Is this about right?

[mikefish]

Im getting closer (I think) to picking the components for my Ebike.

Im considering an Ebikekit rear wheel motor, and a 48 volt battery from Ping.

Im about 185lbs, and I only have one long hill going home from work. my work commute is 5 miles one way. It will be placed on a hard tail Mnt bike with front suspension, and disc brakes. (still looking for the bike)
I figure this set up is good for about 25 mph (give or take) on a flat with favorable conditions. sound about right?

will performance suffer greatly if i chose the 10aH battery over the 15aH battery? I like the idea of the 10aH for less weight, smaller size, and of course cheaper price. I can plug in at work, so I think range wise, the battery will be fine, but Im not so sure about performance hit. i would like to stay around the 25mph range, but no less than 23mph.

i would like to give it my best shot to try to mount the battery in the frame, but if my fabrication skills fail me, Im ok with rack install. I love some of the triangle enclosures i have seen here on ES!

thanks in advance for the help!

 

[morph999]

Have you seen what the one guy did with this special plastic that mends itself with some kind of special glue. He made his own mid-frame battery enclosure using like some kind of plastic sheets that adhere to each other using silicone or something. I can't remember what the adhesive was. It looked pretty easy to do. Something I could even do probably.

Nashbar has this bike mid-frame bag that I bought for $14. It might be big enough to hold a 10ah battery. I fit my 14lb Onguard 5018 chain in it. It's the biggest mid-frame bag that I found. Make sure you get the 90 cu inch one and not the smaller one.

 

[dogman dan]

A good 48v 10 ah battery such as pings or the one sold at E-BikeKit will be fine for a 10 mile round trip, but it would be easier on the battery to get a 15 ah one if you don't plan to charge at work. Winter, and windy days are when you will need the extra amp hours. On a nice day the 10 ah battery will go ten miles or more no problem at full throttle. The size difference won't affect top speed much with lifepo4 the way it does with nicads or slas. Lifepo4 won't have that much voltage sag, so the 10 ah and the 15 ah should have nearly identical top speed. If you get the 10 ah, and find yourself running low on windy days, riding slower that day will extend the range a lot.

If you charge at work then no problemo with the 10 ah battery. The 10 ah should fit in the triangle of most bikes. I found making a battery enclosure for a frame mount pretty easy using flat aluminum sheeting and 3/4 inch thick poplar boards. Cut the boards the width of the battery,and use screws to sandwich the battery into the aluminum sheets. The wood made it easy to screw it all together, and attach to the frame compared to metal fabrication.

I'm not sure about the top speed of the E-BikeKit motor at 48v. It's said to be made for 20 mph at 36v, so 25 at 48v sounds like the ballpark to me, and of course a bit faster if you pedal hard and have a big enough front sprocket. The butter zone for any motor is to pedal about 1 or 2 mph faster than the throttle setting you are using will make the bike go. This puts the motor into the low amp use part of the power band.

 

[morph999]

I think he used polycarbonate sheets to make a battery enclosure in his mid-frame triangle. If anyone knows what I'm refering to, please help. I thought I bookmarked it but can't find it. It was some type of plastic where if you cut it, you put some kind of glue on it and then it mends together really strong.

 

[Drunkskunk]

If you go with the Ping, you'll need to use the 15AH. The 10AH ping battery can handle a maximum sustained of 20 amps. The Controller I got with my 9C kit from them is a 22 amp. Its just a little over what the ping can do, but it will eventualy hurt the battery. The battery Ebikekits sells wouln't be a problem.

 

[mikefish]

hey morph, i think you are talking bout this guy:

http://endless-sphere.com/forums/viewtopic.php?f=6&t=13411

very very sweet job there!

dogman and drunkskunk, you both suggest the battery from Ebikekit will work, but thats only 36 volt, unless im missing the 48volt battery link, i would have to buy elsewhere to stay at the 48 volt speed i want to get. (25ish)

good point drunkskunk about the 22 amp continuous, looks like i would have to shell out the extra money to go the 48 volt route from Ping.

 

[julesa]

It'll be nice to have the extra range you'll get from the 15Ah anyway.

 

[Russell]

If you go with the Ping, you'll need to use the 15AH. The 10AH ping battery can handle a maximum sustained of 20 amps. The Controller I got with my 9C kit from them is a 22 amp. Its just a little over what the ping can do, but it will eventualy hurt the battery. The battery Ebikekits sells wouln't be a problem.

If a Ping is like my generic Chinese LiFePO4 battery I'd take it over the E-BikeKit battery. I'm not sure why people speak so highly of the battery Jason sells and while I have never used one it appears to me to perform no differently than any other 1C battery. Look at the Ypedal video and see just how much the voltage sags under load;

http://endless-sphere.com/forums/viewtopic.php?f=4&t=8452&start=75

39.5V/0A
37.5V/9.69A/1C
36.2V/14.85A
34.8V/19.95A /2C

Out on the road my 48V/10Ah LiFePO4 sags less than that.

-R

 

[DerekG]

I was fairly sure the prismatic cells Jason uses are rated for 3-5 C although it's been a while since I looked on the battery info sheet

 

[Russell]

I was fairly sure the prismatic cells Jason uses are rated for 3-5 C although it's been a while since I looked on the battery info sheet

I very much doubt that but since you have a CA perhaps you can note what the voltage is at various current levels and report back. Nobody else around here seems to be running the pack.

-R

 

[DerekG]

Sure, I'll run the test tomorrow after I get a replacement rack Just letting you know that my voltage numbers will be very close to those already posted just from scannig them over and comparing to what I remember, however, I will do a full test to make sure.

