golftdibrad

What about these?
http://www.ballisticparts.com/tech/faq.php#2

Joe Perez

iTrader: (8)

And on the discharge side, there are actually a couple of devices aimed specifically at the e-bike market to provide in-flight LVC protection as well, such as this: http://www.methtek.com/2011/11/12/lv...lel-boards-10/


What perplexes me is the charger, and specifically the need for both the balance leads and the series leads. Are they using the balance leads only to shunt current away from individual cells (as they reach HVC) and dissipate it as heat during the charging process?




Cute, but I wish they'd actually give "Real" specs. They only list the capacity in "Pb-eq A/H". What does that mean? Lead-acid (Pb) batteries are typically rated at 0.05c (the so-called 20 hour rate), such that at 1c discharge, our old friend Dr. Peukert says that the battery will only deliver about 55% of its rated capacity, and at 2c you might as well be turning a hand-crank.

So is the 8 cell battery, with its "15 Pb-eq A/H" faceplate, actually rated at 15Ah?

That kind of advertising annoys me.





In my "please advise me" thread on ES, one of the members wrote:Which immediately made me think of:

golftdibrad

I agree for your application, but keep in mind they are trying to replace starter batteries. I think they have enough tech info for that purpose on their site. I was giving you the link along the lines of the logic of "hey these start cars/bikes and i bet you could use a small car/big bike battery and run that mtb booster for a good while on one of those."

From the FAQ "6.9Ahr 12 Cell EVO2" that implies .575 Ahr/cell. so a 16 cell is 9.2 ah and the hd would be 18.4 ah Still would need more volts for your application, but it was a thought.

fooger03

iTrader: (2)

My understanding is that the balance leads simply vary the voltage by a small amount. A cell that is undercharged might get an extra .2v thrown at it, while a cell that is overcharged my see a .1v drop. My charger only charges at about 1C because it's limited on the power end, but if you get a charger that can handle the power, the newer batteries will charge at 5C. (That's a full charge in 12 minutes.) With that being said, my charger does get pretty warm at only 50w, so I'm going to make an assumption that there is at least a little bit of voltage regulation through heat dissipation.

Let's see, if you were running a 66v 10,000mah battery and wanted to attain a 5C charge rate, you would need a charger that could handle 66*10,000/1000*5 = 3300 watts. That would give you a charge time of about 12 minutes.

Alternatively, a 660 watt charger would charge your battery from dead to full in about an hour. The TURNIGY charger you linked doesn't give an outright power capacity, but says it can handle 6A per port. If you were charging a 10 amp-hour battery, it should fully charge in about 100 minutes.

Joe Perez

iTrader: (8)

Yeah, high charge rates are probably important when you're out in the field waiting to fly your RC helicopter.

For my application, I'd rather have something that took 8 hours to charge but was capable of running off of 120v household power, as opposed to something that charged in 30 minuted but required 12VDC input.

Joe Perez

iTrader: (8)

Actually, it implies 2.3Ah per cell.

Given a nominal voltage of 3.4v / cell for the LiFe chemistry, a 13.6v battery with 12 cells would be a 4S 3P configuration.



Huh.

If their 12 cell battery ($190 and 2.44 lbs) is only 6.9Ah at 13.6v, then it's a pretty horrible idea for an e-bike. Sorry.

golftdibrad

Well you are way more qualified than me to make that determination. Just FYI then, I enjoy this thread.

fooger03

iTrader: (2)

An overnight charge makes sense, your linked charger has plenty of room for that. My 50w charger is 120/240v capable, which was a primary consideration in my purchasing decision - I definitely think it's ridiculous to need a 12v power supply to power another power supply.

Joe Perez

iTrader: (8)

Joe Perez

iTrader: (8)

Finally, some progress.

EMS is showing that a package has been posted in Minhang, and dispatched the Shanghai sorting center. Presumably, this contains my new wheel, motor and controller.

The battery should be following along shortly.

(Very exciting.)

rleete

iTrader: (21)

We expect detailed pics upon delivery. 8×10 color glossy pictures with circles and arrows and a paragraph of each one explaining what it is.

curly

iTrader: (25)

Joe, to give you a little food for thought, did you ever try pedal operated electric bike? There's no throttle, it's activated by the pedals to give you ~x2 your pedaling power. If you're not pedaling, the systems inactive.

Tried it the other day, it's surprisingly fun, I'm sure much like what you experience, and also stays very much in the background. Unfortunately, my only picture is of the battery:


It's a Pathfinder Torque II apparently, info is annoying hard to find.
http://www.nycewheels.com/ezee-torq-electric-bike.html

Very fun, I can see why you enjoy this.

y8s

iTrader: (8)

I'm still patiently waiting for "progress" to mean "I'm installing the front wheel with hub motor" but you seem to have avoided this topic.

Joe Perez

iTrader: (8)

Yeah, they're called Pedelecs, and are popular in Europe.

The control system is a bit trickier, as you need a torque-sensing hub on the crankset. The new CycleAnalyst which I'm using as the vehicle-control-computer supports the ability to take in the signal from such a hub and convert it to a linear 0-5v signal to drive a traditional controller. It's a neat idea, but I don't really feel like the added cost and complexity is justified.


I have absolutely no intention whatsoever to install a hub motor in the front wheel of my bike. None.

y8s

iTrader: (8)

Why not?

I will use the pro and con list which is a clever way to justify something by generating a silly list of reasons not to that looks just as long as the pros.

PRO:
same power half the current... x2
or double the power at same current... x2
all wheel drive
lance armstrongs never saw it coming
no more inconvenient wheelies

CON:
lots of weight
double the battery and controller cost and complexity
now you need a front milk crate
***** are not actually of steel

blaen99

iTrader: (6)

Pfft, come on Joe, you know you want a fwd bike!

Joe Perez

iTrader: (8)

1: No need. I should be able to achieve sufficient power on the rear alone. Planning to run 52v at a limit of 30A, on a gear-reduced motor.

2: Traction. Bicycles don't have much of it on the front wheel, particularly when said wheel is in the air.

3: My front fork is aluminum, and suspended. It's simply not capable of dealing with a lot of torque.

4: Cost, weight, complexity. I'd need a second motor, a second controller, and a second battery.

5: Reliability. This is a daily-driver, not a dyno queen. As parts count increases, so does the probability of failure.

6: Because not racecar.

triple88a

iTrader: (2)

Imagine a FWD bike burnout!!!

Maybe even get a big wheel in the front like in the pic above...

curly

iTrader: (25)

I don't know if I'd want a bike with lots of front wheel torque. Unless I had a steering stem damper.

JasonC SBB

Joe,

Does your controller actuator act like a velocity command, or torque command?
Mine is velocity which is stupid. It means the slightest throttle from a stop, delivers max torque.