Pre charge (arc suppression)

Sean

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Oct 8, 2016
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Nearly all projects on here will need it, some much more than others.

How are you doing it ?


image_slwslc.jpg


I'm using theLeafs contactor pack complete, twin high amp DC relays, single low amp relay for precharge resistor, all withina compact form.


image_vtijjz.jpg
 

Redpacket

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Feb 28, 2018
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I'm doing it a similar way to your diagram, eg I have 2x 2.2 ohm 10W resistors in parallel to a 10A rated DC breaker as my pre-charge system for the inverter & MPPTs.
I have fuse disconnects instead of contactors :)
For all other electronics incl several step-down converters I have in-rush limiting NTC devices, works nicely.
 

Sean

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Oct 8, 2016
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Some notes for anyone wanting to use the Leaf BMS harness and connectors (based on a second gen pack) the image above is first gen.

Relay A coil - 12v DC non polarised, 370mA coil - brown/grey & white/grey (from harness) blue & orange (internal)
Relay B coil - 12v DC non polarised, 370mA coil - light green/grey & grey/grey (from harness) purple & yellow (internal)
Relay C coil - 12v DC non polarised, 120mA coil - green/grey & blue/grey (from harness) red & brown (internal)

Relays A/B are buss connects, relay C is for the 30 ohm 40 watt precharge resistor.

The current flow on the switched contacts is directional(overlook this at your own peril)


image_isomyx.jpg

image_nknvjc.jpg
 

Sean

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Oct 8, 2016
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Redpacket said:
I have fuse disconnects instead of contactors :)

I need to be able to disconnect the pack entirely, automatically - under full load if needed.

Shunt trips handle the AC side breaking and tripped signalling.
 

wim

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Apr 6, 2017
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I use aABB fuse/Circuit breaker with shunt trip (suitablefor DC).

Not a big fan for relais or contactors, they tend to get stuck in the "on" position when activiated for months without switching.
I beleave the contactors in a EV switch off when the contact is off, so they toggle often,while in a powerwall type ofsetup, they will only switch off if there is a critical event. ( so in best case never ;))

Only kind of downsidewith the shunt trip activated breakers is, there is no way to "remotereset" them onceactivated ... they have to be manual re-activated, in my mind this is not a negative thing but a plus for safety...
 

Sean

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Oct 8, 2016
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946
wim said:
I use aABB fuse/Circuit breaker with shunt trip (suitablefor DC).

Not a big fan for relais or contactors, they tend to get stuck in the "on" position when activiated for months without switching.
I beleave the contactors in a EV switch off when the contact is off, so they toggle often,while in a powerwall type ofsetup, they will only switch off if there is a critical event. ( so in best case never ;))

Only kind of downsidewith the shunt trip activated breakers is, there is no way to "remotereset" them onceactivated ... they have to be manual re-activated, in my mind this is not a negative thing but a plus for safety...

I've got a few points of isolation, those EV relays are sealed hydrogen filled types, they'll stand abuse.

I agree 're the shunts, but likely there's something amiss to be attended to anyway if they do trip.
 

Redpacket

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Feb 28, 2018
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Agree big breaker with shunt disconnect is good - unfortunately my Batrium system isn't stable due to issues with the cellmons when they do any bypassing. Even a few 100 mA, a few deg C rise & they loose comms & the system reports a critical fault.
I have 64 cellmons (32 are BlockMons, 32 are LongMons) so if any one is acting up, a shunt trip would do it's thing & trip.
I'd be living in a disco + the Wife Acceptance Factor would be lost!

I've been in discussions with batrium, but as others have said they seem pretty overloaded.


Sean said:
Relays A/B are buss connects, relay C is for the 30 ohm 40 watt precharge resistor.
Interested in the value/rating of this - do the Leaf's normally have a high voltage pack?
 
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