SSR testing

[Cal]

Steve, to clarify, do they conduct when connected in reverse, even when "coil" is de-energized, or are they open when connected in reverse, even when "coil" is energized?

If the SSR uses a P-channel MOSFET then there's an inherent diode from drain (anode) to source. That means if you reverse the polarity to the SSR, current will flow through the body diode. It won't take much current before the device burns up.

You should be able to test if there's just a diode between the load and power terminals. Connect multimeter, (setting to ohm/diode) with positive lead on load terminal and neg lead on power terminal. You'll get a 0.7V reading if a diode is present.

I think searching for a 200A SSR is asking too much. There are more efficient ways to disconnect a 150A load (inverter). I'm pursuing a low current SSR. My loads consist of a 2500W inverter and other loads which are less than 8A. A 20A SSR is more than adequate. I got some mosfets on order and will see about putting together a switch. Reference my previous post.

 

[Craig]

I was planning on writing something up last night but both my cellular and home internet were down. Im beginning to think that using any sort of larger relay to cut the load will be unpractical. But eoither shutting off ac load or switching the inverter via a remote switch controlled by an SSR would be way easier and more efficient. tonight I wll make a post listing all the possible ways to achieve these things.

 

[Pacer]

I was planning on writing something up last night but both my cellular and home internet were down. Im beginning to think that using any sort of larger relay to cut the load will be unpractical. But eoither shutting off ac load or switching the inverter via a remote switch controlled by an SSR would be way easier and more efficient. tonight I wll make a post listing all the possible ways to achieve these things.

Craig- anxiously awaiting your findings! Thank you.

 

[cass3825]

So, as I go back and forth between relays and SSRs with an inverter/charger, while wanting individual Charge & Discharge protection, I had the following idea:

Working left to right, the RC network in series with the relay coils is to lower the holding current of the coils, with flyback diodes in parallel. Pretty straightforward so far. The NO relay contacts are wired in series, which is the current path when both permissives are energized. And now the interesting part... place a 40A diode in parallel with each relay contact such that the All-In-One inverter can still draw power from the battery if the charge permissive is lost, , or it can still charge the battery if the discharge permissive is lost. Lastly, the resistor in parallel with both relay contacts is to precharge the inverter caps.

Feel free to shoot holes in this approach! Any feedback appreciated...

 

[bdbugbee]

RE: 500 amp DC Relay. Nice looking lower cost deal and option. I saw the new ones too. I wonder what the amp draw is on trigger coil is for the 500 amp rated Relay. Looked for it in eBay description, but nothing found. If you test amp draw of coil/ watts used when contacts are closed ... Interested here, while most likely going the SSR way.

I just ordered a used TE Contactor on eBay to go with my Chargery BMS8T. Looks like the best option available to me right now for my 8-280ah LiFEPO4 battery build.

 

[Capt Bill]

Hey Bill, doesnt that LV2424 have a manual toggle switch for the inverter? I'll bet that switch is already connected to a relay.

My most resent study of manual has be currently believing the that switch is for everything/ as in whole unit. It on the bottom of LV2424 unit I obtained from MPP eBay supplier. I could be wrong, and will look a little closer. I know Will did a clip of slicing in an Occicouple SSR for turning off the inverter in a similar All In One (or looked that way); but I believe that was a different model with an inverter switch on side of unit. If I learn I was wrong in my current belief, I post about it. Non of my belief are black and white, and I use wondering as part of my learning more all the time curve.

 

[BiduleOhm]

@cass3825 You'll probably want to use ideal diodes (mosfets) for the high power diodes as otherwise you'll be dissipating a lot of power, even with schottky diodes.

NB: 1N4007 would be a lot more robust than 1N4148 for the flyback diodes

 

[cass3825]

@cass3825 You'll probably want to use ideal diodes (mosfets) for the high power diodes as otherwise you'll be dissipating a lot of power, even with schottky diodes.

NB: 1N4007 would be a lot more robust than 1N4148 for the flyback diodes

Thanks for the feedback, and welcome back! Haven't seen much of you the last few weeks.

