more clever LiPo charger

[chb]

I am looking for a LiPo charger that has the following feature:

The CC-CV termination voltage can be programmed to something else(lower) than 4.2.

Does anyone know which chargers are capable of this ?

[bigred5765]

sorry i don't but I'm curious as to why you would need to,

[DCM]

the cell wouldn't be fully charged if you reduced the CV of the charge parameter.

[dev]

FMA Direct Cellpro Multi4: http://aurorra.co.uk/aurv2/productDetails.php?id=108

[chb]

Originally Posted by bigred5765

sorry i don't but I'm curious as to why you would need to,

http://www.kokam.com/english/product/kokam_Lipo_02.html (the ORION branded LiPo)
http://www.motorola.com/testservices/article1.htm
http://www.ibt-power.com/Battery_pac...ymer_tech.html

As I really don't need all the capacity, I might as well charge them less(and discharge them less as well) to increase their lifetime/cycles

[chb]

Originally Posted by DCM

the cell wouldn't be fully charged if you reduced the CV of the charge parameter.

Yep, That's what I want. That's the point.

Also, I have another application...For bashing, I want to run 4s with a xcelorin which is only specified to 3s LiPo / 12 NiMh. By charging to 4.0v instead of 4.2V/cell, I would stay in the specified limits of the xcelorin esc (12xNiMh1.35v~16V)

[chb]

Thanks for the tip about the cellpro charger. I am considering it. It's a bit over the top actually. Any other suggestion welcome

[jim76]

how about just stopping the charger early!

[MiCk B.]

The pro-trak (with lipo charge function) has adjustable voltage & current cut-off.

MiCk B. :-)

[chb]

Thanks for all the contributions !

So if we build a list to date :

# stoping early (I am lazy, I prefer unattended chargers)

# FMA cellpro
# Pro-track

[bigred5765]

Originally Posted by chb

http://www.kokam.com/english/product/kokam_Lipo_02.html (the ORION branded LiPo)
http://www.motorola.com/testservices/article1.htm
http://www.ibt-power.com/Battery_pac...ymer_tech.html

As I really don't need all the capacity, I might as well charge them less(and discharge them less as well) to increase their lifetime/cycles

but you never discharge a lipo,you allways leave it in a charged state,its balanced as it charges, and charging at less voltage or amps will have little to no advantage,a 4.2 3000mah 20c lipo charged at 1 c to 3.7 volts will still punch out at 20 c seems pointless,

[chb]

Originally Posted by bigred5765

but you never discharge a lipo,you allways leave it in a charged state,its balanced as it charges, and charging at less voltage or amps will have little to no advantage,a 4.2 3000mah 20c lipo charged at 1 c to 3.7 volts will still punch out at 20 c seems pointless,

I am not sure what you mean here "a 4.2 3000mah 20c lipo charged at 1 c to 3.7 volts will still punch out at 20 c seems pointless"

According to what I read, the fill-up to 4.0 or 4.2V does affect cycle life, like with Li-ion(my lenovo laptop manual states it strongly for LithiumIon). Here, one link to the ORION LiPo that treats the subject...
http://www.kokam.com/english/product/kokam_Lipo_01.html

Beyond that, I need it for my 4S Xcelorin application.

[bigred5765]

but your trying to compare lipo to lion cells, and there talking about cycles as in fully charged to fully flat, theres isn't real any time you would do this in racing, you would only be topping them up, as unlike nimh you should never store flat or fully discharge a lipo,and 500 cycles even if you did fully charge to fully flat them would be 125 race meetings,

[chb]

Originally Posted by bigred5765

but your trying to compare lipo to lion cells, and there talking about cycles as in fully charged to fully flat, theres isn't real any time you would do this in racing, you would only be topping them up, as unlike nimh you should never store flat or fully discharge a lipo,and 500 cycles even if you did fully charge to fully flat them would be 125 race meetings,

I agree with you!
I still think charging to a lower voltage is beneficial to cycle life. Li-Ion aren't really different, only use a gel as the eletrolyte to make it modular, so I am led to believe they are the same in many charge-discharge aspects. In the Kokam experiments, when they want to show how good the life cycles can be, they charge it to 4.14v instead of 4.2v (according to the above page). They don't elaborate as to why.
I found this interesting reading:
http://www.modelflight.com.au/flight...life_cycle.htm
http://www.batteryuniversity.com/print-partone-5.htm
http://www.batteryuniversity.com/partone-12.htm

About my 4S Lipo experiment, the ESC didn't work properly when wheels in the air(Ok when on the tarmac, if only the tyres were not coming off due to centrifugal force). So it sems like I really need to stay below 4V/cell