Thanks! Great additions! Do you mind if I include your google drive link to the first post? Or do you prefer that I would host it in mine?
Yup to you! If you wanted to add to your sheet that probably works be the best for people looking in the future
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Just updated the excel with weight calculations. I also simplified and refactored it a little bit. It still has some duplicate data in the calculator page (since optimal P count is same regardless of store) but I decided to keep that duplicate data to make it easier to read the excel. The cell data along with pricing is now moved into a separate sheet, which sort of acts as a database for the actual pack calculator.
Currently, if the max discharge rate is not good enough in the planned battery pack (design based on Wh), it will just say that max discharge is not acceptable. This happens often with high capacity, low discharge cells such as Samsung 50E and 50G. In the next version I will add the functionality to the excel that it will plan an optimal pack based on continuous discharge rate, Wh (with cont. discharge) and max discharge requirements.
For that max discharge design requirement, what do you guys think, what is an acceptable headroom for the pack? If data from Mooch says it can discharge at 120A, and you will use 100A, is that acceptable? Or would you just run at whatever max discharge rate Mooch specs it at? Maybe it would be best to make the max current headroom configurable… I feel that 20% headroom would be nice.
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I updated the calculator to v0.4. Now it also considers the pack max discharge capability when selecting a final P config recommendation. It rounds the P config that is optimal for Wh, and rounds up the P config that is optimal for max discharge. It then takes whichever one that is higher, and uses that for the rest of the calculations (cost etc).
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Could you add in for Boston Swing 5300 Batteries?
Hi, these batteries are not really applicable for this excel calculator. This battery is already a finished P-group, whereas the calculator is intended to recommend you a suitable amount of cells to use in your own custom P-group, with given S-count and other input variables.
Additionally, you would need actual test results of the cell. Look up Mooch, he has tested a bunch of different cells and if you are interested in any of those, I’ll gladly add a few of them to the excel for you.
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Juha,
This looks great! what size pack are you building for your 4’ board? Do you have the board?
I should get the board in a week or two. The pack will be 14S10P 21700, haven’t decided on the cells yet since I am not 100% sure if I’ll build it in the US or in Finland. 50E or 50G would be nice if I can get the efficiency high enough to not cook the cells. P42A would be an easy choice if it was just a bit cheaper. The Tesla cells from BigBattery are tempting but there is no test data for those yet from Mooch.
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You have done such great work here, Kudos to you and Mooch and Bryce.
Have you decided on the vesc container? I am not sure about switching if that adds to the safety. Will you use the plexiglass like Flight Junkie? Solder or spot weld? BMS or split it into 2 like Flight Junkie and use balance charger? Do you have the remote yet? I have pre-ordered one from Maytech. Felix foil has one on the way as well. For connectors the 200 amp anti spark on OSE look good for the battery. Is a switch inside of the hatch, between the batteries and vesc a good idea? Is it needed?
Thank you!
For my next build with p42a (14s10p). I’m going to use the OSE connectors with no additional switches. Also working on a custom BMS balancer so I don’t need to split the pack if we can get the pcb layout finished (also going to have CAN so might be able to connect into VESC).
Remote: Maytech works fine, but can’t wait for something new to get out though.
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Thanks! The VESC container is Bud Industries AN-2856-A. What do you mean about switching? I will have a 150A resettable fuse as the main power switch. The fuse&switch will be located inside the hatch, between waterproof VESC and waterproof battery enclosures. The battery will have a built-in 200A ANL fuse as an added safety measure. I’ll use a modified waterproof junction box as a battery case, more about that later when I actually start building it. Battery will be spot welded as a whole pack, and I’ll use a 14S LTT Bluetooth-equipped BMS to manage it. Charger is a normal “dumb” CC/CV chinese charger/power supply. My remote is the Maytech one for now. I’ll use Amphenol connectors for the battery connections. I listed those, among a bunch of other components in my preliminary BOM:
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Juha,
I have been busy on other projects. Did your mast or board arrive? Are your vesc and motor ready to go. I have to print a duct and we should review the mast clamp when you have the mast in hand. Good luck.
George
Juha, I am not sure that the vesc that you show on your BOM will fit the box. If it is the potted one, I have it and it is quite high. I also think it is limited to 12S? Hopefully I am talking about the wrong one.
