BMS and main contactor

[hjohnson]

Originally Posted by sailingharry

A question regarding CAN. CAN is originally (??) a sophisticated generalized communication standard in cars. That makes it a logical BMS communication protocol. But it also is the foundation of N2K. Has anyone been able to link a CAN based BMS into a useful N2K output? It'd be wonderful to get data to the chart plotter, primarily SOC, voltage, and alarms. Seems to me it's mostly there, even if there has to be some hardware/transport layer conversion, as well as sentence structure.

Yep, the victron stuff will do this no problem. I don’t have a chartplotter, but I can easily pull up the SoC, current, voltage, and battery temperature on my Garmin instrument.

On a separate page, I have my tach coming from the wakespeed.

[hjohnson]

Originally Posted by Simi 60

I've had ours in for 18+ months and haven't worried about or screwed with it once.

Check the app is all I have done
All 24 cells within 0.005% of each other at any given time.

Yes, but here I am, sitting at the hotel bar in New Zealand. I got curious about the systems on my boat, so I was able to do a quick check.

My SoC is at 98%
My bilge has 4” of water in the sump (a little below normal)
The saloon temperature topped out at 28C yesterday, and the barometer is holding steady.
My holding tank is empty
My hot water tank, and the rest of the AC system is off.
The wind is blowing 4kts in the marina, and there’s 12’ under the keel.

My boat is in Vancouver, BC.

If the parameters go out of band, if the SoC drops below 15%, or the communications goes down for more than 6 hours, I get notified.

This stuff is incredibly cool, and really helps me sleep better at night.

[sailingharry]

Originally Posted by hjohnson

Yes, but here I am, sitting at the hotel bar in New Zealand. I got curious about the systems on my boat, so I was able to do a quick check.

My SoC is at 98%
My bilge has 4” of water in the sump (a little below normal)
The saloon temperature topped out at 28C yesterday, and the barometer is holding steady.
My holding tank is empty
My hot water tank, and the rest of the AC system is off.
The wind is blowing 4kts in the marina, and there’s 12’ under the keel.

My boat is in Vancouver, BC.

If the parameters go out of band, if the SoC drops below 15%, or the communications goes down for more than 6 hours, I get notified.

This stuff is incredibly cool, and really helps me sleep better at night.

So, I have minimal Victron stuff (an inverter and two MPPTs). My fuel/waste/water tank level system is sophisticated, but self contained. I don't have a bilge level monitor of any sort, beyond an alarm. I don't have any digital monitor systems on the AC electric panel (except any info the MultiPlus might give). I don't have a dedicated, fee based internet connection on the boat. I do have wind/water/etc instrumentation that is on a boat WiFi.



How much would it cost to do all this? Including adding the BMS->N2K feature from Victron (unfortunately, Victron doesn't make -- more accurately, sell -- an actual BMS, so it would require buying Victron stuff specifically to make the data conversion from CAN to N2K). I suspect north of $2K, plus monthly fees, just to be able to monitor my boat from a distance. It's comforting, but it's a different social-economic strata than I live in.

[sailingharry]

Originally Posted by Statistical

It is here on the international website. The international website has two versions of the manual one which says "wakespeed compatible" and one that doesn't. As far as I can tell there is only one BMS just two manuals depending on how it is used.

https://www.rec-bms.com/battery-management-system/
https://www.rec-bms.com/datasheet/UserManual_ABMS.pdf



The rec forums should help to clarify.

Statistical, THANKS! This is bizarre. The US site is super heavy on the CAN/Victron/wakespeed integration. The manual is an additional 30% larger to cover all this, and they pushed the simple stuff onto the cutting room floor. Curiously, I think the actual box is identical. The international manual is almost exactly my design intent.


Curiously, I've not been successful in my search for meaningful forums. OGM-Energy hosts a forum, but it's really low volume. I'm still looking.


One small irritant, so far, on implementing REC is that there are 4 outputs. 2 are relay based, and good for significant power (.7A, I think). Still not enough to directly drive any contactor (the Kilovac that they recommend and show as direct connect is 3.8A to close, .5A to hold), but more than enough to drive a signal relay or a MOSFET. The problem is the 2 Optocouplers are limited to 15mA, which is quite limiting. For instance, an 8A DC SSR listed on Mouser has a 15mA control current -- right at the maximum! I guess I could use the optocoupler to drive a MOSFET to drive a contactor or SSR.

[hjohnson]

Originally Posted by sailingharry

So, I have minimal Victron stuff (an inverter and two MPPTs). My fuel/waste/water tank level system is sophisticated, but self contained. I don't have a bilge level monitor of any sort, beyond an alarm. I don't have any digital monitor systems on the AC electric panel (except any info the MultiPlus might give). I don't have a dedicated, fee based internet connection on the boat. I do have wind/water/etc instrumentation that is on a boat WiFi.



How much would it cost to do all this? Including adding the BMS->N2K feature from Victron (unfortunately, Victron doesn't make -- more accurately, sell -- an actual BMS, so it would require buying Victron stuff specifically to make the data conversion from CAN to N2K). I suspect north of $2K, plus monthly fees, just to be able to monitor my boat from a distance. It's comforting, but it's a different social-economic strata than I live in.

