Tag: Electricity

Charging Leisure Batteries at Electric Vehicle Charging Stations

I am not the first and probably not the last, either. With leisure batteries becoming larger and larger, fuel becoming more and more expensive and the EV charging network better and better, I thought it was time to rethink charging leisure batteries in campervans, mobile homes and the like.

For example, in UK the Tesco run EV charging stations currently offer charging at 3700W/16A at 0.288 GBP/kW. This is actually cheaper than the rates I had last year when I rented a flat. And it is still slightly cheaper than the cost of power generation with my JCB generator.

As I restrict the charging of my EVE 280Ah cells to 125A, the maximum power to charge with is either 8* 3.2V * 125A = 3200W for a 8s 24V battery or 16* 3.2V * 125A = 6400W for a 16s 48V battery. But as of now, I only plan for 24V batteries in our vehicles. This means, that even with the lowest single phase Type 2 charger in a EV charging station we get more power (16A * 230V = 3680W) than the battery can be charged with.

With the help from Remo Fleischli of Mobilize I found two adapter cables from Elektroscout:

  1. A single phase Type 2 plug to a Swiss T23 socket, which I ordered with a “loose end” to connect a Neutrik powerCON TRUE1 TOP NAC3FX-W-TOP-L with it;
  2. and a single phase Type 2 socket to a Swiss T23 socket, which they call a “bike adapter” – this comes in handy at charging stations with a 3-phase Type 2 cable.

As a 24/3000 MultiPlus-II (or EasySolar-II) does only support charging of up to 70A (resulting in a nominal charging power of 24V * 70A = 1680W), we would still be 55A “short” of the desired maximum charge current of 125A. With the EasySolar-II GX or the MultiPlus-II GX there is no 24/5000 version and the MultiPlus-II 24/5000 uses considerably more power (18W vs 13W) and is way heavier (30kg vs 26kg [including MPPT charger] vs 20kg). In addition the inverter would be massively oversized as the maximum expected inverter power would be limited to 8* 3.65V * 125A = 3200W (^=4000VA), anyway.

So, I came to the conclusion the least expensive and space/cost-efficient solution would come in the form of a Victron Skylla-TG 24/50A Charger:

  1. Weight: 5.5kg
  2. Price around 500,00 GBP
  3. Dimensions: H 365mm * W 250mm * D 147mm

So, with the combined power of the EasySolar-II and the Skylla-TG (70A + 50A = 120A), I can now theoretically charge at 8 * 3.2V * 120A = 3072W – near the maximum supported power. As the charge current will probably reduce at around 80% SOC, my 24V battery can be charged from 40% to 80% within one hour – at a price of less than 30p per Kilowatt (or 90p the hour)!

Here a comparison with some smaller generators:

  1. a Honda EU10i will deliver 900W with 0.538l
    (around 1671W/l or 0.598l per 1000W)
  2. a Honda EU22i will deliver 1800W with 1.075l
    (around 1675W/l or 0.597l per 1000W)
  3. a Honda EU32i will deliver 2600W with 1.394l
    (around 1865W/l or 0.536l per 1000W)

If one liter of E7 costs roughly 1.50 GBP, the price per 1000W is between 0.80 GBP and 0.90 GBP.

Comparison of different charging options

And with a standard vehicle alternator of 100A the maximum charge current for a battery would not exceed 60A. So, a realistic amount of power to charge the battery with a running engine is around 12V * 60A = 720W. If we expect the vehicle to use 2l per hour running idle, the price for 1000W would sum up to over 4.17 GBP – not cheap.

Only the Honda EU32i comes near to the maximum charging power of 3200W/h. But the initial cost for the inverter and the price per 1000W is far beyond the cost of an additional AC charger, a Type 2 adapter and the energy cost at the EV charging station. And ideally, the energy from the EV charging station is “greener” than the energy from the vehicle or stand-alone generator.

Note: I did not write about solar panels at all. The reason for this is our special “use case” where we are mainly in northern europe where during autumn and winter there are very little hours of sunlight – at a time when we need energy the most. Plus, only two of our vehicles have actually space on the roof for solar panels.

This is my current take on charging larger leisure batteries. What is your opinion on this?

Sizing the electrical installation for our König KHC303630 Trailer

On our seemingly never-ending quest to the perfect “mobile home” and its electrical setup.

Once, someone told me the perfect vehicle for a mobile home would be a tri-fold:

  1. a 20m truck when stationary;
  2. a Unimog when off-road;
  3. and a Porsche when on roads.

