hi guys how can i build a good Battery Pack to fit my case. how big can i go , and how it works
www.all-battery.com -can this give me a idea what i need?

Wayne... Ya posted this as a "MeetUp Idea" and in the wacky MeetUp World I'm not sure how to respond... So here:

BACK IT UP BUDDY...

Watt do you mean by "good"?

Lets assume "safe"? ...but also "best bang for the buck"?

Bottom Line ya need to know about storing the energy you need to generate the power you need to travel X miles at Y speeds (say Wh/kms)... I'm tapping about yer "battery pack".

...where "Wh" = V x Ah

V?... Ah?... Sound familiar? eg four 12V 20Ah batteries hooked up in series to give you 48V so 960Wh BUT how many Wh/kms???

It's really Wh/km that are the key. Not V. Not A. Not km... But a mix of the three, which is a bit of a "dance" :)

Ya have to start by identifying your desired range. Plus Wh/km
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sorrry lol

www.hi-powercycles.com

32 mph is very cool any faster my moped wood fall apart

i know it will cost me but this is the only why i can get what i want and need i guess start with controller BMC 37A 36-52V Custom Controller! can we make this work

51V LiFePO4 High Performance Battery System later i like this batt whats you thinking on this

Ya have to start by identifying your desired range. Plus Wh/km
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...Wh/km... Ya can figure this out pretty easily based on your existing pack. I'll guess that your controller senses how much charge is remaining in the pack based on voltage (an imprecise measure, but in common use) and cuts power when the batts are down to 20% remaining. So if you have for example a 48V pack as four 12V 17Ah batts that'd be 48V times 17Ah = 816Wh. Times 80% gets you 652Wh.

And watt sort of range are you getting these daze from this 652Wh before the controller cuts power?

Say... 30km?? If it were 30km that'd be 652/30 = about 22Wh per km...

Then ya just need to decide how much range you want on one charge. If ya want 50km then that'd be 1100Wh... If ya stay with a 48V pack, that'd be 1100Wh/48V = about 23Ah.

...and this assumes you are only using 80% of your pack. Different battery chemistries behave differently when they are cold too. Most lose effective capacity, with lead being about the worst.

I'd probably go with 30Ah, then I'd know I will still have good range in the cold, and as the pack starts to age, and that for most of my trips I will never be "taxing" the battery by pushing it to its limits...

...but lets simplify things and figure ya can get by with just a 20Ah 48V pack...

Maybe these:
http://www.all-batter...


...so there's yer 20Ah but only 3.2V and ya need 48V...so, 48V/3.2V... 15 cells... Hot off the charger these things will actually measure 3.65V, so 15 times 3.65V = 54.75V max... although that charger settles down pretty quick to their 3.2V nominal rating...

Actually say 16 of those cells, as that is a common number of cells used in series, and yer going to also need a Battery Management System to watch and protect each cell, like one of these:


So lessee... 16 of those cells would be $972.64US plus $73.05US for the BMS plus shipping and maybe HST and brokerage at the border... about $1200 total. Plus a bit of wiring and a fuse and fuse holder...

These are not "fancy" cells BTW, their specs read rather "slow" compared to the bleeding edge stuff that's around. The specs call for only a 1C discharge rate for example. In other words ya should not be drawing more than 20A from these cells continuously... The 10Ah cells I have are rated at 5C for example, meaning they can live quite happily being discharged at five times their 10Ah rating.

But even at only 1C discharging, 16 cells like these Tenergys would be putting out 1024W... about twice the 500W continuous the motor/controller is rated for(?)

The 16 LiFePO4 10Ah cells that I have, rated to handle 5C discharges comfortably, are capable at that rate of putting out about 3.5HP!!!. I am just not using a controller that is capable of "drinking" that fast! ...I am going for long life with my cells (hopefully) by running them well within their maximum capabilities...

I would NOT buy Tenergy myself(!!!) They have a rep for under-performing and being over priced for watt they are... But you can "go shopping" now and start comparing cell specs and to even things out always work out the price per Wh or kWh...

One fun thing to note about those Tenergy pouch cells (and others like it) is the 16 cells together would only weigh about 20lbs...

So anyway... watt IS your average Wh/km?

Lock

Looking at the hi-power.com 51V 20Ah packs:
http://www.hi-powercy...

...$1,529US including the upgrade to the 6A charger (approx. only 3hrs for a full recharge!)... plus HST probably, and shipping. They don't publish dimensions, so I dunno it it'd fit in your battery compartment w/out any mods...

loCk

51V LiFePO4 High Performance Battery System later i like this batt whats you thinking on this

It would be nice to know exactly whos cells they are using, and to be able to read the manufacturers spec sheet.

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...start with controller BMC 37A 36-52V Custom Controller! can we make this work

These controllers may not work with your motor... and if you are thinking of using 37A continuous ya had better have a pack (and BMS) that is capable of dealing with these power levels. Judging from the leads coming out of that controller it is designed for sensored motors... Do you know whether your motor has hall sensors or is sensorless? Ya can tell by the number and size of wires coming out of your motor. If it has the two large conductors plus small ones as well it'll be a sensored motor so that hi-power controller *might* work...

BTW 37A at 48V is 1776W! Waaaaay more than your motor is (maybe) designed to handle. It's pretty common for folks to push way more volts and amps through their motors than they are "rated" for, but ya have to be careful and watch for overheating... If you are comfortable with speeds around 32-35kmh ya don't really need this kind of power, and you will lose range... You will get only half way to were you want to go, but will get there (half-way) twice as fast (hehe)

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