BMV 702 Clone?

[PJJ]

Hello guys

Look what I found on Gumtree today : https://www.gumtree.co.za/a-other-home-garden-items/roodepoort/bmv-702-battery-monitor/1006671109130910023708309

Seems like someone reversed engineered the BMV 702, I am pretty sure selling it as a BMV 702 violates some form of trademark law?

@plonkster

[Gerlach]

Hehehe. They doing there rounds, good luck for the person that entering the code to do the register for update. Slow death of the BMV then. Setsolar actually sell them to.  

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1 hour ago, PJJ said:

someone

It's Fangpusun. There is a story about that. At some Trade Show, the CEO of Stecca congratulated the MD of Victron on having his equipment copied by Fangpusun, since Fangpusun copies only the best (you will also find them copying the Outback MPPTs).

8 minutes ago, Gerlach said:

Setsolar actually sell them to.

So it is notoriously hard to get at this company legally, because... well... China. But Victron has a legal deparment that shuts down the sales channels.

Let me just rant on that a bit. The Fangpusun copies are not the worst in the world... but... they are copies, and they do use inferior components. The solar chargers are based on a very old first-gen design, so they are a decade behind the latest developments. Also, the firmware can't be upgraded (well, you can try, but if you brick it you get to keep the pieces). There is no support for this, and people DO contact Victron support (which I think is somewhat cheeky) trying to get support for these, because very very often they do give trouble. What is more, because the firmware is simply copied (and the firmware is where most of the R & D cost goes), Fangpusun is essentially stealing R & D budget, and so does the person who sells or buys the product. Victron sells a product that includes support and firmware updates, Fangpusun does not.

I really hope SetSolar is not doing this, as they also boast the Victron Logo on their website. That's not going to earn them any Christmas presents...

[Gerlach]

@plonkster for time they were selling that chines stuff " we spoke about it" day later "S" site was off for a time, then it came back, with victron stuff on it and between it with some 芳普森 .

[P1000]

The BMV is one of the most overpriced pieces of Victron equipment. And it is very easily copyable - the hardware is very simple, the communication protocol is open. So should be able to build a copy from Victron's documentation.

[PJJ]

13 minutes ago, plonkster said:

But Victron has a legal deparment that shuts down the sales channels.

I assumed this would be the case.

13 minutes ago, plonkster said:

here is no support for this, and people DO contact Victron support (which I think is somewhat cheeky)

Very cheeky indeed.

I think resellers have a obligation to let people know that it doesn't come with the Victron support or firmware updates, and unlike what the ad says its not "EXACTLY" like the real thing.

 

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8 minutes ago, P1000 said:

The BMV is one of the most overpriced pieces of Victron equipment.

I disagree. Let me bolster that with some numbers!

The BMV uses a 1000A 50mV shunt. That means that at 1000A there is a 50mV voltage drop across the shunt, which means that at 1A there is 50nV drop, and at 100mA (which the BMV is capable of measuring) there is a 5nV drop. That is so low that most oscilloscopes can't measure it. So technically this is in the domain of precision measurement equipment, which does not come cheap.

Second, there is simply nothing on the market with this accuracy and capability at this price. If you also consider what a BMS with SOC tracking costs compared to the one without it, you will see the same price difference, if not more.

[___]

18 minutes ago, Gerlach said:

site was off for a time, then it came back

I remember. I suspect there are many shops who do that, sell them from the back room but don't put it on the website. I suppose Caveat Emptor applies. The final responsibility lies with the idiot that carries the wallet

 

[Gerlach]

And i'm with plonkster there, with quality products come's a price. I have paid some school fees to learn this. 

Edited January 15, 2020 by Gerlach

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2 minutes ago, Gerlach said:

quality products come's a price

I have nothing against proper competition. If a competitor looks at your product and builds a better one, or a similar one at a better price, that's good competition. If he simply copies your hardware design and slaps your own firmware on it (and has the cheek to use your configuration software with it too), that is theft. You may well find that without the overheads, the cloner makes more profit than the OEM. The excuse of "oh but the original is too expensive" just doesn't cut it. Sorry.

[Coulomb]

25 minutes ago, plonkster said:

The BMV uses a 1000A 50mV shunt. That means that at 1000A there is a 50mV voltage drop across the shunt, which means that at 1A there is 50nV drop, 

Um, 50 mV / 1000 = 50 μV? Still impressive. 5 μV even more so.

[___]

1 minute ago, Coulomb said:

Um, 50 mV / 1000 = 50 μV? Still impressive. 5 μV even more so.

