Ianhill said:Go and get a degree then talk yack mate.
I tell you why you can't find it becuase no one's that stupid until now your crazy.l for wanting to go that high and to say I'm spreading nonsense like physics or science has no meaning to you so crack on kill yourself I warned you there a limit to series connections just takecare for god sake.
Ianhill said:You have not proved it's irrlevent everywhere I look it shows a series pack with the connections adding up the voltage goes through the cell nit around it.
And its the dielectric breakdown voltage of the cell is what your looking for
Diplomas are just bits of paper in this instance as where they for battery design ?
Ianhill said:Just unbelievable that you have two diplomas, one on the subject and you say I'm spreading misinformation, I think the truth is someone reads what you write with little knowledge and kills themself's from your misinformation, dielectric brake down is real and the voltage goes through a cell not around it that's basic stuff there you attacked me over and made your self look silly.
Ianhill said:Addy said:Ianhill said:Just unbelievable that you have two diplomas, one on the subject and you say I'm spreading misinformation, I think the truth is someone reads what you write with little knowledge and kills themself's from your misinformation, dielectric brake down is real and the voltage goes through a cell not around it that's basic stuff there you attacked me over and made your self look silly.
I quieted down because I thought you agreed finally. I'm not saying dielectric breakdown isn't real, perhaps you should sharpen up your English skills. I said it is irrelevant, because it isn't going to happen inside the cell, because the cell voltage doesn't change when adding more cells in series. If you were to take a basic electronics course you would learn that voltage does not go "through" anything. Current flows through, not voltage.
I will agree that people who don't understand the complications and risks of high voltage battery packs should avoid them for safety reasons.
Face palm yourself go make a 800vdc battery from hobbyking cells and see if dielectric is relevant or not of course its relevant at high voltage you don't seem to get it at all in a 3s pack the third cells sees 4.2v across it but 8.4v goes though the negative electrode and comes out as 12.6v so your the numpty here in many ways.
I've got more than a basic electronics course I have studied liked mentioned not slinging my passes about like cock length because I'll win, I will take no schooling from you your wrong my English may not be the best but ive learnt fact from fiction unlike yourself 2 diplomas my arse learn from a txt book and come back when you know what your talking about you have yet to use any scientific reasoning to how the voltage multiplys if current only travels through a cell ?
I didn't want a slanging match but you don't seem to grasp the basics your more than happy to call me wrong and make out I have no reasoning or education when it's yourself that idenies basic scientific ruling and stated your well educated and spout's off nonsense.
Ianhill said:A typical pp3 is 9.5v so 244 times that gives 2318vdc and discharge rate at 30ma so no wonder they are poping and hissing the electrolyte is boiling inside the cell, having discharged at well over a few amp for that arc,
Each brand to their own aswell as cell design so the voltage a pp3 fails at is not necessary where a lipo will fail at they are two different designs, I can not say how many more he could of add to his string or where his missing 300vdc was it's clear to me that leakage was occuring at that high level due to physical limitations, If i have give poor information that voltage does not carry across a cell and it's immune to dielectric breakdown someone shoot me and put me out of my miserey because I'm banging my head on a wall by here ?
The most I can find is 700vdc pack with 20ah lithuim iron phosphate cells in a 170s pack, so is this the safe practical limit ? Ask yourself where is the limit trust me 1 gazillion volts aint happening even with one meter terminal gaps it will jump through the cells internal insulator when its brake down voltage is reached due to forward voltage across the cell due to being in a series string and part of a chain it's dealing with more voltage than it can produce on its own surely that makes sence to you?
Ianhill said:So how does the voltage before the cell make it to the otherside amplified ? It enters through the electrode and out the otherside so across the single cell with a meter reads the 4.2v but from the start of the pack to that point there full voltage minus 1 cell so that voltage is the forward voltage that cell is handling.
Addy said:[ and each individual cell doesn't see anything besides it's own terminal voltage.
ElectricGod said:It's just additive voltage...
cell1+cell2+cell3 = total pack voltage
That does not mean that cell1 in circuit "sees" the voltage of cell 2 and 3. It only sees it's own voltage...assuming that there is no other current path. That's why I said there had to be other mitigating circumstances that caused cells to run down.
