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SteamAutomaton
06-01-2010, 10:54 AM
Dear Community:

Quick question, "What is the largest size LiPo that a Premium Bioloid handle?

Note: I am still learning about battery power. I am used to wall power.:rolleyes:

Next quick question, "Where is a good tutorial about batteries?"

Yours,
Steam Automaton

JonHylands
06-01-2010, 10:59 AM
If you're talking about voltage, you need to use a 3S - its pretty much your only choice.

Current wise, it doesn't matter. I use a pair of 8-amp-hour 3S packs in parallel on Brainbot. Roz (my quad walker) uses a 2000 mAh 3S pack.

- Jon

lnxfergy
06-01-2010, 11:45 AM
Issy, SMALdog, and Reaver all use this 11.1V 2100mAH pack (http://www.trossenrobotics.com/store/p/6293-3S-11-1V-2100mAh-Pro-Lite-V2-20C-LiPo-Battery.aspx) On a biped, the most important point will be weight. Seeing as the stock pack is a 9.6V 2300mAh pack, and lipo is quite a bit lighter than NiMH, that pack I linked to *should* be lighter, but I'm not sure.



Next quick question, "Where is a good tutorial about batteries?"

Not sure about "good", but there is a section on batteries in So You Want To Build A Robot? (http://forums.trossenrobotics.com/tutorials/introduction-129/so-you-want-to-build-a-robot-3126/)

Also of interest might be Power Supply Basics (http://forums.trossenrobotics.com/tutorials/how-to-diy-128/power-supply-basics-3258/)

-Fergs

billyzelsnack
06-01-2010, 04:47 PM
You also can get away with a lower C rating pack because the current draw on a Bioloid is so much lower than for typical RC use. Which is nice because that means your pack will be cheaper and most likely lighter.

SteamAutomaton
06-01-2010, 10:45 PM
Issy, SMALdog, and Reaver all use this 11.1V 2100mAH pack (http://www.trossenrobotics.com/store/p/6293-3S-11-1V-2100mAh-Pro-Lite-V2-20C-LiPo-Battery.aspx) On a biped, the most important point will be weight. Seeing as the stock pack is a 9.6V 2300mAh pack, and lipo is quite a bit lighter than NiMH, that pack I linked to *should* be lighter, but I'm not sure.

Not sure about "good", but there is a section on batteries in So You Want To Build A Robot? (http://forums.trossenrobotics.com/tutorials/introduction-129/so-you-want-to-build-a-robot-3126/) Also of interest might be Power Supply Basics (http://forums.trossenrobotics.com/tutorials/how-to-diy-128/power-supply-basics-3258/)

-Fergs

Dear Fergs:

This is from the Bioloid website.


- Voltage : 11.1V
- Capacity : 1000 mAh
- Discharge : 10C
- Dimension : 70 x 35 x 15
- Weight : 83g
- PCM embedded to protect from over charge, over discharge, and excess current.

I check the links and now have a better understanding of what Ah means and other details.

Dear Responders:

Thank you for your input. Of course this information leads to more questions, "How do I charge parallel batteries?", "Would a high Ah blow the fuse?", What is the C rating?", and more to come when I think of them.

Yours,
Steam Automaton

DresnerRobotics
06-02-2010, 12:11 AM
That's the Bioloid LiPo pack, which is not the pack Fergs was referencing (he was talking about a 2100mAh 11.1v LiPo vs the 9.6v 2300mAh nimh that comes with the comprehensive).


"How do I charge parallel batteries?" No. Don't do this.

"Would a high Ah blow the fuse?" Nope, current *draw* will blow fuses. Battery capacity is how much the battery holds.

"What is the C rating?" This is a pretty standard rating for discharge rate on LiPo batteries. 'C' is a rating that doesn't give you much by itself, but can be applied towards the battery in question to get some useful data. To get the rated output discharge rate, the formula is: Capacity (in Ah) x C rating = Ah Discharge

For example:

A 3S 2100mAh (2.1 Ah) battery with a 20C continuous rating and a 40C burst rating is capable of outputting the following current without igniting.

20C: (2.1 Ah x 20C) = 42 A Discharge

40C: (2.1 Ah x 40C) = 84 A Discharge

This means the battery can continuously supply 42 Ah without exploding, and 82. But at the rated continuous discharge rate, given that you only have 2.1 Ah of capacity, this means you'd drain your battery in about 3 minutes. Way more than you'd realistically ever pull from it, but the battery is indeed capable of outputting that much current with59022066out going nuclear.

Luckily, AX-12s are pretty low current draw, a standard humanoid with a 3S 2100mAh pack will run for 30-45 minutes.

