longleg
Newly Enlightened
So I'm thinking about changing out at least one of my two bike light batterypacks, and I think I want to go the DIY route by building a 14,8V battery pack.
I've read this thread
http://forums.mtbr.com/showthread.php?t=571398
but still have some questions, that I hope someone could answer
Protection - single cell vs for the whole pack:
I think I'm going to buy protected 18650's, and just connect them in series using a 18650 holder (link below).
I can't see any other disadvantage of single-cell protection vs pack protection other than if one of the cells reach cutoff voltage long before the others, the cell (and your whole pack) shuts down.
On the other hand - if this happens, the cell in question probably is faulty, and the shutdown of the pack prevents a too deep discharge of this cell. This would not have happened with pack protection only.
Balancing:
Is this really necessary for bike light batteries that don't see very heavy use?
I understand that when batteries are used heavily as in RC, this becomes a more or less requirement.
But - if I'm gonna build a pack from scratch, I might as well build in wires for balancing. 1-6 cell balancing chargers are also quite cheap:
http://www.hobbyking.com/hobbycity/...ame=Turnigy_Accucel-6_50W_5A_Balancer/Charger
Li-Po vs Li-Ion:
On the site linked to above, it seems like you get more Wh's / $ with LiPo's than with Li-Ions. But do these LiPo packs have built-in protection circuits??
If I understand correctly, LiPo can take higher charge- and discharge current than Li-Ions, but that's not really needed for my use.
And the safety aspect: Charged and discharged correctly, I guess neither of these are much safer than the other?
So - a battery solution (4 x 18650's) for a 3 x XP-G light would look something like this:
Balancing charger:
[See above link]
+ suitable balancing wire harness
+ suitable power supply (probably have one lying around the house)
Batteries (2500-2600mAh):
-From DX:
http://www.dealextreme.com/details.dx/sku.5790
or
-From AW (About 4 x (!!) the price of the DX ones - are they really worth it from a safety point of view??)
Holder:
http://www.luminousdiy.com/Light Kits and Parts.htm#holders
Are there other factors I should take into consideration?
..and thanks for reading!
(I've posted this here as well: http://forums.mtbr.com/forumdisplay.php?f=124)
I've read this thread
http://forums.mtbr.com/showthread.php?t=571398
but still have some questions, that I hope someone could answer
Protection - single cell vs for the whole pack:
I think I'm going to buy protected 18650's, and just connect them in series using a 18650 holder (link below).
I can't see any other disadvantage of single-cell protection vs pack protection other than if one of the cells reach cutoff voltage long before the others, the cell (and your whole pack) shuts down.
On the other hand - if this happens, the cell in question probably is faulty, and the shutdown of the pack prevents a too deep discharge of this cell. This would not have happened with pack protection only.
Balancing:
Is this really necessary for bike light batteries that don't see very heavy use?
I understand that when batteries are used heavily as in RC, this becomes a more or less requirement.
But - if I'm gonna build a pack from scratch, I might as well build in wires for balancing. 1-6 cell balancing chargers are also quite cheap:
http://www.hobbyking.com/hobbycity/...ame=Turnigy_Accucel-6_50W_5A_Balancer/Charger
Li-Po vs Li-Ion:
On the site linked to above, it seems like you get more Wh's / $ with LiPo's than with Li-Ions. But do these LiPo packs have built-in protection circuits??
If I understand correctly, LiPo can take higher charge- and discharge current than Li-Ions, but that's not really needed for my use.
And the safety aspect: Charged and discharged correctly, I guess neither of these are much safer than the other?
So - a battery solution (4 x 18650's) for a 3 x XP-G light would look something like this:
Balancing charger:
[See above link]
+ suitable balancing wire harness
+ suitable power supply (probably have one lying around the house)
Batteries (2500-2600mAh):
-From DX:
http://www.dealextreme.com/details.dx/sku.5790
or
-From AW (About 4 x (!!) the price of the DX ones - are they really worth it from a safety point of view??)
Holder:
http://www.luminousdiy.com/Light Kits and Parts.htm#holders
Are there other factors I should take into consideration?
..and thanks for reading!
(I've posted this here as well: http://forums.mtbr.com/forumdisplay.php?f=124)
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