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[DPsSRnSD]

I find it surprising that you need to turn the motorcycle "on" to use the charge tank, when you don't need to do that for level 1 charging.

It's because circuits that are needed to start Level II charging aren't energized by inserting the J1772 plug; maybe handshaking and pre-charge.

[DynoMutt]

How does the QUIQ charger do it, then?

I could swear that I saw in an earlier forum posting that there was a resistor within the Anderson connector itself that would trigger the contactor somehow.

[BrianTRice@gmail.com]

How does the QUIQ charger do it, then?

I could swear that I saw in an earlier forum posting that there was a resistor within the Anderson connector itself that would trigger the contactor somehow.

100kOhm resistor to B+ per Trikester and a few others. Apparently the Quiq charger is configured with this. I have a solution for this on-hand but haven't tested it yet due to a hold-up.

http://electricmotorcycleforum.com/boards/index.php?topic=4690

[Doug S]

How does the QUIQ charger do it, then?

I could swear that I saw in an earlier forum posting that there was a resistor within the Anderson connector itself that would trigger the contactor somehow.

As I tried to explain in a long post earlier, I don't think it's that it CAN'T be done...it can. The question is whether it can be done SAFELY, without causing big arcs on the contactor, and the short answer is, no, it can't, unless you have a way of verifying that the capacitors on the high-power electronics are pre-charged to the same voltage as the battery. If you pull the contactor without the capacitors being pre-charged, you run the risk of damaging the contactor. You might get away with it for a long time, but at some point it might bite you in the posterior.

I've been wondering if you could pre-charge to, say, 105 volts, which should be no more than 10 volts or so from the battery voltage, whether it's fully charged or fully depleted. Then the current surge when you closed the contactor would be much smaller; the question is how much smaller, and is that small enough to be considered truly safe? I'm still not sure I'd want to risk it.

[firepower]

Could you not close contractor with external charger off , this would raise the output caps of charger to battery voltage level, when charger turns on there would be less voltage difference as output caps at battery level.

[Doug S]

Could you not close contractor with external charger off , this would raise the output caps of charger to battery voltage level, when charger turns on there would be less voltage difference as output caps at battery level.

It's not just the caps on the charger that need to charge up, there are also caps on the power elex of the bike that may be at very low voltage if the bike's been off for a while. And if those caps (either set of them) are at a very different voltage than the battery, when you close the contactor, you'll get a big arc as the contacts are closing, as the caps try to charge up very fast. That's why the caps (all of them) need to be pre-charged to the battery voltage before closing the contactor. Once the contactor is fully closed, it can withstand large currents, but as it's closing, you can get an arc if the voltages on the two sides of the contactor aren't the same.

[nevetsyad]

So, if I'm supercharging and the power goes out briefly, or the J plug gets pulled and put back in...the connector will close and my BMS will be destroyed? Or did I miss something in the order of operations from the OP? If that's the case, I'm going to A, always keep my onboard charger plugged in while SuperCharging, and B, ask if the SuperCharger could be wired to power up the onboard charger first, then ramp up it's own charge moments later after the connector is open?

Also, I want to say, I can't wait for my SC to ship, and thank you to everyone that's put in the hundreds or thousands of hours of work on this. I don't think it gets said enough. You've engineered a game changer gentleman.

[Electric Cowboy]

So, if I'm supercharging and the power goes out briefly, or the J plug gets pulled and put back in...the connector will close and my BMS will be destroyed? Or did I miss something in the order of operations from the OP?

Not quite.

Doug's SC did not initiate charging on its own because it thought the bike might be off, however given the timing he had he was able to tell the SC to Force charging while the contactor was open. This is a manual action he had to take at just the right unlucky moment in his hard to repeat timing order just exactly the way he did it.

Without exactly what Doug did and him manually telling the charger to force charge at that one moment it's not possible to repeat. Hunter and I have been trying to reproduce the error and have not been able to, however we have narrowed it down to a very precise timing order and section of code that could possibly allow it.

Frankly, I'm quite impressed Doug was able to do this. We actually had to analyze a lot of stuff to see how it was possible. We're adding in some additional safeguards now that we know how this happened.

But again no, without forcing the charger to start with an open contactor you're BMS will be quite a happy camper no matter what the situation

Also, I want to say, I can't wait for my SC to ship, and thank you to everyone that's put in the hundreds or thousands of hours of work on this. I don't think it gets said enough. You've engineered a game changer gentleman.

