Classic 200 Aux output relay/diode?

[cybermaus]

Hi all

I have a Classic 200 running for a year now. It switches the houseboat's main inverter by means of a relay on Aux1 in 12V mode.

Up till recently, the relay used had a DC coil and integrated reverse protection diode. But it had its contacts-screws corrode and then burn out due to resistance, so needed to be replaced.

I now have a replacement relay that is better build, but can be energized by DC and AC, and thus does not have a protection diode. Therefore if it is turned off, it could send a spike back into Aux1.

So question: Can Aux handle such coil-feedback spikes (either by it already having diodes internally, or maybe because Aux1 is itself a small relay, so there are no electronics attached when it opens?) or should I mount an additional set of diodes into the wiring? If not needed, I really rather not have to solder a diode into a wire without mounting it properly, and I also do not want to have to add another box to the infrastructure for just one diode.

Thanks for your answer.
Maurits

[cybermaus]

Additional question:

I see the latest 1754 beta firmware has SOC %

Does that mean that if I also get the MNWBJR I can now control Aux1 based on SOC % rather then voltages?

Thanks

[Vic]

cyber . .

I do not know the nature of the Aux outputs of the Classic -- relays vs transistor drivers.

As you know,   it is very good practice to connect a small power diode (like a 1 amp 100 V)  directly across the coil terminals.  Quite often this can be directly soldered to the relay of a mechanical relay,  or if the relay has screw terminals,  either under the screws,  or place lugs on the diode,  and place these terminals under the screws.

As you  probably know,  mechanical DC relays are prone do damage in circuits carrying large DC currents.  It requires special construction for this type of relay to survive many make/break cycles.   Contacts can weld when the contact is made,  and the arc of breaking the connection can cause a continuous arc,  at least with higher voltages and at higher currents.

Quite often a Solid State relay is a very good solution to the problems noted above.

Also,  many inverters use capacitors on the DC input terminals.  Initial charging of these caps when the relay first closes can be very damaging to the contacts.
FWIW,  good luck,    Vic

[cybermaus]

I've looked into solid state relays. Especially the ones with zero-cross on/off are nice. For reference, I may be using a DC activation coil, but I am switching AC mains, not DC battery.

The problem with them is they typically have a 1.5V to 2V drop, and thus would require a 40~50W heat dissipation. Also while they have plenty of Amps rating, the VA rating is often a lot lower. Also, despite the zero crossing, their specsheets warn to add external caps to deal with reactive loads. (unless if its an big industrial D-rail solid state, but I could almost buy another Midnight Solar for that kinda money)

Anyway, at this moment, I have the non-solid state relay. After all, the previous one did not fail on the switch contacts, but on the screw contacts (some salt water may have entered somehow, I will address that too). And as stated, I want to avoid an in-wire or hacked on diode, but also avoid mounting an extra box, if not needed.

So my question stands: Does the Aux already have some protection for this? Does it already have a diode? Or more likely as I hear it clicking, is it already a small relay itself, possibly with a anti-spark capacitor?

If any Midnight Tech could look into this, thanks.

(also my secondary question whether on the new beta you can control Aux by SOC% is interesting)

[Halfcrazy]

I will have to wait for boB on the diode. I have never heard it mentioned so I assume that it is not needed but?

As far as Aux functions based on SOC% no not yet. We are still in the Very Early BETA stages of SOC so no aux functions driven by it yet

Ryan

[Vic]

cbyer ..,

Sorry,   did NOT read your first post very carefully.

Yes SSRs do have drop across them,  and that does not seem to be the issue here.   A mechanical relay should do fine if it is protected in a box,  just make certain that the power connections are tight.

Vic

[dgd]

cyber,

Its unlikely that there would be any significant voltage spikes in the AUX1 circuit to your relays's coil, maybe some switching noise. At 12v and at most a few hundred milliamps the AUX1 relay should be able to cope.
I have attached all sorts of relays and SSRs to AUX1 and none of the relays had a diode over the coil connections.

dgd

[cybermaus]

I will have to wait for boB on the diode. I have never heard it mentioned so I assume that it is not needed but?

