corkscrew

Hi all,

I'm looking @ this page: https://www.recumbents.com/wisil/e-be...e/tutorial.htm

I'm interested in RC batteries due to the weight and high power output.

Applications at this point are either for a 9C hub motor or if I get uppity, an actual RC drive. I figure either way, for my commute I need about 15amp/hrs @ 48v.

If I go with the 9C - I want to run it with the optional 35amp controller, which a 1 or 2c battery (ping or even elite power solutions) will have trouble providing.

I'm figuring a RC battery even at their lower ratings of 20C will have no problems delivering a constant 35amp.

So that brings me down to these questions:


1) I'm aware these Lipro batteries require proper care and feeding. However the chargers I'm finding don't go past 6S batteries. How would I properly charge the pack once several 6S batteries are combined?

2) Would hooking this up to a 9C hub motor system work, or would it just be a bad idea? If not, the weight and cost of my battery kit will go down substantially.

morph999 

The LIPO usually have two connectors. One is for connecting and the other is for balancing. I know that some chargers can charge the pack using just the balancer connector so maybe that is how they do it. I don't have LIPO. I have lifepo4. Elitepowersolutions has a new kind lifepo4 called Next Gen or Gen II or something like that but it's about 50 % more expensive. It would be able to easily handle your 35 amp even at 15 AH capacity. You might be happier with LIPO. I have Thundersky's and they are awfully bulky. They are nice and they work very well but I'm already looking at LIPO. Not sure if I'll ever make the switch, though because my batteries probably have at least 2 more years of life left in them.

Yes, LIPO would easily work with your 9C hub motor as long as you get the right voltage for the controller. If you plan on using 48v, make sure you get a 48v compatible controller. I've heard bad things about those RC Drives. Lots of people say they spend a lot of time adjusting and re-adjusting the belts (or chain) on them and that they are a bit of a pain. Hub motors are virtually maintenance free.

morph999 

Also, if you use crimpers to connect the batteries together, you can usually use an alligator prong and put it in on the + and - of each individual battery and charge them that way while they are still connected in series or parallel. That creates a circuit so that it only charges that battery and not the rest. That's how I charge my lifepo4. Just be careful not to have the + and - of the battery touch together.

jethro56 

https://www.bikeforums.net/showthread...-on-LIPO-power

Currently charging 2 - 5000mah 6s packs at a time The charger sees it as one 12S pack. Charging @ 2C (10amps )

corkscrew

Very nice! I'll be going with 8 6S 22.4 5000mAh packs myself. What do you think of your Hyperion charger? I was looking at the icharger 106B, mostly due to cost.

corkscrew

The 9C motor kits ebike.ca sells are compatible (and even warrantied) for use with 48V systems. Yeah, I'm looking at an everyday commuter build on a budget here. Hence my decision to go with the 9C kit (Bundled with a cycle analyst to boot), vs a cyclone or RC system that might have problems in bad weather.

Anyone have any advice for regen charging LIPO packs? The packs I'm looking at https://www.hobbyking.com/hobbyking/s...idProduct=9176 have a max charge rating of 2C. I'm not sure what the max charge a 9C hub motor can supply in regen mode, nor how to properly feed it to a LIPO battery pack.

Also faced with coming up with my own regen button - I'm not giving up my parking brake levers.

morph999 

I think regen is a waste of time and effort. Might want to do some research on endless-sphere.com/forums about regen. I don't know if LIPO is safe to use for regen. I haven't looked into it so if you know something I don't then disregard this. I've also read something about how regen prematurely can break your controller or something.

jethro56 

corkscrew: Hyperion 1420i is every thing i wanted it to be. The directions leave a little to be desired but I read many posts in other forums talking about it. If you can feed it enough power You can network 2 together and do up to 28S. I've went through 8 charge cycles and am figuring out what other people are talking about. You probably wouldn't want to run 28s but it'll balance charge all the cells.