As it seems hard to get hands on such a vehicle we have tried different combinations over the years – with a few “failed” attempts such as our VW California T6 or the Hymer B-MC I WhiteLine.

So, recently we took a different tac and went for a trailer. A “König KHC303630” to be precise; which is a 2m high, 2m wide, 3.66m long sandwich cabin on a twin-axle trailer (with an overall length of under 5m). The idea was to have something more comfortable and spacious than our Hilux with the roof-top tent. If you want to get an impression of how this looks have a look at one of these videos.

Before we actually made the decision to purchase the trailer, we went to Trochtelfingen to see for ourselves. It was then when we decided to have the main battery system voltage different from the 12V standard.

Originally, I thought to have a 16s 48V system with Eve 3.2V 280Ah cells. However, the resulting weight would be over 80kg – without BMS, case or inverter. So, I thought about installing an 8s 24V system with a resulting nominal power of 7168W. And it seemed that such a system would still satisfy our requirements.

  1. The mximum single load would be 2000W for a duration of up to 35min.
  2. The sum of all 12V loads would not exceed 360W.
  3. The total load would not exceed 2300W.

The Eve cells support 0.5C, meaning I could constantly draw up to 2800W (at 2.5V) and 4088W (at 3.65V) at 140A. However, as my largest DC MCB is only rated for 125A I could only use between 2500W and 2650W. But that would be still more than sufficient. And the Victron EasySolar-II GX 24/3000/70-32, the inverter which I had in mind for this installation, supports sustained loads only up to 2400W anyway.

So first determine, how many 24V connections do we need?

  1. 8s 24V battery, via SmartShunt 500A (in/out)
  2. inverter/charger (in/out, interally fused)
  3. 24V/12V DC-DC converter (out, interally fused)
  4. 12V/24V DC-DC converter charger (in)
  5. 2* 24V USB-C sockets (out, interally fused)

With 125A as the maximum expected current the use of the Victron Lynx Distributor bus bar seemed a bit oversized. So, I decided to use a pair of (way cheaper) 6P 150A Victron Busbars.

For the 12V system, I expect to use a 12 port Plus/Minus distribution:

  1. Refridgerator
  2. Bed
  3. 5* lights
  4. 12V socket for shower
  5. 4* 12V sockets

To convert the battery voltage to 12V, I opted for a Victron isolated Orion-Tr 24/12-30 converter. The whole 24V/12V converter will be able to be by-passed and directly connected to the 12V of the trailer, as well.

For minimum chargin on the road, I plan for a Victron Buck-Boost DC-DC Converter 50A. But as this would take more than 6 hours of driving to fully charge, the idea is to mainly charge via AC. However, the EasySolar can only charge with up to 70A. And in order to get closer to the maximum of 125A, I would add a Skylla-24/50 TG . Why I chose the Skylla-TG over the Skylla-I? I only need it for sporadic AC charging and the TG model is lighter and cheaper.

So, with the EasySolar and the Skylla the total amount of charge current adds up to 70A + 50A = 120A, which totals in a theoretic 3072W (just over 13A at 230V). So, any standard 16A cable would do to charge the battery.

A quick overview of the AC connections/RCDs in the trailer (all sockets will be Neutrik powerCON TRUE1 TOP NAC3FPX-TOP):

  1. Inverter/charger (out)
  2. Bath Immersion Heater
  3. Kitchen Microwave
  4. Kitchen Coffee Machine
  5. Kitchen Kettle
  6. Kitchen Stove/Oven
  7. Kitchen Spare
  8. Entrance AC-DC USB-C Charger
  9. Entrance Spare
  10. Back Left Spare1
  11. Back Left Spare2
  12. Back Right Spare1
  13. Back Right Spare2

For external AC input, I plan for a Neutrik powerCON TRUE1 TOP NAC3PX-TOP input with a pass-through and a separate 16A RCD.

Anything that I forgot? We will find out, once the trailer is delivered and we begin with the installation.

Electricity upgrades for our Toyota Hilux

With the next Toyota Hiace and the Saurer 2DM around the corner waiting to be converted, I thought it was time for consolidating our vehicular electrical installations.

