I'll get back to the diagram of G-standards when I have a moment. It's an important issue.

The description you give @robl , tells me that you were one of the 450-ish participants on the 2-year V2G Trial undertaken by OVO.

You are correct that export was constrained differently according to the appraisal by the DNO who issued the G99 approval for each site. I checked another Indra V2G site in detail because that had been limited to 5kW. The distance to the local sub-station, the cable size(s) in the underground ducting and the fact that the house also had solar PV export all played a part in the evaluation.

That location was served by Western Power Distribution, who have permitted me access to their network mapping tool. So I could get a pretty good idea of what factors are being input to the G99 equation.

In your case it seems that there were no mitigating factors. The best that your DNO could offer was the basic allowance of 3.68kW (16A per phase).

Another of OVO's V2G trialists told me that the Indra design had only one setting for current flow. If your export was limited to 16A, then so was the charging rate for the vehicle. Clearly that was pretty restrictive, but understandable for that 1st version of the charger.

I later learned that the 2nd version of the charger was shelved by the OVO board, who own the majority of the seats on the Indra Board. I have no idea why. It's possibly related to Indra being granted government funding to research V2G for EVs with CSS connection ports.

I wonder if you read the Cenex short-form final report of that OVO/Kaluza V2G Trial, named Project Sciurus.

There was a masterful presentation of how effective V2G could be and that it was an essential tool in the future of the UK's electricity distribution strategy. However, the argument was undermined due to there being no accounting of system losses, either at the trial site or the sub-station.

In other words, whilst it was a profitable strategy for the energy industry, that profit was over-stated at the expense of the customers and the DNOs.

If @robi and the other trialists are hopeful of a V2H overlay, then that is totally dependent on Indra and Kaluza arriving at an export limitation technique which is robust and fail-safe. It needs to pass rigorous analysis by the ENA of how it behaves under fault conditions. Without that it can't be granted the necessary G100 certification.

Erm... apologies for going off-topic. This foray into V2G might've been better over in the discussion about Battle of the Charging Technologies. I'll link back to it from there.

Suffice to say that if you really do want to power the home then V2H does offer pretty massive storage. But the batteries in EVs have a lifetime about 20% of the LiFePO4 cells we've been discussing here earlier, and their LiMNC chemistry uses Cobalt, the mining of which is ethically questionable on a number of fronts.

@Transparent

I did see the Cenex report, and yes that is the trial we are on.  For me the report lacked in engineering detail about CO2 saved due to timeshifting, and efficiency issues of the V2G box.  Instead it focussed on money, which seems to hide all of the details as it is at the whim of strange tariffs and subsidies.  The report completely fails to mention that leaving the V2H plugged in continuously results in an horrific ~2kWh/day loss - possibly a software update may reduce this significantly, but for now it leaves the DC charging cable live continuously which forces the car + power electronics + plug lock to stay awake so wasting power.  I think this has not been done due to poor reliability of startup (software/hardware/internet connection?), so improving efficiency this way I think was considered to result in units failing to operate correctly.

I still think V2G or more likely V2H (it avoids the ridiculous tariff issues) can have a future though.  I'm confused by your G100 comment - many people now use this box repurposed as V2H with Octopus Go, and it is in the general specs for the unit - snip below.  Admittedly they may be less constrained than our supply clearly is somehow (the 16A export thing we have).  Nb: we have an 80A cutout which our dno is happy to increase to 100A for free if we swap the tails to 25mm^2.

I think our box is indeed restricted to charge and discharge at 4kW as you said!  It does seem an odd thing.  The cabling and V2G hardware is capable of 6kW, and we occasionally draw more than that from our induction hob (10kW max) + kettle (2.5kW) + toaster (2.5kW) with no effort to desynchronise them.  The supply here seems generally high though - I have a couple of things that measure it, and today (overcast so not much PV, V2G is off) they agree it is 246V.  Turning on the kettle for a cup of tea right now resulted in a 3.4V drop by the way (measured on a different circuit).

@transparent At the risk of asking the obvious question, does one need to pay UK VAT on top of the quoted figures (or at least pre-shipping figures)? Getting quotes on Alibaba it seems as if salespeople tend to state "including tax" which I am guessing means import duty.

Indeed it is unclear about the VAT status of batteries which reside in a UK warehouse; Basen quoted 165 USD a piece and zero shipping cost for delivery in ~1 week, as opposed to 110 USD and 25 USD shipping for delivery in ~8 week. Were the UK stock VAT already paid and the China stock VAT to be paid then it might be worth paying a few pounds extra.

