Schottky Diode Parallel Pack Adaptor

[awol]

The schottky diodes I ordered were 100v 40a. I've folded the middle legs around the back of the heatsinks and screwed them together through the diode holes then soldered the discharge pos to the aluminium heatsinks which was a seperate project all in itself.
Is there a way to test this before connecting up?

 

[WheezyRider]

The schottky diodes I ordered were 100v 40a. I've folded the middle legs around the back of the heatsinks and screwed them together through the diode holes then soldered the discharge pos to the aluminium heatsinks which was a seperate project all in itself.
Is there a way to test this before connecting up?
View attachment 37985
View attachment 37986
View attachment 37987

Safest way to test is to get a couple of old dry cell batteries with different voltages, one old, one new (a couple of PP3 9V cells are good for this as you can crock clip leads from the terminals onto the XT60s). Connect them up to the legs in the Y. Put them both on together, you should see the voltage of the highest output cell at the output of the Y. Disconnect the higher output cell and you should see the voltage of the lower output cell at the output of the Y.

Then, put a cell on one arm and test to see that there is no voltage seen at the arm where the other battery would be. Repeat on the opposite arm.

Check for shorts where there shouldn't be and you should be good to go!

Before use on the bike, connect the e-bike battery packs to the Y without the output connected to the controller, just to check you have all in order with a voltmeter before you connect it to the controller.

 

[alban]

Great write up and pics. Did this some years ago joining a LiFePO to a LiPO pack. and has worked for me. But can't recall how on earth I did it so thanks for the heads up!

 

[awol]

These look interesting, "smart" diodes:

https://www.ti.com/lit/ds/symlink/sm74611.pdf

They have a voltage drop of only 26mV!

They only go up to 30V at 15A, so you would probably have to put several in a series parallel arrangement for an e-bike, but they have the potential to be highly efficient for this sort of application. It will be interesting to see what they are like at coping with inrush currents.

Could this be a similar thing ? This looks quite a complicated bit of electronics to do what you've achieved with a single diode.

14.09￡ |5-75v High-current Ideal Diode Solar Anti-reverse Charge Charging Reverse Current Protection Forward High-end Low Resistance - Counters - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

bit.ly

Also there is a resistor on the board, could that be one of those precharge resistors?

 

[vfr400]

Could this be a similar thing ? This looks quite a complicated bit of electronics to do what you've achieved with a single diode.

14.09￡ |5-75v High-current Ideal Diode Solar Anti-reverse Charge Charging Reverse Current Protection Forward High-end Low Resistance - Counters - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

bit.ly

Also there is a resistor on the board, could that be one of those precharge resistors?

You'd need two of them - one for each battery. It's basically a powered diode with a very low resistance, so no significant power loss or voltage drop. You need a ground to power it. I haven't studied one of those, but I'd guess that the other components are to cut down and regulate the supply to it.

 

[WheezyRider]

Could this be a similar thing ? This looks quite a complicated bit of electronics to do what you've achieved with a single diode.

14.09￡ |5-75v High-current Ideal Diode Solar Anti-reverse Charge Charging Reverse Current Protection Forward High-end Low Resistance - Counters - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

bit.ly

Also there is a resistor on the board, could that be one of those precharge resistors?

As vfr said, you'd need to have two of these, but they are essentially what I was talking about in my post #20. They use a tiny amount of power to drive the "diode", without causing a significant voltage drop.

However, looks like people have already thought about this concept for electric bikes:

Ideal diode electric vehicle three battery isolator intelligent switching 100A three battery modification - AliExpress 1420

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

This one seems to allow you to charge and discharge two batteries together, with minimal voltage drop power loss.

 

[ericmonroe]

I just decided to make a solar-powered bike.

 

[vfr400]

I just decided to make a solar-powered bike.

This guy has done a lot of research over the years:

Maxun solarbike

Here, I share technical solutions that arised during the development of my solar-bike.

avdweb.nl

 

[ericmonroe]

Thank you. I also researched some articles and blogs and found this review websolarguide.com/solar-power-heat-pumps/ Seems interesting.

 

[WheezyRider]

Just bought a couple of these:



Looks like it is based on the 4357 ideal diode chip, driving a power MOSFET:

https://www.analog.com/media/en/technical-documentation/data-sheets/4357fd.pdf

I'll try it out and report back.

 

[Yak]

Just bought a couple of these:

View attachment 42669

Looks like it is based on the 4357 ideal diode chip, driving a power MOSFET:

https://www.analog.com/media/en/technical-documentation/data-sheets/4357fd.pdf

I'll try it out and report back.

Hi Wheezy - I’m coming to this party late, but did you test out the ideal diode setup?

 

[WheezyRider]

Hi Wheezy - I’m coming to this party late, but did you test out the ideal diode setup?

Hi Yak,

Sorry not been on the forum so much these days. Yes, they work really well. However, you do need to connect the IC circuit to ground, which is not obvious and there are no instructions from eBay or the suppliers. If you do not do this, they act as a standard diode and get very hot.

 

[WheezyRider]

This is the pin that needs grounding:


These ideal diodes are pretty good, but there are even better ones out there which use a MOSFET with an even lower RDS on and are even more efficient.

 

[WheezyRider]

Here is the circuit diagram for the ideal diode set up:



The wire from the ideal diode to ground does not need to be thick wire like anode/cathode and battery negative wire. It just has to carry a tiny current to allow the ideal diode to function properly.

 

[Dan7]

What do you think about using this connector and Schottky Diode?


Sudoo Solar PV Blocking Diode Schottky Barrier Rectifier Bypass MC4 Compatible Anti Reverse 1000V 20A (1) https://amzn.eu/d/9okhWiq

Made for solar panels so its waterproof.
Might have to change Diode to a 30amp.

I've had no luck in finding empty ones to use your own Diode.

My controller compartment can't fit anything else in it so looking for something neat externally and no chance on shorting on anything.

Instead of xt60 connectors you can get just the male or female connectors of these for joining

 

[StuartsProjects]

What do you think about using this connector and Schottky Diode?

Whats the forward voltage drop at 20A ?

 

[Dan7]

Looks to be .46v
Not great but they look easy to replace.
Just ordered 2, will see what I get

 

[Dan7]

Parallel splitters like these are super cheap to

 

[WheezyRider]

View attachment 48279
Parallel splitters like these are super cheap to

Good thinking, but I think maybe a bit bulky and heavy compared to XT60 connectors.

If the diode is encapsulated inside a connector, there is also the issue of heat build up. May not be a problem if the heavy duty wire acts as a heat sink though.

 

[Dan7]

The diodes arrived.
They are very light and not as big as I thought.
Just waiting for the rest of the adapters to arrive.
The adapters are rated for 30a and diodes 20 but look easy to swap so I would imagine perfect for most 24/36v setups.

I like the idea of having a proper made to purpose thing than making my own and having to try and find something to put it in so it doesn't short.
Batteries are scary