But before going into details, some history first: In 2019, we started on the VW Calkifornia T6 with a Super B Epsilon 12V90Ah LiFePO4 battery as a simple drop-in replacement and added a Votronic SMI 1200 ST inverter to it. And this was probably where I made my first two mistakes. At that time, I decided for Votronic and against Victron Energy. And I did not pay attention to the non-existing programmability and extensibility features of the Votronic inverter.

And when we later, during the COVID summer of 2020, got our Hymer B-MC I WhiteLine and I installed a Liontron 12V200Ah battery with another Votronic SMI 1700 ST-NVS. And to make things a little more complicated, I added a DC-DC charger: also from Votronic – an emerging pattern.

Once with a vendor stick with that vendor? There a pros and cons to it as we will later see.

When we later prepared our Hilux for our first longer trip to Loch Watenan, I opted for a Liontron 12V200Ah battery again (for the reason Liontron being way cheaper than Super B). And for the inverter/charger, I went for Votronic again (SMI 1200 and the same DC-DC charger 1212-45) .

But when I tried to get the DC-DC charger working, I realised that the D+ signal was not available on the Hilux. All in all, I did not get it to work in any configuration and looked for alternatives – which came in the form of the Victron Orion-Tr Smart DC-DC Charger family. And when I had to add an AC charger (where in the Hymer I could use the existing AC charger) to load the Liontron battery “on-shore”, I chose the Victron Blue Smart IP22 Charger.

So, at that time there was some kind of tie between Victron and Votronic. And the setup was getting more complicated and more complicated. And I am not only talking about the diminishing space in the trunk of the Hilux.

If I had known about the Victron MultiPlus series at that time I could have saved me a lot of headaches and complications.

It was shortly after our first and very successful trip to Loch Watenan, when we got rid of the Hymer and I added the battery from it as a second battery to the Hilux. And I got 2 more Victron DC-DC chargers. But I sticked to my Votronic inverter. And this is how the final layout looked like:

Toyota Hilux setup with 2 Liontron 12V 200Ah batteries, 4 DC-DC 30A chargers

This all worked well end of 2021 when one of the Liontron batteries did not want to charge properly anymore. The combined cell voltage stayed low at 13.1V with no single cell near at 3.5V and the internal BMS still reported 100% SOC.

So it was time for a change. And while doing that eliminting some design shortcomings of the current installation:

  1. Invertert has a power maximum of 1200W.
  2. AC charging is limited 30A.
  3. Both 200Ah batteries are operating separated with one of them feeding the inverter and the other feeding the 12V DC sources.
  4. Each pair of DC-DC chargers is bound to a single battery.
  5. The alternator cannot feed all 4 DC-DC but only 3 chargers at the same time.
  6. The inverter cannot be controlled wirelessly.
  7. The whole system is not integrated.
  8. Fuse boxes are unlabelled fuses from AliExperss.
  9. No bus bars in the system.

So, here is the “new” setup:

  1. Replace the Votronic SMI 1200 ST inverter with a Victron MultiPlus 12/1600/70-16 Compact (which happens to have a similar form factor as the Votronic).
    • increase AC charging power to 70A
    • increase nverter power to 1300W
  2. Add a Victron 500A SmartShunt to compensate for the lack of BMS integration.
  3. Remove the 30A AC charger (to gain space for the bus bar, see next).
  4. Add a Victron 1000A Lynx Distributor bus bar.
  5. Optionally, add a VE.Bus Smart Dongle or a Cerbo GX / Raspberry with VenusOS.
  6. Have both batteries run in parallel to feed the inverter and the DC sources at the same time and thus reducing the maximum current at 1300W to 65A (when both batteries are dropping down to the minimu of 4* 2.5V = 10V) or considerably lower when running at 14V (45A) .

But the “best” of it, I then got rid of all the Votronic devices and can integrate and configure more easily with Victron. And I can do the same in the Saurer and HiAce.

I hope I can start with the conversion mid of March and will post updates on the way.

So, what do you think? (And no, I have no affiliation with Victron at all.)

30 Days into using the Victron MultiPlus 12/1600/70-16 inverter and a Liontron 12V 80Ah with our Swift Sprite Caravan

The Caravan we got last year did not come with an inverter, so getting coffee in the morning or running a microwave was only possible when our main generator was running. And the installed battery for 12V support had a rather small capacity. This was clear to us from the beginning, as we eventually wanted to connect the Caravan to our EVE 280Ah cells.

But since we got our Starlink internet and our router did not seem to run easily on DC power, we needed -in addition to the temporary morning AC coffee spike – a more permanent AC solution.

