Newb Asks: How can a 120 amp Contactor carry more current?

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Newb Asks: How can a 120 amp Contactor carry more current?

Post by Gregski »

forgive me if this belongs in the Getting Started sub forum

I recently tore into bits the BMW 530e Safety Box (ie pre charge circuit container) and found two Panasonic AEV14012 Relays/Contactors call them what you will rated at 400 volts (I'm fine with this spec) but only 120 amps, if I am reading the specs correctly on Digi-Key

I realize there is a big Info on BMW hybrid battery packs? thread and the answer may be buried in it somewheres, but this is more of a general learn me something question. How can this be? I know gals are pulling more current in their conversions than 120 amps through these contactors, upwards of twice as much (think pairing them up with the Lexus GS450h transmotor). So what prevents these from arcing or welding themselves shut? Please take it easy in your explanation as I am a total novice and any time I think I know something I get [ahem] a little shocked.






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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by Gregski »

may be answering my own question here, but I think it's a good exercise and still hope to have someone else chime in

SPECIFICATION per Panasonic's Website

Item - - - - - Performance characteristics

Terminal Type Screw terminal
Coil Terminal Structure Connector
Rated Coil Voltage 12V DC
Contact Capacity 120 A
Protective Construction Capsule contact
Operating Function Single side stable
Operate (Set) Voltage (at20°C) (Initial) Max. 9 V DC
Release (Reset) voltage (at20°C) (Initial) Min. 1 V DC
Rated Operating Current [±10%] (at 20°C) 0.353 A
Coil Resistance (At 20oC) 34Ω
Rated Operating Power (at 20°C) 4.2 W
Max. applied voltage 16V DC
Contact Arrangement 1 Form A
Contact Material Copper alloy
Nominal Switching Capacity (Resistive Load) 120A 450V DC (Carry, 38mm2 wire)

Max. Carring Current 120A Continuity
225A 3 min.
400A 30 sec. (38mm2 wire)


Min. Switching Load (Resistive) 1A 12V DC (at 20°C)
Contact Voltage Drop (Initial) Max. 0.03 V (by voltage drop 6 V DC 20 A)
Insulation Resistance (Min. MΩ)(Initial) Min. 100 MΩ (At 500 V DC, Measured portion is the same as the case of dielectric strength.)
Dielectric Strength (Between Open Contacts) (Initial) 2,500 Vrms for 1min. (detection current: 10mA.)
Dielectric Strength (Between Contacts and Coil) (Initial) 2,500 Vrms for 1min. (detection current: 10mA.)
Operate (Set) Time
(At Rated Coil Voltage) (At 20oC) (Initial) Max. 50 ms (without bounce)
Release (Reset) Time
(at Rated Coil Voltage) (at 20°C) (Initial) Max. 30 ms (with no coil protective elements)
Shock Resistance: Functional For ON: Min. 196 m/s2 (half-sine shock pulse: 11 ms, detection time: 10 µs)
For OFF: Min. 98 m/s2 (half-sine shock pulse: 11 ms, detection time: 10 µs)
Shock Resistance: Destructive Min. 490 m/s2 (half-sine shock pulse: 6 ms)
Vibration Resistance: Functional 10 to 200 Hz, 43 m/s2 (detection time: 10 µs)
Vibration Resistance: Destructive 10 to 200 Hz, 43 m/s2 (Time of vibration for each direction; X, Y, Z direction: 4 hours)
Expected Life: Mechanical Life Min. 2 x 105
Expected Life: Electrical Life (Resistive) 30A 450V DC, Min. 1,000 operations
Expected Life: Switch-Off Life [Forward direction]:
1,200 A 300 V DC, Min. 1 cycle
120 A 450 V DC, Min. 50 operations
[Reverse direction]: -120 A 200 V DC, Min. 50 operations
Expected Life: Inrush Current (Capacitor) 120 A 20 V DC, Min. 70,000 operations
Conditions Ambient temperature: –40 to +80°C
Humidity: 5 to 85% R.H. (Avoid icing when using at temperatures lower than 0°C.)
Weight (Typ.) Approx. 400 g
Inner Carton (Pieces) 1
Outer Carton (Pieces) 20
Usable Voltage Range 10 V DC to 16 V DC
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by Bigpie »

