What size diode?

[garlicman]

I've got a pedal powered generator using an old PM DC motor from a
treadmill. To charge my deep cycle battery, I'll need a diode to prevent the
motor from spinning me backwards. How do I calculate the size that I need?

The battery is 12V, and I'll rarely produce more than 120W of power. Do I
just call it a 10A diode? Larger is okay too, right?

Thanks.

 

[Charles]

"garlicman" <None> wrote in message
news:_PCdnegSbJtODj7anZ2dnUVZ_sGvnZ2d@comcast.com...

I've got a pedal powered generator using an old PM DC motor from a
treadmill. To charge my deep cycle battery, I'll need a diode to prevent
the motor from spinning me backwards. How do I calculate the size that I
need?

The battery is 12V, and I'll rarely produce more than 120W of power. Do I
just call it a 10A diode? Larger is okay too, right?

10A or larger should work.

 

[Tim Perry]

"garlicman" <None> wrote in message
news:_PCdnegSbJtODj7anZ2dnUVZ_sGvnZ2d@comcast.com...

I've got a pedal powered generator using an old PM DC motor from a
treadmill. To charge my deep cycle battery, I'll need a diode to prevent
the
motor from spinning me backwards. How do I calculate the size that I need?

The battery is 12V, and I'll rarely produce more than 120W of power. Do I
just call it a 10A diode? Larger is okay too, right?

Thanks.

If the generator is 120 W (peak) at 13.8 V then we can estimate peak
current at just under 10 A.

The diode current rating should be about 2X the expected curent for normal
operation, however should be much larger to account for abnormal operation
(i.e. the battery shorted or partially shorted)

If the source is capible of producing 10 Amp max I would use a 20 A diode or
larger.

One 'side' of a commonly available 25 A bridge rectifier might be a handy
thing to use. One diode contained in a 'DBI' (dual battery isolator) might
be appropriate. You can get these at the better auto parts stores.

 

[Jakthehammer]

"garlicman" <None> wrote in message
news:_PCdnegSbJtODj7anZ2dnUVZ_sGvnZ2d@comcast.com...

I've got a pedal powered generator using an old PM DC motor from a
treadmill. To charge my deep cycle battery, I'll need a diode to prevent
the
motor from spinning me backwards. How do I calculate the size that I
need?

The battery is 12V, and I'll rarely produce more than 120W of power. Do I
just call it a 10A diode? Larger is okay too, right?

Thanks.

If the diode has no heat dissipation then I would use the diode of the size
2X the load, otherwise 10a would work. (120W * 2) /12V = 20 amps.