Biggest advantage IMHO to regen is extra braking and less brake wear. In hiily areas this is probably valuable. Not so much here.

edcastrovalley

I find regen to be invaluable in the hilly areas where I live. Leaving my house I usually see 4 digit regen watt numbers for 30 seconds at a time going down hills plus, I can actually stop my bike when I need to. My problem is I recently raised my voltage to 72 volts and my regen stopped working. I understand I need to change a resistor in my controller but I haven't done it yet. I miss my regen. Actually, I'm looking to weld a disk brake mount on my front forks. If I blow a fuse I could end up sailing through an intersection. The v brakes are just not cutting it.

gunner65

Most of the e-bike kits I see have optional 36 or 48V 8ah-20ah batteries which are very pricey. does anyone have a link or parts list for using the RC batteries instead of the "normal" do you just series 4 of them? That would make 48v @ 20ah correct?

corkscrew

Nay, for a 44.4V 20Ah package, you need 8 of those cells I posted. 4 of those RC packs @ 22.2V 5000mAh, would have to be broken up into two 44.4V 5AH packs. Then connected to double the volume to 10Ah.

Check the link in my original (top) post. You'll see what I mean.

I have avid BB7's on the trike now, with 185mm rotors. Braking should be fine for the two hills on my commute (Literally downhill and uphill in the same ride, might as well throw snow at it too). The hope with Regen though is that it would help retain that same level of braking after I strap 40+ lbs of motor and battery to it!

corkscrew

Well I'm about to order parts (well, batteries and the motor kit), so yay?

I'm thinking with the regen numbers posted on ebike.ca's infenion controller page, I should be ok. The regen should act as a momentary bulk charge to the LIPO pack, will just have to be sure to balance charge afterwards to make sure it doesnt' cause any weirdness.

I'm looking at chargers. Hoping a guy on Endless Sphere can sell me a 1420i with a 12S adapter (made out of two 6S balance boards) that would let me balance charge the entire pack at once.

jethro56 

Just recieved his adapter kit about 15 minutes ago.

corkscrew

Oh yeah? I wasn't aware he sold it "completed" without buying it as part of the hyperion kit. Hrmmmm...Might just order the hyperion on it's own then, and get a adapter from him.

In other news though, I ordered my 8 6s 5000mAh 22.2V batteries this morning from Hobbyking's USA warehouse.

Shot ebike.ca an order too for a 9C rear motor, 40amp controller,thumb throttle, Upgrade to the large screen Cycle Analyst and an 8 speed freewheel with the proper spacer.

Just need a charger + adapter, some connectors/fuse holders, a battery box, and a rear torque arm now.

jethro56 

Corkscrew:
Don't forget a power supply. I got a order in on a couple 500Watt Meanwells. I'm using 2 tractor batteries now. Charging batteries to charge batteries is just too much trouble. I really like the PowerPoles for connectors.

https://www.powerwerx.com/anderson-po...pole-sets.html

The crimp tool is really nice. I'll also have 8 5000mAh 6s Turnigy's when the second set of 4 arrive.

corkscrew

I was going to do some research on the power supply issue when I got around to ordering my charger. Are you really going to use two 500watt Meanwells for your 6s x 8 setup?

jethro56 

This was just too good to turn down. https://cgi.ebay.com/ws/eBayISAPI.dll...E:L:OU:US:1123

Yes their used and at 120V they "only" put out 420 watts. I could easily run them @220V in the polebarn. They're also CC/CV so I could run them without the hobby charger in a non balance charge.

dougmc

Lower ratings of 20C? I sense some confusion.

In an R/C context, a battery with a rating of 20C means it can be discharged at 20x it's Ah rating. So if the battery has a rating of 1 Ah (1000 mAh) you can draw 20 amps out of it. The key thing to know about this is that the battery can only sustain this for 3 minutes until it's dead.