----

OK, the key acronym is DDP = Delivered Duty Paid. "The seller is responsible for arranging carriage and delivering the goods at the named place, cleared for import and all applicable taxes and duties paid (e.g. VAT, GST)"

Good point @chickenbig !

You need to be very careful what a supplier means by "including tax". Indeed sometimes this phrase assumes that you've selected the item from a 'European Warehouse' where they hold stock, whereas the lower cost (default) sales are actually shipped direct from China. Note also that the VAT from a European Warehouse will be that of the country where the goods are stocked. So for Germany it's currently 19%.

Yes DDP means "Delivered, Duty Paid" and refers to both import tax and VAT. Such mechanisms are most frequently encountered when the supplier uses a well-known international delivery company like Fedex or UPS.

More commonly you'll see DDU, which is "Delivered, Duty Unpaid". Sometimes the goods are held at the port of entry (Heathrow or Felixstowe) in a bonded warehouse whilst you are emailed a customs invoice to settle. At other times the goods are delivered and the invoice arrives from the carrier a few days later.

When the carrier is responsible for sending the invoice, they will normally charge an Agent's Fee for acting on behalf of HMRC. You can't claim this back if you are VAT registered. It's just an additional expense which you should take into account before agreeing the deal with a supplier.

Payments made to suppliers you find on Alibaba are also subject to a banking charge. The exact amount varies according to the method by which you pay (Paypal, T/T, credit card etc) and the 'price band' in which the transaction falls. For a typical set of Lithium Cells you might pay around $50 as a transaction fee.

Air v Sea. There are currently delays in shipping items by air because there are far fewer flights operating post-pandemic.

I've found that goods can be left waiting at an airport terminal for 2-3 weeks before making their way onto a flight.

In that time a ship could have reached the Mediterranean, and the maritime-freight costs are about one-third that of air-freight.

Also consider freight by train for heavy goods. China has invested heavily in the silk-railway over the last 15 years. Transport uses a shipping container and takes about 30 days. The main problem at the moment is that the northern route is most commonly used and this passes through Russia and Belarus. Those border crossings are not currently dependable. The southern route passes through Iran and Turkey, but the freight company may not want to commit to which route they'll use.

Trust. Chinese suppliers tend to assume that we will always choose the cheapest option. That's probably true for their larger USA market. However, us Brits will often prefer a trusting relationship with a Supplier. If they are open and honest about delays then it's more likely that we'll return to them again for future orders.

Within this Forum that can work to your advantage.

Give the URL of this site to potential suppliers and tell them that you'll be reporting here how the transaction went. The better suppliers will be delighted because that tells others about their products and service.

Equally, any 'iffy' suppliers will probably drop out of the running. I had two (out of eight) who didn't provide me with a final quotation last week. The reasons were genuine. I don't believe that either had stock of the items I wanted, nor any existing stocks already committed to them by the manufacturers.

That's fine with me. They're not rogue businesses. They simply couldn't provide positive answers to the pre-sales questions I was asking them. I'd still feel happy to ask them to quote for orders in future.

Hi @transparent

Rather than provide money to China for them to spend on their military, can you recommend any British, or at least European, battery manufacturers? Whilst they may be more expensive, it may be more cost effective in the long term.

I would buy from a UK manufacturer if this were possible @derek-m but alas this is still in the future.

There is strong commitment from HMG to manufacture lithium batteries here. See this story from the Guardian about BritishVolt in Jan'22.

However, the lithium cells of interest are LiNMC (Lithium, Nickel, Magnesium, Cobalt) which deliver 3.6v. These are required for the EV market, which is essential if those cars are to be exported to Europe. It's the cobalt which is the problem. Most of it is mined in NE Congo using modern slavery practices.

Currently there is no matching commitment from the government to ensure that the Lithium is mined in Cornwall. But the prospects exist via the exploratory work of British Lithium.

Even so, the battery chemistry we are discussing in this topic is LiFePO4, operating at the lower 3.2v level.

I would love to have LiFePO4 cells actually manufactured in Cornwall. They'd have tin-plated copper busbars stamped Product of Kernow. 😎 

This is a very important part of ensuring UK energy independence - a topic at the forefront of the government's mind at the moment. Indeed, last week's Queen's Speech announced a forthcoming Energy Bill for which the white paper has yet to be published.

Now would be a good moment to be writing to MPs, highlighting to them the need to switch money away from overseas-based fossil fuels and instead invest in local Cornish mining.

Hi All

Not sure if this counts as advertising, as I’m a private individual but I’m sure the moderators can deal with this if needed. 

