Safe, Reliable,100V+ Battery Switch + Precharge +

[megacycle]

I was looking at getting a higher voltage controller running about 132V and looking at precharge setups and battery power out protection like fuses and being, primarily, electrical background and not so much electronics, i came up with a set up i hope can be a major improvement on the non standard kinda adhoc set ups for high energy and voltage set ups capable of delivering major KF.
Most precharge arrangements, for low energy bikes, like <100V and <100A, use an arrangement with two leads, one large fused main lead and smaller precharge lead with an in-line power resistor and with or without a switch.

Most are then covered in heatshrink sleeving and tape to stop them shorting out during and after prechage.

I was thinking for my higher voltage/amps setup this might expose me to worse cases of KF than this

and more chance of shock in the wet and fires from shorted controllers and incorrect fuse types.
There's quite a few guys using circuit breakers and i had a few solar polarised ones lying around, just hanging for an app like this.

Theres quite a lot available, now domestic solar install has made them common place.
They can be had for sub $10 US, this can be cheaper than an equivalent fuse at 80V+ ratings.
The circuit breaker has about 2 minus points and about 10 plus points for it in comparison to the equivalent fuse.
One of those plus points no often promoted is it is capable of being coupled to ancillary devices to control it.
One of these devices is called a shunt trip release, which could be got for around $10 and basically can make the mcb trip off remotely, like a contactor,except you have to turn the breaker on again.
This can enable the mcb to act with a precharge scheme and also possibly protecting a controller and its wiring from further short circuit damage, as the main power is then interlocked off.

 

[geeeyejo1]

Man - what caused the carbon on your hand??? I have that type of precharge set up for my 48V kit and works very well - When I connect the main battery lead there is just a very small spark if any - seems to do its job!

 

[megacycle]

Not my hand brother, someone else as an example, ive had nice carbon covered fingers with my 72V setup though.
Wanting to go big league and hearing about some off the power control setups some guys have got, makes me wonder.

 

[hydro-one]

yeah watch out , flash burns from electric arcs. ive been lucky and very careful since this!!

http://endless-sphere.com/forums/viewtopic.php?f=2&t=31627

every time i go to plug something in now i double think.

 

[megacycle]

Man that be a major KF incident.
Hope your all good now, been a while since?
Yeh bet you get the shakes before connecting packs now.

Yeh i'm all for stopping these kinda of issues with gear as shown.
The chance of that happing, if there was an mcb, in line, in one of the packs would have been vitually zero, at the most, having to replace your connectors, but even then that would have been a bad beer day or stupidity, leaving the breaker switched on.
Ok, now you have your 100V pack with breaker sitting on the battery, in the off position.
Plug your pack like i think, a shorted ring and normally, all hell breaks loose, giving you an instant 400-500A from a good, fully charged 1S and double that from a 2P and now higher voltage driving a higher energy, longer arc, time to seperation.
Ok your mates pack, even with an auto fuse, waiting for big let through, the auto fuse if you were lucky that it was used and blew, like bang, might try to sustain it due to clearances in the fuse being non existant at 150V+, it will plasma jump the 5mm gap created and try and burn anything around it, till lucky it carbonises out or burns pack to the ground.
Ok our mcb, the 2nd level of protection,inside it, for short circuit faults using the electromagnet effect of the huge overcurrent clicks it off in mS.
Time being related to the energy in the fault, its suddenly reduced to a fraction of the original fault value, with the powerfull dc arc broke up into sections and magnetically sucked into them.
Essentially if you didnt know how the mcb worked you would think it was busted and try latch it again and again.
It will just go click, click and if you listen pop, pop, thats the fault arc clearing, without burning your fingers off.

 

[ZOMGVTEK]

Another option is to simply never disconnect the pack. I didn't disconnect mine in at least a year. I have precharge, and dual main leads. One can be used to discharge while one charges, they both go the same place.

I also consider my 10 gauge wire to be the fuse, so my opinion might not be relevant.

 

[megacycle]

How you going with 5404 on your ride?
Sweet looking machine, last time i looked in.

As an overview of the issue, this area is were electronics and full blown electrical meet.
We leave small electrical problems behind and can get burnt like 'hydro-one' did above, besides blowing your wiring and vapourising connectors, setting fire to packs due to inferior fuses and their connection arrangements, thats another couple of plusses covered, as referred to.

Is your precharge permanetly connected?
What happens when you need to mod or change stuff.
How do you indicate a fault in the wiring or controller your connecting to.
Senario, connect precharge following mod, the resistor not heating more than usual, because its a big watter, connect the main lead and BANG, short somewhere outgoing on the big 4awg.
Thats why i was thinking interlocking. An led at least might be able to indicate end of precharge, but you could still think your safe if you havnt got test gear stopped off out somewhere and think all good, BANG.
If you at least use an mcb, that issue will never arise, as youve not got your hand in a fault path and for $10 for a dc mcb, when your $10 fuse let that fault still leave with :? and still got carbon on you due to its let through, because you have to have a big 100A to deal with all events, instead of a 32-40A dc mcb, giving you much tighter short circuit protect and everthing else it does besides
By the way i know the 10awg isnt in your main line, is it?

 

[megacycle]

Is 10awg melting point 333A starting@approx 30deg ambient?