6V 4AH battery charging

[Lena]

is it fine if I use a constant voltage charging method here? I've set the CV charger at 7 Volts.

[Shey]

constant voltage naman talaga ang typical na charging sa lead acid type of batteries so ok lang yan. 7.25 volts yata ang recommended charging voltage diyan.

[razalas]

Constant voltage with current limiter for me is a better design.

[Lena]

what shud be the max charging current for dis type of battery?

[rdpzycho]

0.3c or 1.2A for 4AH...

mas mabilis constant current then constant voltage...pero ok na rin yung constant voltage with current limiter set at 0.3c...at 0.3c charging roughly 4 hours ang total charging time...wag mo tataas current above 0.3c, mas mabilis masisira yung battery (long term)...

[Lena]

0.3c or 1.2A for 4AH...

mas mabilis constant current then constant voltage...pero ok na rin yung constant voltage with current limiter set at 0.3c...at 0.3c charging roughly 4 hours ang total charging time...wag mo tataas current above 0.3c, mas mabilis masisira yung battery (long term)...

thanx 

[marcelino]

i suggest to generalize the question of Lena. I hope masasagutan din yung tanong nya....

considering that, constant voltage and current will be best for charging lead acid batteries.

Questions:
1. for a certain ratings of a lead acid battery, how do we obtain the voltage and current rating? example for a  7V we use 7.25V. I also heard that for a 12V, we use 13.8V. How do we get this? how do we suggest the current rating?
2. what are the typical configurations for design? (protection circuits, etc...)

[rdpzycho]

this is for Lead Acid Batteries

for charging current that's 0.3C or AH * 0.3 ex. 12AH * 0.3 = 3.6A charging current (max)

for cycle use voltage max voltage is 1.2 * nominal voltage ex. 12V * 1.2 = 14.4V

for standby use max voltage is 1.15 * nominal voltage ex. 12V * 1.15 = 13.8V

to determine if the battery is fully charged, charging current must be 0.03C or 1/10 of the max charging current ex. when charging 12AH battery and current measured is 0.36A battery is fully charged

normal configuration (cycle mode, 1.2 * voltage) constant voltage regulator with current limiter...charging algorithm, constant current up to constant voltage zone, constant voltage to fully charged zone...additional portion when fully charged at 0.03C, drop voltage to 1.15x then trickle charge for 10 to 15 hours...

for information on other battery types:

http://batteryuniversity.com/

[bravokilo]

Lena, f you can find a junked emergency lamp, may ckt dun na nag o off pag fully charged na yan 6v4AH batt mo. DO NOT USE CONSTANT CURRENT. Use constant voltage.  You can use a 7806 and you can increase the voltage to 7V or find a 7807 kung mayroon.  The rule we use for "safe" charging kahit naiwan ay .1C, so 400ma.  kaya na ang 7806 yan.  U C , as the internal resistance of the batt increases as the V goes up, then current tapers down kapag constant V. That is what we want kapag standby ang use ng batt mo. Now, kung kilangan mo mag charge mabilis, use a timer. Ideally sana if you can put a voltmeteracross the battery or a an LED indicator(zener lang) or use the LM3914 voltage displacy IC. Yung China digital,mura lang. Whatever you use, it will be an indicator when to wind up.

     Rule of thumb:Put in 50% more of what has to be replaced sa batt. SLA ya, sealed Lead acid. am sure. problemo, we do not know what has been depleted. Crude way is to graph voltage to capacity left in your battery if you want to be serious.The best way to know your batt is to measure its discharge time at a given load at hindi yun charge time kasi baka di nya natatangap lahat ang na inject. Cge, put a lamp on your fully charge batt. You know fully charge kapag peak and voltage reading mo 6++. Use 4 amp and see kung aabot ng 1 hr. Kung impatient ka, use 8 amps and see if it will last 30minutes.(parallel kalang ng bulbs or use a huge resistor(s).  Measure usable capacity. Now, habang bumabab ang V, log down the remaining time ok pa. Then you have chart showing V to rea=maining capacity, di ba? Yan kilala mo na yung battery mo.  So, kung may V meter ka , yoy can tell anytime ano pa natira dun sa batt, di ba? now if you wish to charge, yung capacity ng batt mo(di yung rated, yung natest mo) minus the remaining capacity, yung ang ibabalik mo x a factor of 1.5.

     Example: you found out na ang batt mo 3 AH ang usable sa purpose nya. After taking a V reading, say 1AH and natira. Eh, di, 2AH ang nagamit or na self discharge. How do you put back the 2AH? Well, u have to put back 2x1.5 o 3 AH. Its up to you on how to do it.  Kung nagmamadali ka use .3C or 900ma. Ok lang 1amp, kahit 1C AS LONG AS YOU HAVE A TIMER.
hanapin mo yung 3 hr mechanical timer ng nga dating electric fan. Or yung 8 hr electric motor timer ng 3D box fan.  Sa 3A, one hour, sa 1 amp, 3 hours. SAPOL yan. in this case, constant current ang config mo sa 7806 at kailangan mo ng bypass ransistor to go beyond 1 amp, max ng ic or even less to be conservative.. (heatsink mo ha). kapag constant V, habang chinachrage, bumabagsak and I.


BK

[Woots29]

subscribing...

[RiDdLeR???]

I have a rechargeable flashflight that uses a 6V 4AH SLA.  Nung nawalan na ng charge, nakalimutan i-off atna-istore ng matagal.  When I charged it with its ac/dc adapter charger, ayaw ng mag-charge.

Ano ba dapat ang charging current at charging voltage for this type of situation.