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Must Inverter not going to Float voltage


Dougiedanger
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I have a 3kva Must 24v Inverter, with 6 x 305w panels and 4 x 205ah Trojan batteries which I monitor with a Bmv712 and have a Ha02 balancer on them. 

Recently with the improved port situation in Zim, I decided to cycle my batteries to reduce my power bill slightly. So I have set my inverter to SBU and configured the battery setting on the inverter to cut off when the battery capacity is at about 75%SOC. This allows me to recharge them fully using Only Solar the next day. 

My issue is the inverter does not seem to reduce the voltage from Absorption to Float when the batteries pass through 90% SOC. 

Previously when it was set to UTI and charge on SNU it seemed to work fine when the power was cut and the batteries were recharged. 

Is this something others have come across on other inverters and if so is there a work around and secondly I presume I am damaging my batteries? 

Any thoughts would be appreciated. 

Thanks 

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10 hours ago, Dougiedanger said:

My issue is the inverter does not seem to reduce the voltage from Absorption to Float when the batteries pass through 90% SOC. 

The inverter charger should go to float when the charge current goes below a threshold, usually around 10A but it can vary a lot.

Perhaps it was going to float tio early when utility charging?

Staying at absorb voltage too long is unlikely to hurt Trojans much, as long as they don't run dry. 

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5 hours ago, Coulomb said:

The inverter charger should go to float when the charge current goes below a threshold, usually around 10A but it can vary a lot.

Thanks Coulomb, ok understood. It used to reach close to 90% SOC then the inverter would progressively reduce the voltage and as a result the Amps being pushed to the battery when it was charging from the utility, now it is keeping the voltage as close to the absorb setting as possible. I am sure it is probably just a deficiency in the programming of the Must being a knock off of the Axpert.

5 hours ago, Coulomb said:

Staying at absorb voltage too long is unlikely to hurt Trojans much, as long as they don't run dry. 

Unfortunately these are AGM's so was concerned as don't want to stuff them up.

Appreciate the time. Thanks

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1 hour ago, Dougiedanger said:

It used to reach close to 90% SOC then the inverter would progressively reduce the voltage and as a result the Amps being pushed to the battery when it was charging from the utility, now it is keeping the voltage as close to the absorb setting as possible.

Actually, it's normal for the battery to be kept constant at the absorb voltage; this stage is sometimes called the "CV" stage (Constant Voltage). The current reduces because of internal reactions in the battery, even with the battery terminal voltage constant.

So the new behaviour is more sensible than the old behaviour.

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