Thanks! It means a lot. Most of what we here these days from those who are not testing or in possession of their SC yet is not quite that encouraging. So we all really appreciate it.

[firepower]

I don't have a zero yet, but I am happy that super charger has been developed, fast charging is a must. As with any high tech and high power system, lots of work in design and testing , glad to see fix is already being worked on to fix this unusual fault, it has to be fool proof and fail safe to be a successful.
Thanks and respect to all who have developed and worked on and tested this,  hope your up and riding soon Doug ,  interesting read.

[MrDude_1]

I've been wondering if you could pre-charge to, say, 105 volts, which should be no more than 10 volts or so from the battery voltage, whether it's fully charged or fully depleted. Then the current surge when you closed the contactor would be much smaller; the question is how much smaller, and is that small enough to be considered truly safe? I'm still not sure I'd want to risk it.

Probably not ok, because the bike could be more than 16v off and we're filling some large caps. From messing with ebikes (that use smaller caps and smaller lipo) I know that being more than 3v or so off is a significant surge that will cause arching.  Its not as strong, but you can see the build up on the connectors. I know it cant be good for the caps either, but I dont have a way of quantifying damage to them... so thats more of an assumption.  Its not the voltage being off, its the amperage going through as the connection is at its weakest.
The other thing to remember is that we're not just connecting the charger. We're connecting the entire bike, (controller, DC-DC, etc) to the battery.
There is no way around using some kind of precharge resistor.. ideally it would be the OEM one that is just "told" to come on.. that might even be mandatory if the monolith is 100% sealed from connecting to the battery easily (I dont know)

[Shadow]

Thanks! It means a lot. Most of what we here these days from those who are not testing or in possession of their SC yet is not quite that encouraging. So we all really appreciate it.

Hopeful my super charger order is shipped when it is *ready* and not as eager to blow up my bike. Can't help the anticipation though, it's very exciting to think about the freedom of travel this product adds to EVs. I've never met an engineer who could ship a product on-time without first making it perfect :-)

[Doug S]

So, if I'm supercharging and the power goes out briefly, or the J plug gets pulled and put back in...the connector will close and my BMS will be destroyed?

Brandon answered in terms of my specific error in judgment, but more generally, no, the situation you described wouldn't be dangerous, for two reasons.

First, a power outage or unplug, however brief, would reset the charger. There's no way the charger can maintain its massive current output for even a fraction of a second without input power. So with its input power gone, it would reset and cycle off, including releasing the contactor. It would be safely off when the power came back.

Second, the arcing happens when the input capacitors have discharged to a different voltage level than the battery voltage. If the capacitors and the battery are at the same voltage, there will be no arc when the contactor closes. In a very brief power interruption, there won't be time for the capacitors to drain sufficiently to cause the problem.

So you're protected two ways from a brief interruption of power: First, the caps won't discharge enough to cause an arc even if the contactor immediately closes again, and second, the contactor won't close anyhow, because the charger will be reset.

[Doug S]

Weekend update: Brandon came by, as promised, and figured out for me (I was going to say helped me figure out, but he did all the work!) what's wrong with my bike. Long story short, it's probably a single resistor (the pre-charge resistor) on the BMS. We briefly discussed just replacing that resistor -- I have a microscope and a good soldering iron at home, and work on surface-mount electronics a lot -- but I don't like the thought that there may be some collateral damage, even something minor, which we wouldn't catch, and would further delay getting the bike back on the road. I'm also not a big fan of riding around with a board that's been stressed in any way, so I'm just going to have my local shop replace the BMS.

MBB and Sevcon both got clean bills of health.

[protomech]

Good to hear Doug. Hopefully you're back on the road shortly.

Unfortunate to be the guinea pig, but it sounds like the net result is some lost time and $$$ on your end and a better product from DigiNow.

[Semper Why]

I don't have a DigiNow but rather have a Charge Tank. I, for one, appreciate the sacrifices that Doug, Brian and the others here have made in furtherance of the Supercharger technology.

I charged via my Charge Tank for the first time today and by @#$?!! accident, I did it the proper way (bike on, charge then switch bike off). Not because I read the instructions, but because I was so anxious to know if my Charge Tank worked. I didn't bother to switch the bike off, like I was intending to do.

If no other benefit comes from this thread (and to my amateur eyes, there is a lot of wisdom in here) I am going to grab my label machine and put a label next to my J1772 plug that reads "Bike On Before Connection".