6V 4AH battery charging II

[Milly Amp]

Hello, una ko po nabasa yung 6V 4AH battery charging article dito rin sa forum na ito, pero 2008 pa siya na post at di ko na mahanap para ituloy at magpagtanungan ko, so start na lang po ako ng bago. Isa po akong DIYer (do-it-yourself) at ako'y nag build ng battery pack for my camera flash kagaya po nito: shutterbug.net/equipmentreviews/accessories/0699sb_howto/

Success naman po ang pagkakagawa at nagamit ko siya sa aking trabaho as a photographer. Ang nabili ko pong Sealed Lead Acid battery ay ang Omni SE6-4 (6V 4AH/20HR) Model SRB-6V4 na mabibili niyo rin sa Ace hardware for Php300.00. Me nakaprint na info sa harap at likod niya:

Cycle Use     : 7.20-7.50V
Standby Use: 6.75-6.90V
Initial Current: less than 1.2A
RECHARGE AFTER USE

Specifications:
Nominal Voltage: 6V
Rated Capacity: 4Ah
Capacity:
0.20A = 20 hours rate
0.36A = 10 hours rate
0.68A = 5 hours rate
2.40A = 1 hour rate


Tanong ko lang po: yung naka specify ba sa battery about capacity (0.2A = 20 hours rate), is that the rate of discharge for certain appliances, or is this a list of charging times? Ang ginagamit ko po to charge kasi is a Sony Discman AC adapter (model AC-MZ60, 6V 800mA) na nahanap ko among some unused stuff sa bahay. I think incorrect yung assumption ko na yung nakalista  na ito ay charging time (800mA yung output nung adapter, so
I just assumed 3 hours ang charge time nung SLA battery. I now realize mali yata ako). And if it refers to discharge rate, how long do i recharge the battery? Ayon sa na-research ko sa batteryuniversity.com, "It takes about 5 times as long to recharge a lead-acid battery to the same level as it does to discharge. On nickel-based batteries, this ratio is 1:1, and roughly 1:2 on lithium-ion." Kung gayon, kung akoy magchacharge, multiply ko discharge rate with 5 (ex: for a 2.40A appliance, 5 hours ang charging since 1 hour ang discharge time, tama po ba?). I'm not sure though and any help sa bagay na ito ay taos-puso kong i-appreciate. Hopefully I can get some confirmation and help on this kasi gusto ko sanang tumagal ang buhay ng battery ko.  Thank you in advance sa tulong niyo po!

[RiDdLeR???]

Continuous discharge rate yun and kung mapapansin mo, hindi linear yung discharge rate sa total capacity.  Supposedly, the battery will be able to discharge 4A in 1 hour but due to the physical limitation of the battery, it can only discharge a maximum of 2.4A in 1 hour before all capacity is used.

But if the discharge rate is only 0.2A, the it can provide the full 4AH capacity.

Discharge rate is the actual cuurent being consumed by your load.

[rdpzycho]

posibleng hindi ma-full charge 'yung battery niyo sir. ang required charging voltage ay 'yung nakasulat sa Standby at Cycle use voltage. since cycle use 'yung gamit niyo, preferably 7.2V 'yung charger at 1.2A.

to full charge ang approximate computation is 4Ah / 1.2A / ~0.7 = 4.7 hours to 90% charge. then around 4 to 8 hours more para ma-full charge to 100%.

kung 800mA, 4Ah / 0.8 / 0.7 = 7.14 hours to 90% charge, that is kung aabot sa 2.25V/cell or 6.75V 'yung ginagamit niyong pang-charge sir.

[Milly Amp]

Thank you mga sir! Sensia na po sa late reply but thank you for clearing up my confusion. More power po at mabuhay sa inyo and keep it up!  Thank you rin rdpzycho sa tulong mo for computing recharge times and recommended charging specs...

