Robin avatar image
Robin asked

Why do I get a different MPPT Amp current reading when I use the USB adapter or the Bluetooth adapter?

As per conversation, moor information and pictures on incorrect smart dongle readings and mppt crashes.

mppt blue solar 100/50 HQ1813R28TA v1.42

VE direct bluetooth smart dongle v2.19

Smart battery sense HQ1827QRJEC v1.04

All measurements with no load connected appart from smart battery sense and bmv shunt.

i have been monitoring my mppt in victron connect via ve direct to usb no problems. battery volts and amps matched bmv 702 reading as well as amp reading taken at the battery.

when viewing information in victron connect via victron blue tooth smart dongle the amp reading displayed in victron connect has been as much as 4.5 amps higher. As soon as i reconnect via ve direct to usb i get the correct readings again.

The pictures of android in red case. Showing incorrect values are via ve direct bluetooth dongle

The computer screen next to BMV is via ve direct to usb showing correct values.

Allso since using smart battery sense and ve direct bluetooth dongle the mppt has frozen twice and had to be disconnected. (see pictures below)

This was the email that was passed onto victron from my supplier.

victrons answer:

Unfortunately the MPPT charge controller does not have the same accuracy as the BMV and is therefore less reliable in values.

I am afraid I cannot help in changing this.

Best regards

Met vriendelijke groet

Johannes Boonstra

No 1. the mppt is correct when hard wired via usb, so the fact that victron says that there mppt's are ok at being 4 amps out dosent apply.

No 2. no response or useful help to mppt freezing.

No 3. I dont wont my £1000's of solar equipment to be so far out.

Any help appreciated

MPPT Controllers
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5 Answers
Kai Curry avatar image
Kai Curry answered ·

I know you mentioned there being no other loads connected. To be clear for anyone else that might find this issue, it's also possible that other chargers could be connected and they too would need to be disconnected for the BMV and controller to match.

Depending on the android device and quality of bluetooth connectivity there can be a delay or stutter in what is displayed. It might be helpful to use the "Trends" tab. Does it reliably show a graph that updates every second?

Do the controller voltages match that of the BMV? If not, how far off are they?

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Justin Cook avatar image
Justin Cook answered ·

@Robin, how are you connecting both a VE.Direct to USB Adapter and a VE.Direct Bluetooth dongle to the same MPPT simultaneously?

My thought is that if you're using some kind of "y" adapter, then the fault may well be in the adapter rather than the attached components. If, on the other hand, the USB adapter is connected to one of the components and the Bluetooth dongle is attached to the other, then that's not a valid comparison of actual accessory components.

My other question is whether or not you have fully updated the F/W in all devices... The BT dongle has F/W that needs updating, as does the MPPT and the BMV. The BMV appears accurate (as it should be), and Johannes is absolutely correct in that the MPPT's internal measurements are not as accurate as the BMV's, but this degree of discrepancy -if it is indeed as it appears- is most likely a F/W issue rather than a hardware issue.

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Robin avatar image
Robin answered ·

Thanks for input.

I am not using smart dongle and usb together. I have to replace one with the other.

Firmware is all updated by victron connect and i supplied victron with all serial numbers and firmware versions.

The dongle did go throw a firmware update

As to the lag i had considered this but what is happening, the bluetooth smart dongle is displaying consistently higher amperage readings getting further apart the higher the currant. Not actually lagging behind.

As for the mppt not being accurate to be 4.5 amps out at a 19.5 amps is excessive. However the reading is bang on when viewed via the usb connection so the mppt is correct. It seems to be some issue withe the smart dongle or compatibility between the dongle and mppt

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Justin Cook avatar image
Justin Cook answered ·

@Robin, based on the assumption that the screenshots posted are accurate reflections of what you're observing in situ, I would contact the distributor from whom you purchased the BT dongle and start a warranty exchange. I'm the tech support manager for a distributor and although I've never seen this behavior before, I can definitely say that it is atypical... a slight discrepancy between the MPPT and the BMV is to be expected, but not a discrepancy between the readings given through VE.Direct to USB vs. VE.Direct to BT... both devices are using the exact same interface, they're just doing different things with it, so both should be giving you the same readings. Again, I've never seen it before, but my best guess is that either one of the little VE.Direct pin inputs on the BT dongle is fouled/defective or that there's a defect in the dongle's PCB or the wiring to it from the VE.Direct plug.

In any case, this is not typical behavior of the dongle, and as such should give you no issues in getting a warranty replacement from the distributor. Each distributor has their own protocol to follow in dealing with warranty returns, so I can't say what your particular process will be, but it definitely qualifies for it.

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Robin avatar image Robin commented ·

Cheers Justin. Thanks for taking the time to read and view what i have put . Have just checked pins with magnifying glass and all seems ok. in my mind it would seem to be the dongle. Will contact my supplier who was going to get back in touch with victron to ask them to take a closer look at the information that they were sent, dont hold much hope with them. But will ask for an exchange.

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Justin Cook avatar image Justin Cook ♦♦ Robin commented ·

Victron is one of the few brands that we trust enough to distribute, and my experience is that they're fantastic about standing behind their products and honoring the warranty when items prove defective... you shouldn't have any issues. From Johannes' reply to you, I'm guessing that he didn't actually fully understand your issue - I trust that if he had, he'd have advised the same thing, to contact your distributor for a warranty replacement.

Personally I'd kinda like to get it on my own test bench just to see what it's doing and why, since this is an issue I've never encountered before and I'm always curious about those... but protocol requires that you deal with your distributor first. That being said, if your distributor gives you too hard of a time, you can call us at 619-320-5899 (press 2 for support), M-F 9-5 PST (GMT -8) and we could probably handle it, though depending on your location the shipping might cost more than the unit :-P

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Robin,

We will test to see if we can reproduce this issue.

In the mean time, it might help if you could please provide more photos of your installation showing all the connections, and also post a wiring diagram of how everything is connected.

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Robin avatar image Robin commented ·

Hi Guy. Thanks for having a look. I need to get the dongle issue sorted out so I can use the temperature compensation. I think it is probably a dongle issue and needs replacing

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