In order to cook in our Toyota Hilux and Toyota Hiace we use a glass ceramic hob Steba HK 30 that – according to the manufacturer – allows for precise adjustment of the power consumption from a company called Steba. However, in reality these ratings seem to be different. In this article, I give an overview of the energy ratings I measured.
Observed Power Consumption
The hob has 2 rings with a nominal rating of
Ring 1 100w, 400W, 600W, 700W, 800W, 900W, 1’000W
Ring 2 200W, 800W, 1’200W, 1’400W, 1’600W, 1’800W, 2’000W
In the table below you see the actual values I measured in comparison to the nominal values as shown on the hob. For our Victron MultiPlus Compact 24/1600/40-16 the highest setting is on Ring 2 with 1600W nominal.
Ring
Wnominal
Waverage
Wmin
Wmax
0
0
0
0.4
4.1
1
100
200
225
254
2
200
450
417
459
1
400
400
375
409
1
600
475
450
477
1
700
600
580
602
1
800
700
708
731
2
800
750
699
770
1
900
860
850
863
1
1’000
930
932
934
2
1’200
900
863
901
2
1’400
1’150
1’108
1’148
2
1’600
1’400
1’368
1’396
2
1’800
1’650
1’645
1’659
2
2’000
1’800
1’787
1’795
Energy ratings of Steba HK 30
Other Observations
There are a couple of (negative) things that I noticed when using this hob:
When using the outer Ring 2 (or the full hob) the lowest level you can choose is 200W or then already 800W which turns out to be too much when trying to cook for a longer period of time. In my case, I use a large cast iron pot and let it cook for 4h to 5h. With 200W it was too little and with 800W it effectively started burning its contents at the bottom.
After 2h – 3h of constant use the hob once switched off after the pot boild over and spilled sauce on the hob. But I do not know if this was just a coincidence. After turning it back on it worked without interruption for another 2h – 3h.
The hob pulses when heating, i.e. turning the heating rings on an off very quickly. This seemed to stress the inverter when it was connected to mains (which was another inverter on batteries). For whatever reason it quite often drew power from the battery instead from mains.
After use the hob keeps a ventilator running for approximately 15min. It is rather on the loud side but not necessarily disturbing. Power draw during the cool down phase is 4W. When cooking something on the move one has to take that duration into consideration before switching it off.
The device is relatively bulky for that it is meant for only a single pot.
Summary
Most of the devices are not perfect (as described in the observations above). But all in all I really like the hob and we use it quite often. It is easy to clean and usable over several hours of constant use. Bon appetit.
Pulled Pork cooked on the Steba HK 30 with a Victron MultiPlus ( 1 )Pulled Pork cooked on the Steba HK 30 with a Victron MultiPlus ( 2 )Steba HK 30, taken from https://steba.com/produkte/glaskeramik-kochfeld-hk-30
I recently wrote about our upcoming solar PV adventure. But before updating our system, I thought it was time to document and explain our current setup (with the help of KiCad).
This system is the main electricity for our barn and currently consists of three batteries with an energy (often referred to as “capacity”) of 3* 14.33kWh = 43kWh (battery bank A, A1:A2 on the plan). These batteries are charged by a JCB G20QS (B1) via three MultiPlus-II 48/5000/70 inverters/chargers (B1:C2) which are by default in “Charge Only” mode. The MultiPlus-II are configured in a 3-phase configuration but only turned on when 3-phase is actually needed.
The main power is delivered by a MultiPlus-II 48/3000/35 (B4:C5) that is connected to a separate battery bank (battery bank B, BYD LVS Premium Battery-Box with an energy of 8kWh). This latter MultiPlus-II is connected to L1 of the 3-phase MultiPlus-II. So, whenever the main batteries get charged the cascaded inverter will also be charged. In addition, we can then use PowerAssist to up to supply 8'000VA (= 5'000VA + 3'000VA) when running on batteries and up to 14'500VA (= 6'500VA + 5'000VA + 3000VA) on a single phase.
