Search found 86 matches

by Solarsail
Apr 07 2021 9:55pm
Forum: Electric Aircraft
Topic: Blackfly AEV
Replies: 10
Views: 1451

Re: Blackfly AEV

Saw your email Slipstream. https://youtu.be/FI8AemQcclY?t=79 Well thanks, there seems to be some live flesh in the cockpit. The architecture is very creative, in that it is an eVTOL that does not require a tilting mechanism. I wonder about the stability of the aerodynamics. If the front (or rear) w...
by Solarsail
Apr 07 2021 4:07pm
Forum: Electric Aircraft
Topic: Battery pack selection for self-launching glider
Replies: 31
Views: 956

Re: Battery pack selection for self-launching glider

Can you also plot the graph for 18s LFP and 16s LCO without diode? Could you also draw pack voltage on the chart? I wonder if you have included the internal resistance in your simulation. The LFP cells will have 1/6 of the IR of the LCO cells. I think this will assure that at high C, 5/6 of the cur...
by Solarsail
Apr 04 2021 1:18pm
Forum: Electric Aircraft
Topic: Battery pack selection for self-launching glider
Replies: 31
Views: 956

Re: Battery pack selection for self-launching glider

For a hybrid pack, I would recommend 14s LCO and 16s LFP. 14 * 4.2 = 58.8 V. 16 x 3.7 = 59.2. If you parallel them without the diode, you get 58.8 / 16 = 3.675 for the LFP which is perfect. You can then use one charger, and two BMS. You can still use a bunch of diodes in parallel to isolate the two...
by Solarsail
Apr 04 2021 5:46am
Forum: Electric Aircraft
Topic: Battery pack selection for self-launching glider
Replies: 31
Views: 956

Re: Battery pack selection for self-launching glider

Well, if your concern is spontaneous combustion, then forget about the hybrid approach and you will have to stick with the A123 26650 (M1A). In which case 15 kg will give you roughly 1.56 kWh, and 47 kW. This should check all your boxes. These cells have high cycle life. BTW, you mention that 25% o...
by Solarsail
Apr 03 2021 10:55pm
Forum: Electric Aircraft
Topic: Battery pack selection for self-launching glider
Replies: 31
Views: 956

Re: Battery pack selection for self-launching glider

Packs should of course be removable, but not necessarily portable. Carrying them to charge makes little sense, even if they are 15 kg. Easier to pull a cable, or install an EVSE where the glider is parked. In a post above I calculated the power needed for 170 fpm climb. Let's say MTOW is 300 kg and...
by Solarsail
Mar 24 2021 4:13pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

No problem Ennoid. I am out of here. I will just have to reply to that self-appointed thread pillock though. Haha, you are wrong. Put six 24S BMS in series. Now try to charge all with one 100V charger. You can't. It will blow up. If you knew how, you would have explained it. With a relatively small ...
by Solarsail
Mar 24 2021 9:30am
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Ennoid -- I found a method to serial string the BMS and charge all modules with a single charger simultaneously. No contactors, relays, or isolation needed. No timesharing required.
by Solarsail
Mar 24 2021 1:33am
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Of course it is the OP's thread to dictate what topic diversions are acceptable Have you even read the thread? It is not Ennoid complaining. It is Flippy dictating what I can post and turning insulting and ad hom. I have no issues with Ennoid -- he has a great product and I plan to be one of his cu...
by Solarsail
Mar 24 2021 1:03am
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

its a bms, not a charger. a charger has no business even being near the bms I am amazed, 100% agree with this. Now programmable CAN signalling, e.g. to control TC / Elcon chargers, that would be great. Emus, Orion, Elithion, EPS and ZEVA all do so. Where have I asked Ennoid to put the power supply ...
by Solarsail
Mar 24 2021 12:07am
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

2) A non-isolating switch mode charger (i.e. CCCV function) does not generate heat. You have a 100% efficient DC-DC? You're a shoe-in for a Nobel prize, then, since that's never been accomplished before. Don't have to be insulting or pedantic, if you have a point. Are you trying to make up for Flip...
by Solarsail
Mar 23 2021 9:42pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

