[Noisebridge-discuss] [HBRobotics] High density 2S LIPO with Charge/Discharge cutoffs - Brainless Battery Pack?

Thu Sep 15 01:54:58 UTC 2011

You folks are absolutely correct and I was unclear.

These batteries are rated to be charged at 1C, which is in the product
description.  What this means is, the battery must be charged at a rate that
is equal to or less than the capacity of the battery, so less than 4 amps.

As a rule of thumb, all LIPO's are usually charged at 1C or less.  This
means, no matter the capacity, you do not want to charge a LIPO battery at
such a rate that an empty battery would be charged in less than an hour.

Sorry about not mentioning that.

To understand how the circuitry in this battery works, we need to understand
how this battery was designed to be used.  This battery is meant to be a
drop in replacement for a transmitter battery.  The transmitter can recharge
the battery when wall power is provided.  The transmitter then trickle
charges a 6 cell NIMH pack over two leads.

This battery is meant to do exactly that.  It is meant to replace a bonehead
simple NIMH pack in a transmitter in an off the shelf fashion.

So, how would one safely use this pack?  Trickle charge it at 9V at less
than an amp.  It will take all night to charge, but it should charge safely.
On Wed, Sep 14, 2011 at 1:59 PM, Taylor Alexander <tlalexander at gmail.com>wrote:

>
>
>
>> For all intents and purposes, a 9v DC source should be all that is needed
>> to charge this pack.
>
>
> I don't know specifics, but I'm inclined to believe that isn't the case.
> The protection circuits are only there to prevent overcurrent and over/under
> voltage conditions. They don't do any charge current regulating and I'm
> pretty sure LiPo cells want that. At least, I do know that even though all
> of Sparkfun's single cell battery packs have protection circuits, they
> always say you need a lipo charge circuit and I've never heard anything
> about charging a LiPo off straight DC. Given how handy that would be, I'm
> inclined to believe I would have heard something about that.
>
> So like I said, I don't know anything for sure, but if you don't either,
> then there's probably more to it. Either way its something you should
> definitely be sure of before trying.
>
> -Taylor
>
>
>
>
>> As long as you only need to provide 7.4 volts at 8 amps, you should be
>> fine.  This pack only has two leads.  That's for voltage in and out.  No
>> LIPO charging equipment required.  My expectation is that there is some
>> circuitry in the pack that does this for you.
>>
>> On Wed, Sep 14, 2011 at 11:04 AM, William Garrido <
>> blackspartan117 at gmail.com> wrote:
>>
>>> Nice! This would be great to drive my motors. I doubt my charger for LiPo
>>> would work, anyone know if a small LiPo charger for 2S? I have my
>>> chargers embedded on my robot.
>>>
>>> Or even my MC, would get rid of the need for a stepup! Too bad its not
>>> 6AH.
>>>
>>>
>>> On Wed, Sep 14, 2011 at 10:10 AM, Corey McGuire <coreyfro at coreyfro.com>wrote:
>>>
>>>> Need to replace NICAD/NIMH packs, but are afraid of the complexity of
>>>> LIPO or added charger cost?  This pack might fit your bill.
>>>>
>>>>
>>>> http://www.hobbyking.com/hobbyking/store/__19481__Turnigy_4000mAh_Spektrum_DX8_Intelligent_Transmitter_Pack..html
>>>>
>>>> Sparkfun and other places have single cells that have such cutoff
>>>> circuitry to protect your single cell from being charged too high or
>>>> discharged too low, but this is the first 2S solution I've seen. 2S LIPO is
>>>> a sweet spot because it nearly perfectly matches the voltage characteristics
>>>> of 6 Cell NICAD/NIMH packs, which are common everywhere.  This could be a
>>>> drop in replacement for such needs.
>>>>
>>>> One draw back, it appears to provide only 8 amps of current.  This is,
>>>> no doubt, because the circuit that regulates charge is in line with whatever
>>>> you plug it in to.
>>>>
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>>>
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>>
>>
>>
>> --
>> Everything should be made as simple as possible, but no simpler - Albert
>> Einstein <http://en.wikipedia.org/wiki/Albert_Einstein>
>> Simplicity is the ultimate sophistication - Leonardo Da Vinci<http://en.wikipedia.org/wiki/Leonardo_Da_Vinci>
>> Perfection is reached not when there is nothing left to add, but when
>> there is nothing left to take away - Antoine de Saint Exupéry<http://en.wikipedia.org/wiki/Antoine_de_Saint_Exup%C3%A9ry>
>> Keep It Simple Stupid - Kelly Johnson<http://en.wikipedia.org/wiki/Clarence_Johnson>
>>
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>

-- 
Everything should be made as simple as possible, but no simpler - Albert
Einstein <http://en.wikipedia.org/wiki/Albert_Einstein>
Simplicity is the ultimate sophistication - Leonardo Da
Vinci<http://en.wikipedia.org/wiki/Leonardo_Da_Vinci>
Perfection is reached not when there is nothing left to add, but when there
is nothing left to take away - Antoine de Saint
Exupéry<http://en.wikipedia.org/wiki/Antoine_de_Saint_Exup%C3%A9ry>
Keep It Simple Stupid - Kelly
Johnson<http://en.wikipedia.org/wiki/Clarence_Johnson>
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