midi avatar image
midi asked

Not getting full capacity from BYD before cut off voltage


I purchased a 2.5 kW BYD 3U battery module and did a fully charge according the datasheet. After trying to discharge the battery while logging the battery capacity, I found after 1550 Wh/29Ah that the battery bms cut off the battery when the voltage drop below 50.2V. Is there a way to change the cut off voltage to e.g 48V as obviously with current settings, I'm not even near to utilize the 2500 Wh capacity?

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

I am making a few presumptions,

Firstly that you, or your installer followed the BYD & Victron manual.

Second, that this is an ESS system, and you are using the recommended values:

It is possible to push the battery further by adjusting the sustain voltage setting in the ESS assistant. You will also need to adjust the alarm voltage thresholds.

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midi avatar image midi commented ·


I haven't connected the battery to the inverter or external BMU yet.

I first want to make a capacity test of the U3A1 battery but at mentioned it cut off when the voltage drops below 50.2V.

How to lower this cut off limit?

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Please have the system installed as recommended by the manufacturers before seeking support.

Without the BMU and approved controller, it will not work properly, and you may void your battery warranty.

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ejrossouw avatar image ejrossouw midi commented ·

@midi I agree with Guy and just want to add that typically smart batteries contain internal electronics unlike a LA or AGMto protect them. They cannot be treated the same. Also, manufacturers have to provide often a very long warranty, it is essential to maintain that warranty using a certified installer. LG batteries are good examples where warranties won't be honoured if not professionally installed.

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