Search found 2634 matches

by SamTexas
Aug 25 2013 2:21pm
Forum: E-Bike Technical
Topic: "LiPO", another "be careful" warning...
Replies: 54
Views: 3609

Re: "LiPO", another "be careful" warning...

No matter if you have a BMS or not, it won't save you from unbalanced cells during a charge. The BMS is similar to an external battery balancer. Some are better than others, but the basic bms that comes with a high voltage 48v pack is a battery balancer. It can only re-balance your cells at a certa...
by SamTexas
Aug 23 2013 12:59pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Monzilla - BURNED IN LIPO FIRE AUGUST 11
Replies: 136
Views: 17574

Re: Monzilla - BURNED IN LIPO FIRE AUGUST 11

dnmun wrote: there are a lot of self righteous people on this board who make it a point to say that using a BMS is stupid.
This is not the thread for BMS. That said, YOU ARE STUPID for using BMSes that don't work. How many times do you need to be insulted?
by SamTexas
Aug 20 2013 1:39pm
Forum: E-Bike General Discussion
Topic: Is there a curse on white bikes ?
Replies: 19
Views: 829

Re: Is there a curse on white bikes ?

Never had a white bike but I'm superstitious. I never leave home without my wallet.
by SamTexas
Aug 15 2013 10:55am
Forum: E-Bike General Discussion
Topic: Amazing Patent 2,5kg 1000watt e-bike conversion kit !
Replies: 23
Views: 2090

Re: Amazing Patent 2,5kg 1000watt e-bike conversion kit !

Why bother with the patent application in the first place? If friction drive is truly useful then the 60 years old Velo Solex would still be very popular today.
by SamTexas
Aug 09 2013 3:21pm
Forum: E-Bike Technical
Topic: "LiPO", another "be careful" warning...
Replies: 54
Views: 3609

Re: "LiPO", another "be careful" warning...

Just to clarify, I had no intention of using this pack for any other purpose than testing. I was not riding it to get anywhere but just to test the capacity. I wanted to know if it could be recovered by balance charging. It could not. I could, I am sure, have removed the cells that went below, say,...
by SamTexas
Aug 09 2013 1:56pm
Forum: E-Bike Technical
Topic: "LiPO", another "be careful" warning...
Replies: 54
Views: 3609

Re: "LiPO", another "be careful" warning...

...the battery capacity was probably a third or less of what it was originally (not surprisingly). I noted with the balance charger that the cells that had the extremely low voltages would very quickly charge up to close that of the "stronger" cells. I placed the pack in a safe location and bulk ch...
by SamTexas
Aug 09 2013 1:28pm
Forum: E-Bike Technical
Topic: "LiPO", another "be careful" warning...
Replies: 54
Views: 3609

Re: "LiPO", another "be careful" warning...

I do not want to start an argument here, but i want to clarify something. I have intentionally tested t he scenario you described with LiFePO4 and consumer LiCo laptop battery. I have built small capacity packs and let them slowly discharged to zero. No dramas at all. In the rare few cases, a few c...
by SamTexas
Aug 09 2013 12:23pm
Forum: E-Bike Technical
Topic: "LiPO", another "be careful" warning...
Replies: 54
Views: 3609

Re: "LiPO", another "be careful" warning...

just because you have not personally had a fire, does not mean it's not possible. That's not true. I have had many fires with RC LiCo under controlled testing environment. I have never had any fire with consumer LiCo and LiFePO4. And I have NEVER said that fire is impossible. I always says that all...
by SamTexas
Aug 09 2013 11:45am
Forum: E-Bike Technical
Topic: "LiPO", another "be careful" warning...
Replies: 54
Views: 3609

Re: "LiPO", another "be careful" warning...

Just trying to add to the cumulative experience of this community. Certainly, it was not the fault of the battery, ... I have to disagree with you. I have intentionally tested the scenario you described with LiFePO4 and consumer LiCo laptop battery. I have built small capacity packs and let them sl...
by SamTexas
Aug 06 2013 7:50pm
Forum: E-Bike Technical
Topic: What is your watthours per mile?
Replies: 26
Views: 3128

Re: What is your watthours per mile?

... At laguna seca we were averaging about 280 wh/mi. What were your average speed? 50mph only requires about 3,500W. At 50% efficiency, that's still only 7,000W or 140Wh/mi. Using the same calculation, 62mph only requires 12,400W OR 200Wh/mi. 4,000+ lb electric cars consume less than 280Wh/mi on f...
by SamTexas
Aug 06 2013 9:08am
Forum: E-Bike General Discussion
Topic: Bicycle headlight with 6x CREE XM-L T6 LED 7800LM
Replies: 44
Views: 3199

Re: Bicycle headlight with 6x CREE XM-L T6 LED 7800LM

I experimented with the benchtop DC power supply some more and found that amperage stayed stable near 2.1 amps even when the volts where raised significantly (my PS can go up to 3A). I got up to 17 volts before chickening out. The light did get brighter as the volts went up. I don't think it was tw...
by SamTexas
Aug 05 2013 12:48pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Just an odd "bike" seen while riding
Replies: 11
Views: 1770

Re: Just an odd "bike" seen while riding

Sounds good. Thanks for sharing.

