1st ebike build, 48v battery suggestions

I would like to convert my bike to an ebike and this is my first attempt at doing so. I feel like I've found a kit I like (yescomusa rear 1000w 48v rear hub kit or something similar off ebay if they don't get kits in stock soon). However, I'm having a lot of trouble deciding on what to do on the battery end of things. I would like around 20 Ah as I need something that can go at least 18 miles. My goal is to go as cheap as possible as I have very limited funds at this point and need something soon so I'll probably have to go lead acid over LiPO.

Thanks for the help!!!

Don't bother with SLAs. You'd have to carry 50 lbs of lead in order to get 20Ah. Save your money to buy some LiPO or A123 LiFePO4.

The problem with the SLA is weight, about 70 pounds for 8 12ah bricks, and space to mount the batteries.

For cheap but plug and play safe chemistry I got a 48v 20ah LiNiCoMn from BMSBattery for $400 plus shipping. It only weighs about 14 pounds:

http://www.bmsbattery.com/48v/249-48v-10ah-lithium-ion-electric-bicycle-battery-pack.html

A number of us, myself included, have had BMS problems with this battery, but I just purchased and installed a new BMS and all has been good ever since. The operating characteristics of this battery are more like the SLA's in that the voltage has a constant drop during use.

sun-thing28 on ebay has the 48V15Ah lifepo4 pouch packs for $404 delivered with charger. that has to be close to what you will pay for lead.

You don't need 20ah to go 18 miles. You can get 20 miles at 20mph with 10ah of 12s rc lipo. Cost $150. Or a 15ah 48v battery pack will be more than enough.

Cool, thanks for all the input. I was kind of hoping someone would come up with a $50 solution (a man can dream). In the mean time I'll look into rc lipo ($150ish seems reasonable) and see what I find. Just wondering though, how do you estimate amp hours to distance?

*****Just a rough estimate, rule of thumb for NewBE****

one amphour = 1.5-2 miles

so 2 times 6 series 5 AMP hour bricks (for 12 series 5 AMP hour) =distance of 7.5- ten miles.

or 3 X 4 series bricks ( for 12 series 5 AMP hour) = 7.5- ten miles

Most people here go for 12 series 10 amphours so you would buy 4 x 6 series bricks or 6 4series hardcase bricks.
No matter what if you ad the cost of the charger, they are similar cost to the LIFE batteries suggested, and they are a little complicated to learn
for a newbe. Still if you get the cheap hardcase packs and two slower( 2 hour) cheap chargers you could get away with $300.00 for 12 series and 10 Amp hours battery

seems hobby king is low on stock, can be a LONG wait too
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=18631

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=7523
need a power supply for that charger too

Without a voltage, you can't use ah, you'd have to state it in watthours. Others may not catch on that we are discussing 48v, even though the thread says it. And any range figure needs the speed. Same battery can have 20,30, even up to 40 miles range depending on the speed you ride. So give the speed and voltage with it to avoid misunderstandings.

My version for 48v. At 20-25 mph, 1 mile = .75 ah of 48v. A bit more conservative so as to allow for windy days.

48v 15 ah sunthing would be your best budget choice. At 25 mph, you should have a solid 20-22 miles. It's got about 750 wh.

Lipo is going to suck for you unless you spend about $200 on a faster charger and monitoring tools. You'll be up all night trying to recharge a big lipo pack with a cheap 50w charger. A lifepo4 with bms you can plug in and go to bed.

Lipo would be a definite option if you only needed about 6 miles range, then a smaller, faster to recharge pack would be cheaper. You could go that route now, and then add range as you can afford more packs.

Two 6 s 5 ah packs, or three 4s 5ah packs, one small cheap charger, and one cheap voltmeter. Add better charging and more capacity later.

Wow this guy sounds just like me a few weeks ago. I had similar requirements when i started to plan. I just finished my first build (ty wes for the help) and I guess I should get started on my build post to help beginners out.
In the meantime the OP should read the forum like crazy and be sure to read the stickies and faqs on the forum. Endless-Sphere Is your friend.

Make sure to check out ypedal's "the rant". Make sure you know what you want.
If you're not sure Dogman's advice is pretty spot on.

what ever kit you get, you can't go wrong with the yescomusa choice either, only problem is I think they are low or out of stock on most kits. maybe they stocked up since I last looked.
anyway, you want 48v and go about 18 miles. this is what you can use... from Hobby king four turniqy 6s 5a bricks. this gives you about 48v 10a in a 2s2p config, for $42 x 4 = about $170.


http://www.hobbyking.com/hobbyking/store/__16207__Turnigy_5000mAh_6S_20C_Lipo_Pack_USA_Warehouse_.html