Best Relay

[audiomick]

Some further thoughts:

I've been noticing temperature specs on various relays. Cheaper ones often have 80°C as the maximum operating temperature. The ones from Hella seem to have 125°C as maximum across the board, regardless of the other specs.

The other thing is, Hella seems to state 100k operating cycles across the board. I haven't seen that specification very often at all, but it seems to me to be very relevant.

That leads me to think about how often the relays in our V11s cycle. As I understand it, they all cycle once every time the bike is started, i.e. most of them go on when it is started, and back off when the bike is switched off. The one that supplies the starter solenoid goes on when the button is pressed and back off when it is released. That means, if the relay is good vor 100k cycles, one could start the bike six times a day every day for about 45 years without exceeding the limit. Even if I have remembered wrong, and it is "only" 10k cycles, that is still six starts a day every day for 4 1/2 years.

The relevance of that line of thought relates to the business with diodes, and that those relays may be prone to arcing across the contacts, which may cause a failure. I can't help thinking that if the relay is rated that high, and if one changes the relay every 4 years or so as preventative maintainance, one would probably not have a problem with that particular issue.

[audiomick]

I had a look for the relays that are in the bike, as I have already mentioned here:

https://www.v11lemans.com/forums/topic/30546-a-look-under-the-seat/

Turns out they are apparently readily available here in Germany, and not that expensive at less than €3.50 each.

The type is HKE 4133

https://www.conrad.de/de/p/hke-4133-s-dc12v-c-r-kfz-relais-12-v-dc-35-a-1-wechsler-1366558.html?refresh=true

https://www.voelkner.de/products/850370/HKE-4133-S-DC12V-C-R-Kfz-Relais-12-V-DC-35A-1-Wechsler.html

https://www.digitalo.de/products/731498/HKE-4133-S-DC12V-C-Kfz-Relais-12-V-DC-35A-1-Wechsler.html

 

Here is a spec sheet. The code on them is 4133-S-DC12v-C-R, so C form and with a resistor.

https://asset.conrad.com/media10/add/160267/c1/-/en/001366558DS01/datenblatt-1366558-hke-4133-s-dc12v-c-r-kfz-relais-12-vdc-35-a-1-wechsler.pdf

 

That looks alright to me. Does anyone see anything there that is not good?

[docc]

13 hours ago, audiomick said:

The type is HKE 4133

That looks alright to me. Does anyone see anything there that is not good?

Yes. The "switching current" is the continuous load rating. if I understand the ratings correctly. In that case, these relays are actually only rated 10 amps N.C. and 20 amps N.O.

That certainly would not qualify as "High Current" relays.

gain, the datasheets are not standardized and can be nearly impossible to compare . . .

[audiomick]

There is a temperature of 85°C mentioned there, as on the spec sheet for the Panasonics that you posted here

https://www.v11lemans.com/forums/topic/19755-best-relay/?do=findComment&comment=216346

 

From other spec sheets, maybe the ones from Hella, I have gained the impression that the current capacity diminishes with increasing temperature.

I just had a look at the Omron spec sheet and the ones for CIT and Picker from here

https://www.v11lemans.com/forums/topic/19755-best-relay/?do=findComment&comment=216605

and didn't see any reference to Amperes @ °C.

So I can't really say if the ones in my V11 are as good as or weaker than those. Still don't know enough about it.

[docc]

The Panasonic datasheet is a good comparison. Notice the phrase that accompanies the temperature specification, "maximum carrying current . . . continuous." 

Are we being deceived by looking at "resistive load" or "switching current" and these phrases are actually the ratings for inrush current and can vastly overstate the contacts' continuous current ratings?

@Kiwi_Roy questions . . .

[audiomick]

8 minutes ago, docc said:

Are we being deceived by looking at "resistive load" or "switching current" and these phrases are actually the ratings for inrush current and can vastly overstate the contacts' continuous current ratings?

 

Could be. As I said, I still don't know enough about it.

Or I can't see the forest for all the trees....

[docc]

12 hours ago, audiomick said:

Could be. As I said, I still don't know enough about it.

Or I can't see the forest for all the trees....

It would be helpful if the datasheet language and ratings were standardized between manufacturers, but they are obviously not. I remember learning the distinction between the higher "inrush current" rating and the more desirable "continuous current" rating.

This helped explain why some seemingly high rated relays were really just typical 10/20 rated Micro-ISO.

[audiomick]

3 minutes ago, docc said:

It would be helpful if the datasheet language and ratings were standardized between manufacturers

Of course it would, but they (the manufacturers) don't really want that, do they? Because then your average consumer (us) could easily compare their products.

 

Ok, that was a bit cynical and nasty, but I am getting a bit frustrated with trying to understand those spec. sheets.

