Search found 761 matches

by major
Oct 11 2019 10:51pm
Forum: Battery Technology
Topic: Lithium Batteries Shipping Rules Discussions
Replies: 290
Views: 55014

Re: Lithium Batteries Shipping Rules Discussions

Well, not necessarily. I am the recipient of the package so how can I be responsible for the sender not putting a sticker on the box? The sender is the one who ships the package and is responsible for following the law and rules. The recipient has no control over that. I am stating my opinions base...
by major
Oct 11 2019 7:10pm
Forum: Battery Technology
Topic: Lithium Batteries Shipping Rules Discussions
Replies: 290
Views: 55014

Re: Lithium Batteries Shipping Rules Discussions

My understanding is you abide by the law or risk prosecution meaning fines and jail time. I would not expect a warning or mere confiscation.
by major
Sep 22 2019 12:31pm
Forum: General Discussion
Topic: 48v Ebike battery powering cordless 40v chainsaw or trimmer?
Replies: 9
Views: 305

Re: 48v Ebike battery powering cordless 40v chainsaw or trimmer?

Hi, I've hacked a number of battery powered tools. A lot of older ones which used nicad/nimh. I've gone over voltage on a number tools without problem. A DeWalt screwdriver originally used 7.2V. Never ran better than now with 12V Lithium. I think my vacuum sweeper was like 16V nicad, now 19.2V Lithi...
by major
Sep 20 2019 4:35pm
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 1270

Re: When to charge the acid battery properly?

borko444 wrote:
Sep 20 2019 12:13pm
Now after 19 km.
The battery is 77 volts.
Batteries average 12.83 Volts.
Check out the video.


[youtube]https://www.youtube.com/watch?v=z5l998v24Ao[/youtube]
Nice job dude. Like it. Easy to measure. Easy to equalize charge when needed. Good luck.

major
by major
Sep 20 2019 1:07pm
Forum: Motor Technology
Topic: Controllers - do they only manage duty cycle?
Replies: 4
Views: 184

Re: Controllers - do they only manage duty cycle?

Hi,
All that the controller can really do is switch. That is to turn on and turn off the switching devices, mosfets, IGBTs, or whatever. Everything else is just figuring out when to do it.

And I = V/Z is valid at stall, otherwise you must include a generated voltage in the equation.

Regards,

major
by major
Sep 11 2019 12:38pm
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 1270

Re: When to charge the acid battery properly?

... And don't be confused by the the difference between equalizing the 6 internal cells that make up one 12v battery, and balancing the 6 whole batteries in your 72v string. The first is done automatically by a good charger, but not the second. Hi Voltron, Can you support your underlined statement ...
by major
Sep 11 2019 12:05am
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 1270

Re: When to charge the acid battery properly?

Here's a paper on lead acid charging explaining the algorithm including float and equalization stages. You should check with your particular battery manufacturer for his charging recommendation.

https://chargetek.com/images/pdfs/equal.pdf

major
by major
Sep 10 2019 5:22pm
Forum: Battery Technology
Topic: When to charge the acid battery properly?
Replies: 82
Views: 1270

Re: When to charge the acid battery properly?

Most lead acid battery chargers take care of balancing series strings by using a float or equalization voltage after the bulk and absorption portions of the charge algorithm. With a good quality charger, this should be enough. With most lead acid batteries you get a 6 cell (12V) jug (case) with does...
by major
Sep 10 2019 7:45am
Forum: Large EV General Discussion
Topic: For an electric kart, what is the relationship of torque and power?
Replies: 5
Views: 261

Re: For an electric kart, what is the relationship of torque and power?

Power = speed times torque.

Watts = Radains per second * Newton meters
(w = rad/s * Nm)

or

Horsepower = Revolutions per minute * pound feet / 5252
(hp = RPM * lb.ft./5252)

Relationship is true for all rotational power including karts.

Regards,

major
by major
Sep 08 2019 10:04pm
Forum: Large EV General Discussion
Topic: Toro Workman MDE conversion
Replies: 49
Views: 4451

Re: Toro Workman MDE conversion

I'd certainly contact the seller.

You could switch positions of cell #16 and say #15. See if the problem follows the cell and is not in the BMS.

Regards,

major
by major
Sep 05 2019 4:47pm
Forum: Motor Technology
Topic: APL's DIY axial-flux motor
Replies: 717
Views: 32916

Re: APL's DIY axial-flux motor

Hi APL,

Can you provide the source for those illustrations? I'd like to see the rest of the machine. Thanks.

major

BTW, just because hub motor RPM is low doesn't mean low frequency. It likely is higher than your 60 Hz motor or transformer.
by major
Sep 02 2019 12:42pm
Forum: Motor Technology
Topic: Field weakening question
Replies: 2
Views: 249

Re: Field weakening question

Hi John in CR,

To my knowledge, field weakening, FW, does not alter performance below base frequency, or RPM. And, FW is not necessarily detrimental to efficiency when applied.

Regards,

major
by major
Jul 04 2019 5:10am
Forum: Motor Technology
Topic: Amp pull “at rest” for Curtis Controller
Replies: 7
Views: 257

Re: Amp pull “at rest” for Curtis Controller

Current (RMS) would be AC.

