Goboatingnow
Solar Enthusiast
- Joined
- Jul 3, 2022
- Messages
- 1,325
Youre welcome.Thanks for all the help @Goboatingnow
Youre welcome.Thanks for all the help @Goboatingnow
Awesome I’ll waitNo I don't mind at all, but I am working on an update, clarifications and improvements and will post for review tomorrow.
Feed to starter should be AWB 3. alternator and fused suitable. Many starters are not fused. Alternator feed should be separate to battery , sized for max expected alternator output and seperately fused to protect that wire at the battery.Agreed, any thoughts about the size of the SLA Emergency dashed red feed with respect to Alternator Charging?
Yes the can bus will be liveAlso ( @svsagres and @wholybee ) when the switch is on LFP Disconnect and SLA Emergency:
- Can all modes of charging (alternator and solar) able to be switched on/off via CerboGX? (keeping in mind the CerboGX is powered by SLA.)
- Obviously all discharge equipment can be controlled via the DC Panel breakers.
- The Wakespeed under these emergency conditions (with the BMS dark and unpowered) will just output 13.8 volts. Is there any way to easily override that to provide more power and charge the SLA properly, perhaps through the CerboGX or the bluetooth interface? In that case the 2/0 wire would be needed.
- We have the BMS canbus wire connected to one of the Wakespeed canbus ports and then the other canbus port connects to the CerboGX, so when the BMS goes dark on LFP disconnect via the main relay, the Wakespeed - CerboGX canbus connection will still be live won't it?
In my system, at least, I just let it all go into limp mode. It doesn’t need to be fully functional, just needs to get me back to civilization. It’s unlikely to ever happen, so I’m not worried about it in the slightest. I just keep a length of terminated 2awg that I can jumper between the alternator and starter. Easy peasy, and I’ll probably never ever use it.Agreed, any thoughts about the size of the SLA Emergency dashed red feed with respect to Alternator Charging?
Also ( @svsagres and @wholybee ) when the switch is on LFP Disconnect and SLA Emergency:
- Can all modes of charging (alternator and solar) able to be switched on/off via CerboGX? (keeping in mind the CerboGX is powered by SLA.)
- Obviously all discharge equipment can be controlled via the DC Panel breakers.
- The Wakespeed under these emergency conditions (with the BMS dark and unpowered) will just output 13.8 volts. Is there any way to easily override that to provide more power and charge the SLA properly, perhaps through the CerboGX or the bluetooth interface? In that case the 2/0 wire would be needed.
- We have the BMS canbus wire connected to one of the Wakespeed canbus ports and then the other canbus port connects to the CerboGX, so when the BMS goes dark on LFP disconnect via the main relay, the Wakespeed - CerboGX canbus connection will still be live won't it?
Perhaps I am confusing things here, but I think the Starter feed from the SLA Battery should be a separate 2/0 awg wire. You advise that "many starters are not fused" and mine is not right now, so I am not going to use a fuse.Feed to starter should be AWB 3. alternator and fused suitable. Many starters are not fused.
Yes I think I need a 250a fuse at the SLA Battery, but why can't I use the red dashed SLA emergency wire shown in the diagram because all the chargers including the alternator are on the Lynx bus. I guess I should size it as 2/0 even though its never going to be above 100a and until I figure out if I can actually charge the SLA (70ah max battery x 25% acceptance= <20A) with the right profile when using the SLA as emergency battery it will only be charging at acceptance 13.8v level.Alternator feed should be separate to battery , sized for max expected alternator output and separately fused to protect that wire at the battery.
Understood. I guess I'd rather not mess around in the tight engine room with a jumper cable at night.... something bad might happen. LATER: Also I might want to actually charge the battery and turn off the engine and sail, due to the distance...limp mode. .. just needs to get me back to civilization. .. just keep a length of terminated 2awg that I can jumper between the alternator and starter.
Well, I’ll probably never have to do that in anger as even if my system takes a dump, my engine will keep going and since I use my iPad as a chart plotter, it can get me into a safe anchorage to deal with.Understood. I guess I'd rather not mess around in the tight engine room with a jumper cable at night.... something bad might happen.
