The link I posted is the second half of the video with the DC side. The first half is the AC side. They do both.
LiFePO4 prismatic cell short circuit current and main circuit protection
- Thread starter sduser
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The link I posted is the second half of the video with the DC side. The first half is the AC side. They do both.
pablo fiasco
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Looked like the labels said 220V. I assumed that was AC. Maybe I wasn't paying close attention. Wouldn't be the first time.
I don't know what happened. The first time I watched it I saw only DC, then when I watched it again I saw the alligator clip get switched between AC and DC. I was confused (and felt cheated!) the first time I watched it.
pablo fiasco
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I have a long history of thinking for myself. To me right and wrong and win and lose are not the point of the game. I have never had a flu shot - or the flu. Never worn a helmet and I have cycle toured Europe. Only wear a seat belt when I think there might be a cop in the bushes. You're right right right. 1000% right. I'm 72 and I've just seen so much silly 'good' advice. I listen to advice and decide for myself whether to take it or leave it. Blind obedience to the Class-T dictate rubs my fur the wrong way. For better of for worse.
I hear ya. When I tell someone that the general recommendation is to use a Class T fuse downstream of the battery/BMS, I hope they don't ask why. I just know it's the best type of fuse to put in there. Now I'll add that it has the highest AIC rating.
And I can tell I'm rubbing you the wrong way, despite me saying "The safest configuration" vs. saying "you must use ..." I always try to present the evidence and use words that leave the choice to you.
TBH the thing that rubs *me* the wrong way is when someone contradicts long-term industry best practices without evidence. You're fine to run the risk yourself, but stating publicly here that it's safe only passes the risk on to everyone else who reads it and blindly listens to that advice. We all have just as much responsibility with our statements as do the vendors.
I hope that makes sense -- I'm not angry or flaming you but I think it's important to have an open and honest discussion about what's happening here. Thank you!
- Ben
pablo fiasco
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-I would never advise anyone to follow my example. If I gave that impression I'm sorry. But as to expert advice and codes and all let me tell you a true story. As best I can remember it.
- Many years ago I knew a man who had a house wherein he rented rooms. That put him under scrutiny form authorities. One year they inspected and said he needed to install smoke alarms. Gave him particulars. He did what he was told. They were battery powered. 5 years later in the next inspection they told him they were no longer acceptable and he needed to change them out for grid powered one. Fine. He did. Another 5 years go by and they come along and tell him that code now says he has to go back to battery powered detectors.
- You see my point? Let me ask you this: what if you woke up tomorrow and were told 1 Class-T wasn't enough? Code now says you need 3 in series to be safe. How blindly will you follow expert advice?
Oh, yeah I don't equate following a building inspector with following experts or specs
Now, obviously I don't know what happened in the case above (inspectors can be misguided), but I think we should also allow room for things like this because we as a society have learned something. The NEC is regularly updated because we learn stuff. We can only do what we currently know to do. 100 years from now people will look back at us and laugh. That's OK.
Thanks for indulging me
pablo fiasco
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Like Marilyn Monroe said, "Better sorry than safe". Consider yourself indulged.Oh, yeah I don't equate following a building inspector with following experts or specs
Now, obviously I don't know what happened in the case above (inspectors can be misguided), but I think we should also allow room for things like this because we as a society have learned something. The NEC is regularly updated because we learn stuff. We can only do what we currently know to do. 100 years from now people will look back at us and laugh. That's OK.
Thanks for indulging me
ArthurEld
Solar Wizard
I'm pretty sure you could take a battery cable and connected to the terminal of a 280Ah cell. Clamp on to a welding rod with the battery cable and touch it to the other terminal. ? You'd get some welding action from 3.4V.
pablo fiasco
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I guess it depends on how you define welding. Sparks or a puddle. Anyway, fly at it. Post a video.
curiouscarbon
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ok, is anyone familiar with the concept of a FET/capacitor array used in conjunction with contactor/relay and current sensing?
a digital arc arrestor
using a resistance vs time model of a given contactor
current sense indicates over current condition. capacitors are at 0V and FET array drivers engage. current flows into the capacitors.
the contactor coil is disengaged with timing such that the capacitors have peak inrush current at or slightly before the arc is expected to have formed.
when the contactor is fully open, disengage FETs and bleed off charge with big resistors
any device being sold that does this?
like a SiC array with a bunch of good heatsinks and ultra caps or something.
eg this SiC MOSFET and this 3400F supercap
a digital arc arrestor
using a resistance vs time model of a given contactor
current sense indicates over current condition. capacitors are at 0V and FET array drivers engage. current flows into the capacitors.
the contactor coil is disengaged with timing such that the capacitors have peak inrush current at or slightly before the arc is expected to have formed.
when the contactor is fully open, disengage FETs and bleed off charge with big resistors
any device being sold that does this?
like a SiC array with a bunch of good heatsinks and ultra caps or something.
eg this SiC MOSFET and this 3400F supercap
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ArthurEld
Solar Wizard
If you do it long enough the terminal will melt off. I didn't say it would be a pretty weld.
Sadly my cell welding experience wasn't caught on film. I shorted 24V with a 1/4 ratchet and socket.
It was worthy of film.
ArthurEld
Solar Wizard
I spend a lot of time thinking about the time I accidentally shorted my battery.
And I never could figure out what I touched to cause the short.
Now I realize you don't have to touch anything. You can have an arch more than 1" long.
When I saw a flash and heard the noise it freaked me out and I dropped my 1/4" ratchet with a deep socket.
I thought the deep socket was enough to keep me away from everything.
It kept sparking for what seemed like a long time. So, I grabbed the wrench and pulled it off.
Another thing the confused the hell out of me was that the socket stayed connected. I dropped the wrench so how could the deep socket stay on the nut and the handle reach all the way down and touch the other busbar?
The socket didn't have to stay on the nut and the handle didn't have to touch the other busbar. They just needed to stay within an inch or two because of the archs.
@AussieInSeattle said he was using an insulated wrench that had a little piece that was uncovered. He probably got bit by the arch too.
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Wrap them in masking tape as needed. Temporary insulation is fine. I'm not going to buy dedicated sockets just for working around my batteries.
Yeah, that’s wise. I figured I’d use them whenever I had my torso jammed into some hole shared by electrical where it’s hard to maneuver, just to avoid damaging anything. Particularly when working on friends stuff…
ArthurEld
Solar Wizard
Electrical tape works good if you don't mind gumming up your tool. Two layers in some spots.
One day I put my wedding ring between a terminal and my BMS and it shocked me. The space between the two was bigger than my ring.
I don't wear my ring anymore.
One day I put my wedding ring between a terminal and my BMS and it shocked me. The space between the two was bigger than my ring.
I don't wear my ring anymore.
Silicone rings are great for folks that work around electricity.
I'm starting to see a pattern here, maybe it's your body chemistry?
I'm starting to see a pattern here, maybe it's your body chemistry?
What? A shock through the wedding ring isn't a good way to rev up the romance? Let me show you my shocked face. It's around here somewhere...
Fuses between each cell would be the equivalent of disconnecting any of the BMS leads -- many BMS'es would be destroyed by doing this.
Do we need to worry about this with connecting two 100ah Battleborn batteries? Where would we put the fuse there?
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