PS: I'll give you a cookie if you drop the 'Dear Diary' posting format. :p

Chench
06-02-2010, 04:11 AM
Tyberius,
I think that should be "A discharge", "42 A" and "84 A", rather than Ah.
A = amps, unit of current
Ah = amps x time, unit of charge, or a stand-in for energy (i.e capacity)when voltage is relatively constant like in batteries.

DresnerRobotics
06-02-2010, 07:39 AM
Wouldn't it technically be Ah Discharge, because the time value is still valid and discharge implies a rate over time? The battery can supply 42 amps per hour as a discharge rate, at least that is how I understood C rating. I thought my previous explaination had implied that, but I'll add 'discharge' for clarity. Feel free to correct me if I'm wrong, I'm no EE.

Edit: Nvm, I think I am incorrect here. I'll leave the statement for someone to correct me for the sake of others learning however.

SteamAutomaton
06-02-2010, 10:44 AM
Luckily, AX-12s are pretty low current draw, a standard humanoid with a 3S 2100mAh pack will run for 30-45 minutes.

PS: I'll give you a cookie if you drop the 'Dear Diary' posting format. :p

Instead of the cookie, can I have the 3S 2100mAh LiPo pack?:D

SA;)

DresnerRobotics
06-02-2010, 11:04 AM
Instead of the cookie, can I have the 3S 2100mAh LiPo pack?:D

SA;)


For $47.99 you certainly can! :D

Chench
06-02-2010, 01:05 PM
Hmm, I'm getting confused now. . . I find it a lot easier thinking in terms of coulombs rather than volts. A coulomb is the amount of charge that moves when an amp flows for a second, so it's 1/3600th of an Ah.
So I think of it like the battery is full of coulombs, or Ah, and as the current flows they take the coulombs out at a rate of 1 coulomb per amp every second, or 1 Ah per amp every hour.
The C rating just tells you how much current can flow, like you said.
The amount discharged is measured in Ah or coulombs.
The discharge rate is how fast this happens and is in amps.

Saying
Ah Discharge Rate doesn't make sense as the discharge rate is amps. Ah, semantics :p

DresnerRobotics
06-02-2010, 01:42 PM
You're correct, though kind of a wonky way of expressing it in general.

I figured discharge rate would have a time specification attached to it, and thus Ah made sense at 1am when I posted that last night. I'm no EE though, I'm just a step up from touching a 9v to my tongue for entertainment on friday nights.

SteamAutomaton
06-02-2010, 02:49 PM
For $47.99 you certainly can! :D
But I thought the cookie was 74.66 plus shipping and handling?:D


On a more serious note, will the Premium charger be usable to charge that pack or do I need a new charger?

SA;)

SteamAutomaton
06-02-2010, 02:59 PM
Hmm, I'm getting confused now. . . I find it a lot easier thinking in terms of coulombs rather than volts. A coulomb is the amount of charge that moves when an amp flows for a second, so it's 1/3600th of an Ah.
So I think of it like the battery is full of coulombs, or Ah, and as the current flows they take the coulombs out at a rate of 1 coulomb per amp every second, or 1 Ah per amp every hour.
The C rating just tells you how much current can flow, like you said.

If I am reading this right the 1000mAh (1000m = 1) is holding a max of 3600 coulombs?

SA;)

DresnerRobotics
06-02-2010, 03:09 PM
But I thought the cookie was 74.66 plus shipping and handling?:D


On a more serious note, will the Premium charger be usable to charge that pack or do I need a new charger?

SA;)

It actually might- I think the new Premium Charger (I have an original one, they don't use it anymore, was included with my evaluation kit) just has a JST balance connector. You'd need to get a JST to Thunderpower balance adapter (these will be in stock shortly), but you could make it work. That said, we just got our new Universal chargers in that will be pretty reasonably priced, and they're capable of charging LiPo/LiIon/NiMH/NiCad/Lead Acid + have a digital display and programmable modes.

SteamAutomaton
06-02-2010, 03:42 PM
It actually might- I think the new Premium Charger (I have an original one, they don't use it anymore, was included with my evaluation kit) just has a JST balance connector. You'd need to get a JST to Thunderpower balance adapter (these will be in stock shortly), but you could make it work. That said, we just got our new Universal chargers in that will be pretty reasonably priced, and they're capable of charging LiPo/LiIon/NiMH/NiCad/Lead Acid + have a digital display and programmable modes.
The charger that I received is a Yuntong YT-0003S. Their product photo gives a good view of the battery connections (the one on the right).

http://www.robotis-shop-en.com/shop/step1.php?number=744

So how much will the Thunderpower adapter be?

SA;)

DresnerRobotics
06-02-2010, 04:43 PM
$10 for a set of 5 adapters (2S, 3S, 4S, 5S, 6S).