power

[Roger_tech]

I guess, when I asked for further details, they said to not try and get the answer from them.

I don’t get it. Paralleled cells of different voltages is a no go. Well, of course you can but not advised.
Can you add circuitry to each battery before they are connected in parallel?

 

[Martaine2005]

I’m sure you’re not telling us everything.
They should know not to parallel different voltages.
Also, you applied for a job as a PCB designer without knowing this as well.
I suppose as long as you’re not charging these batteries, you could add a buck converter to the highest voltage and limit it the same as the lowest.
Or series connect two or three diodes to drop the voltage.

 

[Roger_tech]

I’m sure you’re not telling us everything.
They should know not to parallel different voltages.
Also, you applied for a job as a PCB designer without knowing this as well.
I suppose as long as you’re not charging these batteries, you could add a buck converter to the highest voltage and limit it the same as the lowest.
Or series connect two or three diodes to drop the voltage.

I can't use a linear regulator because of heat dissipation, but can I use a switching regulator?

 

[Martaine2005]

As @Harald Kapp mentioned earlier, a switching supply may work as they are ^90% more efficient than a linear regulator.
But the main problem still arises, paralleling different voltages. It’s not impossible, it’s plainly wrong.
Edit: plus, no load information. Perhaps they want you to tell them that you can’t?, the traces would be thicker/wider for current ?

 

[Alec_t]

Two 4s Lipo batteries at 16.8V and 14.8V, connect them in parallel, minimal heat dissipation.

If that is exactly as the requirement was worded, then note that it does not specify zero current or zero heat dissipation. You could just connect them via a 100 MegOhm resistor and challenge the tester to define 'minimal'.

 

[Roger_tech]

If that is exactly as the requirement was worded, then note that it does not specify zero current or zero heat dissipation. You could just connect them via a 100 MegOhm resistor and challenge the tester to define 'minimal'.

They didn't exactly word it as 'minimal heatng', they said 'no heat'. I just assumed minimal heating because 'no heat' is impossible.

 

[Martaine2005]

they said 'no heat'.

That’s simple then.
Design the PCB for the higher voltage and current, assuming the higher voltage carries more current (if not design for max current), and don’t connect the batteries. Tell them it’s wrong!.

 

[Delta Prime]

they explicitly asked me to design a PCB, and send them the Gerber files, I interviewed for the PCB designer position.

It's crucial to acknowledge the limitations of your potential employers approach.
You’re applying for a PCB designer position, and you do not have a schematic of the circuitry necessary in this endeavor.

I think they just want to see how I approach a problem that isn't very common.

Stick with what you know!
By default your design must adheres to standard manufacturing guidelines like appropriate trace widths, spacing, and drill sizes.
Use thermal vias and copper pours to dissipate heat effectively, anticipating this mythical circuit, that some components might generate significant heat.

I just assumed minimal heating because 'no heat' is impossible.

OK!
OK stands for zero Kelvin that is the point where molecules stop vibrating. it is not impossible.

 

[poor mystic]

Like, how do you deal with a client with an impossible brief?
Ya gotta really need the money, for a start, else you'd take one look and fo.
You have to explain. They're always grateful in the end, but it causes bad gutsaches until they know.
Keep yr chin up

oh yeh PS this sort of thing is nearly always a communications stuff-up

 

[Delta Prime]

Like, how do you deal with a client with an impossible brief?

The only way to discover the limits of the possible is to go beyond them into the impossible.
-Arthur C.Clarke

 

[poor mystic]

The only way to discover the limits of the possible is to go beyond them into the impossible.
-Arthur C.Clarke

See!
DP recommends another set of high current sources on the same board.
If ya can't beat 'em, confuse 'em.
Cheese

 

[hevans1944]

PCB design often (always, actually) occurs post circuit design, mainly because it is difficult if not impossible to layout component pads and connections without knowing what the components ARE and HOW they are connected, Some of us are good at circuit design, and some of us are good at turning circuit designs into PCB designs, Some of us do BOTH as a hobby activity, but if you are seeking employment it makes sense that you concentrate on the job you would be asked to perform. You have been given an "impossible" task, so I would not waste anymore time trying to convince this particular employer that you are qualified to perform PCB design.

If you are really seeking employment, you need to define what tasks you believe you are capable of performing. This includes recognizing impossible requests. You never want to work for someone who issues impossible (or ill-defined) problems and then expects you to perform. Find a potential employer who is responsive to your capabilities. If applying for a PCB design job, bring some examples of your work to the interview and provide the information to the potential employer of what software you use for PCB design. They may already have PCB design software that you are expected to use, but do not miss this is an opportunity to find out what you "need to know" to qualify for the job.

I apologize for responding to an older (dead) post.