So, I grabbed an existing Liontron 12V 80Ah battery that was sitting on the shelf along with a Victron Energy MultiPlus 12/1600/70-16 charger/inverter and connected the inverter AC Output to the CEE16-1 AC input of the caravan and the inverter AC Input to one of the phases of my JCB G20QS generator (of course, all via Neutrik powerCON TRUE1 TOP connectors and H07RN-F3G2.5 cable).

For the connection between the inverter and the battery I used a 35mm2 cable and Klauke DIN 46235 compression cable lugs on one end and insulated ferrules on the other end. In between, I added Anderson SB 175 connectors with 1383 lugs for quick disconnects and crimped as shown here. For the fuse I used a Schneider Electric 125A DC MCB, as I do not expect higher loads in this setup.

Of course, first I updated the firmware of the inverter and configured it work with the battery:

  1. Setting the AC input to 16A
  2. Setting the battery type to LiFePO4
  3. Setting the charge current to 70A (which is over the recommend amount of 50A, but see below for details)

As I did not want to connect a Cerbo GX to the system, I just used the VictronConnect App. Maybe I add a VE.Bus Smart dongle later on, or I connect some GX nevertheless. Who knows … Until now, it needs a wired connection to the inverter to see its status.

After powering on the generator, I confirmed everything was roughly working as expected. During the first run, the SOC was shown as 100% though the BMS of the battery internal saw it differently. In addition, the reported Amps and temperature were seen differently, as well. So, even that I set the inverter over the recommended maximum of 50A for the battery, the actual charge power was never much higher than the actual maximum).

This is what the inverter saw (100% SOC, 14.05V DC cell voltage, charging at 64A):

MultiPlus charging the Liontron battery via the generator

And this is, what the Liontron BMS reported (76% SOC, 13.8V DC cell voltage, charging at 55.5A):

The SOC as seen by the Liontron battery BMS

In the end, the BMS stopped charging when it thought its batteries were full. And the inverter did not complain. However, I noticed that the cells were really not in balance (with a delta of 200mV between the lowest and highest voltage).

Discharging was ok, as well. However, I soon realised that the 100A discharge current could not be achived in my setup. The inverter tried to draw power and the BMS cut off with a “Discharge over-current” (OCD). SO, still no coffee via our Nespresso machine (and no microwave either, for that matter).

So, what is the take away of all this?

  1. It works and now, I can run the Internet all day.
  2. All in all, it is a relatively simple and quick setup.
  3. The Liontron battery does somehow not live up to its specs (and yes, I know the battery could be a size bigger for what I want to achieve; but I did not want to buy an additional battery for this temporary solution).
  4. It is way cheaper and more flexible than to buy this “off the shelf”.
  5. Maybe, I add a Victron SmartShunt to get a more accurate SOC reporting (as I do not see any other way to integrate the BMS with the inverter).
  6. Charging of the battery is quite fast when running the generator.

Everything Neutrik PowerCon TRUE1 TOP

So, a few already know … In the last couple of days, I finally decided for a “universal” adapter standard to get rid of my UK, Swiss and European plugs and sockets. I looked at different adapters and the winner is:

Neutrik PowerCon TRUE1 TOP. Amazing how this rolls of the tongue …

The connector is a successor to the tried and tested “PowerCon” – but with some advantages:

  1. It supports “hot-plugging” (connecting and disconnecting under load)
  2. It is IP65 rated.
  3. They come in a “L”-version for cables with a larger diameter. But even the normal sized connectors still fit a 3-core 2.5mm2 H07RN-F cable.

It is also a locking connector like the original PowerCon with male and female connectors and good for up to 16A. But they are a little more expensive. Interestingly, Thomann was the cheapest supplier I could find in Switzerland. Below you find a simple overview with the existing connectors and sockets along with their part numbers (taken from the Neutrik web site).

Coipyright and taken from http://neutrik,.com

As you can see, there is no colour-coding for power inlets and outlets any more. Water-proof caps for the (wall) sockets are around 1.50 CHF per cap and therefore relatively expensive.

But what problem was I trying to solve in the first place?

We have AC electricity in our cars, the caravan and the trailers and soon in the barn and shed at the Loch. And we have appliances with UK, Swiss and EU (Schuko, Euro) plugs as well. And a plethora of adapters with the right one always not at hand. It was time to change that.

