question

Phillip Gutowski avatar image
Phillip Gutowski asked

[UPDATED] Smart BatteryProtect 48V-100A disconnects without error.

Smart BatteryProtect 48V-100A has shut down on four occasions over the last two months. It is controlled via H terminal in Li-ion mode from ATD relay on LYNX Smart BMS. When the shutdown occurs, there is no error on the device or in the app, and ATD is still active. Toggling the Load output switch in the app, or disconnecting and reconnecting the H wire causes it to reconnect. It does not ever reconnect without this manual intervention.


The output of this 48V SBP supplies power to the inputs of two MPPTs which are being used as DCDC converters to charge two other 12VDC battery banks. Is there something wrong with this configuration, or do I have a faulty device?


UPDATE 6/30/24 - I have replaced the SBP under warranty. The new unit has worked well for a couple of weeks then just last night it exhibited the same behavior as the old one and disconnected the loads without error while the app still reported it was connected. Cycling the "on" switch in the app reconnected things.

UPDATE 7/13/23 - The new SBP continues to behave the same way as the old one.


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Battery Protectlynx bms
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Phillip Gutowski,

This is not an intended use for the smart battery protect, or the MPPTs.

For switching the MPPTs I would recommend this method instead - https://www.victronenergy.com/cables/ve-direct-non-inverting-remote-on-off-cable

But on top of that it sounds like you're using the MPPTs from a DC supply source other than a solar panel?

That is not supported. We have the Orion range for DC DC charging - https://www.victronenergy.com/dc-dc-converters


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Phillip Gutowski avatar image Phillip Gutowski commented ·

Thanks @Guy Stewart (Victron Community Manager),

Would you be able to explain why using a Smart Battery Protect to switch off loads via ATD signal in a lithium battery system is not an approved use?

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ Phillip Gutowski commented ·

The load in this case is the MPPT (Maximum Power Point Tracker) charger. This is designed to be connected to solar panels. The way an MPPT regulates its power output is by adjusting the input resistance, effectively varying between open circuit and short circuit conditions and everything in between. This adjustment ensures that the solar panels operate at their maximum power point by optimizing the voltage and current output, and then reduced to zero when no more charge current is wanted.

PV panels are designed to cope with this short circuit / open circuit behaviour without issues.

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The MPPT expects the power output to vary depending on this input resistance variation. However, this does not happen in the same way with other types of DC input supplies because their characteristics differ from those of solar panels.

I don't know why this charger behaviour would cause an issue with the Smart Battery Protect, but I do know that the intended way is to connect the MPPT to solar panels, not another type of DC supply, and then control chargers (and inverters) via a Remote On/Off cable.

My suggestion is to use the known working solution.

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Phillip Gutowski avatar image Phillip Gutowski Guy Stewart (Victron Community Manager) ♦♦ commented ·

Thanks @Guy Stewart (Victron Community Manager) I really appreciate this explanation. We've been installing some MPPTs as DCDC's since there are not many smart 48>12V options in the Orion range. I'll be more considerate of trying another approach next time.

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Phillip Gutowski avatar image
Phillip Gutowski answered ·

Any input on this question @Guy Stewart (Victron Community Manager)? Should I RMA the unit a second time?

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