Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley...

[alansmith]

You guys are like NASA engineers talking smack and I’m trying to figure out how to get my bike chain back on the sprocket and I don’t have my crescent wrench. He he.

[jmh2002]

Originally Posted by alansmith

You guys are like NASA engineers talking smack and I’m trying to figure out how to get my bike chain back on the sprocket and I don’t have my crescent wrench. He he.

Love it!

[newhaul]

Originally Posted by alansmith

You guys are like NASA engineers talking smack and I’m trying to figure out how to get my bike chain back on the sprocket and I don’t have my crescent wrench. He he.

place the chain on the rear sprocket then on the top of the front sprocket and pedal forward . It will crank hard till it suddenly will remount itself.

Stand by for next rocket launch.

No polish socket set needed

[s/v Jedi]

Originally Posted by CatNewBee

47μF will work, 100μF is safe, 1000μF, 2200μF will work too, it takes just longer to discharge. Impulse length is not critical, only minimal length is important. Use 25V rated capacitors, not the 16V rated for safety, 16V would work without issues, but 25V gives you peace of mind.

If you are crazy about capacitor failures (very unlikely at this application), take two 100μF in parallel, if one fails, the other will work, if capacity gets lost, no problem, you double the capacity by using in parallel and you have already 2 times more than necessary, so 4 times safety. But it is really not necessary, the capacitors don't get warm, they are once charged or discharged and remain in that state for centuries, because your system never switches when set up properly.

No, it is not about the value of the capacitors, it is about the brand. For all I know you may have good ones in there, but I stress to check it against the list, or just put in Panasonic. Some Chinese brands don’t last 5 years.

[beckett]

Originally Posted by s/v Jedi

I had a look at the product pages of the BMS and indeed it appears they did not put any addition I/O pins on the external connector.

In that case the microcontroller adaptor as proposed by Beckett seems the best solution. You scan for the BMS’s commands to control a relay and convert that to a proper control of the latching solenoid with feedback control to make sure all is well.

This is a big step for those not familiar with microcontrollers and programming them. In that case I recommend to look at the schematic from CNB and make sure those capacitors are from 1st tier manufacturers. Panasonic would be my choice but there is a list: https://www.tomshardware.com/reviews...01,4193-5.html
The importance is that the value of the capacitor defines the pulse send to the latching relay and this does not tolerate wild varying capacitance (these are not so precise to start with), drying out, leaking etc. which will actually lead to a failure to switch the solenoid, not just some hum from a speaker like when used in a power supply.
Pretty easy to make sure quality components are put in.

Beckett: you will have fun playing with these solenoids. I could make them jump from the table

Thank you, Jedi! Yes, I will try to CNB's driver first as it is a proven solution, however, I would need to convert it to 24V and make sure I will not mess something up. Once I have my system working I might play with the idea of using an Arduino to listen to the BMS messages and control the relay or just convert the BMS LVC and HVC relays and convert the signal. That should be a fun project but would need to build my bench/working area on the boat where I can play microelectronics as we are now in full time cruising mode as it is more challenging than it was at home.

[beckett]

Originally Posted by CatNewBee

47μF will work, 100μF is safe, 1000μF, 2200μF will work too, it takes just longer to discharge. Impulse length is not critical, only minimal length is important. Use 25V rated capacitors, not the 16V rated for safety, 16V would work without issues, but 25V gives you peace of mind.

If you are crazy about capacitor failures (very unlikely at this application), take two 100μF in parallel, if one fails, the other will work, if capacity gets lost, no problem, you double the capacity by using in parallel and you have already 2 times more than necessary, so 4 times safety. But it is really not necessary, the capacitors don't get warm, they are once charged or discharged and remain in that state for centuries, because your system never switches when set up properly.

Thank you, CatNewBee. For our 24V boat, besides the higher rated capacitors what else would I have to change?

[CatNewBee]

Originally Posted by beckett

Thank you, CatNewBee. For our 24V boat, besides the higher rated capacitors what else would I have to change?

I guess, it will work out of the box, you will have to double the inline resistors for the LED, they limit the current, so for the same current and double voltage, you need the double rating. Same for the optocoupler interface, chose a SIL relay for 24V and double resistance, so inline LED does not get too much current, or add a separate resistor for the LED.

For 24V you need the other BMS from REC, the REC ABMS is 4 cell only (12V pack). I am not in the details with that product, so I cannot comment what is has and how to treat it. Also you need 24V solenoids, but there are 24V REC BMS installations around in yachts, with and without master control units, even with more than one battery pack.

[beckett]

Originally Posted by CatNewBee

I guess, it will work out of the box, you will have to double the inline resistors for the LED, they limit the current, so for the same current and double voltage, you need the double rating. Same for the optocoupler interface, chose a SIL relay for 24V and double resistance, so inline LED does not get too much current, or add a separate resistor for the LED.

For 24V you need the other BMS from REC, the REC ABMS is 4 cell only (12V pack). I am not in the details with that product, so I cannot comment what is has and how to treat it. Also you need 24V solenoids, but there are 24V REC BMS installations around in yachts, with and without master control units, even with more than one battery pack.

Thanks, CatNewBee. All makes sense. The BMS I was going to order is REC SI BMS: REC d.o.o. which is good for 16 cells config, in my case I am only planning 8S config with 700Ah cells. The Blue Sea ML-RBS model 7702 for my 4 latching relays.
What brand relays do you use for the optocoupler interface? I will use good quality 100 mF 50V capacitors. Did you use any connectors for your ML-RBS or just extended the cables? BlueSea just introduced a new ML-RBS
Deutsch flavor model 7702100 with a connector. I might use this model if I can source a cable or make one for this connector.

