Ideally the wakespeed is controlled by the BMS through CANbus, but in case of a critical shutoff of the battery I want to kill the alternator at the same time. I read all the guides, and as far as I can see I need to do the following:
- $SCO command to program the Feature-In to setting 2 (override into half-power mode)
- $SCA command to change the Half power mode to 0 amps
Or would it be better just to put a 20A relay in the alternator + line and have it switched off.
I dont think you want to set it back to half power mode on an OV disconnect. My solution in the past was to just add the interposing relay in parallel with your your OV coil and cut your field as you mention, for then it is instantaneous. Some people seem to prefer to just add the relay into the ignition enable input, but then you have a bit of a delay before the WS500 actually shuts down. There was another way suggested on the forum but I dont recall what it was. The coffee is not working this morning.
Hi Rick,
I have the same concern about insuring that the alternator never sees a load dump due to the REC contactor opening on a fault. Is it the case that the contactor is opened on any of the over- under-voltage, over- under temperature conditions? Are there other conditions that cause the BMS to open the contactor? I’m presently configured so the CAN bus message from the Q BMS to the Wakespeed WS500 should shut off the alternator before opening the contactor but I’d like to be sure I never have the load dump condition. I guess what I’m asking for is the recommended circuit for avoiding this condition.
One other question: What does the REC-BMS do in case of multiple charge sources? For example, if I’m connected to shore power to a Victron Multiplus and I start the engine that’s spinning the secondary alternator, who gets preference as the charging source? Or do they both supply current?
Thanks.
There are several concepts currently in practice and some can be used together, but there seems to be no \"one fits all\" solution.
Some of the ones I am familiar with:
- Add a FET splitter to a conventional battery
- Add a B2B charger to your conventional cranking battery
- simply add a conventional battery into your system
- add an APS(Alternator Protection device)
- interlock your field or ignition cutout with your contactor using a paralleling relay
Your REC BMS monitors the current in and out of your battery system. As I understand it, if it goes above the allowable threshold as configured in the BMS it will lower the charging output of any connected devices. Because it is trying to maintain a current setpoint it will try to compensate for non-smart devices, but failing that it will issue an Error 1 alarm and open your opto relay, then your main contactor.
Looking at the details about the Tyco Kilovac EV200 contactor it seems there’s a model with optional auxiliary contacts for monitoring the state of the contactor. This model is part number EV200H1ANA. This would seem like a valid choice to implement an independent (of the BMS) hardwired connection that would allow simply routing the Wakespeed field wire through the auxiliary contacts and it would open whenever the contactor is open. Have you looked at this model?
Thanks.
the aux contact is only 2Amp rated, thats why I had suggested a parallel relay for field interlocking.
For your safety interlock you might want to consider using your Opto relay output for your charger interlocks. Maybe grab a multi pole relay and wire it into the Opto output that is programmed to first disable your charging sources before it does a hard OV trip, but if you are CANBus connected with CVCC control enabled it might cause problems. You would need to test it to see what happens when it gets pulled back by CVCC, then disabled by the opto output.
And I was doing some testing on the weekend and tested what happened when both the alternator and shorepower were enabled. In my WS500/Cerbo/REC Q BMS system I found that the curent cycled a few times on its MAXC upper limit, then both the WS500 and the Multiplus pulled back nicely and each provided about 1/2 of the power.
Awesome, Rick. Thanks for the quick reply to both questions.
After reading the first post again, the idea of using the Feature IN set to 0% might be worth exploring if for some reason you did not want to interlock your ignition enable wire. If used in conjunction with the opto output of REC BMS and making sure there was a good range between variable CHAR(your opto relay charger disable, defaults to 3.6V) and CMAX(your main relay cutout, defaults to 3.85V) it would ensure your WS500 field was zeroed well before the main contactor trips.
Has anyone had success with the configuration?