And the one thing I knew for sure was: I did not want to install UK sockets in the barn and shed. So, my idea was to install some more space-saving sockets. I already had good experience with the original PowerCon connector. However, they are not meant to be switched under load. Something that I definitely wanted to have with my new solution.

I could have sticked to plain Swiss connectors, as most of my appliances are already equipped with it. However, the typical Swiss triple T13 adapters tend to be occupied quite quickly as soon as we use AC/DC adapters or the Schuko fix-adapters. And if you get a quality product from a company like Feller, each triple socket costs around 50,00 CHF to 60,00 CHF. Compared to 3 Neutrik sockets this is way more expensive.

So, instead of researching any further, I quickly made a decision and went for the TRUE1 TOP system (from Liechtenstein). And it seems that I am not the only one with that idea, as I could see from various videos here, here, here and here.

My only real concern is, that after the “true” TRUE1 and the recent successor TRUE1 TOP, there will soon be an even “truer” replacement in the form of another imcompatible connector. But hey, what would one know anyway these days?

So, after last week the first batch of sockets and connectors arrived, this weekend I started with the conversion.

Inside our caravan, I added a couple of Neutrik sockets in the living room. See here:

Neutrik PowerCon True1 Top in our UK Swift Sprite Major 4 EB

I then updated the connections on the Toyota Hilux and relaced all the inputs, outputs and appliances. With this I could get rid of quite some adapters (from and to EU, UK, CH, CEE16-1, CEE16-3 etc).

Cooking with Neutrik PowerCon True1 Top in our Toyota Hilux

So what do I think so far? I am positively surprised.

  • Exchanging the connectors is simple and quick.
  • Even the thick 3-core 2.5mm2 H07RN-F cables fit in the connectors.
  • All the screws in the connectors are Torx (TX).
  • The connectors are not too bulky.
  • The adapters I made (e.g. from UK to Neutrik) are all rated for 16A (or 13A if we reuse the existing UK plugs). Travel adapters like the ones from Skross are typically only rated to 7A or 8A.

So, I will keep changing more and more of my appliances and will resurrect this post when I have news on this …

Our plans for a mobile hot water shower

While we were building our washroom on the plot, we were thinking of having a hot water shower in there as well. But instead of having a boiler and keeping the water hot for an extended unused time, we were thinking of sth different:

A manual boiler and a 12V camping shower.

The ingredients

How it works

  1. Fill the canister with water (20l max).
  2. Place the thermometer into the canister.
  3. Place the heater into the canister and hook it to the opening of the canister. Make sure the metal of the heater does not touch the plastic or the thermometer.
  4. Power on the heater (either from your battery or your inverter) and wait until the water gets to the destination temperature. For the actual duration see “The maths” section below.
  5. Remove the heater.
  6. Insert the immersion pump of the shower into the canister.
  7. Connect the power bank to the USB-C trigger board via the USB-C cable.
  8. Have the trigger board output voltage to be set to 12V permanently or set it manually to 12V.
  9. Connect the power calbes of the shower to the trigger board.
  10. Have a shower.

The maths

In case you are wondering, how it would take to heat up the water, here is my calculation (with the formula taken from various sources on the internet).

Q = m * C * delta(T)

So in case we want to heat 20l to 43°C from an initial temperature of 15°C with a 2000W immersion heater, we might need to wait for approx. 25min. If we did same but with an initial water temperature, it took us roughly 33min.

With a 1000W immersion heater, the numbers would change to 49min and 66min. And with a 400W we would have to wait 122min or 166min.

The amount of power needed is also shown on the above table. As you can see, it uses between 650Wh and 885Wh. So be careful when using a 12V immersion heater with your 90Ah car battery – don’t …

Conclusion

It quickly becomes obvious that a heater with only 400W will take too long to heat the water. At least I would put it over night into the motorhome, caravan, trailer or wahtever place so it can “pre-warm” a little bit. This might save you between 45min – 60min.

With 20l of water the shower experience will be limited to under 6min on “full throttle”. But with careful “breaks”, I still think the amount of water is sufficient for a full shower (not including washing long hair, of course). And if this does not provide sufficient water, there is always the option to add another 20l.

And: we will post a video with visual evidence as soon as it gets warmer …

Anderson SB175 or 100% compatible

Living in the north of the northern Highland comes with its own kind of specific “challenges” (as one would euphemistally phrase in today’s project world).

One of it would be that most delivery is only to “Mainland UK” which is sort of extends only to south of Inverness (which is only somehow understandable when one looks far back at the “Caledonian orogeny“). Anyway.