Though the generator can supply up 14'400W the chargers of the Multiplus-II can only charge with a power of up to 3* 48V* 70A = 10'080W. This is actually an advantage as the optimal efficiency factor of the generator is roughly at 12'000W. So with 210A we are pretty close. If we ever added more chargers to the system we could even slightly increase the charge current to 250A.
System A with the 3-phase inverter configuration is connected to a Lynx bus bar (A1:B4) that also includes a Lynx shunt (B3) used for measuring over all batteries. In addition, there is an islolated Orion-Tr DC-DC charger (A5) that constantly feeds system B.
System A and B are connected to their separate GX:
system A Cerbo GX, A5:A6 MultiPlus-II via VE.Bus, Lynx Shunt via VE.Can, JK-BMS via RS485/USB
system B Raspberry Pi4running VenusOS, B5:B6 MultiPlus-II via VE.Bus, BYD BMS via VE.Can (on a Pi GPIO Hat)
And this is it for the electricity installation in our barn.
Note: This cascaded setup is officially not supported by Victron, but it has been working for us without problems for months now. This might be different in your case.
We finally did it and decided to get a PV system for our barn. Though we had been thinking about this since we started building on our plot, it never seemed to really pay off. A solar installation in very north of the Highlands?! But with prices for PV modules falling and falling I did another “business case” to see where this would land.
In the following figure you see the condensed outcome. In 38 months we would “break even” and roughly save over a 950 GBP per year over the course of seven years.
Diesel vs Solar cost over the years
Selecting Modules for the Roof
But first, let me begin from the beginning … for the last two years our JCB G20QS backup generator has been sitting outside in the rain and collecting not dust but rust – that is why we decided to build a small shelter on the south end of our barn. Once we finished drawing the shelter with its 36m2 roof, we thought that a south-facing roof would be perfect for collecting solar energy in the summer. Remembering my last calculation, I knew that the slope of the panels for winter and summer time differed dramatically. That was when we started thinking to place additional modules vertically on the south wall of the barn.
After we realised how much sheet metal for roofing would cost, we looked for for cheap solar modules that could be used as a cover for our shelter. We selected the Trina Solar TSM-NEG9R.28445Wp module with dimensions of 1762mm x 1134mm x 30mm that would fit well as a roof.
Selecting MPPT Chargers
With the PV modules selected I had to choose between a AC-coupled and an DC-coupled system or a mix between the two. As our system is off-grid and I expected fast-changing workloads in our environment I decided for a completely DC-coupled system.
Already running a Victron system, I wanted to use Victron MPPT chargers for the installation. After checking and comparing the prices of different chargers (with a VE.Can or a VE.Direct connection), I started the Victron Energy MPPT Calculator and added my solar panels to it. I then did a couple of modifications to the spreadsheet (by prior removing the password and protection from the sheets) and found the Victron Energy SmartSolar RS 450/100 to be the best choice. With this charger I could fit 7 modules per string in order not to exceed Voc. The power would be limited by over 30A at minimum temperature but I do not expect much sun in the colder months anyway. At max temperature there would also be a cap by roughy 15A but I expect to have large amounts of excess energy during the sunnier months – so need to worry.
Calculation for Trina Solar 445Wp modules with dual tracker RS 450/100 (Victron Energy MPPT calculator)Input voltage per stringCharge current per MPPT charger
Note1: there seems to be a bug in the spreadsheet version BHO 01-2021 4.0 when using the “MPPT RS” tab. The calculation table uses the selected voltage in cell E15 from the “Blue- & SmartSolar” tab (and not 48V as the only possible voltage for the RS) and from there miscalculates the currents.
Note2: when selecting the number of modules and the diameter of the cabling, the up/down buttons do not seem to work correctly. Typing the values directly into D16, D33, K18, J35 and K35 works around this issue.
I then combined the info into a table to see if and how much energy could be produced. For this I estimated the amount of energy I would need in the forseeable future per month (electricity and heating) which varies between 480kWh and 1'240kWh.
Note: currently we do not need even 25% of that amount.
