Going to start a backpack foil assist build here and the biggest hurdle for me is getting batteries all the way out here to Kauai.
My 2 goals are 1hr+ sessions in waves and around $1000 all in. (Foil/board not included)
I only know the very basics about battery building but figured it’s going to be required to keep the cost down that low. Hoping you guys could brainstorm with me on battery options.
Backpack setup seems most desirable and simple, allowing room to carry some extra battery capacity while still able to ride a light pumpable board.
Building plan is as follows but can change on your suggestions
Motor: Flipsky Waterproof Brushless DC 6384 Motor 140KV 4400W
Mount and prop: Kpart mount and folding 3 blade prop
Battery:12s external balancing or ???
Charger: icharger x12 or ???
Esc: Flipsky 150a
Remote: undecided (waterproofed eskate maybe?)
Housing: aluminum ip68 box
6L Backpack w/strong rope tether 15.35 x 9.05 x 6.29in
Foil: Lift 120/170/200 ha
I know there are some great battery build guides but is there a standout one for a 12s pack with more capacity than the board mounted boxes?
I’ll make an official build thread when I have parts in hand. The battery seems like the most important part to have figured out first as well as gtting the supplies out here of course.
Just want to say THANK YOU now and that you all are awesome for sharing and helping make this subsection of the sport actually attainable for those of us balling on a budget🤙🏽
You could consider creating two 6S packs that you connect in series. Potentially a bit more flexible for weight distribution depending on how set things up. This would open up the option of more hobby chargers that support 6S voltage. You might even be able to buy 2 6S chargers for less than the cost of an x12.
Aside from the balance chargers, you can also get a regular 12S BMS that you keep external from the pack that is wired to the power supply. Then connect it for charging, same concept as a balance charger
The advantage of an rc charger is higher balancing currents. Icharger x6/8 have 2A active balancing, whereas many BMS just have 30-100mA passive balancing. Should still be OK for a smal 2-4P pack, just takes more time to balance.
Plus the external balancing just simplifies the battery build and I like the idea of actually being able to see the SOC of each cell. Not to mention the safety side of things with a plug in low voltage alarm/soc monitor.
Also considering a hardwired throttle control, keeping with the KISS method on this build making it easier to swim and not have to deal with connection issues.
For anyone wondering cause this comes up with body mounted, I’m planning on making sure the whole backpack set up actually has a small amount of flotation considering the volume of air that will be in the box and will add foam inserts if needed.
The main thing I need some advice on is the choice of batteries and a supplier that will actually ship here (Hawaii) and be cost efficient?
You’re gonna love the waist/backpack mounted foil drive! I live on Oahu and I don’t know of anyone that builds batteries here and shipping is a PITA. So, I had to just build all my own. You can get individual cells shipped here easily, shipping is pricey because of weight, but it’s the only option I found. If you have some basic electrical knowledge, patience and a spot welder then I would suggest building your own. I use external BMS on most of my batteries, but some I permanently connected them for easier charging. I still only use BMS for charging only. You can find 50.4v 10 amp chargers pretty easily on Amazon. I have built a dozen or so batteries and they all are still working very well with only one getting trashed that I built for a friend and he had water incursion in his box. Feel free to message me with any questions you might have. I built my buddy a 12s4p with molicel P45’s and he loves it. He goes out for 4 hour sessions, not e-foiling, but he uses it to take off and taxi back to the lineup.
I’m also considering a backpack mounted option, and wired throttle. Battery wise, I’m planning to parallel 2 Greenworks 40V power tool packs 10S2P which would form a 8Ah 10S4P capable of a continuous 80A, 100A bursts that I hope can take my fat ass on foil… Of course modern molicels have a higher power density, higher discharge, but I already have those battery packs, VESC and throttles from a previous project, so I’m going to go with that for now. I’m hoping that the penalty of a heavier (~3kgs) battery is not as critical if it’s in a backpack, compared to top mounted on a board. On the plus side, there’s a bit of protective shockproof and splashproof casing on those packs, and the safety of batteries is not negligible if it’s close to the body. And it would be able to travel by plane, with a casing and labels that do not make it look too much like an IED.
Well I’m committed now, just ordered enough moricel 21700s to make two 6s3p packs for a 12s3p total. (P42A 4200mAh 45A, haven’t calculated output yet)
Figured this was the better safer way to go, if there’s an issue with one pack I’ll only have to replace half of the 12s setup, building the smaller packs seems less daunting and the dual 6s chargers are more affordable.
Not sure about the ecs/vesc yet. Vesc is more fitting for a hardwired remote using a ebike thumb throttle but not finding a lot of long term success stories with the Flipskys. I’ve learn from my ebike build it’s not worth scoping on the controller just end up costing 3x.
On that note there were a few people reporting vibration issues with the Flipsky waterproof motors and ceramic bearings. Maybe the better balance of a folding 3 blade prop would solve that along with being smoother when surface piercing. I’d just rather not have to go through all the waterproofing steps myself.
Looking for a bigger ip68 aluminum case most I’m finding are to small. Want to have everything clean in one box and figure out some thumb screws to have no tool access.
Just replace the ceramic bering with stailess or „waterproof“ the motor yourself and replace the bearings with stainless. Ceramic don‘t last long.
Why not use a wireless remote, it is available and you have one wire less to tangle.
I like the idea of it being very simple and fool proof as possible, one less thing to connect and charge. In reading I’ve come across many that have had issues with connection dropping.
Also with the backpack set up I can see having it on a light bungee that pulls it right on the hip so it can be run very short. Just drop it and swim to the board unhindered, have both hands to reposition, duck dive if necessary. $15 bucks to replace it if smashed into the board🤙🏽
About wired remote. I was thinking in that direction, hence create the topic, but later on decided not to go in that direction. Here I added a post after you mentioned this:
'Simple cable remote build - #5 by lishine
Well I’ve been in the vortex of foil assist research, found and ordered a hydration backpack to build off of and finally settled on a aluminum ip68/nema6p enclosure that will fit the 21700 standing up for 12s3p, planning on using the case as the heat sink for the vesc. This was not an easy task and for any one looking polycase and bud industries seem to have the most options.
Having to redesign the pack in the staggered honeycomb orientation to fit it. Still learning all I can about safely building a battery. Shout out the 18650batterystore for shipping the p42a cells out here to Hawaii in record time.
For ease of charging and concerns about having to make sure both 6s packs are of equal charge everytime you connect them for 12s. I’m just going to build a single 12s3p battery already ordered the icharger x12 to balance charge.
Still looking for a good guide on 12s3p pack building and how to arrange it for efficiency. Also need to figure out the balances leads. It’s a lot to learn but I’ve been wanting to get into battery building for years.
Here’s a good tool for figuring out the battery size and layout, not sure how it figures the pos/neg. Any help or pointing in the right direction here will be greatly apricated!
This is basically the same battery I’m building same exact cells just many more features. Honestly if they would ship here I would have much rather ordered this and saved time at this price your really not saving much building your own if your only building a few. Just putting this here for someone who may want to try one.
Specs look really good
Nominal Voltage: 43.2V (3.6V × 12)
Peak Voltage: 50.4V (4.2V × 12)
Battery Watt-Hours (Wh): 544.32Wh (Nominal)
Battery Capacity: 12,600mAh (8.4Ah) (4200mAh x 3P)
