Protection Diodes

I am using a Riden RD6006 for a battery charger. FYI: this is a 0-60 volt 0-6 Amp variable power supply. Now because I am old, senile, clumsy and stupid, I might accidentally hook up the battery reversed (which by the way will blow one of the little SMD 10 amp fuses in the back of the power supply module).

So my question for the more electronically knowledgeable is:
What will it cost me to put protection Diodes in my charging cables?

By "cost" do you mean monetary, or electrical?

The former, probably a few dollars.

The latter, a few tenths of a volt, but this varies with the amount of current flowing thru the diode (different for different ones, but higher volt drop across diode with higher current). Also, some watts of heat out of the diode, more with higher current.

The Schottky types are generally used for this. The easiest ones to use come in TO-220 or larger style cases, either one or two diodes to a package. In your case you would use one of these, on either positive or negative lead (not both), and use just a one-diode package.

Bolt the diode to a heatsink (if the PSU already has one, use that if you can drill a new hole to connect it to, and that heatsink isn't already being used to capacity and/or not much heat will be generated). Some of the diodes come in an all-plastic package which while it doesn't get rid of heat quite as well as the metal-backed ones, it doesn't have to be electrically isolated from whatever you bolt it to.

amberwolf said:

By "cost" do you mean monetary, or electrical?

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I meant electrical. From what I have been reading it is the Forward Voltage Drop with heat = that multiplied by the current.
By in-line I meant literally as cut the cable and solder the diode inline.

I am thinking a 5 Amp 100 volt axial Schottky diode. Those have a drop of 0.7 to 0.8 volts.
So the PS voltage setting would be off by less that another volt (seems to already be a variance between the meter terminals and the battery terminals) . I usually only charge at 2-3 amps (paranoid with more time than money).

Would it be appropriate to publish a short review of the RD6006 here. There are lots of reviews on YouTube but none of them cover its use as a battery charger. There are a couple of important points the documentation leaves out.

LewTwo said:

I meant electrical. From what I have been reading it is the Forward Voltage Drop with heat = that multiplied by the current.
By in-line I meant literally as cut the cable and solder the diode inline.

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That normally works fine--the only worry is if you had high currents, which create more heat. I don't think you're going to hae that problem, as 0.8v x 3A (worst case on either for your numbers) is less than 3 watts. Even inside heatshrink, the wires to and from the diode should be able to carry away enough heat to prevent any problems.

I am thinking a 5 Amp 100 volt axial Schottky diode. Those have a drop of 0.7 to 0.8 volts.
So the PS voltage setting would be off by less that another volt (seems to already be a variance between the meter terminals and the battery terminals) . I usually only charge at 2-3 amps (paranoid with more time than money).

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I am familiar with the latter issues...though I don't have much time these days either. :/

As long as you know the voltage drop at *very low* currents will be no less than at high currents (requires a test verification on your setup) you can increase the PSU voltage by that much to make up for it. However, if there is a difference from high current to low current, that increase will then also increase the final charge voltage of the battery, which you may not want.

BTW, if your PSU supports four-wire (kelvin) measurement/sensing, then it will increase the reliability of the readings. What this does is use separate wires for measurement from the current-carrying wires, and measures *at the destination* rather than the source, so any measurement is not affected by voltage drop in the wires themselves (or a diode). The catch is that this means there's no reverse-polarity-protection on the *measurement* wires that way. (a diode could be put in there, too, and a much much smaller one could be used, which would hav ea lower Vf (voltage drop), but it will still affect the readings).

Would it be appropriate to publish a short review of the RD6006 here. There are lots of reviews on YouTube but none of them cover its use as a battery charger. There are a couple of important points the documentation leaves out.

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I don't see any reason not to review whatever even vaguely-EV-related stuff you ever run across.