Cheap LiFePO4 BMS?

[peterboat]

1 minute ago, nicknorman said:

Just a brief update:

1:  PCB manufactured 24 hrs after I sent the files off, now winging its way slowly back to UK

2: I have sussed the Masterbus, so now I can access various data including battery temperature, current, SoC, AH removed etc from the Mastershunt, and can view the parameters on the Combi such as whether shore power (or travelpower) is present, what the maximum charging current is set to, what the bulk, absorb and float voltages are. And more importantly, I can change these voltage and current settings. So my gadget will not only control the alternator but also control the Combi, should shore power or travel power be on. I'm chuffed!

I would give you double greenies for it if I could, this will make Lithium batteries a goer for lots of people

[nicknorman]

27 minutes ago, peterboat said:

I would give you double greenies for it if I could, this will make Lithium batteries a goer for lots of people

Only if it ever works!

[peterboat]

4 minutes ago, nicknorman said:

Only if it ever works!

Thats why I keep my system simple it always works.........................unless it doesnt ?

[MtB]

15 hours ago, nicknorman said:

Just a brief update:

1:  PCB manufactured 24 hrs after I sent the files off, now winging its way slowly back to UK

2: I have sussed the Masterbus (canbus), so now I can access various data including battery temperature, current, SoC, AH removed etc from the Mastershunt, and can view the parameters on the Combi such as whether shore power (or travelpower) is present, what the maximum charging current is set to, what the bulk, absorb and float voltages are. And more importantly, I can change these voltage and current settings. So my gadget will not only control the alternator but also control the Combi, should shore power or travel power be on. I'm chuffed!

 

I'm very impressed. You are annoyingly clever!!

 

 

[Richard10002]

18 hours ago, nicknorman said:

Only if it ever works!

Will a boat need a Masterbus/Canbus, (whatever that is  ), to use it?

[tree monkey]

2 minutes ago, Richard10002 said:

Will a boat need a Masterbus/Canbus, (whatever that is  ), to use it?

The masterbus/canbus is all part of the AI that controls Nick's boat

[Richard10002]

1 hour ago, tree monkey said:

The masterbus/canbus is all part of the AI that controls Nick's boat

Yes - I've heard the words used in relation to cars, but beyond that, it's whooshed over my head, (and it doesn't really matter).

 

I am just wondering whether the BMS Nick is designing will work for boats where some Winstons or Sinopolys are used to create a bank, and the BMS is connected with usual 5 or more cables and a few temperature sensors.... or whether it needs a canbus thing?

 

My guess is that most boats dont have a Canbus.

[Dr Bob]

34 minutes ago, Richard10002 said:

 

My guess is that most boats dont have a Canbus.

I'll be ok. Both me and Mrs Bob both have bus passes.

[MtB]

2 hours ago, Richard10002 said:

Will a boat need a Masterbus/Canbus, (whatever that is  ), to use it?

nick’s ultimate goal is to steer the boat from his phone. That way, he can go for a cruise whilst staying at home in Aberdeen.
 

 

[BEngo]

Since I don't think Nick is remotely interested in jumping through the   regulatory  hoops involved putting his widget into production, it is aimed entirely at his set up.  Hence he is using available Masterbus information to inform his widgets actions and simplify the design process.  That is eminently sensible.  Even so he has said that his design could accomodate other inputs case Masterbus was not decodable.

 

  If it works, I would  hope he might put sufficient information into the public domain to allow others to create their own version, tailored to their existing or planned sensors.  I would certainly be interested in some detail, but I don't expect I shall ever need to make one.

 

No doubt in the fullness of time someone, perhaps Charles Sterling, perhaps another, will release a productionised, configurable and adaptable Battery Management and Monitoring System with (some of) the capabilities Nick and other posters have identified.  I expect it will have a snappy label, lots of flashy LED's and cost real money.?  

N

[nicknorman]

1 hour ago, Richard10002 said:

Yes - I've heard the words used in relation to cars, but beyond that, it's whooshed over my head, (and it doesn't really matter).

 

I am just wondering whether the BMS Nick is designing will work for boats where some Winstons or Sinopolys are used to create a bank, and the BMS is connected with usual 5 or more cables and a few temperature sensors.... or whether it needs a canbus thing?

 

My guess is that most boats dont have a Canbus.

I’ve designed in provision for a digital battery temperature probe and an analogue input for current sensing and a real-time clock, as “insurance” in case the CANBUS thing didn’t work. But there is no point in adding additional sensors when the equipment measuring battery temperature, current, SoC, voltage, time and date etc is already there and capable of transmitting that data. So in the short term I won’t now be developing the redundant sensors, but could perhaps in the future.

 

It also occurred to me that battery charging with Alternator was just one facet of it - the Combi will charge the batteries Either from shore power or from travelpower when we’re cruising, and the system should ideally be able to control them too. Which it will.