 

[Cal]

So, as I go back and forth between relays and SSRs with an inverter/charger, while wanting individual Charge & Discharge protection, I had the following idea:
View attachment 12787
place a 40A diode in parallel with each relay contact such that the All-In-One inverter can still draw power from the battery if the charge permissive is lost, , or it can still charge the battery if the discharge permissive is lost.

Inverter current or charging current must go through one of the 40A diodes. What's the max input current for inverter? The diode would get very hot.

I would look at disabling the inverter or charger separately within their circuits. I know this can be done. Try contacting the manufacturer. Not sure about the inverter, but dc/dc converters usually have a PWM IC which has a soft start pin. At power-up voltage ramps up in an orderly fashion. Grounding the soft start pin will shut down the converter. There might be something similar with the inverter.

 

[KohalaJim]

@cass3825 You'll probably want to use ideal diodes (mosfets) for the high power diodes as otherwise you'll be dissipating a lot of power, even with schottky diodes.

Way less power dissipation for FET's in an ideal diode role... great point @BiduleOhm.
I think the notion/application of this was originally patented, but that's likely not a concern for individuals.
Great white papers on this subject matter as well.

 

[grizzzman]

I just ordered a used TE Contactor on eBay to go with my Chargery BMS8T. Looks like the best option available to me right now for my 8-280ah LiFEPO4 battery build.

The 29.99 ones? Just one TE?

 

[Heap64]

I'm over my head here but I found this on a Victron forum.

optocoupler/optoisolator to split allow to charge / discharge signals? - VictronEnergy

community.victronenergy.com

For those of you much smarter than me, will this work with a Chargery to control a Victron Multiplus?

 

[bdbugbee]

The 29.99 ones? Just one TE?

Yes, I'm going to set it up the way onemorebattery did (see his previous post) with one used $29.99 contactor and the optocoupler utilizing both charge and discharge relay signals from a Chargery BMS. Since the BMS is last resort protection for the bank, if it needs to shut down for any reason (low or high), I'm just going to completely disconnect the battery. I'll set my Inverter/charger and Solar Charge Controller settings such that they should act to drop load or stop charging before the BMS has to take it offline. I also have a Victron 24/12v DC/DC converter that I'm planning to control with the discharge relay control signal from the Chargery BMS through another optocoupler.

 

[Pacer]

FYI on the TE relays form eBay. I offered $40 for 2, and they accepted the offer. I plan on only using 1 now, but the bundle deal was a no brainer and hopefully the odds of both relays being bad is extremely low.

 

[Pacer]

Yes, I'm going to set it up the way onemorebattery did (see his previous post) with one used $29.99 contactor and the optocoupler utilizing both charge and discharge relay signals from a Chargery BMS. Since the BMS is last resort protection for the bank, if it needs to shut down for any reason (low or high), I'm just going to completely disconnect the battery. I'll set my Inverter/charger and Solar Charge Controller settings such that they should act to drop load or stop charging before the BMS has to take it offline. I also have a Victron 24/12v DC/DC converter that I'm planning to control with the discharge relay control signal from the Chargery BMS through another optocoupler.

I am right on with you here. BMS will be a total backup to the SCC, and I’m cool with a single disconnect point for either scenario.

Can you elaborate on what you mean by the 24/12 DC converter part? You are going to control your 12v accessories the same way?

 

[BiduleOhm]

Thanks for the feedback, and welcome back! Haven't seen much of you the last few weeks.

Thanks, I'm still taking care of some things, I'll be back soon. For now I only answer threads I follow or if I'm mentionned.

 

[Capt Bill]

I don't see the appeal of SSR. The forward voltage drop and heat loss is completely disqualifying for solar applications AFAIC.

"... typical 1.2 volt on-state drop...1 watt per ampere..."

d4840_crdmh1.pdf[/URL]

Compared to a contactor/module design that draws 2.6 watts with little or no voltage drop? SSR is a no for me, dawg.

