Ride time : 20 minutes max
Amp during session : 60A (Foil out of the water)
the voltage decrease very quickly (after 1 minute) and it’s more difficult to out of the water when you touch.
Temp after 20 minutes : 60°C ( ESC into the box, watercooling close loop)
Temp after 20 minutes : 40°C ( ESC out of the box)
2 X ZIPPY compact 6S 5A, serial configuration, ESC 130A hobbywing => don’t use this lipo very dangerous, burnt after 2 minutes of ride, 80°C into the box
2 X Zippy 5S 8A , serial configuration, ESC 130A hobbywing
Ride time : 8 minutes max
Amp during session : 50A (Foil out of the water)
the voltage decrease slowly and it’s easy to manage the power, but unfortunatly this kind of battery doesn’t exist in 20A
Temp after 8 minutes : 50°C ( ESC into the box, watercooling close loop)
Temp after 8 minutes : 45°C ( ESC out of the box)
2 X multistar 6S 20A serial configuration, ESC 130A hobbywing
Ride time : test only 25 minutes but there was still 48% power (I think I can ride 35/40 minutes)
Amp during session : 45/50 A (Foil out of the water)
Nice, more difficult to manage the power but you keep the power during the ride
Temp after 25 minutes : 45°C (ESC out of the box)
Nice info. If I recall the multistar lipos say they are 10c but are actually only 4c discharge when tested. Some useful info on battery tests in the link below
About the Zippy… I have been using it for years in my drones, and never had a single problem. Your fire issue is very surprising. Those batteries are actually cheap, but very much appreciated in the drone domain.
But I reckon that drones are flying, not swimming…
Thank you @jeffM, I will order today. I think I fried my esc just connecting the wires like Pacifmeister did. I have to get the fuse/ circuit breaker. Looks like there are plenty of ways to fry an ESC
jeffM, Thanks for sharing these antispark connectors…brilliant idea. I’ll be using these. the first use will be to replace the Deans connector in my safety halyard.
I cannot stress enough the importance of having a safe electrical system. From wire sizing, to batteries. It’s important not only for you, but your family and friends as these explode and burn homes down.
If you watch this video on lipo batteries you will quickly learn how dangerous they are. In fact, if you are using a plastic battery box and for some reason your battery shorts and explodes your box could explode and send plastic shrapnel everywhere, and with most battery boxes between our legs you can see the concern
I have asked a few times what people recommend for their battery box for safety, no one has replied yet, but from my research, just watch this video and you quickly agree that your batteries must be in a strong aluminum box, or at minimum inside a lipo safe battery bag within your plastic box.
That’s one of the reasons I why I don’t use Lipos. I use the Liions intended for Power tools (currently have about 600 Wh of INR18650-13L). I have not built the pack with those cells yet. I have built 2kWh of stationary storage with spot welded contacts. I use a 30 Amp fuse for each cell and have overcurrent shutdown for the whole pack. I think the method is pretty safe considerimg the datasheet guarantees no thermal runaway with any kind of electrical mistreatment. One last problem are overheating cells damaging other cells in the vicinity. This can be solved by giving up compactness of the battery assembly. A sturdy pack is still necessary as puncturing a cell is still not desirable. At University cells were punctured with nails and there was no fire. I still would not be happy shipping those in a finished product however, because of those with a great talent for destruction. Please let me know about any ideas to improve safty in this area.
I’m currently thinking about a closed sheetmetal box with overpressure valves.
we really need to look at working out if there is a pre made 18650 cell pack at a decent price with a BMS and charger available.
much safer option. used in nearly every portable electric device worldwide. lipos are great but holy hell do they burn well.
. ebike battery pack?
.aliexpress
.alibaba
.build your own pack?
Agreed… I know Alibaba has a lot of companies that make custom battery packs like that. Its matter of know what you need and trusting their BMS and building skills really. I don’t know anything about 18650 batteries yet, been focusing on the build of motor/remote but ill have to watch some youtube videos and make some calls to 18650 battery pack builders to learn more soon.
Good price, but low efficiency, 5200mAh * 10C is obtained only 52A. and if you take into account that the data is often too high, the batteries will be blown up on the supposed loads, it only remains to include them in parallel, but it’s only right to disassemble and switch on several cells in parallel.
