Contactors Question

[Domt177]

Quick question about contactors.

My current understanding is that you have 1 positive contactor on the main positive cable coming out of the battery, before your DC-DC, or Motor Controller (GS450H Inverter in my case)

Then a Negative contactor, with the same idea, on the main negative that comes from the battery before anything else

Then a charging contactor which goes on the positive cable coming from the charger to the positive battery connector for charging (this one is called the pre-charge contactor right?)

A) is my understanding correct?

B) can these all be the same make and model of contactor?

[DaveH]

Not quite, the pre-charge contactor is in parallel with the positive one but with a resistor in series as well. This is to limit the inrush current to the capacitors in the inverter (hence pre-charge). Once the capacitors are charged, you can close the main contactor to allow the full motor current through. The pre-charge contactor can be smaller than the others because it only has to handle a small amount of current, but you can use the same one as the others if you want.

[New Electric Ireland]

Then a charging contactor which goes on the positive cable coming from the charger to the positive battery connector for charging (this one is called the pre-charge contactor right?)

We don't recommend installing a separate contactor for charging but rather install the charger/dcdc/inverter/other loads after the two main battery contactors. This diagram shows you the approach that we (and Damien) take;

viewtopic.php?f=14&t=396&p=12105#p12105

Note that we often add a third contactor in the 'middle' of the battery if it's split into two separate packs (front and rear for example). We also fit a crash sensor (fuel cutoff switch) in the 12V contactor power supply to ensure that the battery is isolated in a crash.

[ZooKeeper]

That is a VERY nice diagram!

[Domt177]

Thanks for the useful response, now understand it. Just wondering what the economizers are for in contractors and what are they needed for

Thanks

[Bratitude]

Thanks for the useful response, now understand it. Just wondering what the economizers are for in contractors and what are they needed for

Thanks

A economizer is a current limiting device. Some contractors have them built in, many don’t.

the coils inside a contractor require a certain amount of current to switch on, but generally need much less to hold on. With nothing to stop the contractors coil from drawing as much current as they like, the contractors coil would begin to over heat.

a economizer takes care of this. It allows proper control of the contactor, but without the over heating. this might be a PWM signal, or very a curd high wattage resistor and capacitor wired together in parallel. With that wired in series with the contactor.

Definitely an area that needs more coverage and examples, because a burnt out or improperly controlled contactor could be a very expansive mistake or a safety issue.

[arber333]

A economizer is a current limiting device. Some contractors have them built in, many don’t.

Tyco Kilovac EV200 usually has those mounted and it provides a really good contactor control. Initial coil draw 12V is over 3A! But immediately it drops to somewhere around 0.22A which is like 1/2 of draw of bare contactors even more.

I never tried cap and resistor before. What would be the ratio?

[Bratitude]

A economizer is a current limiting device. Some contractors have them built in, many don’t.

Tyco Kilovac EV200 usually has those mounted and it provides a really good contactor control. Initial coil draw 12V is over 3A! But immediately it drops to somewhere around 0.22A which is like 1/2 of draw of bare contactors even more.

I never tried cap and resistor before. What would be the ratio?

Yeah they are great, unfortunately I got the Tesla ones with out them

Resistor and cap method is pretty inefficient, your just dumping the current into heat off the resistor. cap would be chosen off then inrush current requirements of the coil.

[mackoffgrid]

I actually had an intermittent contact problem with an EV200 - they were second hand after all . I wanted to know more of their current requirements so I did a little investigation.

Initial coil draw 12V is over 3A! But immediately it drops to somewhere around 0.22A which is like 1/2 of draw of bare contactors even more.

It actually drops to around 1/20th !!

you can check out my results https://github.com/mackelec/SolarUte/tr ... 0contactor

[Bratitude]

One thing I’m concerned about with finding the minimal hold current/voltage is that hose numbers don’t relate to the “real” environment they are used in. cars drive in non smooth surfaces. a insufficient hold current, the contractor could “jump” /disconnect if u hit a bump.

Referring to data sheets as much as possible, but being we all salvage oem parts...

[New Electric Ireland]

Has anyone tried measuring what the OEM is doing with their driver circuit?

[mackoffgrid]

cars drive in non smooth surfaces. a insufficient hold current, the contractor could “jump” /disconnect if u hit a bump.

I have also worried about his, especially since some of the roads I have to use would shake your fillings (dental) out

I agree, the economiser on the EV200 may end up being too aggressive in it's power saving. With no economiser the EV200 get's too warm. As seen from my Scope shots, the economiser runs, although variable, at about 20 to 25% duty cycle, resulting in the rms current of around ~120 mA. I would think that an increase in Irms to say 500mA would be a good compromise.

The LEM200 has a higher coil resistance ( about 1 Amp) and may not need so much power saving.

Other brands like Panasonic don't seem to need economisers.

[celeron55]

I think this begs the question, has anyone actually burned any EV200s or inverters connected to them on bad roads? I certainly haven't heard of it. The datasheet specifies 20G shock and vibration, which is quite a lot.

[New Electric Ireland]

I think this begs the question, has anyone actually burned any EV200s or inverters connected to them on bad roads?

Do you mean when used in the OEM vehicle or DIY conversions? If DIY then I suspect the number in regular use on the road is tiny.

[mackoffgrid]

I think this begs the question, has anyone actually burned any EV200s or inverters connected to them on bad roads? I certainly haven't heard of it. The datasheet specifies 20G shock and vibration, which is quite a lot.

I have updated my results to include hold up voltage with out the economiser.

EV200 Results

I hope the G force specs are "with Economiser" - As seen by the results the drop out voltage is significantly higher for the "with Economiser".

The economiser is more sophisticated than a mere '555 PWM" device. I observed the duty cycle changing and I believe it is trying to manage current, as it should. Drop out is quick though so our control circuit must be sufficient to not sag/spike low.

[Bratitude]

I think this begs the question, has anyone actually burned any EV200s or inverters connected to them on bad roads? I certainly haven't heard of it. The datasheet specifies 20G shock and vibration, which is quite a lot.

my concern is more inline with self built economizers. if no data sheet is available, and I do some bench testing to find a low hold current.... how do I know that it’s actually the correct amount to keep the contactor in spec?

my brat build is will be driven 60-70% of the time “off road” So far that’s been a pretty rare project type for ev conversion.

[New Electric Ireland]

my brat build is will be driven 60-70% of the time “off road” So far that’s been a pretty rare project type for ev conversion.

We did some work on a rally car and all the components were tested in a vibration chamber. Maybe you could improvise something similar?

[arber333]

my concern is more inline with self built economizers. if no data sheet is available, and I do some bench testing to find a low hold current.... how do I know that it’s actually the correct amount to keep the contactor in spec?

my brat build is will be driven 60-70% of the time “off road” So far that’s been a pretty rare project type for ev conversion.

I think EV200 will be fine with your application. I have bought several EV200 from Israeli military applications ... never had an issue.
You could mount it in such a way to cancel out the G force influence...