Wow: to your info. saying SSR = typical 1.2 volt on-state drop...1 watt per ampere .. Hope that not true for the SSR Craig and Steve are testing. ... I have a couple of inexpensive AC SSR I plan to test that would not be a typical relay for solar, but I am going test em for volt drop, for possibly placing em on discharge relay wire from Chargery BMS to cut off AC power from an All In One to 120v AC to breaker box. ... I bet an AC SSR might act differently on volt drop .. Then I am going to explore Will's oppicupler SSR relay connected to BMS charge relay to be another off switch for the whole All In One unit. That would need way a smaller amp rating compared to full on battery cable SSR or Relays.

The Other Brainstorming idea that bubbled: If the SSR testing does not reveal a clear winner for a High Amp Battery disconnect, there is the lower amps, but higher volts on the Solar Input that could get switched off via a SSR; to cut off further charging of your battery, assuming any possible grid charger option was configure to OFF, ... until fault trigger was removed.

 

[Craig]

Wow: to your info. saying SSR = typical 1.2 volt on-state drop...1 watt per ampere .. Hope that not true for the SSR Craig and Steve are testing. ... I have a couple of inexpensive AC SSR I plan to test that would not be a typical relay for solar, but I am going test em for volt drop, for possibly placing em on discharge relay wire from Chargery BMS to cut off AC power from an All In One to 120v AC to breaker box. ... I bet an AC SSR might act differently on volt drop .. Then I am going to explore Will's oppicupler SSR relay connected to BMS charge relay to be another off switch for the whole All In One unit. That would need way a smaller amp rating compared to full on battery cable SSR or Relays.

I Im currently testing the monster SSR at 56 amps the voltage drop was 0.08 Volts. the heat generated was about 12 degrees above ambient after 30 minutes.

 

[Craig]

Wow: to your info. saying SSR = typical 1.2 volt on-state drop...1 watt per ampere .. Hope that not true for the SSR Craig and Steve are testing. ... I have a couple of inexpensive AC SSR I plan to test that would not be a typical relay for solar, but I am going test em for volt drop, for possibly placing em on discharge relay wire from Chargery BMS to cut off AC power from an All In One to 120v AC to breaker box. ... I bet an AC SSR might act differently on volt drop .. Then I am going to explore Will's oppicupler SSR relay connected to BMS charge relay to be another off switch for the whole All In One unit. That would need way a smaller amp rating compared to full on battery cable SSR or Relays.

I also think this cutting AC will be the best way in the end to control the Inverter if it can not be turned off by relay to the switch.

 

[Capt Bill]

I guess I could cobble together a schematic. Here's the stepdown that I use.

Amazon.com

Edit: Diagram for common port single relay

View attachment 12677

For two contactors run 12v+ through NO1/COM1 and NO2/COM2 separately to each coil+.

The parts:

Amazon.com: HiLetgo 2pcs DC 12V 2 Channel Relay Module with Isolated Optocoupler High and Low Level H/L Level Trigger Module Triggered by DC 12V: Office Products

Buy HiLetgo 2pcs DC 12V 2 Channel Relay Module with Isolated Optocoupler High and Low Level H/L Level Trigger Module Triggered by DC 12V: Relays - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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TE Connectivity Kilovac EV200AAANA Contactor 500A 12~24VDC Coil USA Shipper. | eBay

Find many great new & used options and get the best deals for TE Connectivity Kilovac EV200AAANA Contactor 500A 12~24VDC Coil USA Shipper. at the best online prices at eBay! Free shipping for many products!

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So basically this is a way to have either charge or discharge side BMS triggers signal turn off / disconnect the whole battery connection via "one relay". The disadvantage I notice, that is not a total disadvantgage; is that if your BMS got trigger for low cell voltage, if charger input to battery was left intact, you could potentially have situation remedied automatically. On the other side of that idea: With everything turned off; that will likely require your attention get it back on? Do you agree? Sometimes, maybe that could be better ? I would prefer auto protection. ... I guess if it was a heat or max amp fault trigger, the BMS could automatically recover operation, but not for a low voltage trigger.

 

[Craig]

Ok so I tested the 500 Amp monster SSR with 160 Amps at 24 volts. After 15 minutes the terminal heat was up to 140F I do not find this acceptable.

My recommendation is as above for very large loads Either interrupt the Inverters switch via relay or interupt the AC out of the inverter. As we have discussed earlier this may be the best way to do things where an all in one unit is involved.


