Please Help DCDC Converter

[Ryan Helms]

Hello I am currently building an Ebike and have been working on this for weeks my main wiring diagram is not in this picture but this is a simplified wiring diagram for a part that I am very confused on the DC to DC converter.

Converter I am using-

https://a.co/d/cjdnIAw

Now I am wondering if you have any questions, comments, thoughts, concerns, or tips. And is this wiring diagram correct.

Explanation of diagram-
Basically straight out of battery we have 72vDC and 150A of power. The main load of this battery is my Ebike controller which send power to my motor. Halfway through the connection I have a ferrule on the positive and negative line which allows the buck converter to get power. If my calculations are correct then there should be 72v and 1.75A of power running through that line. I got these numbers knowing that watts on both sides of buck converter are the same so 12V x 10A = 120W output. Then 120W/72V = 1.666A input. 1.666A/.95 efficiency = 1.75A input. I put a circuit breaker 32vDC 12A on the load side of the Buck converter because it says that this converter can take a max of 10A input or output doesn’t matter just can’t take more than 10A. Since this is Buck converter not a Boost the Output side will reach 10A much faster than input for example when the input of this converter is 72v 10a the output would be roughly 12v 57A. I put the circuit breaker on the positive line. Is the placement of the circuit breaker good? Then I have a 10A load on the buck converter output side. Load will probably more like 7.5A but for simplicity in this diagram I went for 10A.

TLR: is this wiring diagram correct. I would appreciate it though if you could read above what I typed.

Wiring diagram-

https://Upload the image directly to the thread.com/a/rlCtszG

 

[Lucien Nunes]

I think you should fit a circuit breaker on the 72V input, not the 12V output. Two reasons.

The converter states that it has both short-circuit and overload protection, therefore a 12A circuit breaker on the 12V output probably could never trip, because the converter would shut down before producing the >16A needed to trip it. Therefore there is no point in fitting a circuit breaker here, let the electronic protection in the converter take care of overload on the 12V side.

However if the converter suffers an internal catastrophic failure and becomes short-circuit, it could destroy the 72V wiring and possibly damage the battery. Therefore, a fuse or circuit breaker on the input is important, perhaps 3A. The actual value is not critical as the converter's internal protection will prevent overload (The converter itself will do that) it's just to save a major burn-up if the converter shorts the battery. Make sure the fuse/circuit breaker is suitable for 72V DC. Many breakers are OK up to say 32V DC and 120V AC, but not 72V DC. I would probably use a fuse as it should never fail in the life of the bike and if it does, it means that the converter is destroyed so the fuse is a minor issue.

BTW the link to the wiring diagram is broken.

 

[Ryan Helms]

Thanks man here is the link to the digram.