How to build a individual 18650 battery pack, Example 12S8P
- Thread starter ecross
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Man_dizel said:
-thanks for your good question
-the graupner ultramat 18 is a stand alone charger with inside power supply, 120-230Vac input and 12V input
-The AC input is about 90W and the add. 12Vdc input is about 300W
-the Graupner ultramat 18 is a 1 - 12pcs Lipo charger, for your 13S you can`t use this charger
-please tell us your 26650 batteries source
-for your 13S battery you need some other charger, but there are only a few on the RC market like:
-Thunder 1430
-Grauper Ultramat 45
-Robbe E-1
-Hyperion 1420i
-I have test the Graupner, Robbe and Hyperion, because we have here also a service for this charger.
-My recomment 14S charger is the Hyperion, because with +24Vdc about 550W charger power
-My recomment 12S charger is the Graupner Ultramat 18, because AC and Dc input, 300W DC-power, easy SW. good price/power
-Robbe E-1 about 315W
-Graupner Ultramat 45 about 250W
Man_dizel
1 mW
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- May 27, 2013
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- 19
ecross said:Man_dizel said:
-thanks for your good question
-the graupner ultramat 18 is a stand alone charger with inside power supply, 120-230Vac input and 12V input
-The AC input is about 90W and the add. 12Vdc input is about 300W
-the Graupner ultramat 18 is a 1 - 12pcs Lipo charger, for your 13S you can`t use this charger
-please tell us your 26650 batteries source
-for your 13S battery you need some other charger, but there are only a few on the RC market like:
-Thunder 1430
-Grauper Ultramat 45
-Robbe E-1
-Hyperion 1420i
-I have test the Graupner, Robbe and Hyperion, because we have here also a service for this charger.
-My recomment 14S charger is the Hyperion, because with +24Vdc about 550W charger power
-My recomment 12S charger is the Graupner Ultramat 18, because AC and Dc input, 300W DC-power, easy SW. good price/power
-Robbe E-1 about 315W
-Graupner Ultramat 45 about 250W
A friend of mine got trust fire 26650 5ah batteries that he don't need. I think he got t from eBay or alibaba. Batteries give 4200mah and are tested and read to be used. Cheap was it also.
My goal is to make 48v 12ah for daily use. I think that it should work. Have been training on soldering and it seems to work on some extra batteries I got at home.
Now with 12s I get 44,4v at 3,7v. I don't know if I'm going to go with 12s or 13s. The hub motor is 48v500w bafang cst. Hmm
I want a charger that is plug and play and don't want to work with external power an stuff. That's why I asked about the charger issue.
Man_dizel said:
Are these LiIon or LiFe cells and what cut off voltage do they have?
Is the battery removeable or fix installed on the bike?
Another option would be to install a BMS on the bike and simple charge with a cheap "power supply unit". For your 500W bafang you don't need a expensive high power BMS.
This would be more plug and play if your battery is fix on the bike because you don't have to extra connect balancer wires.
Man_dizel
1 mW
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madin88 said:
The batteries is trustfire 26650 5000mah Li-ion batteries. Got 40 pieces from him. Will get it next month I hope. Cut off should be around 2.7v I think.
I was thinking of removable battery pack. Think that's best for my setup. Can someone recommend a good BMS for me then? Maybe that's the best way to go. So a simple charger will do it then?
Man_dizel said:
I more mean charging cut off voltage. Are these trustfire LiFe (3,6V) or LiIon (4,1-4,2V)?
If you are going to remove your pack for charing, than a RC model charger is a good choice, but it can be very expensive if you want fast charging. For this you need a good charger AND a good power supply.
liveforphysics
100 TW
Soldering to the bottom of a can locally decomposes electrolyte in contact with it, even when cooling the cell.
No fuses or chaffing protection on balance taps.
Inadequate support for cells. Unfused discharge leads.
It also appears you are trusting the cell shrink wrapper alone with no additional chaffe protection to prevent can/can shorts from adjacent cell rows at other potentials.
May last OK in a stationary application, and I agree the battery should make a bike move, but I wouldn't trust that pack for anyone who takes offence to radom fires.
Just my $0.02
No fuses or chaffing protection on balance taps.
Inadequate support for cells. Unfused discharge leads.
It also appears you are trusting the cell shrink wrapper alone with no additional chaffe protection to prevent can/can shorts from adjacent cell rows at other potentials.
May last OK in a stationary application, and I agree the battery should make a bike move, but I wouldn't trust that pack for anyone who takes offence to radom fires.
Just my $0.02
cwah
100 MW
liveforphysics said:
you mean soldering cell is inadequate and will damage them?
LSBW
100 W
Man_dizel said:
I'm using since March dual Hyperion 1420i for charging, with 8 IBM small factor desktop power supplies for two configs of 2S2P (24v, 20 Amp). Works pretty good.
You just need to connect in ATX connector green #16 pin to the ground, to turn PS ON, and grey #8 pin to +5 volt to indicate your PS is good to go.
liveforphysics
100 TW
cwah said:
It's not inadequate from an electrical connection stand point, it's just ensuring every cell with a soldered joint to them IS damaged internally. The solvents decompose and introduce gas at best when holding the case at >150C to get the solder to wet the can, so you know you've damaged them just building it.
You guys are aware that the can's are all the negative terminals right? And those in series are touching can's with other potentials and just relying on a very thing bit of shrink rubbing on shrink where the edges of cells contact each-other to prevent fire right? This is why even on the very shitty ebay 18650 packs they put hot-glue and a layer of fish paper or even card-stock paper or something between the rows of series groups.
Shrink does NOT chafe on shrink forever before it wears through, I can assure you of this. Likewise, unfused balance tap leads of that heavy gauge of wire cause some excitement.
cwah
100 MW
makes sense!! I was wondering why they need so much glue between cells, but as you said, a short can happen because of chafe.
