mikeb avatar image
mikeb asked

BYD and Quattro never go to float?


Have set up VEConfigure on a Quattro and byd

As per settings

Battery type lithium

Charge curve fixed

Absorbtion voltage 55.2

Float voltage 55v

Absorbtion time 1 hr

When charging the battery’s the inverter goes in to absorbtion but it hasn’t charged over to float?

Is there something I am missing or is these normal and should just rely on the byd bms?



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2 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi Mike, yes normal.

When controlled by a BMS such as BYD has, it just shows Bulk & Float. Nothing else: Bulk whenever it’s on max current (ie. CC mode). And shows absorption when limited by voltage (ie. CV mode).

Best, Matthijs

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Thanks for the reply

Sorry for the next question but just wanted to make sure things are how they should be

My understanding was if DVCC was in use on the colour control solar would be prioritised if there was a genny running and didn’t need to be as the battery’s were fully charged and the solar was enough to cover loads

Will this still work the the byd system?



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Hi Mike, indeed it does.

Note that normally prioritizing isn’t too necessary for such setup; better configure the generator to stop once there is enough solar. Matthijs

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mikeb avatar image mikeb mvader (Victron Energy) ♦♦ ·

Hi thanks for the reply

Can I just ask if you have some guide lines for generator stop/start soc voltage etc for the byd set up? Will be using the byd bms for the stop start on the colour gx

Is there another way your suggesting ? Ie the Quattro relay pair? And a assistant?



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Hi Mike, best is to use the Color Control for start stop. It offers most flexibility.

Use the SOC condition. stop generator when full (100%); and stop when charge current very low, for example.

Make it start at the threshold as you wish. 10 or 20%. Or more of you want to keep a reserve.

Then, and this is important, add starting on voltage. This is to make sure the generator starts, even when SOC has drifted off. Voltage is a direct measurement: more reliable.

Set it slightly above advised dynamic cutoff values is what I would do.

And now, optionally, add a periodic test run.

Hope that helps


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Writing this makes me think that it might be nice to stop the generator when the current supplied by the generator drops below a certain threshold. Rather then the total charge current, which might also come from solar. I’ll think about that a bit more later.

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mikeb avatar image mikeb mvader (Victron Energy) ♦♦ ·

Thanks for the teply

I am pretty clued up on the stop start values on the previous rolls lead acod

Batterys I have running on systems but this is a new adventure with the byd units

A few figures for battery voltage would be handy as a guide?

Interesting idea with the current supply from the genny

Trust this is something technical you have to run through your head



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For the start voltage; look at our instructions wrt Dynamic cut-off; in the Victron/BYD document (it’s 47V), and then add 1 Volt. So 48V.

That’s what I would do; and then let it run and see what happens.

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mikeb avatar image mikeb mvader (Victron Energy) ♦♦ ·

That’s great

Was looking at 49v so the inverter doesn’t shut down.

And then 53 v for the shut off or higher? Trying to limit the generator run time

There would need to be a series connection in the colour gx relay signal to allow to start on the colour gx and also stop in lowered generator current in put

But both relay pairs can’t contridict each other

Got my head thinking

As I am not to bad at making controls for auto start

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Hi, the voltage start&stop is a last resort. For when SOC is wrong. Yes the 53 volt is probably fine.

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Nice pictures!

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mikeb avatar image mikeb mvader (Victron Energy) ♦♦ ·

Any assistant in the Quattro that can be used for signal for the low generator in put current or such?

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Maybe, but we can’t support you in that. Perhaps someone from the community here can (perhaps start a new question then).

Or open VEConfigure and look for it.

As said elsewhere; my comment was for future software development. Not to now complexify your setup.

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victron-answers avatar image
victron-answers answered ·

That is normal.

When charging the BYD the target voltage is key, rather than the characteristic of the charging profile like in lead acid.

If the system is reaching and staying at 55V, all is well and should indicate a fully charged battery.

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Ah, I didn’t see you’d also answered in the mean time.

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