I ordered 16 280Ah battery cells (lithium iron phosphate Lifepo4 3.2V) with the intention of building my own battery. The source was the same used by Transparent (moderator on this forum). They are Grade A, perfect condition, never used and delivered to me just yesterday. 

Would anyone on here be interested in buying them from me? For collection, I’m based in Farnham, Surrey. 

In-between me ordering them and the cells arriving a few things changed for me, most significantly an offer from a local installer who happened to be working nearby who offered a great deal on a ready-made system which I snapped up there and then, this happened the day after my order for an inverter was cancelled. I jumped at the chance and thought I can sell the cells on to someone else. 

So before I go on eBay, please get in touch if you are interested. I can provide further details too. Does anyone know if you can you send private messages to me through this forum or do I need to add an email address for contact?

I don't think we would count this as 'advertising' because it's a one-off offer resulting from a change of strategy.

Let me just explain what these cells are so that others better understand.

They are made by Eve, one of the top tier LiFePO4 cell manufacturers in China. They are supplied with tin-plated copper busbars and the M6 flange-nuts used to attach these to the stud-terminals.

A boxed set of 16 like this would weigh about 100Kg, which is why @hydros is suggesting 'collection' rather than incurring carriage costs.

I was partway through advising how he could adapt his existing SolarEdge inverter to incorporate these cells as a DIY project, when an alternative 'off the shelf' solution was offered. The cells were in already transit and couldn't be stopped.

We don't know what price this set is being offered for, but ebay UK prices are currently around £700 per set of four. @hydros please post a ball-park figure here for your set (excl carriage at the moment).

16-cells in series gives a nominal 48v DC battery. 280Ah capacity produces a 14kWh battery, equivalent to that of a Tesla PowerWall. Depending on how fast and often they are discharged, it's common practice not to drain them to depletion, so the usual specification for these is 13.6kWh. That's sufficient power to run an average house for a day, provided that you're not running a heat-pump.

To use a battery like this you'd need to add a BMS (Battery Management System) and an inverter/charger. There are a number of options available which would cost between £1000-£1500. Here's just one possibility which allows you to run some 240v AC 'mains' devices off-grid.

If this set of cells are picked up by a member of the Forum, I'm obviously happy to guide you how to install and configure them, provided the discussion is kept here for everyone to read!

In the present energy crisis we need as many people as possible knowing how to connect a set of LiFePO4 cells to a BMS and an inverter. So I'd like to keep the discussion open and available for others to see.

@transparent I will keenly be following this thread as I want to build a battery for myself. The basics can be gleaned from YouTube and internet forums, but UK specifics like G99/dealing with the DNO and earthing requirements are far less readily accessible to the lay person. And safety-wise your post a few weeks ago (type-T fuses) highlighted a big gap in my knowledge of how to do this safely.

However as an "I'm out", HydroS's cells are too far away in Farnham (I don't have access to a motor vehicle), plus I have no urgent need for them in the next two months as any solar panels for my roof (if the roof is suitable) are several months away and I've yet to receive the other kit required to start tinkering (BMS, cell tester, power supply, crimpers etc). I'm considering going with a mixture of Qishou and Xuba cells, to compare and contrast service and quality, and considering something like a 16s2p system, provided the multibattery BMS -> Victron integration can be figured out.

Posted by: @chickenbig

I'm considering going with a mixture of Qishou and Xuba cells

Why?

Both of these companies are Chinese wholesalers, not manufacturers. You won't learn anything by sourcing cells from both of them. It's the manufacturer you need to be specifying.

I stipulated the requirement for EVE cells, and chose Xuba to supply them because Brian Chen communicated with me at the right level of detail.

Shenzhen Luyuan Technology Co. is another wholesaler. Their Amy Wan has gained a good reputation for guiding new-comers through the sales and shipping process. But you tend to pay a few $ more for her service!

It's extremely important that you build a relationship with the wholesaler and establish a high level of trust. The LiFePO4 market is full of 'dealers' who re-badge cells as if from a top-flight manufacturer, and others who pass off B-grade devices as A-grade.

This is precisely where a Forum like RHH should be helping. If the wholesaler knows that their products and service are going to be assessed and open to comment on the forum, then your risk is lowered. They will want to ensure that you recommend them to others.

@transparent thanks for sharing the additional details about the batteries. 

In terms of price, I’m not looking to make a profit, so £1800 would cover costs and I would be willing to deliver locally (<30miles), possibly further if fuel costs were covered. 

Once again, for clarity can I point out that @hydros is suggesting £1800 for the set of sixteen 280Ah LiFePO4 cells.

Compare that with the guide-price I gave earlier for a set of four on ebay at £700.