The numbers with red background reflect the energy deficit for that month. Numbers with green background show an excess power production for that month. The total of all panels is shown in column U. From there it is compared against our generator which would roughly need 0.3l/kWh (row 26).
Power generation and consumption in comparison
So, for the first part of the installation I will add 36 modules on 6 strings as you can see from the image below.
Overview of planned installation
Anticipating Change
It is interesting to see how a 25% increase of diesel cost changes the picture:
Diesel vs Solar cost over years with 25% increase in fuel cost
As we still have space for more modules on our east-facing barn roof, I could add another set of (larger) modules. And this would reduce fuel consumption by approx. 20% by deferring the “break even” to 55 months!
Prediction with additional panels on the east-facing barn roof: 20% fuel rduction
But it gets interesting when we take rising fuel cost into account.
Prediction with additional modules on the east-facing barn roof: 55 months “break even”Prediction with additional modules on the east-facing barn roof: 25% increased fuel cost
With these additional modules we could run the whole winter with only one filling of our diesel tank and thus avoiding a costly refill during the winter season. So, this is something to be considered for the future.
Distributing Modules
Before wrapping it up, I will quickly motivate why I chose three SmartSolar RS 450/100 instead of one SmartSolar RS450/100 and one SmartSolar RS 450/200 and their connetion to the modules. With three instead of only two devices the average power reduction during a failure is only 33% instead of 50%. Power limiting is not such an issue, as the strings will be connected as follows:
Charger 1 117.3 A min temp / 96.2A max temp string 1: 5 modules 90°/7.5° south wall string 2: 7 modules 15°/-82.5° east roof
Charger 2 117.6 A min temp / 96.4A max temp string 1: 6 modules 15°/-82.5° east roof string 2: 6 modules 15°/7.5° south roof
Charger 3 117.6 A min temp / 96.4A max temp string 1: 6 modules 15°/7.5° south roof string 2: 6 modules 15°/7.5° south roof
Conclusion
I certainly do not know how much energy will really be produced. But it is clear, that I will have excess power in the summer when I do not need it and not enough power in the winter when I need it.
Additionally, I merely save a 950 GBP per year – not taking into account:
that I already have a required inverters, bus bars etc;
any labour on my side to design and install the system;
that the system gets more complex and error prone.
So, in reality I probably do not really save much to anything with this installation, as Diesel is still way too cheap. Though I certainly benefit from that, it is actually a shame. There should be more incentives for cleaner power generation.
As a side note: In case you missed why we went for a generator in the first place., here is why. The quote from the power company for a grid connection was way over 35’000 GBP. For this amount I can easily buy a generator, inverters, batteries and even solar modules.
And I already have an idea what to do with all the energy during the summer months that we really do not need: brewing a red ale with green energy …
The other day, I realised that I never wrote about the case build of our 16s 48V batteries, as I did for the 8s case and the 4s case. So, here it is – and I am actually describing 2 revisions as we made some adjustments.
First, the total weight of the cells alone would be roughly 16 * 5.3kg ~ 85kg. This is way beyond what a single person can – or at least should – lift. So, I deciced to split the battery into 2 separate cell blocks of 8 cells each (similar as I did split the 8s battery in the Toyota HiAce). With this approach, I would be able to:
reuse the 8s design (including the RAKO boxes)
be able to move or lift half a battery (which weighs roughly 53kg)
This battery has a nominal capacity of 3.2V * 16 * 280Ah = 14'336Wh and can be charged or discharge with up to 140A ^= 7'168W. We currently have 2 of these batteries running on our 3-phase setup with 3 * Victron MultiPlus-II 48/5000/70-50.
So essentially, I built 2 8s batteries with a connection cable between cells 8 and 9. The main negative and the BMS would be in one box and the main positive with the DC breakers would be in the other box. To avoid confusion, in this setup I went for coloured Anderson SB175 housings, with
Red 2 * 35mm2 H07RN-F cable main positive
Grey 2 * 35mm2 H07RN-F cable main negative
Blue Interconnecting both blocks 2 * 35mm2 H07RN-F cable connecting from cell 9 positive to cell 8 negative
In all cases
16s Battery Connectors
To connect the cells to the BMS balancer cables I extended the balancer cables with 2.5mm2 wire via WAGO 221-2411 inline splicing connectors. I then measured the increased resistance of the additional cable length and adjusted the values in the BMS configuration for cells 1 to 9.
