# question

## BatteryLife slow charge rate (of charge)

What determines ESS #5 rate of recharge rate in a grid parallel system ?

MPII + MPPT

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There are Voltage setpoints that it is aiming for.
There is a good explanation of it here:

https://www.victronenergy.com/live/ess:design-installation-manual#batterylife

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I see no mention of voltage setpoints in that documentation.

I enabled BatteryLife when SoC was around 15% - the average rate of (grid) charge was 5A up to 75%

Lack of daily PV has correctly raised the SoC limit to 80%

MPPT input was added to the 5A rate during the very short periods of sun.

I'm trying to understand what dictates the slow grid charge rate.

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Have you turned this on and thus limiting the Maximun charge power

1550299192562.png (54.2 KiB)
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No, charge power is BMS limited to 25A

I asked the same question, using different wording and received a competent answer - the slow recharge rate is hard coded.

https://community.victronenergy.com/questions/6956/ess-5-recharge-rate-of-charge-control.html?childToView=7855#comment-7855

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#### 4.3.8 BatteryLife state

The different BatteryLife states are:

• Self-consumption: normal operation - discharging allowed.

• Discharge disabled: the battery has been discharged to the actual SOC limit. (The state will return to self-consumption whenever the SOC rises 5% above the set limit).

• Slow charge: ESS will slowly charge the battery when the SOC has been below the actual SOC limit for more than 24 hours. It will keep slow charging until the lower limit has been reached at which point the system once again switches to Discharge disabled.

• Sustain: the Multi/Quattro has gone into sustain mode after the battery voltage has reached the dynamic cut-off voltage during discharge.

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from another thread I've gathered that the 5A charge rate for 'slow charge' is a fixed thing.

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boekel ♦ ·

Yes, that's the thread I linked to above - it's a hard coded recovery rate. I understood the various states but wondered where the recharge rate was defined.

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