 

I think more interesting for other boaters will be the programmable alternator voltage regulator, which is phase 2 of this project. The intention is for it to have rs232 (serial) input from the BMS part, plus alternator temperature sensing, so it can adjust the alternator voltage as required, to avoid cooking the alternator or over charging the batteries.

[nicknorman]

42 minutes ago, BEngo said:

Since I don't think Nick is remotely interested in jumping through the   regulatory  hoops involved putting his widget into production, it is aimed entirely at his set up.  Hence he is using available Masterbus information to inform his widgets actions and simplify the design process.  That is eminently sensible.  Even so he has said that his design could accomodate other inputs case Masterbus was not decodable.

 

  If it works, I would  hope he might put sufficient information into the public domain to allow others to create their own version, tailored to their existing or planned sensors.  I would certainly be interested in some detail, but I don't expect I shall ever need to make one.

 

No doubt in the fullness of time someone, perhaps Charles Sterling, perhaps another, will release a productionised, configurable and adaptable Battery Management and Monitoring System with (some of) the capabilities Nick and other posters have identified.  I expect it will have a snappy label, lots of flashy LED's and cost real money.?  

N

All pretty much correct. There is no plan to make my fortune with it - too much hassle! I made a gadget for our club gliders which measures indicated and true airspeed, altitude, temperature, total energy vertical speed and merges the data with NMEA sentences coming in from the GPS and going out to the moving map / glide calculator device, mainly so it could work out the wind quickly and easily. I’ve sold a handful of these to other club members at cost price, but to go any further involves interacting with the great unwashed public, and that is fraught with difficulties!

 

If you are interested in some brief details (TLDR for non-techies) im using an AD7800 chip for the battery cell voltage measurement and cell balancing FET drives, via SPI to a PIC18F26K83 micro which has built in CANBUS controller (just needs a transceiver chip) and serial port for comms with the alternator controller. There  are also 2 fairly chunky (5A) FET drives for the Tycho bistable isolation relay mentioned earlier (one for on, one for off). There’s an I2C interface to a dot matrix lcd display. And a couple of LEDs I could make flash prettily, plus a push button input to do something, eg reset the bistable relay following a disconnection event. Software (which will be in C) yet to be written - that will be fun!

 

The CANBUS protocol is in fact fairly simple once I worked out that there were always 4bytes of data for each parameter, that were in the standard IEEE 4 byte floating point format, except that the byte order was reversed. A human struggles to make any sense of the format at first sight. Well I do, anyway.

 

The extended 29 bit CANBUS address comprises the device ID mixed with another number reflecting the parameter group and 2 bytes of data representing the particular parameter, second byte always seems to be zero. So you send the message onto the bus with the 29 bits of address + parameter group  and the two bytes giving the exact parameter required, eg <address + parameter group> 02 00. The reply comes back with the same address except for 1 bit (which might be the RTR bit, not sure) and with 6 bytes of data which would be 02 00 xx xx xx xx where the xx etc is the floating point value of the parameter requested.

 

If you want to set a settable parameter (eg Combi charge voltage) you just specific it in the request, ie send all 6 bytes of data with the last 4 bytes being the new value. The target then responds with the new value.

Edited January 17, 2020 by nicknorman

[nicknorman]

2 hours ago, Richard10002 said:

Yes - I've heard the words used in relation to cars, but beyond that, it's whooshed over my head, (and it doesn't really matter).

 

I am just wondering whether the BMS Nick is designing will work for boats where some Winstons or Sinopolys are used to create a bank, and the BMS is connected with usual 5 or more cables and a few temperature sensors.... or whether it needs a canbus thing?

 

My guess is that most boats dont have a Canbus.

Mastervolt devices such as Combis, inverters, chargers and the Mastershunt can all be interconnected using Masterbus, which is a proprietary version of CANBUS. I’m pretty sure that the Victron equivalent (VE bus) is also based on CANBUS. And of course we have an Empirbus dc distribution system which also uses a different CANBUS network. Not many people have that last one, but plenty of folk have Mastervolt and Victron kit.

[IanD]

Wouldn't it be nice if all the suppliers had got together and agreed standard CANBUS message formats/meanings (the hardware is standard) so stuff could not only be interoperable or mixed but one controller/display could be used for everything? Yes I know it's a bit much to ask for competitors to talk to each other, but it's worked in other industries with far more complex things than this...

[peterboat]

23 minutes ago, IanD said:

Wouldn't it be nice if all the suppliers had got together and agreed standard CANBUS message formats/meanings (the hardware is standard) so stuff could not only be interoperable or mixed but one controller/display could be used for everything? Yes I know it's a bit much to ask for competitors to talk to each other, but it's worked in other industries with far more complex things than this...