I spent a few days in Guangzhou in the mid 90's. I was an experience I don't want to repeat again. Macau and Hong Kong were much better for me.
by SamTexas
Aug 05 2013 8:50am
Forum: Battery Technology
Topic: 18650 cell test: Panasonic vs. LG
Replies: 53
Views: 29724

Re: 18650 cell test: Panasonic vs. LG

OK, will do 50 cycles at 1C discharge and 0.5C charge. That's great. I look forward to seeing the results. Just a thought here, not trying change your mind or convince you of anything: Why not do the test at the actual anticipated charge/discharge rate? After all the actual charge/discharge rate is...
by SamTexas
Aug 05 2013 3:45am
Forum: Battery Technology
Topic: 18650 cell test: Panasonic vs. LG
Replies: 53
Views: 29724

Re: 18650 cell test: Panasonic vs. LG

It says "charging current 1325 mA" which is 0.5C. That's what I expected. 1325/3400 = 0.39C I really hope that Panasonic cell failed due to too high charging current. I do have one more cell, so will repeat the tests some day. I hope so too. Panasonic has a reputation to keep. I would love to see t...
by SamTexas
Aug 05 2013 3:20am
Forum: Battery Technology
Topic: 18650 cell test: Panasonic vs. LG
Replies: 53
Views: 29724

Re: 18650 cell test: Panasonic vs. LG

Very interesting data. You're the first individual I know that does a life cycle test. Wow! I have always been interested in the Panasonic NCR18650B cell, but I have also had doubt in mind about this chemistry. Looks like my doubts are valid, based on the result of your test here. Question: Why did ...
by SamTexas
Aug 05 2013 3:02am
Forum: E-Bike Build Threads / Photos & Video
Topic: Just an odd "bike" seen while riding
Replies: 11
Views: 1770

Re: Just an odd "bike" seen while riding

I figured just as much. How do you get by over there? Are you fluent in the language?
by SamTexas
Aug 05 2013 12:11am
Forum: Battery Technology
Topic: Nissan Leaf Cells Test Data
Replies: 383
Views: 70787

Re: Nissan Leaf Cells Test Data

The two red voltage curves. With sense wire the voltage is always about 0.10V higher from begin to end of discharge.
by SamTexas
Aug 04 2013 11:40pm
Forum: E-Bike General Discussion
Topic: hypothetical range question..
Replies: 89
Views: 2718

Re: hypothetical range question..

swbluto wrote: If he does a lot of long distance trips, I'd imagine he'd develop the stamina to do 15 mph continuous under his own power, thus capable of tripling distance at 30 kph.
by SamTexas
Aug 04 2013 11:34pm
Forum: E-Bike General Discussion
Topic: hypothetical range question..
Replies: 89
Views: 2718

Re: hypothetical range question..

swbluto wrote: 30 kph is only 18 mph. My grandma can pedal that fast. :|
That's what everybody says. Most of them can't even do 14mph for 2 hours and that includes young people. Grandma would be lucky if she can finish 10 miles, regardless of hours.
by SamTexas
Aug 04 2013 11:30pm
Forum: E-Bike General Discussion
Topic: hypothetical range question..
Replies: 89
Views: 2718

Re: hypothetical range question..

Looks like 1kwh at 30 kph would propel you about 63 miles or 101 km. (48v, 20ah LiFePO4) If you pedal along, you can easily double or triple that, depending on how much you want to work. Double, yes. Triple, no way, not at 30kph. The OP strength (according to him) is 20kph for at least 2 hrs. Meani...
by SamTexas
Aug 04 2013 10:58pm
Forum: E-Bike General Discussion
Topic: hypothetical range question..
Replies: 89
Views: 2718

Re: hypothetical range question..

Hmm... Going for speed? Forget all the previous estimates. They were based on 30kph and you doing real pedaling.

The energy needed will at least triple to 1,500Whr at 40kph and NO pedaling for 90kms. Good luck carrying that much low-density LiFePO4 battery.
by SamTexas
Aug 04 2013 9:45pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Just an odd "bike" seen while riding
Replies: 11
Views: 1770

Re: Just an odd "bike" seen while riding

Thanks. So is that portion of China bicycle friendly? Are you on a regular bicycle ride, or an ebike ride?
by SamTexas
Aug 04 2013 9:13pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Just an odd "bike" seen while riding
Replies: 11
Views: 1770

Re: Just an odd "bike" seen while riding

Interesting. Do you actually see the pedals? What city is that?
by SamTexas
Aug 04 2013 6:03pm
Forum: Battery Technology
Topic: Nissan Leaf Cells Test Data
Replies: 383
Views: 70787

Re: Nissan Leaf Cells Test Data

That's exactly what I expected to see. What a difference in sag!
Icecube test with and without sense wires.jpg
Icecube test with and without sense wires.jpg (41.92 KiB) Viewed 3410 times
That said, I'm still disappointed. I expected this chemistry to hold voltage much better under discharge.