Not practical IMO to have massive voltage supply variations. While it would be possible to do and i have done it on a 36 v pb scooter with a switch that engaged a 10s 42v lipo for speed boost. The big issue is the KV of the motor / prop needs to be well matched to the battery voltage to have good all round efficient setup.
Intersting idea though.
rcjetman,
When you did it on your scooter, was it the same ESC? This is getting more plausible…
Efficiency is what it is all about, what is the critical “practical” issue?
If experts can pump up to foil, we should be able to survive a “gear” shift.
ESC stays cooler because it is close to full throttle most of the time… right?
Yer same ESC, i just used a mechanical switch that was plugged into the 2 different batteries / 36v PB and a 10S lipo and it worked perfectly.
BUT it was a standard DC ( not brush-less ) ESC and had very little programming or safety features to get in the way and it was happy to accept the voltage differences. The PB cells got me to 38 km and the lipo with the added amp delivery and higher voltage retention got me to 55 kmph.
Im sure you could do it with an ESC that has programmable voltage selection but a voltage drop from 60v down to 20 volts is enormous and you would need to select your motor KV very carefully. .
Oh, the brushed vs brushless example makes me take a step back. My gut says a brushless ESC will shut down or worse. I’m not envisioning this battery, but the concept of reconfiguring our battery cells with a series of relays. The critical requirement IMO, is for the ESC to handle a change in supply voltage under load.
You cannot switch voltage while flying , it is already pretty hard to stay on the board with a constant rpm at first
In my option the only interesting thing to try is two battery pack , a small one high discharge rate for take off and a larger low discharge ( cheaper) for flying
But at the end , high speed demands the same amp as take off …
Or may be a bank of capacitors that you charge when stopped or not at full power and use only when taking of for to short speed increase…
That can allow you to run batteries cooler and with lower max amp capacity…
I have no idea of the amount of energy you can store in capacitor of reasonable price/size though…
Option B is to run it at 60v full time and put 4 batteries in with a parallel setup. Would have 16ah at 16s. Granted it would cost around $1000, but you could also run your tools with it when not riding and get access to their warranty on the batteries.
They also have a four battery charger.
Total newbie here. Just starting out. Did the EGO 56v battery work in your build?
Any advice would be appreciated.
I did not try it. Not sure if it would work. I suspect the draw we have would limit it.
Hi all,
I’m digging out this post as I just finished and started testing a setup with 4 dewalt flexvolt 60V 9ah in parallel with a firduo 65162-100kV inrunner and 75-200 ESC that came along. I’m running everything wet thanks to god sent corrosionX and no I didnt die yet from electric shock 
.As i’m a carpenter and fully equipped with dewalt tools I thought it would make sense to play with what i already have on shelf and keep everything as versatile as possible using my kitefoil without any modifications. so far i’m only able to pull around 40A out of the pack unfortunately not allowing me to ride faster than 10km/h therefore not allowing me to fly. i’m struggling a bit with Vesc tool being a total rookie in electronic and i think i’m probably missing some parameters in the setup.
dewalt cells rate at 30A discharge. and when using the battery at 60v it is in 15S1P config so full 4 packs in parallel should equal a 15s4p if i’m not mistaking and i should be able then to get a max discharge of 120A? If someone with a good Vesc tool knowledge could point in the right direction that would be fantastic. I can feel i’m nearly there and it is frustrating to be limited by lack of knowledge in a software.
Here are a few pics of the build for those who are interested. I’m yet to have printed the parts that will shield the batteries and hopefully help with reducing the drag when everything still in the water.
I definitely wouldn’t submerge those battery’s just a PSA. If you google vesc setup there are various tutorials that are easy to follow, it is a bit to follow but once you do it a few times you’ll get the hang of it.
Hi thanks for the tips and concern about the batteries. Seems indeed I’ll have to take the pain and learn vesc tool. About the batteries being submerged I guess you’d worry about shorting the batteries and set everything on fire. I must admit I didn’t dive with total piece of mind the first time even though I ran some test before and soaked them good in corrosionX to protect all the electronics inside. they have been twice in the lake so far. Didn’t fry my balls (yet) 
and didn’t even notice any noticeable electrolysis that could have happen in between the +/- poles being in fresh waters. the only thing is that the level of charge led indicators gets trigged when submerged as a tiny bit of current leakage is enough to light them up. My opinion is that any seriously manufactured lithium batteries are really not that easy to set on fire under normal use of temperature and you’d really have to shred them to pieces to expose the lithium to water or manually short the cells with wires to reach point of no return. One good thing coming along with these batteries is that in some way you benefit from the electronics built in that monitors temperature and discharge right of the shelf adding safety at no extra cost. I even think they come with antispark solution too as it never occurs to get a spark when plugging in the batteries to your favorite tool. That being said I’m fully aware that there is always a risk to anything and my example is in no way a guideline for good practice. So here is my waiver :"don’t do this at home people 
"
Why run it like this, it creates a lot of drag and a lot of risks for no reason. Please understand that 60V isn’t a safe wet voltage, it’s ok with dry fingers but no more - a waiver won’t do you much good when you’re dead and your friends and family suffers because of it. Please move the batteries to a dry box and to the top of the board!
I would not be able to sleep knowing that batteries that were submerged are under the same roof i am…
Hi Larsb,
I agree with you on the drag at startup using unnecessary battery ressources. Not a problem anymore as soon as you are flying but still you have a point every time you need to water start it reduces your flying time. My goal with that setup was to see if I could pull out something as simple as possible with what I already had. being a carpenter I thought it would be stupid to go and buy more batteries when I already have plenty available in the shop. Already have too many toys in the garage also (boards of all kinds kites wings windsurf…) and thought again I would try to make something versatile and save some storage space.
About the potential risks running everything wet again I agree with you 60v is living on the edge but only if for some reason you decide to grab with both hands positive and negative side at same time which is quite unlikely to happen me not being suicidal and all cables being tucked away out of reach. Direct contact and duration of this contact is where the electric danger lies;
Fire hazard: cells are all water and air tight as long as you dont over heat them I think you run more risks at home leaving your phone charging the whole night on a badly manufactured Chinese charger; The closest I came to burn the house is when my cat peed on my mac charger and it shorted the connectors on the magnet side resulting in frying the cables 
no kidding it really happened to me. (I think pablo_foil will make nightmares after reading this…)
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.
OK, i’m done being Mr safety.
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 
in addition to
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.
If you just keep to wiring them in series, there should not be any worries, other than capacity and discharge rate?
