Unbalance Lipoly Batts charging time is like Forev [Archive] - Filipino Airsoft (FAS)

EnergyFriend

July 25th, 2008, 09:56

Basically, there 4 for ways to balance charge a Lithium batteries :
(1) In the olden days, when they discovered that Lithium batteries can perform better, hold more charge, release more current, longer charge / discharge lifecycle if they are balance, also charging time is less, risk and damage is less, if they were balance. So during then, charging of Lithium is just like charging Ni-MH, electrical energy is fed through the DC DISCHARGE CONNECTOR, basically either Dean Plugs, or Big / small Tamiya connector, after charging, they connect a balancer, to balance the battery so that voltage of the 3 cells would be equal whether it ber 4.17 or 4.18 or 4.19, as long as it balance, it ok even if not totally full at 4.2V which are also a established parameters. Later they evolve and figure out to save time and work, while the DC connector is connected to the charger, a balance terminal is connected to balancer, so it charging while balancing.

(2) This method evolve into charger such as Imax B5 and B6, Yuntong 005 and Yuntong 006, Vislero A6 which charging is made through the DC connector and balancing is made through the balance terminal. So the charger circuit and the balancer circuit are two different. When it charging while balancing, then a 3rd circuit is to monitor and control both the balancing and charger, stop the charger when full.

(3) What follows is the independent charging, wherein each cell is charge by each individual charging circuit, wherein each circuit have it own monitor and voltage comparator set at 4.20V more or less, so when any cells reach 4.20v, that very cell stop charging until all cells fully charged, and when all the 3 cells are fully charging and presumably the 3 cells have reach similar voltage, total circuit stop. This type of circuit is used by NOVATECH, BHE BLUE, BHE BLACK

(4) Then as it evolve, when factory want to reduce cost, make the charger smaller, so even small batteries can avail of balancing charging, but to be small and low cost, they come up with a single channel but with a circuit that will adjust the charging voltage and charging current of each cells connected in series, a single voltage source is fed in but current flowing to each individual cells, balancing is done by adjusting the current to each cells, when combined cells have an average voltage of 4.18V x number of cells, then it stop charging, this kind of charger giv eyou 98% full charge but it already ok, actually we dont need 100% full charge, like in filling up gas tank, u prefer to fill up only up to automatic full and not to top up the tank or fill water into a glass up to the brim. This compact charger is the lowest cost but equally usable like the Yanll charger and Yunting Micro Charger. Balance of this is less accurate, about +/- 0.02V max, but for Airsoft use, it very usable, but for high performance helicopter batteries, people may want to extract more performance out of the batteries so they would choose the Charger with built-in blalancer. The independent charger is also good but it only limited up to 2 ampere charging rate because of the thin wire and small connector of the balance connector. So a big battery have to use big wire and big connector to feed big current into it, then balance done in the small balance connector with thin wires which only drain small current to balance.

Charging time factor for LiPoly is about 1.2 to Max of 1.3, for Ni-MH, it is 1.3 to Max of 1.8, for fast charging factor is less, for slow charging factor is high.

For example :
2000mah battery
charging rate is 1000mA
charging time is : 2000/1000 x 1.2 = 2.4 hours
if slower charging
2000mah battery
charging rate is 500mA
charging time is 2000/500 x 1.3 = 5.2 hours

However, since most charger now have built in micro processor, it will automatically reduce charging rate based on the internal impedance of the battery so not to do overspeed charging, hence under such circumstances, charging time may be long. If charger have this kind of circuit, it always automatic, it stop when full. But charging time may be longer than what would be the computed number of hours.

-----Added 25 Jul 2008 at 09:51:18------
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Addendum:

Make sure to read your charger manual to know, some charger just shut off lights or LED when battery is full, some changes from RED to Green, so make sure what is it.

When charging half empty of battery which still 3/4 full wherein charging is to top up, when charging time will be less. But when charging an over empty battery, if done in automatic charger, it will take sometime to slowly charge with lower voltage and lower current then slowly move up as internal impedance normalize to within the specs and parameters programmed into the charger sequence algorithm. Charger now with many I.C. inside which are digitally operated and controlled are somewhat complicated and of course complicated to explain too. As long as you can use it satisfactorily, it should serve it purpose wherein it function is to charge battery is the most appropriate manner.

-----Added 25 Jul 2008 at 09:56:12------
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Charging rate of Novatech 4 channel independent charger is adjustable from 0.5 amp, 1 amp, 1.5 amp and 2 amp

BHe blue box YT-002SC is automatic and intelligently adjust from 0.5 amp to 1.5 amp. But generally set at 1.2 amp.

BHe black box is automatic but charging current is fixed at 0.8 ampere.

BHe Yanll is set at 0.8 ampere

Imax is automatic but mannually set charging rate from 0.5 amp to 5 amp.

Vislero is the same but come with Battery analyzer.

Automatic means it using a CC / CV charging system, it has a built in voltage comparator so it will auto stop when battery is full.

Intelligent means it will automatically select charging current hence charging time may be lower but also will automatically stop when full.