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        Question Newbie with Two Year old 8S lipo's, Pictures (edit, its also an e-bike)

#1 drebsdorf Aug 28, 2012 10:53 AM

Newbie with Two Year old 8S lipo's, Pictures (edit, its also an e-bike)
 
Hi there

I bought this 8s battery two years ago, to this month. Along with two 4s 1 year old batteries.
I've used them <50 times, but they've been in heavy use powering an e-bike. And now it looks slightly bloated, but I have zero experience grading "bloatation"?

Would you fly?
http://imgur.com/a/vufNx#3 (gallery) and possibly for how long?
I don't mind being on the safe side and disposing it if need be.

Best regards

#2 rick.benjamin Aug 28, 2012 12:15 PM

Hi Dreb
Welcome to RCG
I think that your batteries are a little puffy, due to "heavy use".
I would use them, charge them outside, away from flammables.

Have you measured individual cell voltages, before and after charging?
If the numbers aren't too lopsided, they are still useful for now.

What load are they subjected to?

#3 peak Aug 28, 2012 12:38 PM

What e-bike? How did it work? I've been thinking of this for my "Iacocca" ebike. The SLAs are dead and no replacements.

#4 drebsdorf Aug 28, 2012 12:43 PM

Hi, thanks for your reply.

To put it bluntly, this exact thing:
Electric Bicycle - 1st test run, 50 kph (1 min 32 sec)


The ESC been upgraded to this http://www.hobbyking.com/hobbyking/s...dProduct=10332 200A

I did a couple of 12S runs @ 85 km/h with two 8S and two 4S, mainly run in 8S series.

Its a slip drive, so I maybe only stalled it once when i blew out a 100A HK.

#5 7oneWo1f Aug 28, 2012 01:04 PM

Cool project, and smart move on the disc breaks and helmet.

#6 drebsdorf Aug 31, 2012 10:05 AM

I measured my 8S pack

Voltage, from when i put it into storage mode, ranges from 4.11 to 4.14.
The one 4S measures 4.0 on the first cell from negative, and the rest are 4.16 - 4.19. Charged State.

The other 4S measures 4.19 across the board, so I assume thats fine, also its charged state.

A follow up question, would you parallel couple the 2 x 8S batteries, and if so, what should thier respective voltage difference be? +- 0,5V?

#7 drebsdorf Aug 31, 2012 10:07 AM

Quote:

Originally Posted by peak (Post 22573678)
What e-bike? How did it work? I've been thinking of this for my "Iacocca" ebike. The SLAs are dead and no replacements.

My experience, unless you buy a LIFEPO4 pack on ebay or somewhere else, you're wasting your money. Also, buy a hub motor! :D Heads up, a 48V 20Ah pack only discharges 25A, 35A burst, mostly.

#8 TJWright Sep 01, 2012 09:00 AM

Very cool idea...what motor are you using??
how long have you been working on this......??

#9 TJWright Sep 01, 2012 09:00 AM

Can you post some close ups of the power set up ??

#10 TJWright Sep 01, 2012 09:02 AM

I would really like to build one of these set ups to ride to work.
what kind of range or miles per charge do you get ??

#11 drebsdorf Sep 02, 2012 02:08 PM

Why certainly, but I just wan't to underline how incredibly dangerous this is. My build is far from perfect, or pretty, but it does work, sorta, not really.

This is an updated build where I put everything in a sidemounted bag, mostly to keep a low profile ;)

Here are some images, I would start with the one of the fire-extinguisher. http://imgur.com/a/mIuIs

This setup needs a spark terminator/resistor to connect the batteries safely.

There's an Amp/h meter rated for 200A and a voltage display in the side pouch, a small multimeter on the handle bars is probably easier.

Control is done with an ohm resistor throttle replacing the knob on a servo controller. This is documented in plenty of places.

Theres a powersource for the servocontroller and cooling fan running off the two 3S batteries.

Quote:

Originally Posted by TJWright (Post 22610808)
Very cool idea...what motor are you using??
how long have you been working on this......??

Unfortunately I don't see hobbyking listing the motor anymore, its a Turnigy 80-100-B 130Kv, 60-80cc equivilant i think. I would recommend a smaller diameter motor if you can find it with equally low rpms. Since the gearing is dependt on the wheel size. Maybe 50-80A range.

I put it together in a week, waiting for the parts took the most time. Then winter pretty much happend and I had to put away. Come summer i drove it to work plenty of times, pulling my mate along @ 50 :D Then 100A controller exploded and one of the 8S batteries puffed. These RC parts are very fragile / not inexpensive, I also spent two rear tires.

Quote:

Originally Posted by TJWright (Post 22610825)
I would really like to build one of these set ups to ride to work.
what kind of range or miles per charge do you get ??

I drove it for 25 Km once, going along at 25-40. With 2x8S.


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