lifepo4 and maxxfan

road-runner wrote:

Gdetrailer wrote:

You will have to chose diodes that have a high enough current rating for the max draw of the fan.

Have to worry about getting rid of the heat from the diodes, too. Drop 1.5 volts drawing 4 amps and you've got a 6 watt heater. Maybe put the diodes in the air stream the way fan dropping resistors are cooled?

Each diode drops .6V-.7V and at 4A that is a max of 2.8W dissipation per diode.

There are a variety of package types of diodes, some are heat sinkable on higher amperage diodes. Typically diodes with amperage ratings of 6A or less will not have heat sinks.

Alternate method is to use a bridge rectifier which has 4 diodes wired together in one heat sinkable package.

Here is pix of typical power supply use of a bridge rectifier..



Transformer connects to the bridge terminals marked AC, rectified (-)DC on one terminal and rectified + DC on the other terminal.

Now, if we get rid of the transformer, make those terminals not connected, place your Positive from the battery to the bridge terminal marked (-) and you can connect the + of the load to the rectifier terminal marked +.

Like this pix..



What happens is the diodes on the negative terminal will conduct the positive voltage to the terminals marked AC, the diodes going from the AC terminals will conduct the positive voltage to the Positive output terminal..