging at 8.4 volts and interupts the output when they drop to 6.6 volts.
What would happen If I built a large pack without disassembling them and left the bms board in place? My thought is that it should work, but I would like to hear what others say before I try it. I may run a test with four packs in series parallel and monitor it just to see.
My efforts to re-sell the remaining packs failed so I have been finding uses for them for LED lights and repowering a battery drill. I'm thinking about using 100 of them to put together a 4s 50p, 14.8V storage battery that would run my RC charger and could also be used for camping and possibly run my trolling motor.
Each of the two cell packs has a bms that blocks charging at 8.4 volts and interupts the output when they drop to 6.6 volts.
What would happen If I built a large pack without disassembling them and left the bms board in place? My thought is that it should work, but I would like to hear what others say before I try it. I may run a test with four packs in series parallel and monitor it just to see.
DrkAngel
1 GW
Hwy89 said:
Likely, the cells were for a modest drain device?
If so, discharge rate would be very limited by the BMS.
Great for low drain devices, CFL (Compact Fluorescent Light Bulbs) lanterns, radios etc.
cwah
100 MW
That's a good idea!!
The closest I've found is this one:
http://www.polydis.fr/epages/8d7c81fe-552a-11e0-822f-000d609a287c.sf/fr_FR/?
Or this one but a top part is missing:
http://www.leroymerlin.fr/v3/p/produits/piquet-plastifie-vert-cavatorta-haut-2-25-m-e52828#&xtmc=piquet&xtcr=24
This guy seem to have pvc sheets at excellent price:
http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=181216852575&ssPageName=ADME:X:RTQ:FR:1123
But it looks like it might be pvc foam
The closest I've found is this one:
http://www.polydis.fr/epages/8d7c81fe-552a-11e0-822f-000d609a287c.sf/fr_FR/?
Or this one but a top part is missing:
http://www.leroymerlin.fr/v3/p/produits/piquet-plastifie-vert-cavatorta-haut-2-25-m-e52828#&xtmc=piquet&xtcr=24
This guy seem to have pvc sheets at excellent price:
http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=181216852575&ssPageName=ADME:X:RTQ:FR:1123
But it looks like it might be pvc foam
etriker
100 kW
DrkAngel said:
If you just wanted to use the bms to balance and not use it to limit current it might balance the cells.
Hook the + and - battery output right on the cells and not run it through the bms.
Sounds like an interesting test.
cwah
100 MW
Hwy89 said:
Batteries are quite expensive, and reselling them for ebike with good price tag should be easy isn't it?
Hwy89
10 kW
That's a good point DrkAngel. I will set up a test and gradually increase the current to see if the bms limits it or if at some point it just smokes the board. I won't go over 2.2A which would be 1C for these cells.
Even if the bms cuts them off at .5C my 50p pack would provide 55 amps which should be enough.
The battery packs were made to power hand held CO2 detectors but the company went bankrupt before they were put on the market.
Hwy89
10 kW
Cwah, try this link or just google vinyl fence post.
http://www.homedepot.com/webapp/wcs/stores/servlet/Search?storeId=10051&langId=-1&catalogId=10053&keyword=vinyl+fence%20post&Ns=None&Ntpr=1&Ntpc=1&selectedCatgry=SearchAll[/b
http://www.homedepot.com/webapp/wcs/stores/servlet/Search?storeId=10051&langId=-1&catalogId=10053&keyword=vinyl+fence%20post&Ns=None&Ntpr=1&Ntpc=1&selectedCatgry=SearchAll[/b
cwah
100 MW
Yes I've seen that. But they are all sold in US.
