Hello i buy some h-bridge on ebay http://www.ebay.com/itm/50A-Dual-channel-H-bridge-Motor-Drive-Module-Arduino-Smart-Car-Strong-braking-/150769829276?pt=LH_DefaultDomain_0&hash=item231a95059c when i connect only my battery(3V,10A) to power pin,wires become hot what is wrong? and What is DIS?
Did you connect the battery to the power pins the right way round? if you connect it the wrong way round, the mosfet body diodes will conduct, effectively shorting the battery and making everything hot.
Did you read the bit “By default R1 is shorten. So VCC is shorten with Power…” in the description? If you want to drive it from a 5V Arduino but use a separate 3V motor supply, you need to remove this short (my guess is that it’s a 0 ohm SMD “resistor”).
From the description on ebay, it looks like DIS is a disable input, probably with a pulldown resistor. Connecting it to logic high should turn off the motors, regardless of what the other pins are doing.
strange but if i connect plus of battery to plus of plate and minus of battery to minus of plate,wires begin become hot and if i connect plus of battery to minus of plate and minus of battery to plus of plate nothing happens and what is EN ? and VCC on plate we should connect with +5V on arduino?
I think you would be best off removing the R1 jumper/link or whatever it is and applying 5V to the Vcc line. Only then apply the main power. That way you'll have the bridge driver running off a sensible voltage (I've never seen a MOSFET driver than can go that low). The main power voltage can be as low as you like if the driver gets a proper supply.
Add a current limiting device (here a torch bulb might do) when first testing, its a wise precaution.
And don't apply the power the wrong way round, this can destroy a board in an instant, always double check polarity and which connector pins are which.