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Axpert inverter Questions.


Francois du Rand
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Good day. 

I had a solar system consisting of the following installed at my house

1. 16 x 335 w solar panels

2. 2 x 5 kVA Axpert inverters

3. 1 x 9.6 kWh Dyness Powerbox

I would like to pose the following questions to the knowledgeable persons on line

1. What are the optimal max an min Voltage values for charging the Dyness battery?  I see the broshure indicates 44.5 to 54 Volts. My system currently runs between 46 and 52 Volt.

2. What is the optimal setting to switch over from Eskom charging to battery?

3. My system charge up to 52V during the day up to 16:30 then rapidly discharge to less than 50V in one hour before the sun even sets. Is this an indication of BMS problem?

 

 

 

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3 hours ago, Francois du Rand said:

1. What are the optimal max an min Voltage values for charging the Dyness battery?  I see the broshure indicates 44.5 to 54 Volts. My system currently runs between 46 and 52 Volt.

46 V for the low DC cutoff voltage (setting 29) and 52.0 V for the bulk/absorb battery voltage (setting 27) sound fine to me. I assume that this must be a 15S battery (otherwise 54 V is not 100% SOC).

3 hours ago, Francois du Rand said:

2. What is the optimal setting to switch over from Eskom charging to battery?

Either 50 or 51 V. Since you have a fairly big battery (9.6 kWh), 50 V is probably better (setting 13).

For setting 12, use 48 V.

3 hours ago, Francois du Rand said:

3. My system charge up to 52V during the day up to 16:30 then rapidly discharge to less than 50V in one hour before the sun even sets. Is this an indication of BMS problem?

No, all batteries fall off in voltage when they are no longer charged. LFP bateries have a very non-linear voltage to SOC relationship. 50 V is 3.33 V per cell, which is the upper "plateau" for battery voltage. There is no cause for alarm there.

Also ignore the state of charge reported by the inverter. It's based on battery voltage, which makes no sense for LFP batteries. Trust whatever SOC indication you get from the battery itself.

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Can the coms cable RJ9? (4wire only) on Axpert side of inverter and than a RS232 on the other end be modified straight to a USB plug (+5V,+d,-d,Gnd) to plug in on laptop USB port, or is a converter with some special circuitry required. Anybody been there before?

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On 2020/04/27 at 11:17 PM, Gerrie said:

Can the coms cable RJ9? (4wire only) on Axpert side of inverter and than a RS232 on the other end be modified straight to a USB plug (+5V,+d,-d,Gnd) to plug in on laptop USB port,

No. That's an RJ-45 (8-pin) plug with just 3 wires connected; it doesn't have any USB data connections or +5 V. Some communications boards (5 kVA models from 2015 onwards) have a type B USB connector as well as the RS-232 connector (in the form of an RJ-45 socket).

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or is a converter with some special circuitry required. 

If you don't have a type B USB socket, a USB to serial adapter (with active electronics inside) is needed to connect to a PC without a real serial port (the vast majority these days).

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41 minutes ago, Coulomb said:

a USB to serial adapter (with active electronics inside) is needed

Thanks Coulomb, with the lockdown it’s not easy to get these adaptors, thats why I thought I could just cut off the RS232 and connect the Rj45 straight to a USB. So this mean i will then need to get the right adapter.😬

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