Anyone had a problem with the Victron Battery Switch ON/OFF 275A?
In particular running very hot (all lugs checked good for torque) so eventually it has to be removed from service (smell)?
Running up to 95A on 35mm^2 cable off RS 450/100 MPPT. Near full load the cable runs warm in free air. It was noticed the switch external casing was quite warm, this deteriorated to “hot” over a period of two months this spring. The system has been in for ~2.5 years.
The quattro has a blue sea series 9004E which gets the chill taken off but otherwise unbothered.
PS It would appear that “48V” really applies to 48V lead systems which get close to 60V when charging. This seems to be a common spec and apparently identical isolators of many “makes” seem to arbitrarily say 48V max or 60V max when it’s improbable these are physically/electrically different.
This is inaccurate - there’s a massive difference between “48v max” and “60v max”. 48v max indicates suitability for usage on a 36vNom system, just like 32v max (or 36v max) indicates suitable for use on up to a 24vNom system.
In general, rotary switches should not be used on a 48vNom system (your BS-9004e is also not rated for the system voltage you’re running) since they have no arc suppression or redirection mechanism. There have been more than a few reports of the VE Battery Switch encountering issues on 48vNom systems, as is predictable to be honest. I personally tested 3 on a 48vNom system as soon as they were released and two of them welded themselves shut immediately, with the remaining one surviving - severely pitted, yes, but still serviceable for occasional testing purposes. The OEM switch manufacturer -publicly at least- is very clear that they’re for use on 12 or 24v systems though can handle 48v max, not 60v.
The good news is that since Victron backs them for use on 48vNom systems, you can get a replacement for it under warranty, just talk to your distributor!
As @Justin has said popped up more than a few times on the old forum and went really in-depth on this, I got rid of my one and use my pylons and the multiplus to isolate with the Lynx distributors in the middle with the Adler fuses as space isn’t vast to implement a fused disconnect
That’s great. The victron switch was supplied by my installer. Since it has to be MCS approved, he did the spec and supply. I have actually sourced a 60V isolator, although to be honest I think its identical to others that are only labelled to 48V, like the Victron (see datasheet).
The isolator is probably not intended to be used, nor has it been (all twice), to interrupt any current at all. Nobody with any sense would use it before the device (MPPT or inverter) was turned off. Arcing on disconnect is thus non-existent. If it was required urgently OK (but may damage the switch), but since I have not examined the internals I have no idea if any adequate but simple opening switch arc suppression is installed. I do not intend to test this mode(!).
A problem is, of course, arcing on turn-on even with the device switched off as both the MPPT and multi seem to have significant input capacitors on the DC line. My installer finds this arcing quite disturbing so now I use a 47ohm power resistor before turning on to charge the caps to DC voltage when its time to turn on and of course this avoids an arc completely.
Arc suppression is mostly for switch OFF, because that’s when you draw/strike an arc and want it to extinguish. Either physical distance or arc quenching being the usual methods. Usually rotary switches have quite a large separation (unlike contactors) but without disassembly I have no idea how big they are in these models.
Generally, any pitting on a rotary or lever switch is bad because the pitting prevents a good (sliding) contact. That applies to the capacitor arc as well, as anyone who has (inadvertently or not) taken off the end of his screwdriver on a charged cap knows full well (even audio)!
Anyway, we shall see.
The discussion has been interesting, I now think there is a plausible failure mode which is pitting on turn ON due to capacitor charging arcing interfering with good sliding contact and thus heating as the cause. I will make it easy to temporarily connect a charging resistor.
Agreed about not switching under load - one of the switches I crisped in testing was under load only because the user manual specifically says it can be used for that. It definitely should not be used for that.
The other switch I crisped in testing was -as you surmised- tested not under load but simply switching the system “on” without any precharge, so the inrush current alone is what welded it closed.
The last switch I tested, that’s heavily pitted but still functional for light testing work, was done still without precharge but with the inverter caps not fully discharged yet and, too, making a determined effort to close the switch as fast as possible.
After all the photos and reports of overheating of these on the old forum (and I believe some on the new forum as well) I started wondering if -even in ideal conditions with no switching under load, always using a precharge circuit, and etc- it’s actually a matter of power rather than current. If let’s say the switch’s 275A continuous rating was established at 12vNom (call it 14v) for 3.85kW, it’s no wonder that the switch might have issues with 100A continuous at 48vNom (let’s say 56v) for 5.6kW. That’s a big power difference, and would explain some of the failures we saw in the wild which certainly appeared to be not caused by arc damage, but rather simple overheating of the contact pads.
There’s a lot I can’t really verify - the OEM site does specify a 275A continuous rating but does not specify what voltage was used when establishing that, and the OEM isn’t a direct-to-consumer manufacturer so I’m not able to submit a good inquiry about the real specifications of the unit, so all I’ve been able to do on my side of things is make sure that my company’s listing of the switch makes it exceedingly clear that we do not suggest using it on 48vNom systems regardless of anyone else, so we have this notice on our listing:
I have not time to read your post properly right now BUT assuming the switch is new and not pitted/damaged 100A on a 12V system will have the same ohmic heating as 100A on a 60V system. The power is irrelevant whilst the switch is properly On (or OFF, obviously). The damage caused by transients is quite a different matter, there the voltage will be a significant factor (all other things being equal) because the current and duration going through the arc will be significantly different. That said, accidentally discharging a 400V 2000uF cap is very similar to a 40V 200,000 cap in mm of screwdriver vaporised IME.
The key is not in any manual I have come across, voltage equalisation before switching.
Trouble is its a bit nerdy and only applicable to DC power electronics, not trucks and boats.
