Build Help - Commuter (10Mi RT) For GF. (Update: Now for me)
- Thread starter nlhaines
- Start date
nlhaines
100 W
mark5 said:
I must be missing something. I only see P+ connecting to the Battery+, Charger+ and maybe the b12+ thin wire. I don't see anything for the bigger bullet style connector.
Battery + bullet goes to same place sense wire 13, P+, Load +, and Charger + go. It's just not shown prominently. But you'll realize it if you stare at the battery-side end of sense wire 13 for a bit. The battery symbol's + connects to there.
nlhaines
100 W
mark5 said:
Okay, I see. Since I have only 12 sense wires (presumably because its for a 12s pack), does that mean 12 is wired as 13 is in the diagram? I would assume so. Also, do I need heftier wire than 12 AWG? I've looked online and some people claim 40 Amps through 12 AWG is fine, others say you shouldn't go over 10 Amps.
I don't know. Did you specify 12s lipo when you ordered the BMS? There's a "Product Customization" area on the webpage for that. In which case the B13+ pin and several components aren't present according to helgeo* in the posts listed below. You should read them because they have info about that BMS and use with lipo that might affect you.
Ah, I see. I've been referring to the diagram's wire 13 and you must be referring to your actual BMS. That's why you say "does that mean 12 is wired as 13 is in the diagram?" So yeah, 13 in the diagram would be 12 on yours. And you shouldn't have a 13 pin.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p743767
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p746172
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p746270
* http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p750286
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p754565
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=125#p822328
Ah, I see. I've been referring to the diagram's wire 13 and you must be referring to your actual BMS. That's why you say "does that mean 12 is wired as 13 is in the diagram?" So yeah, 13 in the diagram would be 12 on yours. And you shouldn't have a 13 pin.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p743767
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p746172
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p746270
* http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p750286
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=100#p754565
http://endless-sphere.com/forums/viewtopic.php?f=14&t=20971&start=125#p822328
nlhaines
100 W
mark5 said:
Yeah, I had been assuming 13 on the diagram was 12 for me, and that I got 12 instead of 13 because I customized the setup for 12s (the board is for anywhere from 5-13).
I'll check out all those posts you linked. Thank you for being so helpful. When I get this thing put together I'm going to post a bunch of pictures for other newbies that need guidance.
nlhaines
100 W
[/quote]mark5 said:
So a lot of that is greek to me, but I get the impression that this BMS is nearly worthless.....
wesnewell
100 GW
Here;s how I see it.
nlhaines
100 W
wesnewell said:
Ah, okay. I didn't realize the negative lead on the balance cable had to be hooked into the positive balance lead for the next cell....Someone should make cables that go from 3 4s balance leads to one 12s, and do the same for common configs. I'd pay a premium for one of those at the moment.
Now, I'm going to work on wiring up the 9 batteries into 3s3p. Can I connect the batteries in parallel out of the box? Is it safe to assume they are close enough in voltage that there wont be a quick charge/discharge that damages the cells?
Rodney64
100 kW
wesnewell said:
Just get a good Battery and don't play around with what Wes is talking about.
Somthing like this. Or buy one of his complete kits.
http://em3ev.com/store/index.php?route=product/product&path=35&product_id=160
nlhaines
100 W
Rodney64 said:
Well, it's a little late for that, as I already bought a bunch of stuff. I may be in over my head at this point, but I know to be careful with these things. I wouldn't mind reversing course and just buying a prebuilt battery if I could sell the lipos and bms, but none of this ebike stuff is very liquid.
Rodney64
100 kW
nlhaines said:
Just remember that lipo is dangerous and if miss treated charging over 4.2, damaged, out of shape or punched then there's a chance that things will go wrong. For a 200 bucks you could have purchased something plug and play. The main thing is you charge in a safe area where fire is not a issue and set a time when there's 10 minutes to go.
If you've used guns then lipos the same requires the same respect.
wesnewell
100 GW
In truth, they don't need to be hooked up like I showed with the thin red wires as long as the mains are in series, but I found that without them hooked up you get a few millivolts off, and I prefer to get it as close as possible. I have those cables, but I made them myself, and I made them to get to 2 6s balance plugs since that's what I needed. I don't use a bms. I charge the packs as 12s with a 12s capable balance charger.nlhaines said:
3s3p would be 3 cells in series for 11.1V. You're building a 12s3p pack for 44.4V, 12 cells in series. Normally, they are close enough to parallel out of the box, but you should check the voltage of each before hooking them up. You should probably do a store charge on all of them before using them to weed out any bad ones if you got any.
nlhaines
100 W
wesnewell said:
So what's advantage of the BMS over getting a 12s capable (6s x 2) balance charger? Seems to me that would be much easier.
wesnewell said:
Yeah by 3s3p I just meant 3 of the 4s blocks in series, but it's confusing to say that way I suppose. So how do I do a "store charge"? Just use the BMS on each of the 12s1p packs?
wesnewell
100 GW
The only advantage a bms gives is easy single point charging and cell level lvc, which is way over rated imo. The disadvantages of the bms method is that the bms limits the amp draw and charging amps to whatever it's max is. But as long as those 2 are high enough for your needs, it doesn't matter. But it also means there's another failure point possible compared to a direct battery connection.
