I want open this topic to see others experience with mixing different types of battery packs with high current diode.
5-75V 300A High Current Diode Charging Reverse Current Protection Solar Anti-backflow Forward High Side Low Resistance
https://a.aliexpress.com/_mKqkdDr
I’ve seen that this kind of diodes are used to separate solar panels.
I am aware of the dangers and it is best to use only one type of battery with good contacts and I agree with that. Especially after reading about Waydoo problems with battery and others. I think it would be interesting for other members to share their experiences on this topic.
I have used a configuration of 2 batteries and large shottky diodes on an ebike to gain maximum performance and range before. The smaller booster pack had a much higher C rating to stiffen the output. It reduced voltage sag and abuse on the larger, but older and weaker battery. It worked well the limited times I did it. I decided it was not worth the risk and complexity of having the “booster pack” and ultimately just built a larger battery using the superior performing cells. I would probably never try it on an efoil.
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… that could be challenge 
I am using 3 x 13s5p with 40a bms indentical batteries with no issues so far - without diodes. I was wondering what would be happen if we create similar battery (for example one battery 10ah other 12ah similar c rating) packs in parralel protected wit high current/voltage diode.
As for safety if we can split one big battery to 3 or 4 parts it would be easier and safer to storidge and transport.
I was running two different chemistries of batteries with very different characteristics.
Are the three 13s5p batteries identical? If so and you charge them together, you do not need to worry about diodes at all. They will essentially just act as one battery.
If you run 10ah and 12ah packs of identical cells that start at the same voltage in parallel, then you should end up with one pack still holding roughly a little more than 2ah at whatever depth of discharge you plan to stop. The larger pack will retain a little bit more capacity percentage wise in the because its overall C rating is increased.
Double check the three chargers and make sure they are outputting identical voltage.
If you always charge and discharge these three batteries together in parallel you will not need any diodes.
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And continue to check them. Probably best to get a voltage readout for your charging setup. I recently had a charger for one of my ebikes decide that it wanted to output at ~83v instead of ~88v for no apparent reason! I caught it right away, but it is an example of how something that worked consistently for 5 years can suddenly throw you a curve ball.
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