Gaaah... I need more coffee. You are right

 

[P1000]

34 minutes ago, plonkster said:

I disagree. Let me bolster that with some numbers!

The BMV uses a 1000A 50mV shunt. That means that at 1000A there is a 50mV voltage drop across the shunt, which means that at 1A there is 50nV drop, and at 100mA (which the BMV is capable of measuring) there is a 5nV drop. That is so low that most oscilloscopes can't measure it. So technically this is in the domain of precision measurement equipment, which does not come cheap.

Second, there is simply nothing on the market with this accuracy and capability at this price. If you also consider what a BMS with SOC tracking costs compared to the one without it, you will see the same price difference, if not more.

None of what you posted seems really that challenging - you need 13.28bits of resolution on an ADC to measure that, coupled with an analog front end to measure 5uV. That seems challenging, until you realize that you have plenty of time to filter - your update rate does not need to be very fast (especially at lower current levels.)

(something like a very cheap ADS1115 could do that without any additional amplification)

SOC tracking is not that difficult if you are not chasing nW self-consumption numbers like in laptops/cellphones, and also very well documented.

Edited January 15, 2020 by P1000

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5 minutes ago, P1000 said:

None of what you posted seems really that challenging - you need 13.28bits of resolution on an ADC to measure that, coupled with an analog front end to measure 5uV. That seems challenging, until you realize that you have plenty of time to filter - your update rate does not need to be very fast (especially at lower current levels.)

I agree with that, precision measurements is not in itself challenging to build, but my point is that in the market you tend to pay a bit of a premium for that kind of instrument. When comparing a BMV, it has to be apples for apples, but I am not even sure what you'd compare it with. You can get really cheap monitors on Banggood, but those measure voltage only. There is the CTek batterysense and a few others aimed at the 4x4 market, at R600, but that also measures only voltage. So it seems like we're looking at a band of R1000 to R2000 (the cost of a BMV-700). I see in Australia there is something called the Amptron, which is AUD125, which fits in that bracket.

So that is the challenge. Mass-produce a precision monitor and sell it for between R1000 and R2000. It can be done, and there is room for profit.

I think people forget that manufacturers don't sell at the lowest possible profit. The point of the exercise is to make a profit, and it is also correllated with the demand in the market. The price is somewhere between the manufacturing cost and what people are willing to pay for it.

[P1000]

1 minute ago, plonkster said:

I agree with that, precision measurements is not in itself challenging to build, but my point is that in the market you tend to pay a bit of a premium for that kind of instrument. When comparing a BMV, it has to be apples for apples, but I am not even sure what you'd compare it with. You can get really cheap monitors on Banggood, but those measure voltage only. There is the CTek batterysense and a few others aimed at the 4x4 market, at R600, but that also measures only voltage. So it seems like we're looking at a band of R1000 to R2000 (the cost of a BMV-700). I see in Australia there is something called the Amptron, which is AUD125, which fits in that bracket.

So that is the challenge. Mass-produce a precision monitor and sell it for between R1000 and R2000. It can be done, and there is room for profit.

I think people forget that manufacturers don't sell at the lowest possible profit. The point of the exercise is to make a profit, and it is also correllated with the demand in the market. The price is somewhere between the manufacturing cost and what people are willing to pay for it.

Compared with other consumer electronics, it is very overpriced. You also have to remember that they don't really have to certify it against an accuracy spec like with residential utility power meters, but it is priced as if it is.

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3 minutes ago, P1000 said:

other consumer electronics

Sure, compared to a Kill-a-watt, which is the kind of mass-produced consumer item I think of first, it's like 7 times the price. But there is a large market for this sort of thing.

I remember seeing only one other shunt-based monitor in the last decade, and I can't even find it anymore. Which is a bit of a shame, such a product would be popular with 4x4 enthusiasts (who presently use voltage-based National Luna stuff... ugh...), and the 4x4 market do seem to shop one bracket lower than solar people

Also do keep an eye on the product line, as there are new products coming

 

[PaBz0r]

https://www.gumtree.co.za/a-other-home-garden-items/roodepoort/bmv-702-battery-monitor/1006671109130910023708309

Eish.

[___]

8 minutes ago, PaBz0r said:

https://www.gumtree.co.za/a-other-home-garden-items/roodepoort/bmv-702-battery-monitor/1006671109130910023708309

Eish.

His price is too high too IMHO. I've seen the BMV-700 sell at that same price, and I suspect few people have the need to monitor a starter battery or add a temperature sensor, so I'd rather buy a genuine BMV700 than a fake 702.

Edited January 17, 2020 by plonkster