A "store charge" is a function of the rc charger. If you don't have an rc charger, just disregard that and check voltages of each pack. If they are close, just go ahead parallel the balance plugs. If they are not, parallel the mains for a couple of minutes to get them close. I've never had a problem paralleling them without checking them, but I knew the risk. I'd think the voltages would have to be way off to cause any real damage.
A "store charge" is a function of the rc charger. If you don't have an rc charger, just disregard that and check voltages of each pack. If they are close, just go ahead parallel the balance plugs. If they are not, parallel the mains for a couple of minutes to get them close. I've never had a problem paralleling them without checking them, but I knew the risk. I'd think the voltages would have to be way off to cause any real damage.
nlhaines
100 W
Well if I screw up the BMS I'll just get myself a good 2 or 4 channel RC Charger. What do you do for LVC? Does the yescom kit handle that or do you have to add something?
wesnewell
100 GW
All controllers have a lvc. It's typically 42V for a 48V controller which is perfect for a 12s pack.
nlhaines
100 W
wesnewell said:
What's the difference between the new model and the slightly older model kits? I'm asking because I'm thinking about this:
http://www.endless-sphere.com/forums/viewtopic.php?f=9&t=62066&hilit=trek
wesnewell
100 GW
The newer models have a disc brake and different rim, and 19mm rim compared to a 24mm rim, and it comes with the display controller and display.
That Trek doesn't say which motor it is. It could be the anything from the 250W to the 1000W model, and the controller may not be the stock controller, which is a 15 fet for the 1000W kit, 12fet for the 500W kit. I don't know what the 250W model comes with, but it may come with a 6fet, so it may be the 250W model. Know what you're buying before buying it.
That Trek doesn't say which motor it is. It could be the anything from the 250W to the 1000W model, and the controller may not be the stock controller, which is a 15 fet for the 1000W kit, 12fet for the 500W kit. I don't know what the 250W model comes with, but it may come with a 6fet, so it may be the 250W model. Know what you're buying before buying it.
nlhaines
100 W
wesnewell said:
Thanks! I haven't been able to find any details about the Yescom kits. Do you know what the KV rating is for the new 1000W kit? I'm looking for something with a pretty high KV, and I'm hoping the Yescom kit has it because it seems to be a great bang for the buck.
wesnewell
100 GW
Well it's rated at 470rpm@48V, so that's what, ~9.8kv. This is the highest 1000W motor I know of, ~14.6kv. IMO, only good on flat ground under light loads.
http://www.leafbike.com/products/diy-bike-conversion-kit/26-inch-electric-hub-motor-kit/newest-version-26-inch-48v-1000w-rear-hub-motor-bike-conversion-kit-903.html
http://www.leafbike.com/products/diy-bike-conversion-kit/26-inch-electric-hub-motor-kit/newest-version-26-inch-48v-1000w-rear-hub-motor-bike-conversion-kit-903.html
nlhaines
100 W
wesnewell said:
How are you calculating 14.6kv? The performance chart suggests 18.75 KV. A top speed of 45 MPH at 48V on the other hand suggests a KV of 12.1
I think 14.6 is a bit too high, but I will have a 20" wheel, so I think I can go with a higher KV than would make sense for a 26" bike. The ground here is flat, also, so I dont need a ton of torque. However, I dont want it so fast that it doesn't also work in a 26" wheel....I think a KV of about 12 would be perfect actually.
wesnewell
100 GW
RPM /voltage
http://en.wikipedia.org/wiki/Motor_constants#Motor_velocity_constant.2C_back_EMF_constant
470/48= 9.79kv. 731/50=14.62kv.
http://en.wikipedia.org/wiki/Motor_constants#Motor_velocity_constant.2C_back_EMF_constant
470/48= 9.79kv. 731/50=14.62kv.
DanGT86
100 kW
nlhaines said:
If you do end up running without a BMS, get some Lipo alarms to handle the cell level LV warning. They are cheap and loud so you know when there is a problem. Lipo is most dangerous when its over charged or over discharged. The manufacturing tolerances are pretty bad on these packs so having bad cells in the bunch is common. Controllers do LVC for the whole pack total but they are blind to the individual cell voltages. If one cell fails and is about to explode but the rest are fine you can still be above the LVC at the controller. Cell level monitoring through BMS or at least warning alarms is an absolute necessity with LiPo in my opinion.
I learned more about batteries in just a few hours watching my RC balance charger than I learned from all of my reading online. A balance charger is a good thing to have around anyway. You can cycle your packs and make sure they all behave the same way before you hook them up to the BMS.
As far as paralleling the balance leads without checking them, that is a bad idea! There are varying opinions about how much difference you can have between cells when you parallel but I wont do it if they are off by more than .05v. High output batteries like these will try to balance instantaneously through those small gauge wires. I'm probably more careful/paranoid than most but its just not worth risking burnt fingers or the entire house. You can form your own opinion about how much imbalance you are comfortable paralleling but at least measure so you can base that opinion on something!
I'm not trying to talk you out of what you have already bought but keep in mind that these packs are dangerous and make sure the girlfriend understands that before you let her out of your sight with the bike. Might be easier said than done but maybe she should help you hook up the pack and the BMS so she has an understanding of how it works. You could always pick up a turn-key pack from ping or em3 that is as easy to charge as a cell phone. Then keep the Lipos for your own personal hotrod bike.
nlhaines
100 W
wesnewell said:
I know what Kv is, I just don't see 731 RPMs, or 50V anywhere in the info for the leafbike motor. Did you calculate the 731 or is that provided somewhere?
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