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[JohnC]

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[spinningmagnets]

Zippy makes 8aH LiPo bricks, so two of them will provide the 44V you need in a simple package.
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16228

I started with the absolute cheapest LiPo charging set-up I could find, a 5A laptop power supply and a $33 7A Turnigy charger. They allow balance charging of each cell (many LiPo users only balance charge once every 10 charges to maintain cell health, they bulk-charge the other 9 times). The power supply died almost immediately, and the same model charger at a slightly higher $40 will charge at 10A (also includes some extra connectors that are very useful). Here is the cheapest LiPo charging set-up I recommend ($80 for charger and PS):
http://endless-sphere.com/forums/viewtopic.php?f=16&t=23465#p341300

Most LiPo chargers will charge to 4.15V or 4.2V per cell. I recommend charging on the LiIo (Lithium Ion) setting of 4.1V per cell.

If you want a plug-and-play bulk charger for LiPo at work, it might be useful to use a 48V LiFePo4 charger, which charges to 4.1V per cell
http://endless-sphere.com/forums/viewtopic.php?f=28&t=26717

[neptronix]

6 miles on 5 amp hours of 44v does sound bad, if this is flat land we're talking about.

How many amps is your controller drawing in reality?
Do you have a turnigy watt meter, cycle analyst, or some other method of monitoring your amps, volts, and amp-hours used?

If you don't, buy one now. It will help you diagnose this issue.

Also, what battery are we talking about, lipo? what brand?
And what charger do you have? what voltage are you charging to, and what is your pack's voltage when your low voltage cutoff point hits?

Also, if we're talking about lipo, when your battery is fully discharged, are any cells below 3 volts?

[JohnC]

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[neptronix]

Oh, i'm sorry, i was not aware that this was all theoretical.
See this is what happens when you throw down a bunch of questions at once.

I'll tell you this about 5AH, you should be getting about 10 miles on it with most motors while pedaling on flat land if we're talking about 36-48v.

If you want more amp hours, buy more packs and put them in parallel.
Currently the best deal would be the 6S 5AH 15C zippy packs AFAIK. ( they are also the lightest )

That would give you 46v nominal ( 3.8v/cell is the real nominal value ), and 10 amp hours, good for roughly 20 miles on the flats, or about 10-15 miles if you have major hills to contend with.

[JohnC]

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[neptronix]

Yep, you'd need 4 bricks.

And use parallel / serial harnesses.



Parallel..



Serial..



Parallel + serial.. ( btw, pay no attention to the color coding of the serial connectors, they are incorrect. but the polarity of the connection is correct ( it is hard to screw up a serial connection ) ).



Or you can do a permanent serial like so.
( mind you, these packs were cycled a few times and tested otherwise to make sure they were good before i wired them up like this. Don't do this unless you have known good lipo packs. )



Then use a big ol' parallel harness to link it all.

or for 6s packs, you may want to do 2 big parallel harnesses to 1 serial harness. This makes more sense, here i am using 5S as an example, and have used permanent serial since i have a 10S balancing charger.

make sense?

[dogman]

I agree, you should be able to squeeze 12 miles out of 10 ah most days. But it will be tight when you have a headwind. You may want to consider a 15 ah setup just so your batteries have a lower depth of discharge each ride, and might last longer that way. Also that allows you to take the long way home from time to time.

You can start with 4 bricks, and see how it does. If you ride pretty slow, and use just 8 ah, then you are in the ballpark for having a decent setup that allows the batteries to only be discharged 80% most rides. A lot depends on how you ride, how fast, how many stop signs, wind, etc. I tend to ride too fast, and have hills. My rule of thum is about 1 AH per mile for 36v. .75 AH per mile for 48. So for 12s, about .85 AH per mile. That rule of thumb does include your 10%- 20% reserve. So 10 ah could be enough, if you don't have to stop much and ride less than 25 mph.

[spinningmagnets]

If you bulk charge your pack to only 4.1V per cell (12S = 49.2V) you will have fewer individual cell balancing troubles, and the pack will also last longer. Many users charge to 4.15V or 4.2V per cell, and the pack will not last as long, and they might only be getting an extra 1/4 mile from the pack.

To reduce the number of joints in the wiring harness, get four of the 8aH bricks to give you 16aH for an average of 46V. Just a thought...

edit: six of the 5aH bricks (15aH pack @ 46V) will be a little cheaper, but you have a couple more connections to manage, and I prefer to keep things as simple as I can.

[wesnewell]

Just for reference. I get about 10 miles @15mph, no pedaling, using 5ah 14s1p 15c zippy lipo with 48V 500W rear hub motor kit. I weigh 270lbs. At 220, you might get 12 miles @ 15mph with no wind or hills. But, I'd get at least 8ah 14s (~470wh), or 10ah 12s (~500wh).

[neptronix]

Man, you guys get bad efficiency.
On the flats with very slight inclines here and there, and adding my pedal power, i get 2 miles per amp hour at 36 volts.

Anyway i guess that is a cautionary tale. Buy more amp hours than you need. Luckily with lipo, you can add more later..

[dogman]

My daily ride climbs 1000' vertical. So what I get is often as bad as it gets. Slowing down really helps too, stay under 20 mph, and I get much better wh/mi.

Climbing that hill with a "normal" winding motor makes heat. When I was using a slower motor, I climbed cooler and also never exceeded 20 mph. Definitely got close to 2 miles per ah with that setup.

[neptronix]

My daily ride climbs 1000' vertical. So what I get is often as bad as it gets. Slowing down really helps too, stay under 20 mph, and I get much better wh/mi.

Climbing that hill with a "normal" winding motor makes heat. When I was using a slower motor, I climbed cooler and also never exceeded 20 mph. Definitely got close to 2 miles per ah with that setup.

That explains it. As far as my hill climb amp hour / watt hour per miles goes... it is too horrible to even mention.
But the geared motors have a wider efficiency spread than a DD according to ebikes.ca.

Everyone says that a slower wind is less efficient. But i always thought that they use less amps to create the same amount of torque, sacrificing top speed, which can be gained back by adding more voltage, and volts do not create heat in wiring, amps do, am i correct?

Comparing efficiencies is complex. We need a standard way to do it.

[miuan]

Everyone says that a slower wind is less efficient. But i always thought that they use less amps to create the same amount of torque, sacrificing top speed, which can be gained back by adding more voltage, and volts do not create heat in wiring, amps do, am i correct

Absolutely. I now run a rear 2809 at 24S and am very happy with it. However the best blend of torque, speed, efficiency and reliability was my dual 2807 setup, before it got stolen. Imagine how much more current you'd need to double the torque of a 9c run at 30A with one motor only.
I am a little disappointed with the 4310s in my Lyen 9fet, I feel it gets too warm at 24S/30A, and may decide to purchase a bigger one eventually.

[o00scorpion00o]

Nice one David, Those pics are very helpful, I think I will just get you to wire up everything for me!

[JohnC]

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[wesnewell]

and volts do not create heat in wiring, amps do, am i correct?

But volts ties directly to amps. 10Ax10V=100W. 10Ax100V=1000W. Now which one will produce the most heat?