BM-712 shows 100% instead of real value 92%

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urbanr asked Jul 30, '23

BM-712 shows 100% instead of real value 92%

I have 2x 160Ah Sunlux Lithium batteries. My problem is that the BM-712 always shows 100% before it is fully charged compared to reality and the Sunlux app. What can be the problem? see my attached pictures.

BMV Battery Monitor

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img-7265.png (149.0 KiB)

img-7254.png (254.8 KiB)

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Alexandra ♦ commented · Jul 30, 2023 at 07:23 AM

@UrbanR

Your bmv is set up differently to the sunlux. The real question is the sunlus also accurate? Does it use a shunt to measure?

What i would suggest is that you set your charged voltage much higher, since it is a lithium battery. What is the bulk/absorption target for the battery? The charged voltage should be quite a bit above float level but not too close to the bulk voltage

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urbanr Alexandra ♦ commented · Jul 30, 2023 at 07:35 AM

I hope they are correct. It is directly from the BMS.

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Alexandra ♦ urbanr commented · Jul 30, 2023 at 07:42 AM

What has happened is the 100% has been triggered too early there.

Reason

1. Charged voltage is low. Use @klim8skeptic suggestion there.

2. Charge rate is also low.

There is a total of about 3.4A there which is just around the 4% threshold of tail current and you above the charged voltage set on the bmv.

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Answer 1 · 2023-07-30T07:24:06Z

klim8skeptic answered · Jul 30, 2023 at 07:24 AM

@UrbanR you could adjust the BMV setting "Charged Voltage" to 0.2 volt below your chargers bulk / absorp voltage.

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urbanr commented · Jul 30, 2023 at 07:37 AM

I have tried it now, the bulk voltage is 13,8 so I changed the setting to 13,6 will see if it helps.

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