Oh Ian you are asking for a miracle! At one time I think there was 3 different voltages on can network 12  9 and 5 if memory serves me correctly.  The 12 went fast and I don't know what won the battle at the end 

Edited January 17, 2020 by peterboat

[nicknorman]

2 hours ago, IanD said:

Wouldn't it be nice if all the suppliers had got together and agreed standard CANBUS message formats/meanings (the hardware is standard) so stuff could not only be interoperable or mixed but one controller/display could be used for everything? Yes I know it's a bit much to ask for competitors to talk to each other, but it's worked in other industries with far more complex things than this...

Nice? Yes! Going to happen? No!
 

The hardware all seems to be 5v but it isn’t that standard if you include the bit rate. CANBUS max bit rate is 1MB/s, Masterbus is 250kB/s, I think Empirbus is slower because no special twisted pair cable is required, but I haven’t look at that yet. There is a reasonably standardised marine system ie NMEA2000, and (at great cost) you can get a widget to interface between that and Masterbus.

 

Its complicated because every device on the bus must have a unique address, not just an address that is fixed for a given type of device, in case you want to have eg several Mastervolt Combis on the same system. So not only would the protocols have to be the same between manufacturers, but they would also have to have a central register of device addresses and ensure no 2 devices (even if made by different companies) had the same address.

Edited January 17, 2020 by nicknorman

[LadyG]

On 16/01/2020 at 16:11, peterboat said:

I would give you double greenies for it if I could, this will make Lithium batteries a goer for lots of people

oh

[IanD]

3 hours ago, nicknorman said:

Nice? Yes! Going to happen? No!
 

The hardware all seems to be 5v but it isn’t that standard if you include the bit rate. CANBUS max bit rate is 1MB/s, Masterbus is 250kB/s, I think Empirbus is slower because no special twisted pair cable is required, but I haven’t look at that yet. There is a reasonably standardised marine system ie NMEA2000, and (at great cost) you can get a widget to interface between that and Masterbus.

 

Its complicated because every device on the bus must have a unique address, not just an address that is fixed for a given type of device, in case you want to have eg several Mastervolt Combis on the same system. So not only would the protocols have to be the same between manufacturers, but they would also have to have a central register of device addresses and ensure no 2 devices (even if made by different companies) had the same address.

Far more difficult networking problems than this have been solved by the industry, including unique manufacturer and device addresses. You think this is hard, I'm currently working on 400Gbps optical transceivers which have to be interoperable...

[MoominPapa]

3 hours ago, nicknorman said:

Its complicated because every device on the bus must have a unique address, not just an address that is fixed for a given type of device, in case you want to have eg several Mastervolt Combis on the same system. So not only would the protocols have to be the same between manufacturers, but they would also have to have a central register of device addresses and ensure no 2 devices (even if made by different companies) had the same address.

From a quick read, CANbus IDs are 15 or 29 bits, and encode not only addresses but also bus priority (the more zeros you have at the start of your address, the higher your priority is) They must be unique on a single CANbus. However they don't have to be globally unique: devices need a globally unique address, but that's easy to achieve in the same way that globally unique ethernet addresses are: have a large address space (48 bits for ethernet) and carve it into chunks allocated to manufacturers who allocate addresses serially withing those chunks. I didn't look at protocols which allow a CANbus instance to allocate IDs (with priority) to a changing set of nodes with globally unique addresses but if it's not already been standardised it would be simple to design a protocol. CANbus is a broadcast network, so simply allowing a node to pick an address at random and use it if no other node responds to it should work fine. This is the same idea as RFC 3927 link-local addresses in IPv4.

 

MP.

 

[nicknorman]

9 hours ago, IanD said:

Far more difficult networking problems than this have been solved by the industry, including unique manufacturer and device addresses. You think this is hard, I'm currently working on 400Gbps optical transceivers which have to be interoperable...

I’m sure it could be solved if there was any interest in doing so. However without any external pressure, companies typically like their products to not be interoperable because it forces the customer to stick with the one brand.

[Richard10002]

Could this be the BMS that does everything boaters need? (It's sold out because Will Prowse used it in one of his videos, and the supplier was obviously not geared up to the demand he creates).

 

https://batteryhookup.com/collections/smart-bms/products/12v-lifepo4-smart-bms-w-low-temp-cutoff?rfsn=2267412.b1bf25

 

 

 

[IanD]

4 hours ago, nicknorman said:

I’m sure it could be solved if there was any interest in doing so. However without any external pressure, companies typically like their products to not be interoperable because it forces the customer to stick with the one brand.

True, but customers want the opposite, it depends how big the market is how many suppliers there are -- while the market is small like this one is at the moment (at least, outside cars) there's little pressure to standardise. If the market gets a lot bigger this may change, many people don't want to have a very expensive system locked into a single supplier. There's also the general growth in home automation using standardised network hardware and protocols (and controllers/apps/software) which is likely to take over from dedicated proprietary buses like Mastervolt/Victron.

