Constant .7 amp discharge from Quattro during float

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geomz asked Sep 5, '19

Constant .7 amp discharge from Quattro during float

I have a Quattro 24/5000/120 connected to a pair of 12V lithium batteries in series, with a BMV 712 monitoring them.

After the Quattro completes its absorption cycle, and goes to float, I am seeing a constant .7 amp “parasitic” draw that is being reported equally by the BMV and the battery BMS.

It starts almost immediately after absorption is complete and float starts. It shifts from 0 amps, growing to .7 over the span of a few minutes.

That draw will remain constant for hours/days without any action on behalf of the inverter/charger. Even if the battery SOC continues to drop (below 85% at last test).

That draw appears to be caused by the Quattro itself. I established that as follows:

1) there is no other 24V device in circuit. It’s just the Quattro, the bmv, and the batteries.

2) I shut off the Quattro and watched the load drop to 0 amps, as reported by both the bmv and the BMS. Turned it back on and watched it happen again.

Does that behavior make sense?

Is the Inverter supposed to generate a constant draw? I understand it needs its own internal power consumption, but assumed it would come from shore power -which is currently connected.

Will the Quattro at some point stop discharging and return to keeping the batteries, well, floated? Last time I let it get to 85% before forcing a bulk cycle (out of float) by triggering a (heavy) discharge.

The entire time the display on the CCGX just says float and idle.

This is not a grid tied system. Just an RV with 50 amp shore power.

I have rebooted/power cycled both the Quattro and the bmv and removed the batteries from circuit and put back in, for troubleshooting.

Thanks in advance for your help.

battery charging float

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Answer 1 · 2019-09-05T15:33:47Z

Daniël Boekel (Victron Energy Staff) answered · Sep 05, 2019 at 03:33 PM

Hi @Geomz

What are the charger settings? My guess is that float voltage is lower than the actual battery voltage.

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geomz commented · Sep 05, 2019 at 08:09 PM

Hi @Daniël Boekel (Victron Energy Staff)

Thanks for your reply.

My float voltage is set at 27.2, which is indeed slightly lower than the batteries' resting voltage when full.

So when that happens, what is triggering the .7 amp draw? Is that the inverter itself? If so, does that mean that some portion of it is constantly running off of the batteries, until such a point as the battery voltage drops below that of the float voltage setting? (Then at which point the charger "wakes up" and begins putting current back in?)

And of course after I wrote the above question, I woke up this morning and that behavior had stopped that .7 amp discharge (coincidentally that was after the last reboot).

But prior to that, the .7 amp discharge was remaining constant even as the batteries were drained to mid-80s% soc of charge (which is a lower voltage than float).

Could something have been "stuck" with the inverter that it kept taking current out of the batteries and never sensing the lower voltage?

As I write this, the reported battery voltage is 27.07 and I see 0 amps flowing in/out of the batteries as confirmed by the BMV and BMS.

Thanks again!

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