So at a minimum, what you’d need is a GX device. This is either a Cerbo GX, or a Raspberry Pi running Victron’s freely available Venus OS (there are also a couple of other victron gx devices).

That in turn talks to your multiplus, your MPPTs via cables and also interfaces to your n2k network and BMS. I’m running a REC ABMS, so that easily interfaces over CAN. But there’s a whole list of supported BMSs beyond just Victron’s offerings. Also, there is a third party driver for serial connected bmss like JBD and similar.

I went with the cerbo myself, largely because it came with all sorts of interfaces already built in (dual CAN bus, 4x resistive tank inputs, 4 digital inputs, 2 relay outputs, and the VE.Bus interface to talk to the multiplus. If you go the Raspberry Pi route, you’ll need to add a bunch of interfaces to whatever you have aboard. There are plenty of YouTube videos of people who have gone that route.

I’ve also added a GX tank 140 module, which is a usb connected box that adds 4 additional tank inputs that are compatible with 4-20ma current based sensors (or voltage based ones). I bought a set of 4 “toss in” tank sensors for $40 each on amazon. Google “panbo gx tank 140” for more info. I

I’m also running the “Venus OS Large” image which adds SignalK and Node Red. SignalK lets me pull in the data off my N2k network and do stuff with it, and Node Red gives all sorts of opportunities for automation.

For connectivity, it all goes through Victron’s free VRM service. The data usage isn’t much. I have an LTE router onboard, and over the past 15 days, there’s only been 216MB of usage, and that includes me remoting in and doing a bunch of stuff beyond just letting the monitoring run.

So cost wise? It’s tough to put a number on it, since I was already building an integrated system. But if you were going to do a cerbo plus all the other toys, probably $1000 CAD?

[hjohnson]

Originally Posted by sailingharry

One small irritant, so far, on implementing REC is that there are 4 outputs. 2 are relay based, and good for significant power (.7A, I think). Still not enough to directly drive any contactor (the Kilovac that they recommend and show as direct connect is 3.8A to close, .5A to hold), but more than enough to drive a signal relay or a MOSFET. The problem is the 2 Optocouplers are limited to 15mA, which is quite limiting. For instance, an 8A DC SSR listed on Mouser has a 15mA control current -- right at the maximum! I guess I could use the optocoupler to drive a MOSFET to drive a contactor or SSR.

I’m actually using their precharge circuit. Since I have a 2kva multiplus, it’s much nicer on the whole system if the unit gets a soft start. The precharge circuit basically connects a 50ohm power resistor across the contactor for 2 seconds, allowing the capacitors in the multiplus to partially charge, before closing the contactor. This significantly reduces the inrush current. As I recall, the precharge also has a stronger driver for the contactor.

[CaptainRivet]

Originally Posted by sailingharry

So, I've been quiet. But I've been reading the responses.


First, Jedi -- you need to develop a "Jedi's best" or some sort of link to all the really awesome stuff you've posted. Not the generally good stuff, but the awesome stuff. I just came across your post on pre-charge circuit. I'm pretty sure you've posted a circuit to make a latching relay respond to a on-off signal (this thread? I've already forgotten). So much really good stuff!


The main contactor question. I've been convinced that a solenoid with economizer is not a power concern. But the discussion on the Blue Seas RBS is interesting. I find that generally Blue Seas puts a staggering markup on industry products, but this one is unique and it provides some benefit for your extra $50 (West wants $270, but you can get it as low as $170). A nice recognized marine product, with the built-in circuitry to make it act like a relay, and a big knob on top to make it manual, and visual indication. If I can fit it (no known issues, but I haven't started that level of detail), it's probably in the design.


Integration. I need to make it super clear that I am NOT integrating. I'm not getting a CERBO GX. I am not getting a Wakespeed. I don't need CAN. My system is too entrenched, and I'm not replacing everything. I have:
* TWO Balmar regulators for two alternators. Yes, a single Wakespeed (or single Balmar) can easily and happily control both alternators, and I used to do that before I inherited a second, but TWO gives me redundancy as well as an installed spare (I can go back to one regulator).
* A Watt and Sea water generator. No external controls at all! No integration possible at all.
* 3 out of 5 solar controllers are Genasun, with no integration.
* A dumb old Victron Pegasus multi-voltage charger. I don't use it because I sail in North America, but it's ready if the boat ever goes back to a 220V country.


It's worth noting that all of my chargers SHOULD throttle back to zero charge before the BMS trips the charge control output (concurrent with the HVA). So it shouldn't ever trip. And since it will trip the regulator power supply (the alternators go to the main bus, not the charge bus), there won't be any negative impact if it does.


The LVA will trip the inverter (but it should already have tripped on its internal setting). In my view, the alarm will notify me to manage discharge, but if I don't, shortly after the LVC will open the main disconnect, and, in the words of the Navy, I'll be "cold, dark, and quiet."


The BMS.



