11.1v CMB with high-current charge capacity

lavaslippers

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May 10, 2015
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Hi! I just wrote out a long post only to have it disappear in a page that claimed I wasn't logged in. So here is a short version:

I want to build a battery to take bicycle camping this summer. It needs to have around 12v to charge my portable speaker, and to work with automotive 12v to 5v USB chargers for my phone.

I plan to get a battery like this: http://www.hobbyking.com/hobbyking/store/__16225__ZIPPY_Flightmax_8000mAh_3S1P_30C_Lipo_Pack.html
which is 11.1v 3S lithium polymer.

To make things simply and clean, I want to avoid having multiple plugs such as those with typical balance chargers, so I am looking at this CMB (charge management board) at Battery Space: http://www.batteryspace.com/CMB-for...ck-10A-limit-RoHS-Compliant-with-DC-char.aspx

I like that is protects the battery, it balances the cells and it has a fuel gage. I don't like the wimpy 2.5A charge limit, since this battery is stated as being able to charge at 2C. Being able to fully charge in under an hour is ideal, since where I'll be camping the only AC outlets are at the public area.

I have a couple of questions. What is the difference between a CMB and a BMS? Are there any CMBs that I could expect to pay the same or less for that allow higher current charges of 8+ amps?

Thanks!
 

SemiMan

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Joined
Jan 13, 2005
Messages
3,899
Hi! I just wrote out a long post only to have it disappear in a page that claimed I wasn't logged in. So here is a short version:

I want to build a battery to take bicycle camping this summer. It needs to have around 12v to charge my portable speaker, and to work with automotive 12v to 5v USB chargers for my phone.

I plan to get a battery like this: http://www.hobbyking.com/hobbyking/store/__16225__ZIPPY_Flightmax_8000mAh_3S1P_30C_Lipo_Pack.html
which is 11.1v 3S lithium polymer.

To make things simply and clean, I want to avoid having multiple plugs such as those with typical balance chargers, so I am looking at this CMB (charge management board) at Battery Space: http://www.batteryspace.com/CMB-for...ck-10A-limit-RoHS-Compliant-with-DC-char.aspx

I like that is protects the battery, it balances the cells and it has a fuel gage. I don't like the wimpy 2.5A charge limit, since this battery is stated as being able to charge at 2C. Being able to fully charge in under an hour is ideal, since where I'll be camping the only AC outlets are at the public area.

I have a couple of questions. What is the difference between a CMB and a BMS? Are there any CMBs that I could expect to pay the same or less for that allow higher current charges of 8+ amps?

Thanks!

I would consider a 4S pack. 3S will get you down to 10.5 when discharging which may cause chargers and other items to shut down from under voltage.

The board you are looking at has both the battery management/balancing function and the charging function build into a single unit.
 

lavaslippers

Newly Enlightened
Joined
May 10, 2015
Messages
2
I would consider a 4S pack. 3S will get you down to 10.5 when discharging which may cause chargers and other items to shut down from under voltage.

The board you are looking at has both the battery management/balancing function and the charging function build into a single unit.

Thanks for the reply! I may use a 4S battery, but I worry the higher voltage would be too much when fully charged. Either way, it's definitely close.

I realize the CMB I linked to has all the functions I need, but it only allows for 2.5A of charge, which would make the full-charge time greater than 3 hrs. I need to be able to charge the battery more quickly, and the battery itself can take 16A, so hI'm wondering if you or anyone else knows where I could get a board that handles high current charges of 8 or more amps :)
 
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