With these inline connectors I am now able to disconnect the blocks from each other so I can move them around independently, if needed.
On the BMS, I connected a USB RS-485 TTL adapater with a USB extension cable which leads to one of the USB ports of the Victron Cerbo GX. With the help of dbus-serialbattery and BatteryAggregator I can control the DVCC settings in Venus OS.
The rest of the build is, as I already mentioned, pretty much like the 8s build.
Revision 1
Here are some images of the completed build of revision 1.
16s Battery top view16s Battery Block 1 main negative with BMS16s Battery Block 2 main positive with DC breaker
Revision 2
These are the changes I am currently making for the next revision:
add additional connectors for the balancer cables to further facilitate the disconnection of both blocks;
use 16mm2 M6 Klauke DIN46235 compression cable lugs for the connection of the main negative (cell 16) to the B- of the BMS (only relevant to the older JK-BMS), to be able to disconnect and potentionally replace the BMS;
use a WAGO 35mm2 DIN rail connector in the main negative block on cell 1/9 for the outgoing cable;
use cable glands on the external connections; (this allows for easy disconnection and re-building the block as an 8s battery);
use ratchet straps for compressing and mounting the cells to enable easier maintainability of the cells;
use Anderson PowerPole PP180 connectors instead of SB175, so I can use mounting plates for the PP180 and do not have dangling cables on the outside of the case (these connectors are expensive and increase the price of the overall build by roughly 60GBP).
Though this could have been our first “unboxing blog post” in this article we only describe an already unboxed table grill.
Being able to have fires in the open less and less often it was time to find an electric BBQ alternative – with the constraint that it should run on a Victron MultiPlus Compact 24/1600/40-16 (or any other 1600VA sized inverter). After some frustration we finally found a nearly perfect match: the WMF Lono Quadro.
According to its spec sheet and product brochure, it uses 1250W – which is just under the nominal maximum power of 1280W that the MultiPlus can deliver.
Plus, the BBQ is relatively cheap. With a MRSP of 79.99 EUR it is available for as low as 60 EUR (PP included depending on your location). So, we ordered one of these table grills and gave it a try.
Upon powering up the device it uses its full power (regardless of the dial setting 1 .. 5) which results in a current draw of around 50A as seen on the BMS. The setting of the dial only seems to affect the intervals between heating (drawing current at 50A) and not heating (not drawing current at all).
The initial heating phase lasts naturally longer which results in the fan of the inverter kicking in at some point. But once the BBQ is at its operating temperature the fan is silent most of the time (as the heating intervals are relatively short). With 1250W nominal power consumption and a heat-up time of around 5min this consumes roughly 104Wh – about the same energy to boild 1.1l of water from 20°C.
During the use of the BBQ the inverter is pretty much at its power maximum and so has little to no resources left to power anything else. Though it seems possible to leave a fridge running, it might be better to unplug any consumers during cooking.
But all in all, with this table grill we now can do the BBQ inside (or outside) in our Toyota HiAce – even when we are on the move.
Some additional observations:
Weight The device is relatively heavy – especially the grill plate.
Size The usable size of the BBQ (270mm x 270mm) in relation to its overall dimensions seems quite large (while the whole device is still not bulky).
Power consumption Though the power consumption is rated at 1250W the heating intervals are relatively short which turn leads to a moderate overall power consumption.
Cleaning The grill plate can easily be removed and thus easily be removed (even in a dishwasher if you happen to have one in your car). Also, the drip tray can easily be removed and cleaned. Only the base plate is not meant for dishwashing.
Drip tray If the BBQ is not positioned horizontally (maybe due to the parking position of the vehicle) then the drip tray might have difficulties to catch all the fat that might float around the grill plate.
