True, I use the 200A:
https://www.digikey.com/en/products/detail/littelfuse-inc/142-5631-6202/2515909
which BMS is limited to max 180 amp and reacts in max 17ms for over power and in less than 10us for shortcut detection configured for 300A. Fuse is slow blow and bms will react before always.
Super helpful thread! Without going too off topic, my goal is simple: I want a battery with 50% of the weight. @foilmore given your better understanding of the setup, can you comment on potentially removing some of the cells with a view to having a shorter run time but lower weight?
Im guessing the power would not be high enough but really curious to hear peoples thoughts.
In my opinion, the weight of the lift foils is the biggest disadvantage, especially for wave riding.
I am glad this helped someone already. If you are okay spending 5-15 hours and risking $3,500 going up in smoke it seems maybe doable, but I canāt say for sure, because I am not going to be pulling apart the welded zinc and cells since they all look healthy. I donāt recommend it.
Here are some thoughts:
- The case itself is surprisingly heavy without the batteries in it. I will weigh it to see, but it is one thick piece of plastic!
- Due to how it was manufactured, it would be a major undertaking by an experienced person to pull half of the cans out. It looks possible since I am not seeing the batteries themselves epoxied together (despite what was shown in the B-roll in the video) and they are separated nicely in the case.
- You would only be able to drop half of the cells which is just under 5kg from the pack weight (only about 1/3 of the total) for this effort. The 30Q cells are rated for 15amp discharge and 25amp burst, so running them at 7p at full throttle you are approaching their limit and they are going to heat up and have diminished life. You are going to need to be pinning the throttle at times to scramble out of the whitewash, right?
It seems Lift made it very difficult for you to build your own custom weight-weenie as you would have to reverse engineer the BMS <-> ESC CAN 2.0B data connection to make the ESC work.
I think the time and money would be best spent doing the following:
Bypass the Lift ESC and use your own custom battery, VESC, and remote. Or maybe just build a board setup for wave riding and swap over your Lift motor, LOL. In essence, Lift made it pretty dang hard to avoid purchasing their $3,500 batteries in the future for owners.
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Lift is one of the lighter boards. But compared to a wave riding foil, any efoil is always going to be chunkyā¦
Battery wise if you really want to lighten up, then the best bet is a lipo or lifepo as you can use a high discharge pack with a much shorter run time.
I wouldnāt run the 30q cells under 14s10p which results in a Ā±6kg packā¦
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I heard the Lift board (5ā version) was over 20 lbs without electronics or foil. Their website shows 30kg for board only on the 5ā, but I assume thatās a typo/mistake.
Many thanks @foilmore, very helpful indeed. Yes, I have a battery on its way out so tempted to dig in. Your thoughts on overall weight savings are really useful, so only about 1/3 of the weight.
As @Jezza mentioned, these will always be on the heavy side.
FYI Nick talks about a more wave orientated version coming out next year in this podcast.
Good food for thought and thanks again for the comments.
Lift battery is 15kg and full setup comes in at 30kg (including battery). I actually thought they were a bit lighter. My setup is under 20kgs so I now consider myself very lucky! But Iād like a set-up under 15kg for surf and wake hijackingā¦
Can anyone confirm what the Lift board-only weighs?
I got the weight from the jetsurfing nation review.
Soā¦
3kg foil assembly
15kg battery/electronics
12kg board
?
@tylerclark @Flightjunkie Have either of you weighed your Lift board by itself?
I have not but next time itās apart Iāll weight the 5ā0. I know Flightjunkie has the 4ā4.
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Iād hazard a guess based on my motor units that it would be:
10kg board and ESC
5kg foil and motor unit
15kg battery.
Since these boards are only a few years old I was under the assumption you would be tearing apart a perfectly good battery. How many cycles do you have on the battery and why is it on the way out?
If you think it wonāt be much more than a boat anchor soon anyways due to the cells wearing out from use and you might as well ( VERY, VERY CAREFULLY cut it open with some new instructions I can provide) then you could go with option C:
Open it up and replace all 196 cells with a 14S lipo pack and wire the parallel groups to the 14 leads of the FFC going into the BMS. It looks like it will easily detach from the case to make a franken battery. You can and will need to also reuse the thermistors. Two of them will be very easy to switch over and tape to your new batteries and two will be a janky as they are burried in epoxy and you may have to just cut the plastic around the epoxy. In this process you could also replace some or most of the case by wrapping it with CF to reseal it.
Lipo batteries use the same top and bottom level charge voltages as the 18650ās in there so the rest of the electronics may very well just carry on without any issues.
I believe the battery is 13.5 kg (29.7 lbs)
I ended up with 13.5Kg with 3dprinted nad single layer of carbon fiber plus 1.5mm thick ALU plate under the cells for better thermals, and a 2mm thick ALU heatsink for BMS (kinda overkill) with lots of 3mm silicon thermal pads for electrical isolation. Plus I had to fill the gaps of my oversized box with at least 0.5Kg silicon. I use LG HG2 cells in 14S14P and 0.4mm thick nickels. with a good mechanical design and production process I am sure it is possible to reduce 1 to 1.5kg
For reference, the lithos case with just the cables and contactor in it is 5.6 lbs.
No. Havenāt weighed the board.
Everything is a trade off. I like the range and ride time, so the extra weight is worth it in my opinion.
Thanks @foilmore - super helpful. I would really appreciate those instructions if you find some time. Can you suggest a suitable 14S lipo pack?
Yes, i think ive been a bit unlucky with the battery life. Lift have been excellent in their service. A replacement is on its way.
Sick!! That looks superb @michion, exactly the type of thing I was thinking about. Motor at the top just to get you up and riding on the wave.
Would love to see a few more pics with batteries and board. Do you have a link?
Itās going to be a few more days until I can finish dissection to remove the contactor. I will provide more info soon. I am going to try another blade type and will also provide the STL, for the dremel tool adapter that allows cutting it perfectly.