I don't understand :/ You should probably use a single BMS in a master slave configuration like all automotive manufacturer are doing. If 2 main contactors are too heavy for your design, you can design your own master board with 1200V fets. it will end up being lighter & cheaper with all the sp...
by Solarsail
Mar 23 2021 9:12pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Can someone explain Flippy's comment? Sure. 1) Safety comes from a BMS being completely separate from the load and the charger. That results in redundancy - no one failure can cause damage to the cells. 2) The BMS is usually in intimate contact with the battery. This is already a bit of an issue wi...
by Solarsail
Mar 23 2021 8:33pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Just go yourself and visit the E-skateboard forum & you will see all requests that I received from many user about the initial BMS size...it was considered as "huge" or would not fit in most builds even when only 6x14cm...so I decided to swith the SS design to dual sided components &a...
by Solarsail
Mar 23 2021 8:12pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

I would like to hear your solution to this problem. Clearly you did not understand the problem. your solution is to start your own topic and flesh out your project there. your problems do not belong in this topic. You still don't understand the issue of charging serial modules, do you? An enhanced ...
by Solarsail
Mar 23 2021 7:58pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

basically anything you are planning on doing. starting with using a 400V bms in a 900V system in a PLANE. are you nuts? start your own topic and detail your setup. its very clear you need help with your setup. but stop polluting this thread. this is not the bms you are looking for. Ahhhh ... so you...
by Solarsail
Mar 23 2021 7:13pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

and please stop using 1980 tacky sales tactics. Please stop being condescending. No need for that, in particular you have not understood the issue. pretty sure you need to stay inside the box. you have no concept of the basics, What basics is it that I don't have a concept of? That electric potenti...
by Solarsail
Mar 23 2021 6:37pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Is there any way to add a CCCV charger on board? A longer board such as 6 x 15 is just fine. Even a 5 A or 10 A charger on an HD board would be highly desirable. 5 A charging will take 10 hours for a 10p 21700. Which is great for overnight charging. its a bms, not a charger. a charger has no busine...
by Solarsail
Mar 23 2021 5:49pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

No offense to you, but I have to agree with flippy. Look for the basics first before asking for nonsense. A longer board such as 6 x 15 is just fine. No, not fine. 6 x 15 is fine for me and many others. Prove me wrong Ennoid. Can someone explain Flippy's comment? It sounds nonsense. I understand it...
by Solarsail
Mar 23 2021 3:08pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

flippy wrote:
Mar 23 2021 2:59pm
do a number 2 before taking off to compensate. :roll: :mrgreen:

or just wait until he releases his 18S and 20S models. :roll:
??? :?:
by Solarsail
Mar 23 2021 3:00pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Is there any way to add an isolated CCCV charger on board? A longer board such as 6 x 15 is just fine.

Even a 5 A or 10 A charger on an HD board would be highly desirable. 5 A charging will take 10 hours for a 10p 21700. Which is great for overnight charging.
by Solarsail
Mar 23 2021 2:37pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

OK, I see that this is an open source project. Beautiful. Are the schematics also available? The current limit in HD type is 150 A and 120 A. That should be adequate for my project. My modules each have two banks of 14s11p for 5.6 kWh per module. So that is 2s14s11p. It can also be configured 2p14s1...
by Solarsail
Mar 23 2021 12:38pm
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Nice firmware. I think the SSD1309 2.5" should do the job. Would I have access to the firmware, to patch in my display and rotary encoder code? Also in-pack statistical monitoring I would like to patch. Actually the 3.5" display is not SPI. It is embedded. But 2.5" would do. I2C is ju...
by Solarsail
Mar 23 2021 4:16am
Forum: Battery Technology
Topic: Open source BMS for 48V to 400V lithium-ion battery pack
Replies: 319
Views: 57005

Re: Open source BMS for 48V to 400V lithium-ion battery pack

Looks like 21700 is coming on the scene. eBay lists not only square brackets for the 21700, but also hex brackets. I am going hex. I think I will move to the Samsung 21700 50E, with either 14s8p or 14s11p modules,depending on the total voltage I need, which I am not sure yet. Since it is 2C, the cur...
by Solarsail
Mar 22 2021 11:32pm
Forum: Electric Aircraft
Topic: Battery pack selection for self-launching glider
Replies: 31
Views: 956

Re: Battery pack selection for self-launching glider

To raise 400 kg takeoff weight to 1000', the energy needed is U(kWh) = 400*9.81*1000/(3.28 * 3600000) = 0.332 kWh. Assuming a glide ratio of 30 (will be less while the motor is out) and a prop efficiency of 70%, motor of 90%, inverter of 90%, battery of 95%, and everything else at 95%, you get ener...