And this is it for today. Happy BBQing …
WMF Lono Quadro running from a Victron MultiPlus Compact 24/1600/40-16 at roughly 1250W/50AHeat-up time is roughly 5min when turning the dial to the maximum position
However, in this case we wanted a kind of “special” setup which included the use of MultiPlus Assistants. So, in this article I will quickly describe what we wanted to achieve and how we implemented it.
In general, when connected to shore power we want to be able to limit the AC current drawn from the shore power. This is easily accomplished by setting a limit on the MultiPlus itself – or, as in our case, via the VE.BusSmart Dongle. Though the Phoenix does have a VE.Direct interface and is able to be connected to a GX device, in our setup we did not want to use a GX device. So, essentially the Phoenix can only be controlled via Bluetooth and the VictronConnect app. But configuring the AC input limit on two devices (Phoenix and MultiPlus) is not only a nuisance from a usability standpoint, but also error-prone as one (or at least we) tend to forget things quickly. So, a different and better solution was needed.
Enter the MultiPlus Assistant in form of the Programmable Relay. With this, we can configure the built-in relay of the MultiPlus to open and close based on the availability of an AC input.
Note: we have to disable “Virtual Switch” in the MultiPlus to be able to use the MultiPlus Assistant.
The Phoenix has a Remote Input connector, that can be used to stop charging when the connection is “off”. So in our case, we enabled two Programmable Relay assistants:
Programmable Relay, NC – On/Open After 5 seconds of AC input on the MultiPlus the relay is opened.
Programmable Relay, NC – Off/Closed After 1 second of no AC input on the MultiPlus the relay is closed (which is the default state).
Below you find some screenshots with the configuration in VE Configure:
Disable Virtual Switch on MultiPlusAdd 2 Progammable Relay assistantsProgrammable Relay ON after 5 secondsProgrammable Relay OFF after 1 second
So, five seconds after the MultiPlus has power via AC input it will open the relay which in turn will enable the Phoenix to start charging.
One second after AC input is gone the MultiPlus will close the relay so the Phoenix will stop charing (if it was charging at all).
The AC input of the Phoenix is connected to the AC output of the MultiPlus. So, when there is a AC input limit configured on the MultiPlus (such as 3A @230V) the MultiPlus and the Phoenix will not be able to charge with more than 3A. And from the MultiPlus perspective, the Phoenix is just an arbitrary consumer.
This can lead to some undesired behaviour if we were to limit the AC input to e.g. 1A. In this case, the MultiPlus would – when in Inverter mode – draw from the battery so the Phoenix could charge the battery. perpetuum mobile … ? And when the AC input is gone, this means that for roughly one second the Phoenix will also charge form the battery. But this is something I can live with easily.
And if we really had a very low power AC input (of e.g. 1A) we can still unplug the remote input and force the Phoenix not to charge. Or manually switch the MultiPlus to Charger mode only.
For us this is a usable solution without the need for multiple configuration changes nor the presence of a GX device.
Now, that we got our Toyota HiAce we thought it might be a good idea to add more power to the vehicle: in form of an 8s EVE LF280K LiFePO4 battery and a Victron MultiPlus Compact 24/1600/40-16 inverter/charger. In the following, we describe our setup and the reason why we built it like this.
The Requirements
The sustained output power of the inverter must be over 1'200W.
Charging via AC via EVSE or generator must be possible.
Charging via alternator must be possible (but is not the norm).
Charging of 60% of the battery (from 20% – 80%) via AC should take less than 180min.
The installation should use the minimum amount of space possible.
We should be able to use our existing Eve LF280K cells, thus limiting the overall current to 140A.
As the vehicle will not have a diesel heater, it should be possible to run a 150W infrared heater for at least 3 * (4+2)h = 18h (^= 2'700Wh).
In addition, the battery should be able to run a refrigerator with an average power consumption of 50W for at least 72h ^= 3'600Wh (next to other power consumption).
Design Considerations
With a maximum current of 140A and a cable run length of 1.5m, we should plan with a cross section of at least 35mm2.
