Comments by Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 8 July 2013

    David,

    I'm not sure what you are asking. Is your safety guy saying the fuse approach is not acceptable? If you're thinking about using a 12 V lead-acid battery, those are commonly used in alarm systems, and I doubt they all need to get building permits. If they do accept the fuse or other current/power-limiting device right at the battery, the capacity shouldn't really matter, and you could use a 40 Ah battery (it would be the size of a car battery) to give you 4 A for 10 hours.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 8 July 2013

    Ashish,

    Did you read the post? Or the comments? Your question is answered many times.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 20 May 2013

    Stephen,

    That generally sounds reasonable. The current at peak loads might be higher than what you calculated, so the performance you see in the max torque sense could be lower that what you saw with the original NiCd pack (when it was new). I have no experience with the Panasonic Evolta, but if the performance ends up being limited, you might look around for NiMH cells that are better about high discharge rates.

    Also, you probably should not use the original charger for the new NiMH pack.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 13 May 2013

    It typically drops quickly, then flattens out around the nominal voltage, then drops quickly again. You should search for something like "battery discharge curve" for more details.

    - Jan

  • Servo control interface in detail

    Servo control interface in detail

    - 2 May 2013

    Hi, Brad.

    What is your basis for the 50% duty cycle requirement? In my experience, from textbooks to discussions with engineers to labels on test equipment, "square wave" means what you are calling "rectangular waveform". For instance, I think most function generators have a "square wave" button to access the rectangular waveform-generating features, not a "rectangle wave" button.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 2 May 2013

    Hi, Joan.

    I'm not sure what you mean by "mandatory", but in the typical, government-backed sense, that is a very bad thing. Imagine if you bought a bottle of water without knowing how much water was in there and someone put you or the seller in prison.

    If you're just talking about making a capacity specification a personal prerequisite for you to consider buying a battery, keep in mind that there are all these other variables, including discharge rate, temperature, how old the battery is, how low the voltage can be before you consider it discharged, and on and on.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 4 April 2013

    I showed you the exact assumptions and calculation that led to the 2.5 Ah result.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 1 April 2013

    Anand,

    You are not providing the right kind of information to answer your questions, and I do not know if this is the appropriate venue for going into the details of your project. But, here are some general points that might be helpful to you and others:

    * I think 2.5 years is unlikely to be practical for a rechargeable battery. (Maybe that was a typo since "charging" and "changing" are pretty similar.) I think there are various non-rechargeable battery types, like lithium batteries, that are supposed to last a decade or more.

    * It is not helpful to go into details like how many characters are sent without talking about the time it takes. And, for all I know, the wakeup and autosleep stuff might take longer than sending the message. Anyway, let's say your power requirements are 2A for 5 seconds every day. You would need 2 A x 5 seconds = 2.8 mAh per day. Multiply that by 365 and then 2.5, and you get to a little over 2.5 Ah for your 2.5 years. That's not some particularly huge number, though you might need to pad it quite a bit since the capacities might be based on very low discharge rates, not the 2 A pulsed discharge.

    * How do you expect anyone to know the "best alternative" for your application? We cannot know if your system will be in the sunlight for some solar option or how practical it is to power your system from a wall outlet.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 7 March 2013

    Kavan,

    I can confirm that your two specs do not make sense. Without any context, it's difficult to guess the intended meaning.

    - Jan

  • Introduction to servos

    Introduction to servos

    - 28 January 2013

    Thomas,

    This is not a very good place to ask a question like that (anyone reading this post is likely new to servos and unlikely to have meaningful experience with a particular servo you are considering).

    Anyway, while I have heard of no problems with that servo and think it's generally decent, if it were my $1000 plane, I would probably put some higher-end servo in there. At least for critical control surfaces.

    - Jan

New Products

Magnetic Encoder Disc for Mini Plastic Gearmotors, OD 9.7 mm, ID 1.5 mm, 12 CPR (Bulk)
RoboClaw 2x7A Motor Controller (V5B)
Free Circuit Cellar magazine November 2016
Magnetic Encoder Disc for 20D mm Metal Gearmotors, OD 9.7 mm, ID 2.0 mm, 20 CPR (Bulk)
488:1 Metal Gearmotor 20Dx46L mm 6V with Extended Motor Shaft
156:1 Metal Gearmotor 20Dx44L mm 6V with Extended Motor Shaft
313:1 Metal Gearmotor 20Dx46L mm 6V with Extended Motor Shaft
Magnetic Encoder Pair Kit for 20D mm Metal Gearmotors, 20 CPR, 2.7-18V
100:1 Metal Gearmotor 20Dx44L mm 6V with Extended Motor Shaft
25:1 Metal Gearmotor 20Dx41L mm 6V with Extended Motor Shaft
Log In
Pololu Robotics & Electronics
Shopping cart
(702) 262-6648
Same-day shipping, worldwide
Menu
Shop Blog Forum Support
My account Comments or questions? About Pololu Contact Ordering information Distributors