For myself I will use the original 500 Amp SSR I had tested to control my DC loads. I suggest if using a SSR to get one that is rated about 5x your maximum continuous loads.
For short term things I think I would want the SSR rated at 2x the load (something like a DC on demand water pump that will run for less than 15 minutes or so at a time).
I will use the AC cut off method to cut inverter off if needed for LVD.

 

[BiduleOhm]

It's very sad to see we're limited by the terminals and not the silicon. They really need to be better on terminals.

Also, general advice: be careful with cheap AC SSRs, they tend to go up in flames. So either buy reputable brand from reputable seller (to avoid counterfeits) or upsize a lot and test the hell out of them before using them in your system.

 

[Cal]

I Im currently testing the monster SSR at 56 amps the voltage drop was 0.08 Volts. the heat generated was about 12 degrees above ambient after 30 minutes.

I'm assuming the 12 degree rise is in F? Which makes 6.6 C rise in temp.

Based on your data I'll extrapolate the temperature rise for larger currents and max SSR current.

The SSR on resistance is: R = 0.08V / 56A = 1.43 mohm

The thermal resistance from the junction of the mosfet to case is : thetaJC = Temp rise / P = 6.6 C /( 56A * 0.08V) = 1.46 C/W

At 100A, temperature rise is: T = thetaJC * P = 1.46 C/W * 100A^2 * 1.43 mohm = 21 C
At 200A, temperature rise is: T = 1.46 C/W * 200^2 * 1.43 mohm = 83 C

If ambient temp is 20C when conducting 200A, the mosfet temperature is 103C or over 212F. That would be the limit. The SSR is dissipating 57W.

 

[Capt Bill]

So far the best combination I've found for a Chargery relay setup is these two gismos. Everything you need to run one contactor for common port (by wiring the relay controller NO contacts in series to one relay) or two contactors. Plus you get an extra controller for cooling fans or whatever. Lowest operating current and the coolest running of everything I have tested. Probably my final setup.

Amazon.com: HiLetgo 2pcs DC 12V 2 Channel Relay Module with Isolated Optocoupler High and Low Level H/L Level Trigger Module Triggered by DC 12V: Office Products

Buy HiLetgo 2pcs DC 12V 2 Channel Relay Module with Isolated Optocoupler High and Low Level H/L Level Trigger Module Triggered by DC 12V: Relays - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

TE Connectivity Kilovac EV200AAANA Contactor 500A 12~24VDC Coil USA Shipper. | eBay

Find many great new & used options and get the best deals for TE Connectivity Kilovac EV200AAANA Contactor 500A 12~24VDC Coil USA Shipper. at the best online prices at eBay! Free shipping for many products!

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I bought two of the contactors and they looked new.

I wired the Chargery relay wires to the high triggers and common and brought 12 v in from my stepdown to power the controller and the contactor coil.

Ok so I tested the 500 Amp monster SSR with 160 Amps at 24 volts. After 15 minutes the terminal heat was up to 140F I do not find this acceptable.

My recommendation is as above for very large loads Either interrupt the Inverters switch via relay or interupt the AC out of the inverter. As we have discussed earlier this may be the best way to do things where an all in one unit is involved.


For myself I will use the original 500 Amp SSR I had tested to control my DC loads. I suggest if using a SSR to get one that is rated about 5x your maximum continuous loads.
For short term things I think I would want the SSR rated at 2x the load (something like a DC on demand water pump that will run for less than 15 minutes or so at a time).
I will use the AC cut off method to cut inverter off if needed for LVD.

Thanks for your testing and sharing these results. What do you think of idea of possibly finding a SSR for switch solar in to inverter / off when trigger/ and back on when charge side fault is removed. That would require way less amps/ but more volts. Food for the Options Basket ???

 

[Craig]

Thanks for your testing and sharing these results. What do you think of idea of possibly finding a SSR for switch solar in to inverter / off when trigger/ and back on when charge side fault is removed. That would require way less amps/ but more volts. Food for the Options Basket ???

Yes I think we need to target switching whatever area that moves the least amount of amps.