Ni-Cd Power Supply Resistor

[kodiac]

I would like to know how to calculate the value of resistor R1 in the enclosed Ni-Cd Power Supply photo.

Thank You

[kodiac]

Re: Ni-Cd Power Supply Resistor

photo

[sam_sam_sam]

Re: Ni-Cd Power Supply Resistor

Use an online ohm calculator you need
18 volts @ 500 milliamperes or
25 volts @ 500 milliamperes the resistor value will a little bit higher
Use at least 2 watt resistor for this device at a minimum

If you use this method above do not leave the battery on the charger continuously this will shorted the life of the batteries

However you would be better off if you used something like a LM317 voltage regulator in current mode this will give you better current control which can also be found on how to use it in current mode in the data sheet for this device

If you use a voltage regulator in current mode I would recommend that you use 50 milliamperes and 500 milliamperes if you want to leave the battery on the charger all the time use the 50 milliamperes mode and if you want a faster mode charging mode use 500 or 750 milliamperes just make sure that you switch it back to the lower current mode after charging if you leave it on charger

I hope this helps you

[stj]

Re: Ni-Cd Power Supply Resistor

14ohms
and it's going to generate 9w of heat!
(so maybe consider a chinese intelligent charging module instead!)

[sam_sam_sam]

Re: Ni-Cd Power Supply Resistor

14ohms
and it's going to generate 9w of heat!
(so maybe consider a chinese intelligent charging module instead!)

Here is one of these chargers

https://www.ebay.com/itm/23346573025...IaAq7rEALw_wcB

One note about these battery charger do not get the idea that you can put a led on the charging board remove all components from the device board and use jumper wires because if you do not do this the charger will not work correctly I have tried this before and the results were that the charger keeps charging the battery instead of lowering the current when fully charged or refuse to charge the batteries

If this person is building from ground up and designing this charger to charge nicad batteries the same thing will hold true do not add a led at the battery pack you would have the same exact results

[sam_sam_sam]

Re: Ni-Cd Power Supply Resistor

Here is the website link to the connector for the charger from the same seller

https://www.ebay.com/itm/23416696459...53.m2749.l2649

I have bought some of these myself

[stj]

Re: Ni-Cd Power Supply Resistor

for that money you could get a B6 clone!

[kodiac]

Re: Ni-Cd Power Supply Resistor

My diagram is of a Jobmate Ni-Cd charger
Board # KW14-V0
R1's outside coating has burned away,leaving no color code bands
In circuit R1 measures 3.9 ohms

Are these formulas correct

VR1=1.17 x Battery Voltage + 3.3v

R1 = 3.3 / (1/4 of Battery Voltage)


Thanks to everyone for your information.

[sam_sam_sam]

Re: Ni-Cd Power Supply Resistor

My diagram is of a Jobmate Ni-Cd charger
Board # KW14-V0
R1's outside coating has burned away,leaving no color code bands
In circuit R1 measures 3.9 ohms

Are these formulas correct

VR1=1.17 x Battery Voltage + 3.3v

R1 = 3.3 / (1/4 of Battery Voltage)


Thanks to everyone for your information.

Okay

Like what was mentioned earlier in this post if just replace the resistor the same exact thing will happen again because this is the cheapest way to charge a battery which has all kinds of issues

[kodiac]

Re: Ni-Cd Power Supply Resistor

Thank You