I wouldn't use those contactors, I've welded one, as have quite a few others, then killed my inverter when I turned it back on.
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by Gregski »

Bigpie wrote: Mon Feb 07, 2022 5:32 pm I wouldn't use those contactors, I've welded one, as have quite a few others, then killed my inverter when I turned it back on.
thanks for sharing that, I stumbled upon similar form factor contactors part # AEV6505A in the Nissan Leaf and I think they are rated with more better specs, and if I choose to use the stock BMW safety box may fit right in, though I can't find any actual specs on these, and the parts ID key doesn't seem to apply

found this interesting thread on taking one apart: Taking apart the Nissan contactor (Panasonic AEV6505A)
Leaf Pre Charge.jpg
Panasonic Part ID Key.jpg
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by celeron55 »

You can't use these contactors as an active safety item in a DIY conversion as they are unable to cut the currents we use. When the precharge works perfectly and you never switch off a contactor under load, as in their original carefully controlled and tested OEM application, they work fine. In a DIY application you want to be able to cut motor power using the contactors if your car goes crazy, and at the least you might set your precharge timing slighly off which may weld these.

For these reasons you should be looking at something beefier like EV200 or GV200 unless you have a specific reason not to.
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by Gregski »

thank you, I just picked these LEV200 A4NAF part # 1618387-5 up on eBay, $30 bones each I could not pass that up, I know nothing about contactors, aside from the fact that Kilovac ones are good, welcome any thoughts

LEV200 = 500+ Amp

12-900VDC Contactor
IMG_8442.JPG
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LEV200 Series Data Sheet.pdf
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by EV_Builder »

Maybe old thread, but don't forget that those contactors may need some form of economizer...
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by joeflickers »

celeron55 wrote: Mon Feb 07, 2022 7:23 pm You can't use these contactors as an active safety item in a DIY conversion as they are unable to cut the currents we use. When the precharge works perfectly and you never switch off a contactor under load, as in their original carefully controlled and tested OEM application, they work fine. In a DIY application you want to be able to cut motor power using the contactors if your car goes crazy, and at the least you might set your precharge timing slighly off which may weld these.

For these reasons you should be looking at something beefier like EV200 or GV200 unless you have a specific reason not to.
I can confirm this as true as I have so far welded shut 4 passonic leaf contacors even with they original precharge.. Load were below 300amps running gs450h.
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by johu »

As always I want to tip the scale to the "good enough" side. Now that all the modes of closing contactors without precharging are known to me I haven't welded them Nissan relays since.

Cutting power to your inverter stops any torque generation just as well as we're all using AC nowadays. LEV200 is rated ONE full load disconnect so you're back a the dilemma "should I really emergency stop and kill parts of my components?" (and be stuck at the side of the road)

That's why back in the day when my FOC ran away I decided NOT to turn that ignition key but stomp on the brakes instead. Would have made the same decision with LEVs in place.

Apart from that I'm not concerned about the continuous rating of drive contactors in road use but more about the continuous rating of charge port contactors as they carry high current for a longer time.

EDIT: haha, resurrection after 1 year :) oh well
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by Gregski »

johu wrote: Wed Feb 14, 2024 8:33 pm EDIT: haha, resurrection after 1 year :) oh well
indeed, that was my take away also, Young Padawans ?
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Re: Newb Asks: How can a 120 amp Contactor carry more current?

Post by MattsAwesomeStuff »

I posted about this a bit on the DIY EC forums.

Because you can buy EV200 contactors from batteryhookup.com for $12.50 (Christmas sale), I was figuring that was so damned cheap I'd just use them for almost everything I'd need switched rather than go with some elegant solution. Some people were pooh poohing using a physical contactor rather than a solid state relay, and I asked what I should buy instead that's even in the same price ballpark, but got silence.

Here's the charts...
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1706136054373.png
They're spec'd for 500A continuous, but 2000A interrupt ONCE.

A 4000w heater or A/C at 200v would be 20A, and would be off-the-chart 100,000+ cycles. Perhaps 300,000 or so. Getting pretty close to the mechanical life anyways (springs/levers wearing out around the same time as the pads).

Otherwise, the chart's there to make a decision on the lifecycle of the contacts.
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