[Tomchri]

aoudiomick Don’t worry about the relays, Omron works. It’s the rest of the electrical Luigi you need to take care of  .

Cheers Tom.

[audiomick]

Found a couple of useful (I think) documents....

https://www.pickeringtest.com/de-de/kb/hardware-topics/relay-reliability/switching-and-relay-specifications

https://media.digikey.com/pdf/other related documents/panasonic other doc/small signal relay techincal info.pdf

[docc]

> From DigiKey, regarding Switching versus Carrying current:

• Maximum Switching Current
The maximum current which can safely be
switched by the contacts. AC and DC
current maximums may differ.

• Maximum Carrying Current
The maximum current which after closing
or prior to opening, the contacts can
safely pass without being subject to
temperature rise in excess of their design
limit, or the design limit of other
temperature sensitive components in the
relay (coil, springs, insulation, etc.). This
value is usually in excess of the maximum
switching current.

 

 

>From Pickering, regarding current (amperage):

Switch Current 

When a relay is hot switched, the switch current is the maximum current that the relay can sustain when being opened or closed and not sustain contact damage. 

Carry Current 

If a relay's contacts are already closed, the relay may be able to sustain a higher current than the switch current. This is called the carry current. The carry current is normally limited by contact resistance, which causes the contacts to heat up. When a relay is carrying a current greater than the switch current, the relay must not be opened until the current is reduced. 

 

[audiomick]

Yes, I noticed that difference. What I haven't yet been able to find is anything that explains the relevance of 85°C. That is a temperature that seems to turn up in lots of spec sheets, along with 125°C maximum ambient.

I have the impression that it (85°C) may have something to with coil temperature rather than ambient temperature, or that the coil is warmer when the ambient temp. is high.

In one of those Documents I think, I saw that the coils warm up when they stay activated (logically...), and that it can take more Volts to activate a warm coil, i.e. turn back on immediately after it has been shut off after a period of operation. Not a usual scenario on the V11, I think.

I also wonder if the 85°C might be specified as a limit or maximum tolerance in some Standard.

[docc]

My impression is that 85ºC is a standard rating temperature, something approaching maximum operating temperature. At "room" temperature or common ambient temps, the relay could likely be rated much, much higher. But then fail at operating temperature. We have seen some very hot readings from under-rated relays in position #5.

Also, it has been noted that the higher maximum operating temperature of a given relay "may" represent a higher quality relay.

What I would like to see reconciled is the various amperage ratings we are seeing on datasheets that sometimes specify "nominal", "resistive/resistance", "switching", "inrush", "continuous", "carry" . . .

Presently, I now have doubts that the Picker and the CIT (same company, as @al_roethlisberger noted) are actually capable of sustaining a continuous amperage over their contacts at the rating they are publishing.

[audiomick]

55 minutes ago, docc said:

What I would like to see reconciled is the various amperage ratings we are seeing on datasheets that sometimes specify "nominal", "resistive/resistance", "switching", "inrush", "continuous", "carry" . . .

 

I can at least guess at least some of that.

"nominal" is a word that turns up in relation to audio gear. "Nominal level" is the level that the gear is designed to work best at. Given that audio signals are a.c., and very dynamic, the gear is almost never running at exactly the nominal level. The value states a theoretical level, and the real world is (hopefully) within foreseeable limits around that value.

"resistive (load)/resistance" is as opposed to inductive and capacitive loads. A resistive load complies the formula p=VI. Work done (Watt) is the product of voltage and current. Inductors (coils etc.) and capacitors don't exactly. The current for the work done (Watt) can be higher than the formula would suggest for the applied voltage.

"Continuous" and "carry" seem to me to be two different words for the same thing, i.e. the current (load) that the contacts can deal with when they are closed.

"Switching" is the current that the contacts can deal with when they are opening and closing. We had mention of the problem with arcing when the contacts are slightly open, and you, docc, quoted out of those documents I linked regarding the fact that the "carry" current can be larger than the "switching" current. That is pretty logical to me when I think about how a welder works, and the sparks that happen when attaching the clamps of a battery charger to the battery.

"inrush" has to do with the way some devices pull a heap of current when they are switched on compared to how much they draw when they are up and running. Things with coils (including transformers in power supplies) in them, or capacitors, tend to do that. I gather tungsten lights do too (read that somewhere this evening...). Things that do that need a relay that can deal with that "switch on" current, and not just the steady state when the device is running.

Wikipedia has an article about inrush current:

https://en.wikipedia.org/wiki/Inrush_current

[docc]

Can we conclude that, for these relay contact ratings:

Carry = Continuous = Resistive = Resistance Load ?

And that this is the condition we are primarily concerned with with the V11 in operational mode?