I'm digging into the REC. It might be the ticket. It is FAR too complex, with all its integration with CERBO and Wakespeed and direct management of the charge profiles. But it "seems" like I can configure the outputs to simply give a LVC, LVA, HVA, and HVC based on individual cell voltages. I like the general form factor and construction, and programming complexity isn't a deal killer if I can make it do what I want. Price is not unreasonable.



I'll look again at the Electrodacus. I really like it's support and general design, but I'm even more concerned about the programming. The price is noteworthy.


Jedi, you mentioned in another thread the Daly, and using a super small size to control relays. If the power doesn't go through anything the BMS controls (either the BMS or a supported shunt), it has no idea about current -- but the only thing a good BMS does with current is track SOC. SOC is simply useful info to the operator, and has little value to the BMS internal programming. Since I'm intending to keep my Link2000 for user info on SOC (and start battery SOC), this may be an interesting approach. Have you posted on how to integrate a cheap SCR BMS into a robust LFP system? I'm thinking if the SCR output provides power to the main contactor, the cheap BMS will trip on HVC and LVC. That leaves LVA and HVA outputs to be addressed, as well as balancing (although many have opined that balancing in our low current applications, but charge and discharge, is of limited benefit).

I have eletrodacus BMS myself and meanwhile helped 20 boats to install it.
There is no real programming, the only thing you adjust is it’s so called EXT IO which are simple on /off optocoppler switches that are a load or a charge control or alarm based on cell voltages or/and SOC (your choice) that switch on/or off the sources via remote.
You don‘t need an expensive and unreliable main contractor on the high current side as the BMS shuts off all sources via remote signal. If the device doesn‘t have a remote switch but a physical on/off switch you modify it by connecting two cables to the switch and ready is your remote. If the device has neither then you use a victron battery protect. That’s what you do with your 5 MPPT, you combine all 5 on the output and put a Batterypotect BP220 in and electrodacus Switches them off when bank is full and enables if charge is welcome.
The BMS controls the charge on cell level not the charge sources themselves as with the other you mentioned. With your non integrative charge sources that’s exactly what you need, the REC is the wrong overly complex and expensive choice here.
Electrodacus has 2 shunts, one for load and one for PV which you use at boats as your charge shunt and connect all charge sources to it so electrodacus knows exactly what goes in and out so SOC and charge Management is very accurate. the shunts need to be on plus terminal but if they are on plus or minus makes no difference in the installation. I personally like that more as i have the electrodacus shunts on positiv and a victron BMV 712 battery Monitor shunt on negativ. it a) integrates shunt for Cerbo Integration you don‘t want and b) it is my 2nd fail safe as its Relais output will do the all disconnect/cutoff if BMS fails due to any reason before **** hits the fan. That makes a clean installation and i can compare and calibrate perfectly SOC and what goes in and out of the bank.

The electrodacus fits your setup well but

With all BMS incl. electrodacus you have the following problems:
The Watt and sea if it gets disconnected while running because BMS does cut off its regulator is toast. You need a dump load for it or run it via dc2dc charger with a lead starter. The electrodacus then simply switches on and off the Dc2Dc charger. Or ask watt&sea, they should provide you with a modification option how to cut the field wire like with an alternator as LFP gets more and more commonnand they need to offer a solution.

Stay away from the Daly, if you want a simple FET based similar to Daly I highly recommend the mueller JK BMS which does 250A constant and has a 5A active balancer. The alarm and cut off can be done by a victron BMV battery monitor.

[Maine Sail]

Originally Posted by s/v Jedi

This is not true. If you can’t or don’t want to use the 7700 style of contactor then you simply take the 7713 style which is exactly what you want: on when the control signal is on and switch back off when the control signal is lost.

I prefer the 7700 style and this is compatible with the REC BMS for sure. REC sells the modules to drive these or you can simply use the simple circuit as posted in the largest LFP thread on the forum. I forgot who did this but it isa 1,000Ah LFP battery and it’s been in use like this for many years. So it’s a proven solution.

Bingo.!

[CaptainRivet]

I choose Electrodacus because:
- All components except of the old legacy main DC load distribution cable is Victron that can be switched on/off by electrodacus
- the Concept that electrodacus is the Spider in the Web that controls everything, it’s a battery management system that also has all the BMS functions needed
- charge control on cell level by BMS independent from charge source
- the Profiles in the victrons are the 1st line of defense in case BMS fails, an additional layer non of the other BMS has.
- it’s non current carrying and that’s important because I have a catamarankkk and run it as Lithium hybrid starter and house bank incl. windlass. Eg FET based BMS like Daly,JDB or jk BMS would be killed by the reverse current of windlass or starter...
- it steers load and charge sources based on SOC eg hot water boiler switches on at 70% SOC (programmeable)
- easy Monitoring via Webbrowser, I use an old iPad 1 as display.
- support And Price

downsides:
- it’s not water resistant but you can easy achieve this by mounting it into an ip67 plastic enclosure and seal with sikaflex.
- the fidily plastic connectors for the ExT io where you need to connect the cat 5 cables...I use ferrules that are tiny in diameter to crimp to cat5 cable but extra long so they fit into connector, very hard to find and source as Standard are to short. Dacian recommends solid cat5 cable directly which is noGo in boats as they break easly