There has been mention of an additional part on the motor controller board of later Vectrix models which has the function to limit the constant power drain on the battery.
According to my measurements, the unmodified Vectrix MC draws 7mA just standing around.
Does not sound like much until you do some maths:
Calculated discharge due to 7mA drain of MC: 14days x 24h x 0.007A = 2.352Ah over two weeks!
Could anyone please explain how the add-on device works and where one can get it? Buy or DIY?
How can one design one for oneself?
Any of those people who bought late model Vectrix bikes without warranty could greatly assist this by taking photos of the MC board, particularly the top right corner (IIRC that's where the new gizmo sits).
Ideally I would like a mid-pack main fuse (150A to 200A rated) in combination with a big mechanical OFF switch and Inrush Current Limiter (ICL) all in one. That would completely eliminate standby drain and make fuse changes easy.
But it might cause problems, like when someone turns the switch off during charging or turns it on too fast before inrush current has settled.
Any ideas about all this, anyone?
You're talking about 1W of power draw. That's not to much, in my opinion. Any modern appliance consumes 1W or more in the standby mode. Ok, I completely shut down most of my stand-by appliances, but I don't think 1W for a motorcycle is a lot.
It can be devastating when you have a bike that's down for repair and there's no way to charge it.
Case in point. I discovered after a full day of use that my Vectrix has a bad charger. It has two bars on the meter (or at least it did a week ago when I discovered the problem). The bike is in the shop now, with concerns over whether a new charger is even available for it at the present time. Meanwhile, the clock is ticking and I am in danger of losing the battery while possibly waiting weeks or months for parts.
The Corbin Sparrow (now known as NMG by Myers Motors) comes with a "BRB" (Big Red Button), which is there specifically for emergency battery disconnect, for fire prevention and for storage. I don't know that that vehicle even requires an inrush limiter, but the ability to perform a battery disconnect when necessary could mean the difference between owning a repairable vectrix or a boat anchor.
Agreed. But can't your dealer disconnect the battery?
The origin of this current draw is the DC/DC converter. The bias current when it is "off" is 8 ma, when its "on", it is 0ma...go figure. The DC/DC is actually the alternate of 2 converters that were considered. Look closely and you will see 2 footprints on the PCB (on older boards). The first choice of converters did not pass EMI testing (which by the way had the bias currents reversed...0ma when "off"). Fixing this problem requires putting in a switch at the DC/DC input. Unfortunately this is not a DIY project. The daughter board uses FETs to switch the battery voltage to the DC/DC input, eliminating the bias completely.
Thanks for this explanation! How does the electronic system manage to tell these FETs to fire up before it has 12V available from the converter? Is a software modification needed for this to work?
Would disconnecting the entire battery likely cause any problems, like wiping the stored battery SOC information or resetting the time interval to the next EQ charge (with new firmware)?
There might be enough space to add a contactor to the MC board if the fuse is moved elsewhere. But, to incorporate an ICL, one would probably need two contactors.
This information may be used entirely at your own risk.
There is always a way if there is no other way!
The fix itself is biased by the battery voltage but at the micro-amp level rather than mA. It is a typical high side PFET switch circuit. It is all HW no SW needed.
You can disconnect the battery anytime and for as long as you want and no timing info is lost. The instrument cluster has a backup battery and tracks all time.
The simplest inrush limiter is a resistor in parallel with the big blue connector. The connection can be made through a second 2 pin connector in parallel with the blue one. Put a 5K resistor in each leg of the second connector.
Hey Mik,
I remember your comment when I did a main fuse replacement last year. I used an 11-watt incandescent bulb for ICL on the reconnect, and mentioned I had to cycle the main switch ON then OFF to get the current to die down - nice it was visible by the lit filament. Maybe this explanation from X-Vextrix solves the mystery.
Thanks, but the ICL I am talking about here is different. The ICL (for servicing/repairs) question in in my opinion long solved: Two light bulbs, one in each lead, is best. That is about the same resistance that X Vectrix suggests, but gives the reassuring glow and most importantly disappearance of glow when the current reduces to safe levels. We had two reports here where simple resistors would have failed to detect continuing current flow.
But, as I said, the ICL needed for this application is different. It is a built-in ICL which completely disconnects the battery from the 8mA power drain of the DC/DC converter (and every other power drain except for the voltage divider on the rear battery temp sensor board, which is probably negligible).
This automated ICL then needs to close for a sufficient time - before the main relay (contactor) is closed - to re-connect the battery. Toyota have used three "System Main Relays" in the MK1 Prius battery. One of these SMR's has the ICL function, I believe, closing the battery circuit through a 10 Ohm resistor, before the third SMR is closed to make the connection for the high currents.
I don't think three SMR's are needed, but two. And some sort of timer.
Alternatively, a Big Red Button (BRB) with dual-stage-reconnect process (if this exists): Hit BRB to get to the OFF position, one click to ICL connection, wait 5 seconds or so, second click to full connection. Hit the button to turn off again.
This information may be used entirely at your own risk.
There is always a way if there is no other way!
I had also been thinking about that last idea, two switches accesible to user, one connected to a classic ICL or resistances (+led for control?), and one BRB.
Would set my mind at ease too, now that I'm waiting for a fuse. Third week now, I'm happy that my pack was full at the time.
cheers
d
"doing nothin = doing nothing wrong" is invalid when the subject is environment
While you are waiting for a fuse the current drain is absent, anyway! No need to worry....
This information may be used entirely at your own risk.
There is always a way if there is no other way!
SPAT!
(sound of my hand colliding with my forehead)
"doing nothin = doing nothing wrong" is invalid when the subject is environment
I don't understand your comment, but maybe I just don't see the forest for all the trees....
How does X-Vectrix comment explain this ongoing current draw upon reconnection, until the "ignition" key is turned on and off again?
Another related post is this one: http://visforvoltage.org/book/ev-collaborative-hand-books/6620#comment-45831
This information may be used entirely at your own risk.
There is always a way if there is no other way!