Assuming my numbers are the same I agree with you that they can't be 3-5C cells, however, I also remember a link to the spec sheet of the prismatics he used and it was 10C max discharge 3 C rated 5 C for a min (or some time interval I forget)

Let's see what tomorrow shall bring

 

[Russell]

Take a look at Doctorbass' tests here;

http://endless-sphere.com/forums/viewtopic.php?f=16&t=8926&p=138796&hilit=doc+headway+discharge+curve#p138758

Look at the second JPEG for 5C Yesa cells and note the cell voltage at 3.19Ah is about 3.16V at a 2C discharge. In a 12 cell 36V pack that equates to 37.92V then compare that to the Ypedal video where the battery voltage sags to 34.8V under a 2C load. Those are definitely NOT 5C or even 3C cells but I was probably wrong to refer to them as 1C and maybe should call them 2C since they can sustain a 2C+ discharge.

On one trip I took with my generic 48V/10Ah battery I held 10A then 20A going up a number of hills along the way and jotted down the voltages so I could draw a rather crude discharge curve. At a 2C discharge (20A) the voltages were as follows:

1Ah: 48.0V
2.5Ah: 47.4V
4.8Ah: 47.0V
7Ah: 46.0V
8Ah: 44.5V

Divide those numbers by 16 to get the per cell number then multiply by 12 to achieve an equivalent 36V pack and the voltages would be:

1Ah: 36.0V
2.5Ah: 35.6V
4.8Ah: 35.2V
7Ah: 34.5V
8Ah: 33.4V

These derived numbers are better than the battery in question which sagged to 34.8V at 2C with 3.2Ah used. I will be the first to admit this isn't conclusive data but that's why I ask that you perform a similar test. It does however appear that the cells in the battery in question are no better and perhaps even worse than the cells in my generic battery.

-R

 

[mikefish]

one more thing, i plan on pedaling all the time. call it anti beer belly program! :lol:

also, I am confused as to why some members here are suggesting the 36volt battery after i mentioned that im looking for 48volt speeds?

seems like most guys on here think 48 volt is for wussies! i read all these fellas running 60-72 volt, with boost packs!?! why should i go to 36volt when i have the opportunity to build a bike that wont disapoint? all im saying, is that i want to try to do it right the first time.

 

[Russell]

one more thing, i plan on pedaling all the time. call it anti beer belly program! :lol:

also, I am confused as to why some members here are suggesting the 36volt battery after i mentioned that im looking for 48volt speeds?

seems like most guys on here think 48 volt is for wussies! i read all these fellas running 60-72 volt, with boost packs!?! why should i go to 36volt when i have the opportunity to build a bike that wont disapoint? all im saying, is that i want to try to do it right the first time.

Sorry I continued taking your thread off course when they recommended the E-BikeKit battery.

The voltages at 2C I show above for my 48V/10Ah pack were obtained when I used it with my E-BikeKit 9C and 22A controller so yeah I think a 48V/10Ah Ping would perform at least as well though I would suggest opting for the 48/15Ah. I had the 9x7 9C laced to a 700C wheel with 35mm tires and my top speed was about 29 mph and it was easy to spin 'er up to 30 mph with pedaling pretty much at will. This was actually too much for me and encouraged me to ride aggressively. The novelty would have worn off I'm sure and I would have settled down but the brakes on the bike were also not up to the task of hauling me down from high speeds either. Finally riding that fast did drain the 10Ah battery rather quickly (at full throttle about 0.7Ah/mile) which is another reason to go for the 15Ah.

-R

 

[morph999]

yeah build a 48v one. Or whatever you want. Don't listen to some of these guys. Everyone told me not to get a 5303 motor when I first got here. The 5303 is what made me happy ultimately though. No one can really tell you what you want. Some people are vendors and they are competing with crystalyte and they don't want you to buy crystalyte products because they want you to buy theirs. Replace the name crystalyte with whatever name it is. Same deal.

 

[morph999]

Everyone on here said "oh, you need to solder your wires" and blah blah. I found a $3 metal piece at the hardware store that can work on any two wires to hook them up without soldering. Honestly, some guys on here think they know everything but they don't. I put my bike together without a solder gun and without expensive tools.

 

[dogman dan]

Oops. I had forgotten the E-BikeKit battery was only 36v. So you want to get the ping, or if you are really concerned about c rates on a 10 ah pack, then get the headways from EV componentes.

In my opinion, if you are only riding about 6 miles between charges AND have no steep hills or 2 stop signs per mile, the 10 ah ping will be good enough. If you want to do a lot of fast starts, or uphill starts, then you'd have bigger amp spikes at those times.

But yes, I also agree that a 15 ah battery will be happier running a 22 amp controller than a 10 ah battery. Lowering the c rate will extend the life of your battery. But at a mere 12 miles per day, I doubt you will have a problem with lifespan since it will take you at least 4 years to get 10,000 miles on it.
No way is your contoller going to put out 22 amps for the entire ride. Even with a 10 ah battery, I bet your average c rate is below 2c. With a 15 ah ping, it would be likely to average below 1.5c. So a 48v 15 ah is a good choice. 48v 15 ah ping fits good in most rear carrier bags but it may be just a tad big for the frame triangle unless it is ordered in a custom shape. Depends on the bike. Old school MTB's have big frames, new stuff has lower bar at the top tube.

 

[mikefish]

well, looks like i have to write down all the sizes of the 2 different batteries im looking at, and the motor/wheel width...ect, and take them to the bike shop to see what will fit, and what wont fit. thanks for all the info!!!