[Milly Amp]

Nga pala, sa paggamit ba ng voltage na mas mababa kesa sa recommended charge, mas nakakaigsi ng battery life? wala kasi akong mahanap na 7.2v 1.2A na charger (at saka sa 1.2A na charger, di po ba malakas sa konsumo ito at siguradong tataas ang electric bill namin?) TIA ulet sa mga sagot ninyo

[rdpzycho]

hindi iigsi 'yung actual battery life pero iigsi 'yung usage time dahil hindi siya fully charged talaga.

kahit ano 'yung current rating nung charger ang magiging approximate power consumption niyo is Voltage x Ah rating / 0.7 / charger efficiency or roughly 40Wh sa case ng 6V 4Ah battery which converts to roughly 40 cents per full chrage.

[Milly Amp]

Ok, gets ko na. Thank you rdpzycho! Salamat sa tip and computations...

[rdpzycho]

pwede niyo nga palang bilhin sir 'yung mga adjustable na power supply 'yung may settings na pinipihit ng screwdriver. 'yung 6V output nun, halos 7V din ang output.

[Milly Amp]

Ay, talaga? Meron ako nun ah. Sige, madali lang i-setup naman ito. Thank you ulet sir 

[bravokilo]

Milly sister. Yo can use yor 800 ma power supply. The practical approach is to use anything above 14 volts, then insert a resistor to set the charging rate.

The safest charging rate is 10% of capacity, thes .1 x 4AH is 400ma. The rule is to charge a fully depleted battery for 15 hours. Note, it is 50% more than inserting 100% of the battery's capacity(15x400 ma = 6AH). Your problem is you relly do not know the charge left in your battery. With the C10(10%) charger or .1C charger, you can leave it logn without damage to your batteries.Best approach is to test the V of your battery. disocnnect charger and read V. It should be 13.8V wdhen charged. Now, load it with bulbsand see the V. an ginagawasa Motolite, d b? Yung kanilang V probe, may load yun sa loob.At may ammeter yung to indicated the load.

<ay GE circuit sa Alexanh, yung car battery charger nila. Good yun dahil may cut off pay umabot na ang peak |V. maseset mo. Iniiwan na lang namin yung sa batt during our CB days.Automatic siya. E mod lang natin para sa 6V.


Ndi mo pwede magcharge ng batt with a V lower than its peaked V. parang drum ng tubig yan. Yung source k langan mataas sa destination drum.

Call me: BK 0922 281 0680 or 8253867. Kung saSouth ka, drop by. 54 Jaimer Laya st., BF Homes, Pqdue

[Milly Amp]

Best approach is to test the V of your battery. disocnnect charger and read V. It should be 13.8V wdhen charged. Now, load it with bulbsand see the V. an ginagawasa Motolite, d b? Yung kanilang V probe, may load yun sa loob.At may ammeter yung to indicated the load.

<ay GE circuit sa Alexanh, yung car battery charger nila. Good yun dahil may cut off pay umabot na ang peak |V. maseset mo. Iniiwan na lang namin yung sa batt during our CB days.Automatic siya. E mod lang natin para sa 6V.


Ndi mo pwede magcharge ng batt with a V lower than its peaked V. parang drum ng tubig yan. Yung source k langan mataas sa destination drum.

Call me: BK 0922 281 0680 or 8253867. Kung saSouth ka, drop by. 54 Jaimer Laya st., BF Homes, Pqdue

bravokilo, thanks for the explanation. although i had to re-read several times (noob here), i think i can get the gist of it. sorry for the late reply, and i also have a follow-up question  : why would it be 13.8v when fully charged? Thanks for the Ge charger tip, i'll check it out...

PS I checked out this link i found somewhere here in the threads: http://www.csgnetwork.com/batterychgcalc.html and isa siyang charging time calculator, which includes an efficiency loss rating (20% default) is this anywhere near reliable. with my battery specifications, its computed result is 5 hours recharging time. Somehow I find that 'alanganin'. any thoughts on this?  tia dude!

[rdpzycho]

yup, ganyan talaga katagal mag-charge ng Lead Acid, actually, optimistic times pa 'yun dahil ang computed lang ay 'yung time para ma-reach 'yung peak voltage. after kasi ma-reach 'yung peak voltage, 90% charge pa lang talaga siya.

for 6V cell, 13.8V / 2 dapat or 6.9V. ang ideal charge kasi is around 2.2V to 2.4V per 2V cell (with 6V battery, that's 3 x 2V cell, at minsan makikita 'to doon sa packaging as embossed circular caps).