[Dr Bob]

1 hour ago, Richard10002 said:

Could this be the BMS that does everything boaters need? (It's sold out because Will Prowse used it in one of his videos, and the supplier was obviously not geared up to the demand he creates).

 

https://batteryhookup.com/collections/smart-bms/products/12v-lifepo4-smart-bms-w-low-temp-cutoff?rfsn=2267412.b1bf25

 

 

 

I dont think so!

It is only rated at 100A so it wouldnt be enough for many boaters who may be looking for 200A. We use a number of things on the boat that pull more than 100A when on the inverter, ie the Nesspresso machine pulls typically 140A when working. Washing machine pulls more than 100A. If you have your starter battery hooked up into the system as a dump load for the alternator then can the starter motor pull more than 100A?

At $89 it looks cheap enough but if I was putting Li's on board I would be looking for more power handling which is why the peeps here using bare cells have gone for the tyco relay or the BEP motorised switch which both can cope with 200A. It looks fine for system where 60A is the norm.

The balancing function may work for the 100Ahr bank but will it be passing enough current if connected to a 400Ahr bank....ie it would take 4 times longer to balance?

If they made one that could handle 200-300A then that would be great.....but then you still need something to control your alternator. I think it will be a while before us boaters have a one stop shop for a BMS. Maybe Nick will be there first.

 

@nicknorman

Edited January 18, 2020 by Dr Bob

[nicknorman]

9 minutes ago, Dr Bob said:

I dont think so!

It is only rated at 100A so it wouldnt be enough for many boaters who may be looking for 200A. We use a number of things on the boat that pull more than 100A when on the inverter, ie the Nesspresso machine pulls typically 140A when working. Washing machine pulls more than 100A. If you have your starter battery hooked up into the system as a dump load for the alternator then can the starter motor pull more than 100A?

At $89 it looks cheap enough but I was putting Li's on board I would be looking for more power handling which is why the peeps here using bare cells have gone for the tyco relay or the BEP motorised switch which both can cope with 200A. It looks fine for system where 60A is the norm.

The balancing function may work for the 100Ahr bank but will it be passing enough current if connected to a 400Ahr bank....ie it would take 4 times longer to balance?

If they made one that could handle 200-300A then that would be great.....but then you still need something to control your alternator. I think it will be a while before us boaters have a one stop shop for a BMS. Maybe Nick will be there first.

 

@nicknorman

Plus I think we’ve worked out that just because the battery is below zero doesn’t mean it mustn’t be charged at all. It just needs to be charged very slowly. Hence the need to be able to control alternator and charger outputs. Our batteries sit on the counter in the engine room at the back (inside, but unheated with engine not running) and whilst I can’t recall seeing the battery temperature below about +5, I guess it could go below zero during a particularly cold snap. In any case, you certainly wouldn’t want the battery to disconnect completely so it wouldn’t even supply boat services.

49 minutes ago, IanD said:

True, but customers want the opposite, it depends how big the market is how many suppliers there are -- while the market is small like this one is at the moment (at least, outside cars) there's little pressure to standardise. If the market gets a lot bigger this may change, many people don't want to have a very expensive system locked into a single supplier. There's also the general growth in home automation using standardised network hardware and protocols (and controllers/apps/software) which is likely to take over from dedicated proprietary buses like Mastervolt/Victron.

I think NMEA2000 is the format to suit that need in the marine environment. What is annoying is that the widget to interface Masterbus to NMEA2000 is about £400.

[peterboat]

51 minutes ago, Dr Bob said:

I dont think so!

It is only rated at 100A so it wouldnt be enough for many boaters who may be looking for 200A. We use a number of things on the boat that pull more than 100A when on the inverter, ie the Nesspresso machine pulls typically 140A when working. Washing machine pulls more than 100A. If you have your starter battery hooked up into the system as a dump load for the alternator then can the starter motor pull more than 100A?

At $89 it looks cheap enough but if I was putting Li's on board I would be looking for more power handling which is why the peeps here using bare cells have gone for the tyco relay or the BEP motorised switch which both can cope with 200A. It looks fine for system where 60A is the norm.

The balancing function may work for the 100Ahr bank but will it be passing enough current if connected to a 400Ahr bank....ie it would take 4 times longer to balance?

If they made one that could handle 200-300A then that would be great.....but then you still need something to control your alternator. I think it will be a while before us boaters have a one stop shop for a BMS. Maybe Nick will be there first.

 

@nicknorman

I am with you Bob , my drive batteries are on the counter but in insulared heated boxes which gives me a chance in winter of moving my boat.  Solar at this time of year isn't great early on so again with a large bank no issues with high amps and cold batteries