Still working on getting the foil and board. Electronics are ready to go (they work on the bench). I will build the battery after getting the board, which should be any week now. I agree, let’s perfect the clamp when I get the mast… Although I’d be happy to make a few more iterations for you even before getting it.
My VESC is the one without potting, and it definitely fits the box. The potted one is too tall for my planned board layout. The FSESC 75200 can go up to 16S.
Thank you Juha, I will have to switch to that Vesc as well. Thanks for the offer to modify further. I will gather dimensions for the Slingshot mast. Did you print a duct? did you print the one that attaches to the fuselage? I have lost track but I should get that ready now as well. What Prop will you be using and what remote? My FR prop should arrive today. Then I will open the motor and do the corrosion x.
hi @jkoljo what nice contributions you made here ! Amazing details ! I try to read all I can here but it’s difficult to be exhaustive. I wondering one thing. Flipsky 65162 is max rated to 200A peak. Your flipsky 75200 is 150A max @75v. Is is the reason why you choose resetable fuse @150A ? I will recieve a 65162 with 75350 vesc. Do you thing I must order a 150 or 200A resetable fuse please ? (I think 200A but will appreciate your advanced advice thanks)
Hi, it really just depends on how much battery amps you are planning to use. I initially prepared for about 100-120A from the battery, so I got the next bigger size from Amazon which was 150A.
Now that I have my board fully working, I can see that I don’t really exceed 75 battery amps, sometimes not even more than 60A during the entire ride including takeoffs. So I actually gave my 150A fuse to my friend who is building his own eFoil, and got a 100A model for myself.
If you are heavy and/or you have a very small board, plan for 150A max. You don’t need more than that unless you are running less than 12 cells in series. Note that motor amps are always higher than battery amps. I use 120A through the motor quite often.
Check this out for example. Max about 50 battery amps. So 150A main fuse is unnecessary. The 100A version is a better choice for me.
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Super advice, kudo !
So from what you say, if foiler is not to heavy, efficiency could be better and draw less amp.
I am doing wingfoil and have multiple foil size.
For my efoil beginning, I will be building a “foil assist” not fully integrated like the build here.
I would like to go gradually from my wingfoil board I have to a complete mod DIY mod next winter.
I come from Ardupilot ecosystem for drone/plane and have some knowledge in RC/Battery/telemetry but I didn’t find to much info on logging here. I read about Metr but didn’t find which model you use. Could you be kind enough to share which logger model (link)do you use please because most model seem discontinued ?
So because I build multiple battery without BMS with success for Plane and I have reliable SKYRC charger, I would like to start with 2 pack 6S10P > 6S14P in serial.
I don’t know BMS and read so much bad think about them. But from what you wrote above, 60A BMS is enough - it was a non-sense initially when I read this previoulsy to your message due to theorical AMP motor (200A) but now I understand the choice of 60A BMS.
My board is a Fanatic 105L and I’m 85kg with Fanatic Wing from 2000 to 1300 surface area. The good choice will be to limit the drag so 1305 will be the good fit (The one I use in low wind and high wind almost eveytime this year).
I’m also in the middle of thinking about how to take this 1st step, and it’s clearly the battery that’s the hardest part, along with its waterproof case + waterpump, which I’ll probably be designing in solidworks over the next few weeks.
Thanks again !
Jean
I think I’d prefer to discuss build details in my actual build thread, but here goes… 
I am using Metr Pro CAN + separately bought MRo M9N GPS for logging. Unfortunately Metr is currently discontinued, and the original creators are working on a new project. Meanwhile I would look into the used market or the new Vesc Express logger. It seems to be a capable unit, but I also think that the software is not as finished as Metr.
I am using the 30A BMS, not 60A. I am not using my VESC through the BMS so discharge ratings don’t matter. Only the charge rating matters, and it is 20A for the 30A (discharge) model of LLT BMS.
You should not connect packs with different parallel cell counts in series. Unless the actual battery capacities are an exact match, you’ll end up discharging the lesser battery more, which may not trigger a low voltage cutoff early enough. This may cause the lesser battery to discharge too deeply, which damages the cells and makes charging dangerous as well.
Also, water-cooling for the VESC is probably not necessary. And it’s definitely not necessary for the battery. For me it’s enough to have the VESC in an aluminum box. It doesn’t even conduct the heat anywhere, but still stays cool enough.
I answeer in your build thread you true it s better ! sorry about that but really appreciate your answer)
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