Basically, with Eve LF280K cells we have three choices regarding the battery size:
1* 4s (“12V”) Configuration 4 * 3.2V * 280Ah = 3'584Wh This would lead to a required nominal AC charge power of at least 716.8W/h and a charge current of at least 56A/h.
2* 4s (“12V”) Configuration 2* 4 * 3.2V * 280Ah = 7'168Wh This would lead to a required nominal AC charge power of at least 1'433.6W/h and a charge current of at least 112A/h.
1* 8s (“24V”) Configuration 8 * 3.2V * 280Ah = 7'168Wh This would lead to a required nominal AC charge power of at least 1'433.6W/h and a charge current of at least 56A/h.
The Victron MultiPlus Compact xx/1600VA inverter/charger provides enough sustained power output (while being smaller than the non-Compact edition). Depending on the voltage of the battery, this will slightly impact the amount of charge current.
To charge the battery via the alternator we would need a DC/DC converter that depends on the battery configuration as well (either 12-12 or 12-24). So, let’s have a look at the battery first.
1* 4s (“12V”) Configuration
The smallest, lightest and cheapest configuration. But capacity requirements regarding the fridge are only fulfilled, if there are no other loads. In addition, the discharge current is relatively high (scratching the maximum discharge rate of 0.5C).
2* 4s (“12V”) Configuration
More complex setup, as each battery needs a separate BMS, which leads to the need of an aggregator for both batteries to correctly report SoC and calculate CCL and DCL. In addition, more cabling and fusing is required (and probably to a large bus bar). Comes with the advantage of having a redundant battery in case a single battery fails. Most expensive configuration.
1* 8s (“24V”) Configuration
Custom battery build needed, as there is not enough space for a typical 2 * 4 cells setup behind he seats. But, only a single BMS and thus less wiring is needed. Comes with a slight disadvantage of not having native 12V from the battery. This is actually not an isse, as all our DC devices also accept 24V. Cells can better balance voltage differences across a single 8s bank.
The Setup
In the end, I decided for the 8s configuration, due to less complexity. Splitting the 8s configuration across two cell blocks seemed to be an acceptable compromise.
As a regular MultiPlus 24/1600/40-16 would not fulfill my AC charge requirements, I had to decide to either add a second MultiPlus or to add a dedicated charger. I opted for a Phoenix Smart IP43 Charger 24/25 instead of a second MultiPlus. The MultiPlus in parallel would always consume 10W though most of the time I would not need the output power. Whereas, the Phoenix would only need power, when connected to AC. And reconfiguring the MultiPlus every time I charge was not an option for me. And yes, I lose redundancy – but also save some money (Phoenix is much cheaper). So, in the end the nominal charge power is 40A + 25A = 65A, which lets me charge at 1'560W reaching 60% within 165min.
The HiAce comes with a 70A alternator, so I chose a Orion-Tr Smart 12/24-15 DC-DC Charger. With this charger, I could run the engine in standby and still have the car heater running. And this is probably the predominant use case (if charging via alternator at all).
For the DC bus bar I went for a Victron Lynx Distributor, so I could use and install MEGA fuses. Having a 1’000A bus bar seems certainly overkill, but a separate bus bar and fuse box that accepts 35mm2 cable and MEGA fuses would be not be much smaller.
I changed the existing AC inlet of the HiAce to Neutrik PowerCON True1 TOP (congrats to the marketing department, I am still amazed how this name rolls of the tongue) and installed 2 Siemens compact 16A CRCBOs (external AC in, internal AC out). I am aware that theoretically I could support more than 16A on the internal AC out (via PowerAssist). If ever needed, I can replace the RCBO with a 20A version.
I added a VE.Bus Smart Dongle to the MultiPlus and opted against a complete (Raspberry-based) GX installation. The reason, I keep a USBMK3 with me anyway (in case I need to reconfigure the MultiPlus) and still have (Bluetooth) access to the most important settings and information of the MultiPlus. With the GX, I would to be running a WiFi hotspot (and consuming more energy as well). The disadvanage of not being able to use DVCC with information from the BMS is clear to me and accepted.