[CatNewBee]

I dont remember the brand of the relays, I just used an online catalogue for electronic parts and searched for the desired specs. REED contact signal relay, 12V and compared the coil resistances to find one that is OK as resistor to limit the current for the LED and switch reliably at the same time. Goal was to minimize the current draw but have a visual representation of the state.

Regarding the solenoids, originaly open wires, soldered and shrink tubed to the extension signal wires and connected to the screw posts in the interface box, no other connectors inbetween.

[beckett]

Originally Posted by CatNewBee

I dont remember the brand of the relays, I just used an online catalogue for electronic parts and searched for the desired specs. REED contact signal relay, 12V and compared the coil resistances to find one that is OK as resistor to limit the current for the LED and switch reliably at the same time. Goal was to minimize the current draw but have a visual representation of the state.

Regarding the solenoids, originaly open wires, soldered and shrink tubed to the extension signal wires and connected to the screw posts in the interface box, no other connectors inbetween.

Thank you. In the diagram it hard to tell if the OPTO CH and DCH interface relay's contacts NO or NC are used, or it does not matter and Quatro could be configured either way?
Have you designed a PCB for your interface or just used a Prototype PCB board? I really like the clear lid enclosure box so you could see all your LEDs, what enclosure case have you used for your interface?

Am I exceeding my allowed question quota for today? )) Thank you!

[tanglewood]

I agree on having some way of verifying contactor operation, and many contactors are available with aux contacts that follow the main contacts and are designed to provide exactly this feedback. So you command the contactor while at the same time sensing the aux contacts. They should follow each other, all the time. I'm using this approach to build a cross-bar switch to connect a couple of load panels to several possible power sources. The connection of power sources to any given load panel must be mutually exclusive, and this ensures it even under a variety of failure modes.

[CatNewBee]

Originally Posted by beckett

Thank you. In the diagram it hard to tell if the OPTO CH and DCH interface relay's contacts NO or NC are used, or it does not matter and Quatro could be configured either way?
Have you designed a PCB for your interface or just used a Prototype PCB board? I really like the clear lid enclosure box so you could see all your LEDs, what enclosure case have you used for your interface?

Am I exceeding my allowed question quota for today? )) Thank you!

Hi, if the contacts are drawn open, they are NO, if there is no gap / drawn closed, they are NC. So here NO contacts, they close when the opto coupler darlington transistor passes through and switches on the current trough BASE / EMITTER of the NPN transistor, that results to allow current flof between COLLECTOR AND EMITTER, so the coil is powered through it and the LED.

Universal prototype board, I needed only one of those, so no effort spent on making a PCB. The box and the board are that big because off all the wires that need to be connected, it could be much smaller of course, but some space and good moisture protection was on my mind. It is a two sided PCB, I used the bended contact legs of the components to make the connections to each other on the other side and soldered them there, only few bridges of wire were necessary. Left side the inputs, right side the outputs, (2 solenoids are in parallel)

PCB picture shows state LEGACY sources (BMV) off (red LED), CH, DCH and opto coupler CH, DCH all enabled by the BMS.

The box is an universal IP65 DIN Case available in many sizes in electronic stores, ordered at amazon.

https://www.amazon.de/edi-tronic-Lee.../dp/B0747N4X58

[CatNewBee]

for the opto relays, you can choose bigger with more contacts to control not only the quattro charge, but also remote control the MPPT controllers and stop charge or put them to float when the BMS sends a stop charge signal.

You can change or improve to your own liking and at own risk. [emoji6]

[beckett]

Originally Posted by CatNewBee

for the opto relays, you can choose bigger with more contacts to control not only the quattro charge, but also remote control the MPPT controllers and stop charge or put them to float when the BMS sends a stop charge signal.

You can change or improve to your own liking and at own risk. [emoji6]

Thank you.
Tonight I am a bit disappointed with myself ... I got an email from REC to realize that I was reading a manual for the wrong BMS. I was looking at the REC ABMS(that you use), however, I need to be looking at REC SI BMS: REC d.o.o. ...
I will have 8 cells(8S) and this REC SI BMS allows for 5-16 cells but does not have features of REC ABMS. Specifically, it seems to have only 1 optocoupler and 1 user-defined relays. I think they betting on CAN bus communications via CCGX, VINUS GX, or CERBO GX.
I have to re-think everything and look for other examples of an 8S battery built with REC BMS SI and the battery protection I have been learning looking at your design. Do you have any advice where do I go from here?

[hzcruiser]

Originally Posted by s/v Jedi

[...]

Looking at a control signal instead of actual state is a mistake but it’s made often and one of the reasons automated systems like BMS can (and do) fail. It’s when things don’t go as expected and this often doubles programming effort so often skipped to save money.

Not necessarily a mistake but often a design decision and, as mentioned, ultimately a matter of increased complexity, chances of false positives, energy efficiency and cost.

I can't recall seeing relays with some extra feedback line?

One might think it can't be too hard to detect if a relay has switched state successfully, or can it?
Well, I thought I had this fully covered by measuring the voltage on either tab of the relay as well as the current going through the relay. Some might already say that's over-engineered...
Turns out even this approach is neither fool nor bullet proof: if you have a number of batts in parallel (like I'm handling every batt like a batt bank) and the system is at rest, meaning current flows are close to zero and voltages are equal, opening the relay cannot be detected by the means mentioned above.

Only later on, if some load or charger gets introduced, a discrepancy can be detected.
This can be seen as a negligible side-effect, but it nevertheless shows that even measuring a lot can sometimes be misleading.