Seems excessive what’s the total peak current the lynx is carryingHere is the Sept 26, 2022 revision, with recalculated wiring sizes & lengths, starter and SLA revisions, and additional notes.
Does the boat ground from the Lynx BMS to the Engine really need to be 1/0?
Overview:
The REC BMS can form an integral part of a networked Victron Energy System by working together with your inverter, MPPTs and chargers to help avoid hard shutdowns.
The REC BMS functionally acts as a Master DC source on the CANBus network via the Cerbo, and becomes part of the Victron Ecosystem. You just need to set a few parameters in your Cerbo to use the REC as your main DC supply. I have attached a few page snippets showing what the REC BMS looks like in a Victron VRM and Cerbo. With this setup the REC BMS, as the cell approaches a high voltage condition, will send a CANBus maximum current/voltage setpoint to your MPPT, MultiPlus, and the WS500. This will work as a high limit function and start to pull back the charging of all smart charging devices attached. The WS500 will actually get the signal directly from the REC BMS, based on the CCN setup parameters of your WS500, so it does not need to be fully compliant with rest of the Victron devices. You just wont be able to see the WS500 parameters and alarms on your Cerbo yet. (But it should be available in a future release in the next year or so, I would guess.)
What does this all mean? The premise here is that with an integrated system you can modulate your "Smart" charging devices to avoid a hard OV trip. Even better, it will throttle the output to allow your cells to top balance without nuisance trips. For instance, lets say you have one cell that hits 100% before the others. With a conventional system, your overall voltage is still telling your chargers to charge, but the BMS will have to issue a hard OV trip to save that cell. In a "Smart" configuration, the REC BMS throttles back all of your Smart charging controllers, to allow the out of balance cell to top balance and remain within the normal range, while the others slowly top up.
Note that the above list has changed recently because the new version of the WS500 is now using the CerboGX VE.Can cable.You will need a couple of cables to do this.
REC BMS to Victron Cerbo: https://www.offgridsoftwaresolutions.com/product/rec-victron-canbus-cable/
WS500 to Victron Cerbo: https://www.offgridsoftwaresolutions.com/product/rec-ws500-canbus-cable/
And if you dont have a Victron system and just want to connect your WS500 to your REC BMS directly: https://www.offgridsoftwaresolutions.com/product/rec-ws500-canbus-cable/
Unless you think I should go to 1/0 AWG for a safer circuit.1. Chargers Alternator (field restricted - belt managed) 100a + Solar 15a - DC Panel 10a = 105a (3 AWG 16' 2 AWG 20')
13.7.7 No electrical connections should be made directly to a lithium ion battery that would bypass a BMS or the protection relays.
The standards do allow manual override on extremis. So I believe you are compliant because in normal mode with the switch to “ off” you have nothing connected to the battery terminals except the bms.Yes, I've got that covered under Procedures, that the DC-DC charger has to be turned off at the DC Panel manually otherwise it is a runaround circuit (I don't think it would hurt anything, and maybe the battery would actually get charged rather than sitting at 13.8v, but then the regulator would back off and not do absorption charging at all).
But recently I saw your post about automatically disconnecting the DC-DC charger with the switch AFD?
Would running the DC-DC Charger switch through the smaller NC relay (or even a second NC relay) make it automatic?
I am going to just pick
Unless you think I should go to 1/0 AWG for a safer circuit.
Also the note for 1-Off-2 Position 2 has to be changed to be like Position 1 with the NC powered on and open, BMS NO relay depowered.
Regarding the statement that this switch is bypassing the protection relays and is against
- I believe context is important. It does bypass the protection relays when on "LFP Bypass Override", however "Off Normal LFP Operation" and "SLA Emergency Feed & LFP Disconnect" does not.
- The LFP Bypass Override is there to allow charging which is necessary to get the batteries back on line in the event of a LVD shutdown.
- As I said earlier, I am not going to be horsing around sailing on a dark night, with a dark boat, when singlehanded with jumper cables trying to get discharged LFP charging!