I’ve run ebikes in salty conditions for the last 6 winters, been riding about 15000km per year in total. It’s not so pleasant when you start to hear fizzing between your DC leads due to the wet and salt. Another more efoil related example is that my charge lead was unprotected on my board at first. It only took one trip to the sea to completely erode away the connector so there was a constant leakage current, strong enough to remove some millimeters of material - what you’re doing is not on the edge, it’s over it.
Lethal voltages in wet conditions start at something like 28V, can’t remember exactly but i looked it up at some time after a fizzing incident. A box and some longer leads will remove the risk. As for not touching any current carrying parts: a typical situation is that you have to flip your board in the water since it’s too shallow or need to carry board to your car. It’s bulky and heavy and you will accidently touch the mast and wiring for sure.
Been testing my setup with 4 dewalt flexvolt 60v 9ah batteries for a few days now and here is my conclusions on why grouping and using powertools batteries to power efoil or any high amp device is a false good idea.
To recap my setup, I wired the 4 batteries in // having the 60v switch pulled in so it created all together a 15s4p pack. Dewalt uses 21700 cells with 30A continuous discharge so I technically could feed my ESC with 120A continuous. Well turnis out this is not as simple as that.
1st issue: in order to water start with a 65162 100kv motor you’d need the full 120A. at least I do me being 100kg and my setup having terrible hydrodynamics when in the water. This is not the best handling discharge rate for the batteries. to overcome this and avoid shortening drastically the life of the batteries you’d need more units in // and well I don’t need so many of that type of batteries in my everyday carpenting job. I would have to end up buying more batteries than I actually really need.
2nd issue: run time foiling is about 10-15mn on that pack meaning that It would lead me buying double as many batteries should I intend to ride longer while first batch being recharged
3rd issue: balancing the packs. For the first runs I charged all 4 batteries to the max using Dewalt’s fast charger that came with before going into the water. My batteries have not had an equal amount of charge and discharge during their life serving their carpentry duties and therefore when plugged // you’d assume the newer units would feed the oldest weakest ones. add to that the strong current demand and again you are totally out of the best use practices. On the last run I had and in order to finish some job before heading down to the lake I used one of the battery in its tool without recharging it before assembling with the rest of the pack… big final mistake. Pulling so many amps out of such an unbalanced pack simply killed the electronics built within each pack. Surprisingly though when testing back home each cells of each pack they all where still in balance within their pack and holding 4,1V after charging them individually. Balance board (I dont think you can call dewalt’s built in elctronics a bms) is dead on 2 of the 4 units meaning I can’t charge them using dewalt’s charger anymore as safety features of the charger won’t allow it.
My conclusion of all that worst practices I meaningfully went through in order to foil using powertools batteries is: DO NOT DO IT. Saddly for our ressources Lithium batteries are being built for an exclusive type of use in order to last and be safe hence forcing us to have in our homes unnecessary redundant power supplies. Can’t wait for a major break through in powering EV.
Until then it will be like Churchill says about democracy, Lithium is the worst form of power source except for all those other forms that have been tried from time to time.…
Note1 on CorrosionX and running everything wet thanks to it: No corrosion noticed anywhere on the new batterie I had just purchased to complete my setup. In comparison my 3 other older batteries had signs of corrosion on the nickel spotwelded strips before I put them to the submerged test (fresh water lake).
Note2 even though CorrosionX seems to allow submerged applications and in the light of my demonstration above next build will be traditional 27100 cells enclosed in the board and watertight because… well, why take unnecessary risks for something that doesn’t even work better. Will definitely still use CorrosionX in addition of watertightness and will treat my powertools with it so I don’t need to tidy after my day’s work and leave all the stuff in wet snow ready for use again the next day or the next spring
Good points but I am not discouraged, my conclusion are:
1 - don’t mix leisure and professionnal use. The units must be efoil dedicated.
2 - the pack must be correctly dimensioned and charged/discharged simultaneously.
Looking at the 60€ PARKSIDE 20V 8AH battery from LIDL based on 21700 cells, it is easy to cast multiple adapters following YT tutorials.
3 - it should be possible to travel by air with one or two of these units, and ship the rest in small parcels.
There are some issues with mixing and breaking up modules to build a pack - the best option i’ve seen for this is the Grin Ligo batteries (LiGo Batteries - Grin Products - Product Info)
Too expensive of course, i wish they were more reasonably priced, then i’d get a bunch instantly when they get back in stock.
looks promising on paper but not sure how they can perform in the long run though. You sometimes can have good surprises with parkside though.
