Ideal Diodes when using multiple batteries

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Not when they are cheap copies you never know what you are going to get like the VNH2SP30 monster motor controllers from aliexpress we tried them when sparkfun stopped production, 1 in 4 would be faulty some just burnt out, you can tell the Mosfets the print is out of alignment or of poor quality just google it and believe me they do get hot

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We are, @rmackay9 is talking about commercial usage on mapping boats

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What MOSFETS are you using and how many on the board?

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If you go through the entire thread you have two different audience here. The author is doing commercial development and then others are looking for cost-effective alternatives.

I am addressing the needs of students and others who can’t afford such solutions.

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I am still looking for a commercial solution for 12S and 150A that somehow addresses the huge voltage spikes, which generate when the motors spool down.

If you have a one-off project, cost is not really an issue in a commercial environment, but if you need to install it in multiple vehicles, it does add up.

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And that raises a really important issue with using Ideal diodes with all modern ESCs !
…at least for multirotors and planes.

This may not be an issue with boats or some types of motor controllers that dont do regenerative braking.
How important is it for you to use Ideal diodes? (a question for everyone thinking about ideal diodes)
Is it better just to use parallel batteries and ensure they are always in good condition.

The ESCs are trying to feed back voltage into the battery system when doing regenerative braking. You would need to use ESCs that allow you to turn that off, or don’t use Ideal diodes.

Blocking the regenerative braking with ideal diodes between the ESC and batteries could even cause other ESCs in the system to see the regenerative braking from one ESC as an over-voltage and shut down or start limiting output.

The regenerative braking is happening all the time, when ever a commanded output is lower than the current output (RPM). Any attempt to circumvent the battery/regenerative braking relationship with diodes, MOVs, tranzorbs, or TVS diodes is going to generate a lot of heat.
You could use a bank of large capacitors I suppose, but that might have other disadvantages too - might need some more thought, but could be workable.

Even if you can turn off regenerative braking, think of all that wasted energy in your battery powered flying machine!

EDIT:
Just thinking a bit more - it’s probably a good idea to use a capacitor bank between the ideal diodes and your ESC even for boats or controllers that dont do regenerative braking.

There’s some discussion of these aspects further back in the thread, but I wanted to put it in one place.

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Yep we ran into the same realization when looking into adding ideal diodes into our system for redundancy. We decided to roll our own smart battery and rely on the battery to cut its own power when it has an issue, we are still including ideal diodes circuits in some areas.

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Do you make them with XT60 connectors?

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Hey Jed! I just ordered a pair of the ideal diodes from you, I shot you an email with a question about them. Do you mind taking a moment to have a look?

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Ji @Jed_Freeman do you stil have boards?, i want to order a couple to test, and need them shipped to the US. I tried to contact you by email but I did not receive an answer.

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I sell an Ideal Diode Controller for high current applications. This unit was originally designed for battery powered subsea and land/sea based vehicles that use multiple battery packs, but if the weight can be managed they may be a good solution for areal vehicles.

The weight of each Ideal Diode Controller is 1.6 Ounces.

I always recommend a heat sink of some sort, but they easily handle 50 amps with no heat sink at 100% duty cycle. With a heat sink currents well over 100 amps are possible.

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That looks very useful! Do you do a higher voltage version by any chance? Something suitable for 12S (50.4V) setups?

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Hi Michael, the current configuration is only capable of up to 40VDC.

To work with a higher voltage I would have to change one TVS diode and use a different MOSFET with the correct specs.

If there is enough interest I will make some that will handle up to 80VDC and test them.

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Jed may have closed his shop. Is anyone else making these? Anybody know a reliable vendor out there?

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Hi there, I am interested in an 80V version, I need to run two 12S batteries at 16000mAh.

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Ok, I am building a new batch of these and I will make a few with 80VDC rating and test them.

So that I can do a better job testing these, can I ask what your application is?
Max current (surge) of the whole system?
Nominal current (normal operation) of the whole system?
Are you able to mount the diodes on a heat sink?
Are they in open air or inside an enclosure?

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  1. Can I ask what your application is?
    30kg MTOW drone

  2. Max current (surge) of the whole system?
    Currently testing

  3. Nominal current (normal operation) of the whole system?
    5 Amp+

  4. Are you able to mount the diodes on a heat sink?
    Maybe I can mount a heat sink on/near the diode?

  5. Are they in open air or inside an enclosure?
    Inside fuselage

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It’s what is being offered. It is also at least and better than my spec so that leaves room for me to evolve.

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Has anyone simulated/verified if this circuit works?