RMS = Root Mean Squared
by major
Jul 03 2019 7:00pm
Forum: Motor Technology
Topic: Amp pull “at rest” for Curtis Controller
Replies: 7
Views: 257

Re: Amp pull “at rest” for Curtis Controller

No worry. DC refers to battery current. Been a while since I used the Curtis AC drive and I don't recall if they monitor and display DC or not. That's why I asked. Edit. BTW. The controller does output some DC, like 15, 12, & 5V for throttle pot, communication, and sensors. And also a selectable DC ...
by major
Jul 03 2019 4:01pm
Forum: Motor Technology
Topic: Amp pull “at rest” for Curtis Controller
Replies: 7
Views: 257

Re: Amp pull “at rest” for Curtis Controller

OnI have an electrical go kart using a 48 V AC-9 motor and a Curtis 1236 SE controller. The controller software menu (under controller current and controller temperature), shows that the current (amp) range is between 2.0 and 4.2 Amps with no throttle action at all and the Controller temperature se...
by major
Jul 03 2019 1:22pm
Forum: Battery Technology
Topic: Could someone check my math?
Replies: 4
Views: 228

Re: Could someone check my math?

3.35Ah/cell * 13 cells = 43.55Ah for 13P.

43.55Ah * 25.2V = 1097.5Wh.

major
by major
Jun 25 2019 12:59pm
Forum: Motor Technology
Topic: variable field motor demo
Replies: 3
Views: 284

Re: variable field motor demo

link to variable filed motor, windings move in/out of the stator to adjust speed also torque I assume, anyone care to explain this phenomenon? I vaguely remember it being discussed many years ago but I've not seen it put into action before. video link is to solar car racing team from japan [youtube...
by major
Jun 17 2019 8:22pm
Forum: Motor Technology
Topic: Motorpoles
Replies: 11
Views: 489

Re: Motorpoles

Hi, Number of poles = 120 * frequency / RPM. Frequency is in Hz or cycles per second. Rotate motor at known RPM. Measure frequency of the signal generated on motor phase leads with frequency meter or oscilloscope. Or, apply known frequency to motor leads and measure RPM. Then use above formula. Magn...
by major
Jun 06 2019 11:22pm
Forum: Large EV General Discussion
Topic: Error Code I can not clear - Curtis Controller 1236
Replies: 17
Views: 1037

Re: Error Code I can not clear - Curtis Controller 1236

Yes, the reverse switch wiring doesn't look like the diagram. The middle wire on the switch goes to pack voltage (J1-1) in the diagram. I appreciate all of the great responses. I want to make sure I do this right so please see photo below. Currently, J1-25 (Red/Blue wire) is connected to the the mi...
by major
Jun 04 2019 6:28pm
Forum: Large EV General Discussion
Topic: Error Code I can not clear - Curtis Controller 1236
Replies: 17
Views: 1037

Re: Error Code I can not clear - Curtis Controller 1236

Looks like J1-1 needs to be wired to center of SPDT switch, not 12V.
by major
Apr 12 2019 7:23pm
Forum: E-Bike Technical
Topic: Recommended Soldering Iron for 5AWG?
Replies: 11
Views: 621

Re: Recommended Soldering Iron for 5AWG?

Ever consider a torch?
by major
Mar 30 2019 9:04pm
Forum: Alternative Energy
Topic: Solar Well Pump
Replies: 6
Views: 780

Re: Solar Well Pump

Hi TPA, I live out in the sticks. Need a back-up for my well pump. Don't like gas engine generators. I have plenty of batteries. So I have a number of UPS units which I can use for different appliances. The well pump was a challenge due to inrush or start-up current. It is a single phase induction m...
by major
Feb 24 2019 11:08pm
Forum: Battery Technology
Topic: Could you rate these 18650 cells for me?
Replies: 10
Views: 540

Re: Could you rate these 18650 cells for me?

I was impressed with the NCR18650PF. Tested total of 32. All virtually the same. Manufacturer's spec sheet gives rating of 2750mAh, 2700 min. My charger was only getting cells to 4.05-4.10V which accounts for some slightly low Ah readings. I was able to fully discharge at 10 amps as per spec. At 12A...
by major
Feb 24 2019 5:17pm
Forum: Battery Technology
Topic: Could you rate these 18650 cells for me?
Replies: 10
Views: 540

Re: Could you rate these 18650 cells for me?

I recently bought and tested some Panasonic NCR18650PF GA Cells, new. These were rated at 2900mAh, high drain hybrid, 10A and have a light green wrap and white washer. Attached are my curves.
Pana1thru12at5A.png
Pana1thru12at5A.png (37.49 KiB) Viewed 485 times
Pana1thru8atVariousA.png
Pana1thru8atVariousA.png (38.78 KiB) Viewed 485 times
by major
Jan 23 2019 11:12pm
Forum: Motor Technology
Topic: Air gap, magnet shape, and voltage questions
Replies: 12
Views: 926

Re: Air gap, magnet shape, and voltage questions

On the chart which archer321 posted, I see 48V, 80V, 96V, 330V, & 560V models listed each having different different design constants. With the "air gap" in permanent magnet motors you need to consider the distance of the magnet. Here is some discussion on the subject. https://www.eng-tips.com/viewt...