Looks like the 8ah is a 5s4p and not sure what the continuous discharge rate is. I’d assume it is definitely not 30A like the dewalts; safe bet is probably 20A max and 10 to 15 continuous. Meaning that to power decently a 6516X motor at 60v and have enough range you’d need at least 12 units of these to make a 15s16p. Quite a fair bit of money to which you have to add the price of a few chargers… in the end a lot of space wasted by the casings and the docks plus the problems I pointed above in a previous post. You may prove me wrong but the more I think about it the more I believe in a dedicated pack assembled with reliable big name cells coming from the same batch (well a bit like everybody does hard to reinvent the wheel). I do think though that a solution that allows to split the pack like Larsb pointed (LiGo) is definitely a nice feature to have. I came across a link on the forum for a video of an english guy building packs with individual fused cells in a 3D printed sleeve. Can’t find the link anymore but he was doing it in the same way you pop AAA batteries in your TV remote. I thought that was kinda smart to have such an easy access to each cell. Rises the question of the potential sparks and heat on the contact area should the cell come loose. Contact is only maintained by pressure of the nickel strips used as a spring…
There is no choice but wiring them both in series and parallel in order to reach operating voltage and capacity and to balance the load at discharge unfortunately…
I think you have a very good point here specially if you could recharge the capacitor bank using the energy that you input while pumping the board. pumping would act like a dynamo on a bike or a piezo on the bbq. Maybe even couple the sinusoidal movement of the pumping with a flywheel to add extra energy storage feature on can dream. Not sure how the ESC would handle such a system…
There’s a youtube video where the guy drops all different brands of battery into a bucket of water and EGO 56v is the only battery that still works https://www.youtube.com/watch?v=FgZDYkZlUBI&t=4s
I’ve seen the disassembly videos of the ego battery and they are very well protected from splashes and moisture from outdoor use but I still wouldn’t dream of just letting them get repeatedly submerged–even though I’ve heard anecdotes of people leaving these particular batteries outside all winter under big piles of snow and seeing them work fine in the summer even after all the snow melts through them.
I just got two of the ego 56V 12Ah batteries I’ll be using using to try out a build here to see if they have enough power in parallel to get me up onto foil and whether the total capacity will really be enough to make it worthwhile.
At the very least it’s going to be an upgrade for my electric skateboards where I’m currently using 40V 5Ah kobalt and ryobi batteries in a cheap ‘weatherproof’ plastic ammo box.
Biggest issue with the ego batteries is the size of the plastic casing but the cases appear to come off and go back on pretty easily with a security bit so I can fit two batteries inside my pelican case, use them for a while and then reassemble and put them to other uses as needed.
Ok I just got my two 12Ah ego batteries taken apart and they fit inside one of these Apache 2800 cases from Harbor Freight with Internal Dimensions of 11-7/8" x 9" x 5-5/16" which is equivalent to Pelican 1400 case.
(Pictured is the T120 thruster I am using on my SUP which is basically what led me into these forums)
Looks like a 14s-4p arrangement of Samsung 30Q INR18650 which are rated for continuous discharge of 15 amps and 30A pulse discharge rating. Theoretically that 4p would get you 60A continuous discharge (120A pulse) from each pack. One pack weighs in at about 3kg/7lbs and the height once you take the case off is about 4.8" h x 5.75" x 5.5" (122mm x 146mm x 140mm).
The BMS is potted up pretty good but from other teardowns I’ve seen the BMS is only wired on up the charge side while the discharge circuit just has a sacrificial copper trace that acts as a fuse (of uncertain rating).
Disassembly and reassembly are very easy with a T15 security torx bit on the outside and then 2 phillips head screws holding the connection plate. It’s a bit bulky to fit into a board box but I do like the ability to have a battery that’s not completely dedicated to an efoil build that’s mostly just in my head at this point. These batteries can be used with your lawn/yard equipment, two stage snowblower, and a 3000W inverter system that can serve as backup power in an emergency.
The cells alone would cost about $305 from 18650batterystore and I paid $400 for each of my batteries with 2022 manufacturing markings in “new” condition from some pawn shop on ebay. Each battery arrived in ‘maintenance mode’ at about 35% charge.
At the retail battery price of $550 there are probably better options but I think this will work for me once I get my build underway.
hard to reinvent the wheel). I do think though that a solution that allows to split the pack like Larsb pointed (LiGo) is definitely a nice feature to have. I came across a link on the forum for a video of an english guy building packs with individual fused cells in a 3D printed sleeve. Can’t find the link anymore but he was doing it in the same way you pop AAA batteries in your TV remote. I thought that was kinda smart to have such an easy access to each cell. Rises the question of the potential sparks and heat on the contact area should the cell come loose. Contact is only maintained by pressure of the nickel strips used as a spring…
on can dream. Not sure how the ESC would handle such a system…
