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MaverickCT
Posts: **2**

Hi

Can someone please help

I want to put a 2 Ohm resister into a 12 volt battery chargers, 2 amp rated charging line to halve the current but i do not know what size resister I need that will handle the current flow without frying the resistor

I was thinking of using a 50 watt Wire Wound Aluminium Housed Resistor

would that handle the current

Any help is appreciated

Can someone please help

I want to put a 2 Ohm resister into a 12 volt battery chargers, 2 amp rated charging line to halve the current but i do not know what size resister I need that will handle the current flow without frying the resistor

I was thinking of using a 50 watt Wire Wound Aluminium Housed Resistor

would that handle the current

Any help is appreciated

## Comments

22,930It's not clear just what you're trying to do with this resistor. You mention halving current. Remember that the current will vary as the battery charges. Battery chargers these days tend to be "smart" about the actual charging voltage and current used as the battery charges. The voltage produced by a battery also varies as the battery becomes more and more charged up.

8,5172Thank you both Mike Green and Kwinn for your much appreciated assistance

To answer Mike Green, in order to properly desulphate a battery, my understanding is that you need to use a old style battery charger that is not smart and then allow the voltage to climb over 15 to 16 volts. This would normally damage the battery, but with a reduced current this will not be the case

I am having trouble finding a adequate 2 Ohm resistor, but can find a 1 Ohm resister.

If i put 2, 1 Ohm resistors in series, will that give me a 2 Ohm Resistance

1,079Yes. Resistors in series add. (Rx = R1 + R2)

3,362https://www.goldmine-elec-products.com/prodinfo.asp?number=G23074

They also have a couple of 4 ohm range 15-20 watt resistors which could be used in parallel to get 2 ohms and would run very cool.

67044But if so, it causes the battery dangerously overcharged and generate hydrogen, I think.

(Edit)

Sorry I misread and misunderstood much.

Now I guess that you might think that an X ohm resister divides the current by X ?

8,517The resistor will be connected between a 12V battery and a charger limited to 2 amps. No need for more than 8-10 ohms.

6,007670I put a 10 ohm 5 watt resistor on my power supply set at 12 volts. The amp draw was about 1.2 amps. The 5 watt gets hot fast so you'll need a 50-100 watt to dissapate the heat if your chargeing for many hours.

This method is not the way to do it. But if you want simple, cheap, and a rig use the resistors.

6708,517Sorry, I meant 8-10 Watts, not ohms.

542I'm not sure I understand what MaverickCT means in his second post, if he says he is actually using that not so smart old style battery charger. I also cant see what kind of battery technology he is using here.

I'm using a simple solution for charging some of my lead acid batteries (like 7,2Ah size); a cheap wall wart 15-17V or so, 1A max, and a PB137 regulator.

PB137 does probably not cost more then a big resistor and is rated for 1,5Amps at 13,7V output. Maybe two can be put in parallell to handle 2Amps but I'm not sure.

Forgot to mention but

Datasheet can be found here: http://www.farnell.com/datasheets/1767487.pdf