Laurentia and Mainland UK, https://en.wikipedia.org/wiki/Caledonian_orogeny

But even worse: Along with that delivery restriction comes the fact that there are also only very little shops with proper (or professional) selection of material up here. And this is also quite logical in itself. What could be sold in a shop, if nothing can be delivered to it?

This seems to have led to a “What we don’t have, you don’t need” attitude (no offence) and a supply:demand ratio that equates to higher sales prices.

So why am I writing this? I was looking for high current DC connectors for the battery systems I am making, I was looking to buy the Anderson Power Product SB 175 Connector. But the trusted (or only) electrician shop up here (CEF, a nationwide chain of 390 shops across UK) does not stock them, so I would have to resort to Mouser Electronics or Digi-Key Electronics for online ordering. There prices are about the same around 20 GBP per connector, which is not spent easily and about twice as much as other resellers or distributors charge (according to the Anderson web site).

Anderson SB 175 connector pricing, https://www.andersonpower.com/us/en/shop/sbr175-standard-housings-gray.html

In Switzerland I saw Distrelec selling compatible connectors under its house brand “RND Connect” for a converted price of 15 GBP (depending on the current exchange rate). This is not much of a saving taking into consideration that these are only rated for 175A instead of 280A.

And then there are numerous sellers on Aliexpress where we do not know beforehand what we actually get – but at a much lower price point.

So I went shopping to see the quality of the different manufacturers. My criteria for ordering were availability, low shipping cost and good reviews.

A selection of Anderson SB175 clones

I also ordered a shop with pre-manufactured cables and one with handles (where the price difference is even bigger).

I post an update when the items arrived and I had time to test them. So then we will see if these connectors can compete and are really compatible.

BYD Battery-Box LVS Premium 8.0 vs. Pylontech 2* US3000C

In one of our last posts we wrote about the upcoming, yet to be built, electricity setup in the vNext Car.

And now we changed our plans – slightly. Before deciding definitely for the Pylontech as the battery supplier, we thought we would install and test a comparable setup with both BYD and Pylontech.

Why did we do that? Having a look at the US3000C specs, we see that the recommended (dis)charge current is considerably lower than those from BYD (37A vs 65A). Of course, both batteries supply higher currents than that (74A vs 90A). But the cables sizes of the Pylontech box only supports a maximum of 2*100A, whereas the B-Box supports up to 250A. This maximum recommended current makes a difference when only having 2 batteries at your disposal, as the maximum surge current of the Victron MultiPlus II 48/3000 inverter is 5500W. So with Pylontech I can only support 2* 37A * 48V = 3552W without going over the recommended current and with BYD I can draw 2 * 65A * 48V = 6240W which is over the supported maximum of the inverter. So this is an advantage for BYD. Plus the overall capacity of BYD is higher (and comes at a larger weight).

Consequences and some calculation

But of course this has a drawback, as I want to use a DC Circuit Breaker with an integrated isolator, instead of a mains switch and a regular one-time fuse for the batteries. Most of the DC breakers only work up to a 63A and the larger ones are considerably more expensive.

On the other hand, the guarantee and fine-print with BYD declares indicated values are only achieved at a 0.2C rating, meaning that I could only constantly draw a 8000Wh * 0.2C = 1600W anyway, if I wanted to make use of the whole capacity (100% DoD).

Unfortunately I could find no C rating for Pylontech. However, in their warranty, Pylontech writes that the denoted values are only achieved when (dis)charging at 10A per battery (95% DoD). If I calculate this correctly, this would be an equivalent of roughly 2* 10A / (2 * 3374Wh / 51.2V) = 0.15C. In both cases the inverter should only much less than needed to support an induction cooktop and frankly any two devices at a time.

As a side note: Interestingly the B-Box seems to be cheaper per kWh than the Pylontech (as long as you stick with a single battery group).

So what does this mean?

In either case I will overrun the C rating of both batteries, meaning I will not get the full “official” capacity or life-time out of it. On the other hand, for our car installation this will not make much of a difference, as the Safiery Scotty DC-DC charger will recharge the batteries anytime when needed.

But when designing a complete off-grid system this will make a difference, as there we probably want to achieve a maximum amount of usable capacity and life-time.

But anyway, I will be making two installations and compare them in respect of the ISO25010 main product characteristic categories:

  • one installation with BYD Battery-Box LVS Premium 8.0 and
  • one with a pair of Pylontech US3000C batteries.

