Lipo cells, balancing on the typical charger, etc.
08-14-2014, 10:47 AM
#1
Senior Member
Thread Starter
Lipo cells, balancing on the typical charger, etc.
Currently, I have and use several different chargers.
FMA DPL-8 (high power) with 2 MPA adapters and 24v 65A Lambda-TDK PS
Vista Q6320 AC/DC (80w per port)
Bantam BC6DX-II AC/DC (50W)
Occasional balancing problems occur with any and all of the above.
High balance current capability can make things worse.
Some individual Lipos are more prone to the problem than others.
The Lipo mix includes mostly 4S and 6S Lipos from different sources, and different ages.
Why?
The single most common culprit found is the Lipo battery balance connector and pins.
How I determined this - - -
Using different cell checkers to eliminate an individual unit, as well as a Bantam 2 Meter watt/checker/balancer
It turns out that the female battery connector pins can make intermittently poor contact.
The female pins have a spring action that supposedly is enough to make good contact.
For whatever reasons the female pins spread with use, reducing the spring tension.
The second part has to do with the balance current and how it's applied via the balance connector, as well as
how and when the cell voltages are measured. Kelvin connections are the ideal, but, with only one wire from the charger
or balancer to an individual cell balance pin, they are not possible, for other than the end Lipo + and - connections.
The combination of the balance current and a poor or intermittent contact Lipo balance connector pin can fool the charger,
resulting in less than desired balance accuracy.
It now comes down to charge rates. If the normal charge rate is 10A, the problem will likely be more noticeable
and acute than at a charge rate of 1A or less with the same Lipo.
This can be used to advantage. Say you have a Lipo that is almost fully charged, but the cells are not balanced
as closely as you'd like. Change the charge rate to the 1/10 of normal, and charge some more. The charger uses
a percent of the charge rate as a base to calculate the end current. (C/10 or C20 usually)
Some of the balance connector pins have a wiping spring tab that can be reshaped,
Others require replacement.
FMA DPL-8 (high power) with 2 MPA adapters and 24v 65A Lambda-TDK PS
Vista Q6320 AC/DC (80w per port)
Bantam BC6DX-II AC/DC (50W)
Occasional balancing problems occur with any and all of the above.
High balance current capability can make things worse.
Some individual Lipos are more prone to the problem than others.
The Lipo mix includes mostly 4S and 6S Lipos from different sources, and different ages.
Why?
The single most common culprit found is the Lipo battery balance connector and pins.
How I determined this - - -
Using different cell checkers to eliminate an individual unit, as well as a Bantam 2 Meter watt/checker/balancer
It turns out that the female battery connector pins can make intermittently poor contact.
The female pins have a spring action that supposedly is enough to make good contact.
For whatever reasons the female pins spread with use, reducing the spring tension.
The second part has to do with the balance current and how it's applied via the balance connector, as well as
how and when the cell voltages are measured. Kelvin connections are the ideal, but, with only one wire from the charger
or balancer to an individual cell balance pin, they are not possible, for other than the end Lipo + and - connections.
The combination of the balance current and a poor or intermittent contact Lipo balance connector pin can fool the charger,
resulting in less than desired balance accuracy.
It now comes down to charge rates. If the normal charge rate is 10A, the problem will likely be more noticeable
and acute than at a charge rate of 1A or less with the same Lipo.
This can be used to advantage. Say you have a Lipo that is almost fully charged, but the cells are not balanced
as closely as you'd like. Change the charge rate to the 1/10 of normal, and charge some more. The charger uses
a percent of the charge rate as a base to calculate the end current. (C/10 or C20 usually)
Some of the balance connector pins have a wiping spring tab that can be reshaped,
Others require replacement.