I selected a B2A8S20P JK-BMS that has an integrated 2A balancer and an RS485, CAN and heat port. In case, I ever add a GX device, I am still able to connect them and use DVCC.
The Specs
Nominal power (“capacity”) 8 * 3.2V * 280Ah = 7'168Wh
Maximum discharge power 1’600VA (1'280W, capped by the inverter) with a maximum current of 80A/63A/55A (at 2.5V/3.2V/3.65V)
Maximum AC charge power 1'560W
AC Charging from 20% – 80% in 165min
Maximum DC charge power 360W
MultiPlus self-power consumption 10W
The Build
As mentioned before, due to space constraints I had to split the battery in 2 parts (with each having 4 cells). Instead of using utz RAKO boxes I used 12mm (sanded) plywood which I did not screw together but tied down with a banding/tensioning tool and a ratchet strap. With this setup, I can easily access und disassemble the cells if needed, while still having a sturdy case. Both cell blocks are connected with a (blue) Anderson SB175 connector.
The BMS itself is mounted to the side of one of the cases (I took extra care to use short screws, in order not to drill into the cell casing). I used M6 Weidmüller 35mm2 90° angled compression cable lug to get the wire away from the BMS and into the bus bar. All other compression cable lugs are DIN 46235 from Klauke (M6 35mm2 on the cells, and M8 16mm2/35mm2 on the bus bar).
The AC and DC wires are all Eland H07RN-F (except for the last two points):
Charger to bus bar, battery to bus bar: 35mm2
Cell block to cell block: 2 * 35mm2
Alternator to DC-DC converter, DC-DC converter to bus bar: 16mm2
External AC in to RCBO, RCBO to inverter/charger (both directions), RCBO to internal AC out: 3G2.5mm2
For the connection of the Inverter/charger to the bus bar, I used the Victron installed 25mm2 welding cables.
Images
The installation is barely visible behind the seatsView from the back with preliminary wiringConnection of cell blocks with SB175 connectors, cell block 2 and DC-DC converterLynx Distributor with cell block 1Inverter/charger with space for second charger and cell block 2 (left)
Note: the Phoenix charger is not visible on the images, as I am still waiting for it to be delivered.
Charging via EVSE
Conclusion
We now have more than 7'000Wh of additional energy without losing any storage space for roughly 2'850 CHF/2’500 GBP (parts without labour). We can survive an extended weekend of 72h without recharging while still being able to enjoy amenities as using a coffee machine, heating and refrigerator. In case of longer periods of usage, we can recharge at any EVSE, or via shore power. And in emergencies, we can also charge via our Honda EU10i or via the alternator of the vehicle.
The battery is placed directly over the engine which helps in cold weather conditions to easily warm up the batteries to a chargeable level.
On my goal, to build a battery with a Venus OS compatible CAN interface I decided to have a look at he BYD CAN protocol – for several reasons:
It is supported with Victron and Venus OS.
I happen to have a BYD Battery-Box Premium LVS dual battery system.
I heard mixed information about the Pylontech CAN protocol implementation.
So, I got myself a Kvaeser Memorator Light, in order to be able to sniff the CAN traffic between a Venus OS and the BYD BMS. For whatever reason, I did not get it to work, so I ended up with candump – which proved to be more that sufficient for what I needed.
Note: of course, before I started reverse engineering the protocol, I made some effort to find resources and someone who might have already done that – but no luck. However, there were some fragments regarding HVS systems. But they did not seem to be compatible with the LVS implementation.
If you are interested in the result, you can head right here. Otherwise, stay with me and I explain my approach to correlate the identifiers and data pieces.
First, I just started candump to check the general message flow and to see some recurring patterns (working/normal operation, UseCase A).
I then verified that the communication (which runs at 500kb/s) only consists of 11bit identifiers and no FD frames.
I then identified the several message ids based on sender (TX, Venus OS) and receiver (RX, BYD).
I then monitored the message flow, when I disconnected the BYB BMS temporarily (UseCase B).
And then I monitored the message flow, when there was no BYD BMS present at start and then powered it on (UseCase C).