Hi Ryan.

Any word from boB?

Thanks
Maurits

[Halfcrazy]

I will ask today. He has been so deep in SOC% stuff I have not wanted to bother him. I guess we should have Aux functions based on SOC% today as well as Rebulk based on SOC% and possibly even a timer on End Amps.

Ryan

[SolarMusher]

and possibly even a timer on End Amps.
Ryan

Ryan, could you explain it a little deeper? Is that because of the end amps jitters?
Is it included in the update you posted today?
Thanks,
Erik

[Halfcrazy]

Sorry. There as been a request or two for a time delay after reaching the End Amps setting. So boB is working on that.

[Resthome]

Sorry. There as been a request or two for a time delay after reaching the End Amps setting. So boB is working on that.

I hope it's more like having to maintain that end amps setting or less for a period of time like 5 minutes.

[SolarMusher]

Sorry. There as been a request or two for a time delay after reaching the End Amps setting. So boB is working on that.

Ryan, don't be sorry, it's obviously a good idea. Just curious to know what could be done to improve/solve the jitters issue.
Erik

[boB]

Hi all

I have a Classic 200 running for a year now. It switches the houseboat's main inverter by means of a relay on Aux1 in 12V mode.

Up till recently, the relay used had a DC coil and integrated reverse protection diode. But it had its contacts-screws corrode and then burn out due to resistance, so needed to be replaced.

I now have a replacement relay that is better build, but can be energized by DC and AC, and thus does not have a protection diode. Therefore if it is turned off, it could send a spike back into Aux1.

So question: Can Aux handle such coil-feedback spikes (either by it already having diodes internally, or maybe because Aux1 is itself a small relay, so there are no electronics attached when it opens?) or should I mount an additional set of diodes into the wiring? If not needed, I really rather not have to solder a diode into a wire without mounting it properly, and I also do not want to have to add another box to the infrastructure for just one diode.

Thanks for your answer.
Maurits

The Aux outputs have a 200V fast diode in series with them so that positive voltage up to at least 200V should not affect the aux circuitry.  Don't want to drive it backwards !  You will want to add a "cache diode"  (or is it "catch" ?)
across the relay coil with the cathode at the Aux 1 hot output and anode at the coil's negative side though for anti-flyback suppression if at all possible.   Or, a zener diode of something less than 100V or so.  A Zener will help the relay to turn off faster rather than having the current keep flowing in the inductive loop of the diode and relay coil.

Also, the latest software, coming in a day or two has the Aux 1 SOC% active HI and LOW functions available.  Works like diversion except is bases on a low and high battery SOC % thresholds, with delay and hold, not that delay and hold are really all that useful.

boB

[cybermaus]

I will ask today. He has been so deep in SOC% stuff I have not wanted to bother him. I guess we should have Aux functions based on SOC% today as well as Rebulk based on SOC% and possibly even a timer on End Amps.

Great news.

Just in case my remark may actually influence these things: Do remember that I not so much switch the inverter on, but I switch shore-power off. So High SOC% means I want to energize Aux1 (and shut off shore; the invertor comes on automatically); Low SOC% I want to stop energizing (and shore comes on again)

Its a bit opposite than what you may expect.

---

And about that relay protection?

If you can't get to boB over the coffeebreak, don't interrupt his work . SOC% is important to me. Been waiting for that since I first read about the WBJr 6 months ago.

I guess if I cannot get a good answer on the matter, I'll take your and @dgd's practical claim he has never had it break anything despite numerous relays (though his remark a relay coil cannot send a significant spike is a bit uninformed)


Got the answer while I was typing, thanks.
So, series diode, but not anti-parallel diode. Maybe best add that myself then, just to be sure.

And best order the MNWBJR somewhere.

Thanks