How can you prevent chafe on balance lead? and why do we need fuse on balance lead? I usually only have fuse on main leads
How can you prevent chafe on balance lead? and why do we need fuse on balance lead? I usually only have fuse on main leads
liveforphysics
100 TW
cwah said:
If you use tiny balance leads with high temp insulation and test the shorting failure mode to be acceptable, you wouldn't need them. If you use larger wires (like in the photos of this build), and they pinch/crush/short to another balance wire, you will find you rapidly have glowing red lengths of wire snaking around inside your pack, which I find seldom brings desirable effects.
blisspacket
100 W
Power supplies for model chargers are readily available eBay as "switching power supply"
http://www.ebay.com/itm/240W-Switch-DC-Regulated-Switching-12V-20A-Power-Supply-for-LED-SMD-Strips-/190959841624?pt=LH_DefaultDomain_0&hash=item2c7617f158
Great information on this ES thread. Thanks to all....
http://www.ebay.com/itm/240W-Switch-DC-Regulated-Switching-12V-20A-Power-Supply-for-LED-SMD-Strips-/190959841624?pt=LH_DefaultDomain_0&hash=item2c7617f158
Great information on this ES thread. Thanks to all....
t3sla
10 kW
liveforphysics
100 TW
That tiny wire with high temp jacketing is fine.
To me, that pro pack seems like inadequate wire routing and protection for a pack that is used in a high vibration environment (bicycle), unless the wire jacketing is something pretty special, because there are plenty of spots it's going too flop around and chafe in there if shaken/bumped around adequately. Getting packs to survive a shaker table that simulates long periods of bumping down a road is not easy, and what chaffing can do would amaze you guys.
I think if you execute almost any method of pack design/construction very well you can have success if you go through enough testing/development/refining. I do think if you're going to try to draw a winner the first time around in your own garage that taking extra precautions with respect to things shorting cell-cell or cell-wire or wire-wire etc.
Things that don't chafe through are good things to have when doing DIY pack design. Silicone impregnated fiberglass sleeves for wires, wires bundled neatly inside and mounted every few inches with wire tires, fuses on circuits or tested non-fuse short handling method, cells need to be very secure and insulated relative to each other if they are going to nest closely, or tiny relative motions will cause chaffing and eventual failure of the insulation and shorting.
At least that's my $0.02. I've built more sketchy looking packs for my own shit before, but I think it's a good idea for people who may want to follow that path to at least be aware of the many real potential failure modes with designs like this.
To me, that pro pack seems like inadequate wire routing and protection for a pack that is used in a high vibration environment (bicycle), unless the wire jacketing is something pretty special, because there are plenty of spots it's going too flop around and chafe in there if shaken/bumped around adequately. Getting packs to survive a shaker table that simulates long periods of bumping down a road is not easy, and what chaffing can do would amaze you guys.
I think if you execute almost any method of pack design/construction very well you can have success if you go through enough testing/development/refining. I do think if you're going to try to draw a winner the first time around in your own garage that taking extra precautions with respect to things shorting cell-cell or cell-wire or wire-wire etc.
Things that don't chafe through are good things to have when doing DIY pack design. Silicone impregnated fiberglass sleeves for wires, wires bundled neatly inside and mounted every few inches with wire tires, fuses on circuits or tested non-fuse short handling method, cells need to be very secure and insulated relative to each other if they are going to nest closely, or tiny relative motions will cause chaffing and eventual failure of the insulation and shorting.
At least that's my $0.02. I've built more sketchy looking packs for my own shit before, but I think it's a good idea for people who may want to follow that path to at least be aware of the many real potential failure modes with designs like this.
t3sla
10 kW
liveforphysics said:
I think it rates OK (relative to high end), but I would make some tweaks if it were mine.
My biggest gripe with pack builders is the use of 'craft' grade hot glue with it's stupidly low melting point and poor bonding to smooth surfaces.
It's somehow a substitute for 'white silicone' which correctly handles vibration and temperature.
This pack handles the balance wires better, flat and using filament tape for each channel.
Shaker table aka two belt sanders (X & Y) and a washing machine (Z)
agniusm
1 MW
This why I think cell holders are very good for diy pack building. First they insulate cans negative edge by lifting it of yhe cell. Now you must spot weld the tabs. Second, it leaves some 2mm gap between the cells which could be used for balance wire routing and introduces some cooling. This is what I will be doing for my next battery along with thermal fuses.
t3sla
10 kW
agniusm said:
That not only enable greater airflow for cooling, they reduce vibration issues.
If you are going for a high discharge setup take note of the C rating VS Tempreture, sure you can push allot of the newer NMC tech but there is a decent heat trade-off and you have to consider the effects on the SEI layer when you cluster them with no venting under high load (Right?)
http://www.comsol.com/stories/kobelco_lithium_ion_batteries/full/
One factor to look out for is the quality of your welds, using a crummy ebay welder won't be adequate, I've seen tabs get hot with packs only pushing 500/800W, so a multi-kW setup is going to be exponentially taxing.
agniusm
1 MW
t3sla said:
I will not use a crappy welder. I bring the cells to people who do have pro equipment and specialize in spot welding. They check IR and group cells accordingly. i was never fancy about soldering.
Wheazel
10 kW
liveforphysics said:
So we have seen this being stated numerous times, and I don't doubt that the cells take damage from the heat.
But in reality, how much of a problem is it? What negative effects can one expect to a soldered cell compared to a spotwelded one? (With this I mean soldered with good tools and minimal heat exposure)
I am evaluating if I am going to solder my 200cells or build a spotwelder. But I want the cards on the table if anyone have an idea.
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