Control 2 DC motors with 2x DPDT relays, 4x solid state relays, or 2x H-Bridges?

Other Hardware Motors, Mechanics, Power and CNC
1

Control 2 DC motors counter clockwise and clockwise directions:
2xDPDT (double pull double throw) relay, 4x solid state relays, or 2x H-Bridges?

Which of these would be better options in terms of wiring simplicity, programming simplicity,
cost, and if speed control isn't necessary for the application?

I have 2x DC geared motors I'm using for a project.
I'm trying to make the controls aspect of it as modular and simple as possible without increasing cost.
Basically I want someone to be able to use a higher powered motor if the size of the project scales up in size.

I am currently using:
https://bit.ly/2XbuiSp

Cost: $4.17 each (2x = $8.34)
5.5V to 27V, 43 A
Number of outputs from Arduino: 8 (4x enable, 4x ccw/cw pwm)

My next approach is to simplify the project.
I was thinking of using these solid state relays.
Miniature SSR 100Amp Single Phase SSR Industrial Relay DC Input 3-32VDC control Output 12-60VDC Black SSR Relay(SSR-120DD)
https://bit.ly/2N8Ac3q
Cost: $3.70 each (4x = $14.80)
12-60VDC, 100 amp (will need heat sink of course :), but my DC motor is a 6v motor currently with low amps, but this would be useful for someone with large current requirements)

My logic here was I can hook up two solid state relays to each dc motor.
I would have the incoming wire polarities coming from the relays switched when going to the motor.
I'll activate one and keep the other off to switch motor directions.
Number of outputs from Arduino: 4 (4x ccw/cw direction change? correct?)
Is there an electrical danger to this method?
The only thing I can think of is if I activated both relays at the same time going to one motor and creating a short. Yes/No?

I recently came across this: DPDT Switch to change DC motor direction, Question 11
It seems like a much simpler solution to use a DPDT relay, however I'm having trouble finding a higher current DPDT relay with a nice DC voltage range (they all seem to have specific voltages).
I also can't find a solid state version of DPDT relays do they even exist?
This would simplify wiring even more no?
Number of outputs from Arduino: 2?

2

my DC motor is a 6v motor currently with low amps

The major challenge for the designer is the correct sizing of the circuit, so that not much resource is spent. If the value of the component has a similar value when buying at retail, you need to be careful in projects for large scale production, because the large purchase value may differ greatly.

If the engine is small, there is no reason to use very powerful components.

It seems that there have been reports of large aircraft crashing due to failure of relays. If you can avoid using electromechanical relays, it is better.

3

In this case lets say the person wants to upgrade their machine and move something that's heavier and their current motor doesn't support that, so at least they won't have to upgrade their controls because it will be ready to accommodate a larger motor.

It seems that there have been reports of large aircraft crashing due to failure of relays. If you can avoid using electromechanical relays, it is better.

Yikes. What about solid state relays? They last longer, but are they prone to failure too?

4

You mentioned electromechanical relays, wouldn't using solid state relays increase this reliability?

Over here they used 2 SPDT relays to change direction: