Is that 138 kWh their remaining capacity or nominal rated when new?I can buy right now 432 Nissan Leaf modules for $5784 (7842 CAD). I need 432 for my configuration and it will provide me with a 138kWh battery.
Is that 138 kWh their remaining capacity or nominal rated when new?I can buy right now 432 Nissan Leaf modules for $5784 (7842 CAD). I need 432 for my configuration and it will provide me with a 138kWh battery.
Remaining. The original capacity of each module is 500W and 64Ah. The one I found they are tested with at least 41Ah leftIs that 138 kWh their remaining capacity or nominal rated when new?
With such a low power requirement, why don't power everything in 48V?I decided to give a try to 4kW direct drive electric motor
The thing is that for 48V 4kW is the maximum motor size powervise that you can install. In my case, I’m using this motor just because I already have it and it will help to do all the tests and collect enough data. The thing is that I don’t know anyone who would retrofit the power yacht of this type with electric power yet. So to build something you have to do some research. Plus using 100.8V (I don’t know why I mentioned 96V before…) allows me to scale up my system easily. There are so many cheap options up to 15kW which would be more than enough but again, we will see everything pretty soon. Because right now I already working on the battery for the testsWith such a low power requirement, why don't power everything in 48V?
That will be way more easy and reliable.
Life is a dangerous thing. If you want to achieve something big - you should go out of your comfort zone.High dc voltage and salt water ?
The whole concept absolutely TERRIFIES me.
Two not insignificant dangers, electrolytic corrosion and electrocution.
Thanks for your kind words. More to come soon. Silent 60 is amazing but to unreal for us now. But we will see that will be in the future. Technoloy is already here so it is time to do something cool with it)This is AWESOME please keep us informed!! Once my RV remodel is finished and we're bored of exploring the land I'm planning on getting an electric yacht or building my own.
Yes, I understand. I'm also looking at a motor solution for a big sail boat and it's hard to stay at 48V if the need is 10-15kW continuous.The thing is that for 48V 4kW is the maximum motor size powervise that you can install.... There are so many cheap options up to 15kW
I will tell you a true story.Life is a dangerous thing. If you want to achieve something big - you should go out of your comfort zone.
And use technology to make everything safe
Edit:
P.S. I already have 130V DC from my solar panels and will have more than 200V when I finish my setup
Yes, I understand. I'm also looking at a motor solution for a big sail boat and it's hard to stay at 48V if the need is 10-15kW continuous.
I would like to find a big 48V hub motor who turn less than 1000 rpm and output around 100 Nm continuous, but this is non existent.
About voltage, with 12S Leaf cells that give you around 45V nominal, so 90V total. Voltage range 72-100V
About your battery, can I suggest you a simple and reliable solution? Instead of building 24 batteries/24 BMS, please do you a favor and build 2 batteries with 2 BMS.
Based on 41Ah cells and 432 modules, you can connect 36 modules together to create one big 7.5V and 1476Ah modules. Then, connect 6 modules in series to create one 45V 1476Ah battery (12S and 66.4kWh).
Do this 2 time and add a simple 12S relay BMS to each battery.
And by the way, do your search, but Leaf cells have terrible degradation and many problem. So I suggest you to take your time and put your hands on better cells. There is plenty of EV at scrap yard and you will end to find something at good price for large battery (60-100 kWh).
I will tell you a true story.
Many years ago when I was still a young fella, I helped launch a small aluminium power boat from a sandy beach into salt water.
I was in the water up to my thighs (with wet hands) when I accidentally contacted 12 volts from the top of the exposed on board battery.
I received a hell of a belt, and I will never forget it.
These days I have a solar system with a 100 volt battery (thirty lithium cells) and regularly come into full contact with that, and never feel even a slight tingle.
I guess us old farts tend to have have very dry skin.
So laugh at me if you like, call me a wimp, a coward, or totally crazy.
But I am a retired power electronics engineer, very used to working around dangerous high voltages as part of my job.
That is not a problem, because I know where the dangerous voltages are. Electrocutions always come completely unexpected.
The idea of working and maintaining a system with 350 volts of dc in a salt water boat just scares the shit out of me.
I have no problems working with 350 volts dc on an EV or solar system in a dry environment.
Salt and damp changes everything.
Consider two 48V battery banks wired in series. Place a bypass diode across each (reverse polarity diode, sized and heatsinked to carry 100% of current.) That should protect their BMS from over-voltage if they disconnect.
That gives you 96VDC.
Alternatively, parallel multiple 48V batteries. Connect three European 230V inverters as 3-phase. Feed output to VFD to power motor.
3x Sunny Island would be 18kW.
I think SolArk (check out Deye for 230V model) being 120/240V split-phase and supporting 120/208Y as well, could probably be wired for 240V to neutral.
Other inverters should work - to feed a VFD.
If you had 360V or so battery, that could feed VFD directly. I don't think you can get away with stacking 48V batteries that high, due to voltage rating of EMI components.
What really surprised me was that 12 volts could even produce an electric shock at all.Nobody wants to tell you crazy. But in your story, it was your mistake and the person who left the exposed terminals. It is the same if I put my fingers into the 120V socket, get an electrocution, and tell everyone how dangerous it is. I respect your experience and would really appreciate it if you would share your insides on how to make things even safer but for now, it all sounds like an off-topic. Everyone knows that electricity is dangerous.
P.S. I think I have to update my first post because for some reason everyone still thinking about 350V DC…
I know QS motor and their 12kW car hub motor is attractive. But spec and reality can be different. A sprint of few minutes in the rear of a motorcycle at 12kW is different of powering a boat at 12kW for hours.You should check their website https://www.qsmotor.com/
Yes, but how long. A 1 kW bike hub motor can provide 1000Nm... for 2 sec before meltingThe motor I have should provide more than 200Nm
Ha! really. Ok, I have to tell all the engineers from Tesla, GM, Ford, VW, LG chem, BYD, CATL and other they are idiot because they connect cells in parallel.If you have more then 2 cells connecter in parallel in your battery pack it is already not good.
This is exactly why I want to test it out. There is no data on who would ever try to do it.I know QS motor and their 12kW car hub motor is attractive. But spec and reality can be different. A sprint of few minutes in the rear of a motorcycle at 12kW is different of powering a boat at 12kW for hours.
Still, this 12 kW motor is probably a 4-6 kW motor at 48V.
I don't know about GM, Ford, and others but I studied how Tesla builds their batteries. I've had an internship there and they use the same ideology. They have groups of cells connected in parallel after those parallel groups connected in series in modules and after big modules connected in series into the whole battery pack. At the low level yes, they had to connect 30-70 cells to one balance wire but it was a physical limitation because they had to connect thousands of cells. They are going away from this with each new iteration but the main idea is the same they don't create two high-voltage batteries and just connect them together.Ha! really. Ok, I have to tell all the engineers from Tesla, GM, Ford, VW, LG chem, BYD, CATL and other they are idiot because they connect cells in parallel.
Can you tell me more about using the diode to protect the BMS? I do not really get an idea of how it is possible. And yeah the trick with three inverters is pretty smart. I will think about it if I will go 230V or more but for now, I’m going to stay at 100.8V)
I was thinking of disconnecting the load at all as soon as one of the batteries goes Into over-discharge protection. Because if there is one of the batteries triggers this protection it means all others will trigger it soon. It means that the battery is drained and I had to turn on the generator way before it happened. And in this case, I don’t need to deal with increased current for the rest of the battery because it will be already disconnected from the loadBypass diodes in a PV panel prevent current from being pushed through, which would cause a large reverse polarity and blow them out.
BMS in series are fine until they try to disconnect. Typically, someone might have 4x 12V batteries in series for 48V. If one disconnects, the load pulls battery+ down to battery-. A BMS could have 36V from other batteries connected to its (12V) battery negative terminal. Its last cell would be at +48V. Other side of BMS FET would be at 0V, so FET sees -48V and will fail if not spec'd for that voltage.
My theory is that a reverse-biased diode across each battery & BMS assembly would prevent application of that volage. But it needs to be able to carry the current, if remaining 36V is applied to load. In your case, 2x 48V packs, so current if 48V feeds motor when one BMS disconnects.
Just an in-my-head design, but I think it is valid.