Pros/Cons of Dual Battery Systems

[JD_L (JD Lancaster)]

Hello, Any real world cases someone would like to discuss of one battery fail with flight resumed on second battery? I have a dual battery system that I’ve been planning to hook up to a hex build I’m working on, but the whole thing and second battery is quite heavy relative to a single high capacity battery system of the same capacity. Is a dual+ battery system recommended for payload carrying multirotors in the 900mm size class? If I favor low weight and increased flight time for the build with a single battery system, what kinds of risk of failure numbers am I looking at? Thanks for the help.

[dkemxr (Dave)]

@JD_L

would like to discuss of one battery fail with flight resumed on second battery?

How would that be accomplished? In a typical multiple battery system where they are in series or parallel if one battery fails it’s essentially the same as cells failing in one battery.

[JD_L (JD Lancaster)]

Oh well I might be completely misunderstanding the point of a system like this, lol, but I’m working with this: Mauch Premium Line Dual Battery Kit – Craft and Theory

Is the only benefit to a system like this capacity related?

[hendjosh (Josh Henderson)]

Ideal diodes can used to do this quite efficiently (for packs that are in parallel). (There are other ways of course such as using a normal diode.) Allows the packs to drain from both batteries during use and can prevent charging of packs amongst themselves (such as the case of a failed pack).

Ideal Diodes when using multiple batteries

[ideal-diode] Despite having worked on drones for 10+ years I only recently learned of the existance of “ideal diodes” and how useful they are on vehicles that require multiple batteries so I thought I’d share in case others have also not heard of them. Technically speaking an ideal diode is just a regular diode in that it only allows electricity to flow in one direction but what makes it special is that the forward voltage drop is extremely low. In a quick test I did on the ideal diodes sho…

[dkemxr (Dave)]

@JD_L

Is the only benefit to a system like this capacity related?

Yes. That’s just 2 batteries in parallel with independent monitoring.

But what @hendjosh is suggesting is what you would want to look at.

[hendjosh (Josh Henderson)]

That looks like a dual sensor only.

Mach has an ideal diode board but they aren’t big enough for a full copter amperage.

100A / 200A Hall Sensor PM for Pixhawk / APM

I’m not really sure of any readily available boards, but there is a user here selling them I think.

[dkemxr (Dave)]

@hendjosh

but there is a user here selling them I think.

I was thinking that too but then realized I was thinking about @Artem_Skorsky power switch. Actually he does have a product:
Power module

[JD_L (JD Lancaster)]

@dkemxr

Yes. That’s just 2 batteries in parallel with independent monitoring.

Well thanks for this! Not sure what to say other than I misunderstood what I was doing here.

[JD_L (JD Lancaster)]

Thank you, this is very helpful. I really like the idea of this kind of redundancy, but struggling with the weight requirements. I’ll have to read up and see what can be done. Cheers.