It's those other current paths like the shells on those 9v batteries popping tiny arcs back and forth that are a problem. That guy in the video was lucky that none of his batteries had bad internal insulation or that two that did were no where near each other in the whole bank or else he would have gotten a nice big spark like he did with the alligator clip.
rainmaking said:I'm sure sorry I brought up the Tesla charge connector....now it appears I don't even know what the difference between salt and rain water is even when I state it's a completely different environment. BTW Tesla is likely using 400V because it is inconvenient to boost high current charge voltages higher than what you get rectified from 240VAC. The prius uses up to 700VDC in its drivetrain. Tesla batteries are split into 24V modules that are series'd together. the car could quite possibly get submerged in saltwater and the occupants will be isolated from the major current flow even if they are touching the saltwater.
In my case I think it would be counter productive to pot each cell top. I think in the catastrophic event of sinking with a simultaneous battery enclosure failure that I would want the cells to have every path possible to discharge. Keep in mind the entire outside of the jet ski is fiberglass, i.e. non conductive. the drive shaft and some control wires are the only conductive things that penetrate the enclosure. I will consider how to protect these items from transmitting high voltages outside the ski hull but I am not going to consider potting the entire pack. There is an electric jet ski on the market as are quite a number of maritime energy solutions in this voltage range.
ElectricGod said:rainmaking said:I'm sure sorry I brought up the Tesla charge connector....now it appears I don't even know what the difference between salt and rain water is even when I state it's a completely different environment. BTW Tesla is likely using 400V because it is inconvenient to boost high current charge voltages higher than what you get rectified from 240VAC. The prius uses up to 700VDC in its drivetrain. Tesla batteries are split into 24V modules that are series'd together. the car could quite possibly get submerged in saltwater and the occupants will be isolated from the major current flow even if they are touching the saltwater.
In my case I think it would be counter productive to pot each cell top. I think in the catastrophic event of sinking with a simultaneous battery enclosure failure that I would want the cells to have every path possible to discharge. Keep in mind the entire outside of the jet ski is fiberglass, i.e. non conductive. the drive shaft and some control wires are the only conductive things that penetrate the enclosure. I will consider how to protect these items from transmitting high voltages outside the ski hull but I am not going to consider potting the entire pack. There is an electric jet ski on the market as are quite a number of maritime energy solutions in this voltage range.
Is 240 volts AC rectified 400 volts DC? I don't honestly know...Id' have to go google that, but if it is then yeah that would 100% explain the 400 volt typical voltage for electric cars. Hybrids don't count. You don't charge the battery off your AC mains. You charge them off a purpose built generator incorporated into the car. IE: Prius which is a total POS in my opinion can run at any battery voltage Toyota chooses. Anytime you boost voltage whether that's with a giant transformer or via a step up switching power supply, you are always trading current for more voltage. When you step down voltage, you also gain current. Since your AC mains are typically a couple hundred amps, it is logical that Tesla would try to take advantage of that fact with as minimal losses as possible. They would want to rectify the AC mains directly to DC and then not mess with it much other than to manage current loads so that they don't overheat your mains wires or blow your main breaker at your meter.
Tesla splits up their packs into chunks for really good reasons. Each chunk can be individually replaced if it goes bad. Those chunks are the basic building block for any capacity or voltage they could ever want to build. Tesla has some pretty smart folks working there. They tend to think of this sort of thing.
Potting...yeah not the critical element, just keep inside that pack uber dry and make sure there is no chance of a current path into the water. How do you suppose people get electrocuted by their blow drier when they are in the bathtub? It's the voltage potential in the blow drier traveling to a lower voltage potential that happens to also pass through the person. In the case of your jet ski, you have 800 volts at a zillion amps potential spreading outwards in every direction that happens to include you and anyone else nearby in the water. Zap...your are dead...just don't let that happen.
You would want a way to vent gasses out of the battery box, but you absolutely do not want water penetration...water = corrosion = bad. I would not trust the jest ski hull to be my only insulator from all that voltage. I bet the commercially available units don't either! I want to live long enough to ride my electric beast more than once! There's nothing wrong with an electric jet ski...it just has implications to work out.
ElectricGod said:Is 240 volts AC rectified 400 volts DC? I don't honestly know...
If you blow a cell in that situation, you will need an ejector seat !.....Venting needs investigation. I would want a gore vent on it to minimize humidity. Also need to vent a blown cell without enclosure failure. Like a pressure relief valve but a pretty low pressure.