The B-Box has already been ordered. For Pylontech I am still awaiting a confirmation of the quote.

I keep you posted.

Update

Due to the difficulties of getting Pylontech batteries I had to skip the test and go straight for the BYD Battery-Box. See here for how it runs next to our caravan.

But even the delivery time for the BYD was months. So, in the end I decided to build the batteries from EVE LF280K cells myself.

Appendix: Pylontech Documentation

Pylontech Documentation as this does not really seem to be available on their website.

If you read the warranty card carefully, we see that the warranty extension from three to seven years has to be taken with a grain of salt. In addition, the replacement process (even to dead-on-arrive) is not

pylontech-product-warranty-us-serie-eu-2020-oct-inDownload
US3000C Operation Manual 20CQSV1103Download

More Power

What does it take to run an off-grid Household on Wind and Solar only

Our plot in Caithness is not really what you would call developed. The next water line is 2 miles away, and the electricity lines just connect our distant neighbours to the grid.

When I made an enquiry with Scottish Power to get me a grid connection to my plot, I was quite surprised, that I would become the partial owner of the company. At least, this is what you could think, when looking at their price tag.

For the ridiculous amount of 35’000,00+ GBP I would get a grid connection to a single place on my plot. Any other point on the plot, stretching a couple of 100m meters, would have to be installed and paid separately.

This and the news of rising energy prices for the next couple of years made me think. There must be something else we could do, like installing a miniature nucelear power plant on my plot, of have perpetuum mobile generating all the power thatI would ever need.

With nuclear energy out of fashion, and expected Planning Permission to be very unlikely, I actually found the perfect couple of “perpetuum mobile”, seeming just perfect for what I would need. Wind + Solar.

Located at the northern parts of the North Sea, near Wick, wind speed is excellent, as you can see from the map.

Wind Speed m/s @ 10m Height

Distribution over the year shows, most of the wind is to be expected during autumn, winter and spring.

Wind Speed m/s per Year

Furthermore, the actual distribution of wind speed reveals, that 60% of all wind speed is in a usage spectrum for wind turbines:

Distribution of Average Wind Speed m/s

The problem however, in the summer months, there is probably not enough wind to sustain the amount of needed energy production. And the star of our solar system comes into play: solar power.

According to data from the PVGIS-5 database of the European Commission, the expected irradiation of sunlight at our plot roughly looks like this:

Montly Solar Irradiation Estimates

In numbers for the last years 2015 and 2016 that gives some really impressive values:

Local and Global Irradiation monthly kWh/m2

And as we can see from the curve, the sun just starts to shine more when the wind is more asleep.

According to UKPower a medium household in 2019 used 12’000kWh for Gas and 2’900kWh for Electricity, totalling in about 14’900 kWh per year.

This amounts to the following power consumption for a Medium Household:

  • kWh/year 1’4900
  • kWh/month 1’241.67
  • kWh/day 40.83

With some calcuIations from the wind and solar database, I figured out, that with a 5kW turbine and 5m2 of solar panels I could roughly produce this amount of energy over the year:

Power Generation from Wind + Solar with 5kW Turbine and 5m2 Solar

So as we can see, this is just not enough to produce enough energy on your own. But it looks very promising. With more Solar, a larger turbine (or more turbines) or just a backup generator this could easily be addressed.

Regarding backup generator. Of course, energy sources like wind and solar are not stable, so we would have to have some battery storage capacity anyway.

A storage capacity for a single day in 3.2kWh blocks would cost roughly 22’500,00 CHF (list price for a Pylontech US3000). Adding the turbine with 40’000,00 CHF, solar panels 5’000,00 CHF and inverters 20’000,00 CHF you easily end up with a total price of 80’000,00 CHF – 100’000,00 CHF.

Electricity costs of roughly 3’500,00 CHF – 4’000,00 CHF per year will take a 25 years to pay off – if at all. And if the energy prices rise (as heard, by 50%), it would still need a 15+ years to reach a break even.

So what does this mean? There is no perpetuum mobile? And better use the grid and pay as you consume?

Probably not. Betting on higher energy prices, rising inflation, smarter and more efficient technology in the future and outages ocurring more often and often, this could really payoff much earlier than one would think.

Plus, it can be taken as an example, that it might actually be possible to produce your own energy without being dependent on anything else than wind and sun.