If you discharge a battery at 20C, it's dead in 3 minutes, 10C, 6 minutes. 1C ... one hour.

R/C planes are typically built around 10-15 minute flights, which corresponds to a 4-6C discharge rate. Double that for extreme parts of the flight, and you're at 8-12C, and of course having plenty of extra is nice, which is why 20C or 30C is nice.

But an electric bike should average around 1C or less, so any R/C battery should support a more than adequate discharge rate, as long as it's big enough to last for more than 20 minutes. (Unless you want an electric bike with a tiny battery that only lasts 3 minutes (20C rate), of course.)

9C is a company -- unrelated to the C ratings in batteries.

As for charging multiple 6s batteries, you can charge them separately if you wish -- either add appropriate charging plugs to your custom pack, or add the packs together with a wiring harness of some sort.

As for a good idea or a bad idea, R/C packs tend to give up capacity, low cost and lifetime for high discharge rate and low weight. For an electric bike, you probably want high capacity (more distance), low cost (duh!) and high lifetime (you want it to last many charge/discharge cycles) -- a high discharge rate is likely not important.

But you are right ... even a small R/C battery can put out 35 amps. Like https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9368 this one - it only weighs four oz. But it won't do it for long unless you get a bunch of them and put them in parallel.

dougmc

They're CV, not CC. Be careful using them without a charger if you don't know exactly what you're doing -- you could easily ruin your batteries or worse.

jethro56 

Did you dig into Meanwell's site and read the specs?Like I did?
Edit: misread the specs It's a current foldback design. Sorry

corkscrew

Yes, the lower rating of 20C - on Hobbykings site the smallest C-rated battery LIPO they have is 15C - they highest is 60Cish. Everything is relative after all.

I won't be discharging them at the full rate of 20C. That's just the capability. We'll see how long the 20AH pack lasts on my 40amp controller though.

@Jethro - I might go ahead and order that same PSU if you don't mind. Seems like one would be a good match for when I get the Hyperion + 12S charge/balancing kit.

Edit - HA! Ok, bought one, hopefully it'll be here by the time GGoodman gets back to me with a charger and kit.

dougmc

No, I didn't. I didn't have to.

It's sold as a CV charger -- it's designed to deliver a relatively steady voltage at any current up to it's maximum current. What happens above it's maximum current is undefined, but it could 1) keep delivering even more current at the rated voltage, 2) reduce voltage as the current goes over the rating, 3) reduce voltage but hold the current at the rated maximum, 4) reduce voltage and current, 5) simply shut off, 6) release the magic smoke. (If it's a current foldback design, that would be #4 -- a good, safe design.)

If by CV/CC you mean it'll go up to 20 A at 24 V and above that the current will stay at 20 A as the voltage drops to match the load, that would be #3, that's certainly possible, but I don't recall seeing many power supplies set up that way. When I see a power supply that explicitly says CV/CC, it's generally either for welding (and I'm not sure what they mean by CV/CC in that context, but it might be what I just said) or a bench power supply where you can change modes, voltages, currents, etc. (I even have one of those.)

Of course, the spec sheet may very well tell you what happens. That would be part of "knowing exactly what you were doing", but even better is to make sure the current load is never higher than it's rated at.

As for the batteries, if the voltage output of the PS (can it be adjusted?) is the same as their maximum (not nominal!) voltage or slightly lower, that could work. But be careful of what would happen when the batteries are fully discharged and then hooked up -- make sure they don't exceed a 1C charge rate (unless your batteries can be charged faster) and don't overload the charger. If either is true, you might want to add an appropriate resister in series (make sure it's rated to handle your maximum calculated current and can dissipate all the heat it develops!) And a fuse would be very wise. I assume you know all this.

But if the voltage is too high, it'll ruin your batteries the first time you forget to stop it before it reaches that point, and may cause them to catch fire if it's bad enough. And at 20 A, things could go bad very quickly.