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Author Topic: Recharging a Battery on the fly  (Read 2456 times)

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Offline ShagsTopic starter

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Recharging a Battery on the fly
« on: February 24, 2008, 03:05:31 PM »
Ok,  I did a search on the forums for topics on this but I came up empty.

My question is this.  Can one recharge a NiHM battery while it is being used through solar or electromagnetic means in order to extend the life of the robots run?  Or alternatively,  can one supplement energy electomagnetically or by solar means along side the batteries discharge to extend the life of the robot run.

I know that on my cell phone I can be recharging and using it at the same time.  Is this just a matter of connecting solar panels to the positive negative lines of the battery or will that blow something up?  I am not an electronics expert but only the most basic of beginners but I was curious to explore this problem with my robot.  I would like my first robot to be as efficient as possible but I don't want a pure solar powered bot that is herky jerky filling up capacitors and then discharging every so often.

Has anyone else attempted something like this on their bot.  If so were your successful in supplementing power/extending the robots run?
Matt (aka Shags, hey you have to keep at least one nickname)

Offline HDL_CinC_Dragon

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Re: Recharging a Battery on the fly
« Reply #1 on: February 24, 2008, 09:00:40 PM »
just hook up the solar panels Negative to the batteries Negative, and the positives together so they are in parallel. That should extend the batteries life and probably charge the battery when the circuit is turned off... provided the solar panel can supply more voltage than the battery.

... I think you might need diodes though so the battery doesnt try to discharge through the panel
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Offline airman00

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Re: Recharging a Battery on the fly
« Reply #2 on: February 24, 2008, 09:05:10 PM »
... I think you might need diodes though so the battery doesnt try to discharge through the panel

correct
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Offline Admin

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Re: Recharging a Battery on the fly
« Reply #3 on: March 01, 2008, 10:22:11 PM »
Yeap you can do this . . . but if you do the math (calculate mAh), you'd find the energy you get from the solar panel will probably only extend your robot run for a minute tops.

If you are using wall power, don't do this with NiCad batteries since if you recharge improperly, it will reduce the battery lifetime. NiMH should be fine.

Offline ShagsTopic starter

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Re: Recharging a Battery on the fly
« Reply #4 on: March 02, 2008, 05:03:34 PM »
I was afraid someone would say that Admin. 

I think I am going to continue to focus my efforts on efficiency to lengthen run times between recharges,  I think if one could take a minimalist approach to power consumption (like the apollo projects did) one could greatly increase the use of robotics around the house to complete chores and such. 

I wanted to work on a robot that would haul things to a dump spot on the property and then come back for another load but if the thing runs out of batteries after a couple of trips and you have to haul the heavy thing back to the garage then that isn't much help is it?  I am sure this problem has been worked on a million times but if I only get a better understanding of the limits posed in modern robots then at a minimum I will have educated myself on current limitations of robotics.

Needless to say I will be spending a lot of time calculating battery life!
Matt (aka Shags, hey you have to keep at least one nickname)

Offline Ro-Bot-X

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Re: Recharging a Battery on the fly
« Reply #5 on: March 02, 2008, 05:08:31 PM »
Install a battery monitor sensor. Calculate how long will take the robot to travel from the farthest point back to the garage. Calculate how much power will that take. Then set the trigger point for just enough power left in the battery to get back to the garage for a recharge.
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Offline paulstreats

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Re: Recharging a Battery on the fly
« Reply #6 on: March 02, 2008, 06:06:55 PM »
In most cases, the extra torque that would be needed to pull the extra weight provided by the solar panels would be counter productive to the actual energy they provide(which is why solar poppers are solar poppers, because the motors only need to be as large as they are in order to move the solar panel itself, otherwise you would use smaller motors).

Also remember that anything electromechanical such as a motor spinning to generate electricity will provide at maximum only the same energy as is used to move it to start with

Offline HDL_CinC_Dragon

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Re: Recharging a Battery on the fly
« Reply #7 on: March 03, 2008, 10:23:05 AM »
Also remember that anything electromechanical such as a motor spinning to generate electricity will provide at maximum only the same energy as is used to move it to start with
And thats with 100% efficiency... which is physically impossible... which means it might just take a little longer to figure out how to do it :)
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Offline ShagsTopic starter

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Re: Recharging a Battery on the fly
« Reply #8 on: March 06, 2008, 04:35:07 PM »
No no the electro magnetism is for coasting etc.  Its the same as the Honda hybrid that used pedal presses to generate energy back to the batteries thereby making it more efficient in city driving but it lost alot of its advantage on long trips.  This idea works when the robot is in motion and the motors are not engaged.  Another concept that uses similar ideas is a piston that pops up when a vibration occurs through the drive (potholes are my best friend).  It is not my idea and there is actually a company in Australia that is trying to perfect it, and it is actually used in those shake flashlights that create a surface charge for use as light.

If we could generate more energy than we consumed on our robots, well then that would be a perpetual machine and that violates the Physical law of no matter (or energy) can be created or destroyed (or something like that).  We can convert energy and matter back and forth (light is actually matter) but we can not actually destroy either.  Eventually when the universe winds down everything will be matter (Geesh I am a geek).

Anyway as boring as it may seem I like the idea of efficiency so I am currently working on a board that does just enough (no fancy lights).  I hope to explore how to make a robot run as long as possible.

Matt (aka Shags, hey you have to keep at least one nickname)

Offline HDL_CinC_Dragon

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Re: Recharging a Battery on the fly
« Reply #9 on: March 06, 2008, 07:24:28 PM »
Everything is matter and that shake flashlight thing works on inductance which is inducing a current in the wire by a passing magnet. You can get a lot of efficiency by exploiting that sort of thing but you wont get 100% or greater. But still, the more the better.
« Last Edit: March 06, 2008, 07:25:23 PM by HDL_CinC_Dragon »
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Re: Recharging a Battery on the fly
« Reply #10 on: March 15, 2008, 05:31:28 PM »
You have seen my battery and energy calculators, right?
http://www.societyofrobots.com/calculator.shtml

 


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