Have alarms and warnings being sent by the BYD BMS (UseCase D). (see note below)
Things to consider:
What are the units of the data being sent (e.g. temperature came in Kelvin/K)?
What is the byte ordering (e.g for WORDs expect the low byte first and then the high byte)?
Is there a scaling on the data being sent (e.g. 1/10mV)?
Is information distributed over different messages? Or does one message have a special meaning in correlation to another message? (e.g. cell voltage and temperature)
For most of the parts, I *knew* what data to expect or to look for. I just looked at the BMS device inside the Venus OS and looked for data that matched the information shown on the GUI.
In the end, I identified most of the messages. For alarms and events, I will verify them once I have a working prototype on my ESP32 by simulating and sending them to Venus OS. [Edit: Alarms and Warnings are now identified and described. Events seem to be not supported. With 17 frames/messages I can now setup a complete BYD battery simulation towards a Venus OS.]
When we run Venus OS without any modifications on a Raspberry Pi 400 no WiFi is detected – though the Pi 400 certainly has WiFi onboard.
As it seems, I am not the first one to notice that. bipedalprimate presented a solution by copying a bunch of Raspbian /lib/firmware files to the Venus OS. But as it turns out, things can be achieved much simpler.
It seems, that the driver on the 400 is differs from the chipset of a _regular_ Pi 4: it is the brcmfmac43456.
When looking at the /lib/firmware/brcm folder of a Venus OS these drivers are missing:
Venus OS v3.00 contents of /lib/firmware/brcm
On a Raspberry Pi 400 things look different:
Raspberry Pi 400 Raspbian 6.1.21 contents of /lib/firmware/brcm
As it seems, only a few files are required for a Raspberry Pi 400 and only a few belong to the brcmfmac43456. Most of the files are in fact links to other files (and some are in the cypress directory).
So, I did the following: I copied the brcm and cypress directories to a USB stick and inserted it into the Pi 400. From there I copied the driver files to the respective directories inside /lib/firmware, added some links and adjusted the permissions. Below you see the commands I used.
Note1: I am a novice when it comes to Linux, so pls do not expect any sophisticated shell scripting.
Note2: by default the root file system is _read-only_. Therefore I re-mounted it as read-write (so, maybe our changes will not survive a firmware update).
Note3: my USB stick was mounted as /run/media/sda1. Yours might be different.
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In our trailers and vehicles I prefer 24V 8s batteries, as the price-weight-power triangle of our Eve 280Ah cells is hard to match. With a gross weight of roughly 55kg we get a nominal “capacity” of 7168Wh. Even at a low cell voltage of 2.7V we can still get more than 2400W (3000VA) out of the battery. Exactly what a Victron MultiPlus-II 24/3000/70-32 (or any 3000VA inverter/charger for that matter) can deliver.
The Honda EU 10i has a sustained output of 900W which equates to roughly 3.9A at 230V. Now, this is not too interesting by itself.
However, the minimum AC current input of the MultiPlus is 3.6A. So, exactly within the range of the Honda EU 10i. A 5000VA inverter for example, would drain the generator with its minimum input of 4.6A+. And with its fuel tank capacity of 2.1l it runs nearly 4h on full load. Which in turn means, I can charge our 24V 8s battery about 50% without refueling.
Note: ideally we would charge it from 25% up to 75% SoC.
So, for me this generator is the ideal backup when I am away without any EV station nearby. With its 13kg and small form factor (and price) there is always a place in my vehicles where I can put it.
And as a side benefit: when I run the generator along with the inverter I can generate up to 3300W (or over 14A). That is: run my oven and boil potatoes at the same time …
And the generator even makes sense when combined with a Victron MultiPlus Compact 24/1600/40-16 (or its 12V counterpart). They are the smallest inverters/chargers in that power range. They strong enough to run a coffee machine or immersion water heater, but are not pwoerful enough to run a full 2000W appliance. However, in combination with the Honda, they just reach 2180W. Of course, charging a 24V 8s battery with a “Compact” device takes much longer, due to its smaller charger.
Our Journey to Scotland 