The closest equivalent in france is quite expensive:
http://www.polydis.fr/epages/8d7c81fe-552a-11e0-822f-000d609a287c.sf/secaad781e415/?ObjectPath=/Shops/8d7c81fe-552a-11e0-822f-000d609a287c/Categories/%22PVC%20pour%20cl%C3%B4ture%2C%20portail%22/Cloture_Portail_Blanc/Clotures_portail_en_applique_sur_traverse/Poteaux_PVC
The closest equivalent in france is quite expensive:
http://www.polydis.fr/epages/8d7c81fe-552a-11e0-822f-000d609a287c.sf/secaad781e415/?ObjectPath=/Shops/8d7c81fe-552a-11e0-822f-000d609a287c/Categories/%22PVC%20pour%20cl%C3%B4ture%2C%20portail%22/Cloture_Portail_Blanc/Clotures_portail_en_applique_sur_traverse/Poteaux_PVC
Hwy89
10 kW
Cwah, if you can find someone who has that fence they will probably have some broken pieces to give away. I worked at a horse ranch where we were constantly repairing and replacing parts of the plastic fence. The stuff is pretty but it doesn't stand up to being used as a rubbing post for 1000 pound hay burners. I think the UV from Arizona sunshine makes it more brittle.
cwah
100 MW
Yeah but I live in paris so not many people have fence lol
What about this?
http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=181216852575&ssPageName=ADME:X:RTQ:FR:1123
What about this?
http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=181216852575&ssPageName=ADME:X:RTQ:FR:1123
Hwy89
10 kW
cwah
100 MW
Can I use any pvc cement? This one for exemple?
http://www.ebay.co.uk/itm/118ML-BLACK-SWAN-SOLVENT-WELD-PVC-CEMENT-/300462557170?pt=UK_DIY_Materials_Plumbing_MJ&hash=item45f4f6c7f2
http://www.ebay.co.uk/itm/118ML-BLACK-SWAN-SOLVENT-WELD-PVC-CEMENT-/300462557170?pt=UK_DIY_Materials_Plumbing_MJ&hash=item45f4f6c7f2
Hwy89
10 kW
I'm not familiar with that brand but yes it should work. You should also find primer to clean the surface before you apply the cement. Make sure you have everything lined up and some kind of clamp ready because the cement works very fast. Practice on some scrap material first.cwah said:
cwah
100 MW
thanks. I'll get some primer, the glue and the sheets then 
cwah
100 MW
Seller just told me it's PVC FOAM. He said it's 5mm thick so it's quite strong and rigid. Able to handle 50kg weight without breaking.
I'm a bit dubious because it's still foam... But he has good price at 3.5USD for an A2 sheet.
Can I use it for battery box?
I'm a bit dubious because it's still foam... But he has good price at 3.5USD for an A2 sheet.
Can I use it for battery box?
DrkAngel
1 GW
See - "Forming" Custom Sized Battery Casescwah said:
nukezero
10 kW
Hi there, can someone help me a bit about this battery I bought? It is a 36V 10.4Ah pack with BMS.
I bought these batteries on eBay and they seemed like a nice pack, although a bit expensive. At $6-7/ea. I figured the pack, along with the BMS, 42V smart charger, plus assembly was worth the price I paid.
It turns out these are Samsung "pink" ICR 18650-26F cells. Can anyone tell me the following:
1. What is the chemistry? NCM ?
2. Are these what everyone uses now when they talk about Samsung's new NCM cylindrical cell?
3. Why are these cells given pink colors? What is the difference between these pink colors and other colors?
4. Should I have bought Sanyo cells?
I went to samsung's website but could not find much details about this cell. Only that the remark says NCM/LCO. But what does LCO mean?
thanks
I bought these batteries on eBay and they seemed like a nice pack, although a bit expensive. At $6-7/ea. I figured the pack, along with the BMS, 42V smart charger, plus assembly was worth the price I paid.
It turns out these are Samsung "pink" ICR 18650-26F cells. Can anyone tell me the following:
1. What is the chemistry? NCM ?
2. Are these what everyone uses now when they talk about Samsung's new NCM cylindrical cell?
3. Why are these cells given pink colors? What is the difference between these pink colors and other colors?
4. Should I have bought Sanyo cells?
I went to samsung's website but could not find much details about this cell. Only that the remark says NCM/LCO. But what does LCO mean?
thanks
Attachments
DrkAngel
1 GW
NCM/LCO = Nickel-cobalt manganese /Li-cobalt.
