how to properly charge a NiMH battery

[titekubo]

http://www.national.com/an/AN/AN-946.pdf

pwede po yan gamitin sa dalawang series na 6v NiMH battery na available sa e-gizmo?

[insomartin]

http://www.national.com/an/AN/AN-946.pdf

pwede po yan gamitin sa dalawang series na 6v NiMH battery na available sa e-gizmo?

ang ginagamit ko is dalawang lm317
isa in constant current
isa naman in constant voltage mode
nasa datasheet lahat nang schema and formula
may battery university din. i googol mo lang

kailangan mo nang multimeter to watch out for the current.
kung nasa 5mA na lang yung current disconnect mo na.

[Macgyver]

usually sa charging ng NiMh,  meron yung Delta V, Delta T measurements meaning minomonitor yung change in voltage  and change in temperature over time.   May characteristic alam ko yung Nimh na habang di pa sya fully charged,  pataas ng pataas ang voltage nya habang nag chinacharge mo.  Then there will come a point na mag di-dip yung voltage.  Pag pababa na yung voltage,  yan yung point na fully charged na sya.  Then may protection ka na monitoring of temparature.  Pag sobrang init,  cutoff mo na yung charging.

May mga ICs for battery charging.  Usually naka program na yung DeltaV, DeltaT monitoring dun.   

Sometime may fast charging pa  so malakas ang current sa simula then before reaching their peak or after a certain threshold voltage,  mag ti-trickle charge na sya to top off the remaining part hanggang maging fully charged sya.

Gamit ko yung maxim 713

[insomartin]

usually sa charging ng NiMh,  meron yung Delta V, Delta T measurements meaning minomonitor yung change in voltage  and change in temperature over time.   May characteristic alam ko yung Nimh na habang di pa sya fully charged,  pataas ng pataas ang voltage nya habang nag chinacharge mo.  Then there will come a point na mag di-dip yung voltage.  Pag pababa na yung voltage,  yan yung point na fully charged na sya.  Then may protection ka na monitoring of temparature.  Pag sobrang init,  cutoff mo na yung charging.

May mga ICs for battery charging.  Usually naka program na yung DeltaV, DeltaT monitoring dun.   

Sometime may fast charging pa  so malakas ang current sa simula then before reaching their peak or after a certain threshold voltage,  mag ti-trickle charge na sya to top off the remaining part hanggang maging fully charged sya.

Gamit ko yung maxim 713

i think that's for charging for >= 1C... deltaV talaga.
but trickle charger lang gamit ko for ni-mh.
i'll stick to my 70 peso charger for now. hehe

[titekubo]

thanks for the reply. meron po kayo sample schematic?
http://www.e-gizmo.com/pmaster.php?dpage=PRODUCT/ROBOT/batt.htm

dalawang 6V series sana balak kong gamitin to make a single 12 volts, kaya po ba?

[insomartin]

thanks for the reply. meron po kayo sample schematic?
http://www.e-gizmo.com/pmaster.php?dpage=PRODUCT/ROBOT/batt.htm

dalawang 6V series sana balak kong gamitin to make a single 12 volts, kaya po ba?

mas cheaper ata mag 12V sealed lead acid than series nyan...

[Macgyver]

@titekubo

san mo ba gagamitin yun batteries?  ano application?

[titekubo]

pwede po ba gamitin yung available na NiMH battery sa cdr king then gawa na lang ako ng charge controller using MAX712?
bale ganito po:

yung circuit mag-dadraw ng power sa main battery, then kapag disconnected na yung main battery, sa backup battery(NiMH plus charge controller) na siya huhugot ng power.

thanks.

[Macgyver]

di ko sure kung ano NiMH battery sa cdrking ang nirerefer mo but if yung mga AAA or AA size, pwede.  Nakokontrol mo naman sa MAX712 (using dip switches) kung ilang cells ang ichacharge mo.

1 cell = isang AA or AAA battery


In terms of using the NiMH pag disconnected ang main battery, I think wala naman kaso dun.  Wag mo lang ipaparallel main battery mo sa backup battery (NiMH) specially kung di naman rechargeable yun main battery mo at hindi NiMH.

[titekubo]

ok po sir, thanks for the info. lead acid po yung main battery(sa sasakyan), yung device kasi naka install sa sasakyan.
+1!

[fantom_mayonaise]

Or you can simply buy NiMH chargers used in RC models. Mura na lang ngayon ang chargers, may makukuha ka nang 1.5K na kayang mag-charge ng NiCad, Ni-MH, PB, or Li-poly/Li-ion at 5ampere charging current. DIgital, maganda ang packaging and pwede mo pang ibenta pag nagsawa ka.

[profpat]

the charger i use for my nicads and NiMH is TLP expro, very automatic, peak charger sya, adjustable amperes, auto volt select, but the minimum batteries in series is 4 pcs. and the maximum is 8 pcs..so 4.8Volts to 9.6 volts lang..the newer TLP EXpro charger kaya up to 15volts ...medyo mahal lang 4.5k pesos na..

i read one electronic enthusiast from india, he made a charger where he connects it to his pc and is also automatic..will try to dig my downloaded files  for it..

[zrehtiek/keitherz]

^ most likely USB power lang.

[BhongTech]

the charger i use for my nicads and NiMH is TLP expro, very automatic, peak charger sya, adjustable amperes, auto volt select, but the minimum batteries in series is 4 pcs. and the maximum is 8 pcs..so 4.8Volts to 9.6 volts lang..the newer TLP EXpro charger kaya up to 15volts ...medyo mahal lang 4.5k pesos na..

i read one electronic enthusiast from india, he made a charger where he connects it to his pc and is also automatic..will try to dig my downloaded files  for it..

sir Profpat yun bang gamit nyung charger ay trickle po ang pag-charge?

[BhongTech]

^ most likely USB power lang.

hindi po kaya may masunog kung sa usb kukuha ng supply para mag charge ng nicad at NiMH?

[zrehtiek/keitherz]

may current limit up to 500mA ang USB ports, pero pwede magparallel(2 usb port iparallel ang supply magiging 1A)
kapag naabot mo yung 500mA icucut nya supply sa port na yun or sa iba magshushutdown, pero walang mangyayaring masama.
maganda ang regulation ang protection ng mga power supply ng mga computers.

[bravokilo]

The only time we should worry about better chargers is when we want to FAST CHARGE. Otherwise, there is nothing like the C10 charger.l The C10 charger is the 10% charging rate. If for example, your NiCad or Metal Hydride is 1000 ma, set the simple traffo diode charger to 100ma. That is all. You cannot ruin your battery with this charger. You could leave it theere the whole week. Do not put any regulator to your traffo and diode charger, just diode and resistor to calibrate the charging rate.  The current will taper as the battery gets charged.


     For a long time and up to now, RC manufacturer supplies this klind of charger, sometimes called charger for Dummies. It is because they know the average modeller will forget it for a week or more being pluuged to the wall outlet. Our TX pack is 8 AA cells at 500mah. That will peak at 11.2V.  The traffo is a 300 ma, 9-0-9 volts. A diode is simply in series on the 0-18V terminals. A 10 ohm in series with an LED shunted on it will light up the LED when it is connected to the battery. Another resistor is to asjust the current at 50ma when the battery is fully discharged, meaning the V is each cell is 1.1V or 8.8V on the 8 cells. If you want 12V nominal and 14V peak, series 10 cells.

BK