DrkAngel
1 GW
Moved to it's own topic - Determining Optimal Charge Voltage
Important highlights:
A Picture is worth a thousand words ... so ...
Important highlights:
A Picture is worth a thousand words ... so ...
powersupply
100 W
Very informative, DrkAngel.
Does such a thing exist for LiPo, too?
I.e. do LiPo exhibit similar float/charge voltage vs cycles?
Does such a thing exist for LiPo, too?
I.e. do LiPo exhibit similar float/charge voltage vs cycles?
DrkAngel
1 GW
To a great degree, the Li-ion described are the standard Lithium Cobalt based cells.
Li-ion 18650 cells are basically the same lithium cobalt formulation as the standard "LiPo" and in many respects and to a great degree are very comparable.
Li-ion 18650 cells are basically the same lithium cobalt formulation as the standard "LiPo" and in many respects and to a great degree are very comparable.
powersupply
100 W
Cool, thanks DrkAngel.
How reliable do you think is the info from batteryuniversity?
I overbought batteries (4p) and was thinking of saving some (3p+1p spare).
But with this info, I'd rather use them all and just charge them less.
Will have to program the BMS accordingly.
Thanks!
How reliable do you think is the info from batteryuniversity?
I overbought batteries (4p) and was thinking of saving some (3p+1p spare).
But with this info, I'd rather use them all and just charge them less.
Will have to program the BMS accordingly.
Thanks!
DrkAngel
1 GW
BatteryUniversity.com has been a reliable reference for many many years.
I have never found any site more dedicated to the sole purpose of freely, and without self-serving agenda, providing battery information.
I have never found any site more dedicated to the sole purpose of freely, and without self-serving agenda, providing battery information.
DrkAngel
1 GW
Latest cell testing methodology
Before building packs I do thoroughly test and evaluate every cell.
I have developed and refined simple and effective procedures ...
Step 1
I bulk charge all cells to just above working voltage, then I allow cells to set several days and remove any with bleed down.
Step 2
Then I "Bulk" capacity test all cells - Method 2 preferred.
Step 3
Any unfamiliar brand, I choose a good sample and run a Charge Capacity Test to build a capacity map.
This test is performed by discharging cells to maximum DOD, then charging in 2/100th V increments, recording mAh required for each step. This gives an accurate map of each portion of capacity added at each fraction of a volt.
Previously, I have built capacity maps based on Discharge - mAh /100th V.
While interesting, the discharge map was flawed due to voltage sag and IR.
Step 4
Finally, I Match up the best cells for pack build. Equal total mAh per bank works nicely.
So far, and preferably, each pack is constructed from cells of same brand and oem rated capacity and results have been excellent.
I've been building eBike battery packs from recycled laptop cells for 6+ years and am continually finding-developing better methods.
The thread Homemade Battery Packs is a reasonably complete documentation of my progress.
Before building packs I do thoroughly test and evaluate every cell.
I have developed and refined simple and effective procedures ...
Step 1
I bulk charge all cells to just above working voltage, then I allow cells to set several days and remove any with bleed down.
Step 2
Then I "Bulk" capacity test all cells - Method 2 preferred.
Step 3
Any unfamiliar brand, I choose a good sample and run a Charge Capacity Test to build a capacity map.
This test is performed by discharging cells to maximum DOD, then charging in 2/100th V increments, recording mAh required for each step. This gives an accurate map of each portion of capacity added at each fraction of a volt.
Previously, I have built capacity maps based on Discharge - mAh /100th V.
While interesting, the discharge map was flawed due to voltage sag and IR.
Step 4
Finally, I Match up the best cells for pack build. Equal total mAh per bank works nicely.
So far, and preferably, each pack is constructed from cells of same brand and oem rated capacity and results have been excellent.
I've been building eBike battery packs from recycled laptop cells for 6+ years and am continually finding-developing better methods.
The thread Homemade Battery Packs is a reasonably complete documentation of my progress.
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