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daveinfl avatar image
daveinfl asked

Smart Battery Monitor Disconnects with an adjacent Parallel Load

Hello,

Just installed a Smart Battery Protect (220A) on my boat to protect my house batteries. The device is set to default position 6 which I believe is 11.5 Voltage shutdown.

Discovering something very strange. When I turn on my Audio Amplifier which is wired directly to the battery (not in-line with the BP) the Battery Protect turns off power for about 5 seconds then turns back on. The batteries are 8D AGM with 1700+ CCA with ample power. The amplifier and House duties will run once the 5 seconds have passed; just curious how an adjacent load is causing this to happen.

I entered a custom voltage of 8V for shutoff and the Battery Protect still shutdown the amplifier upon startup.

Any ideas what is causing this? I have another BP I planned on using for another project; swapped them out and the behavior is the same.

Thanks!

Battery Protect
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2 Answers
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wkirby answered ·

Do you have an error code displayed on the Smart Battery Protect? An error code should be displayed for 5 minutes after the event.

I think that your SBP is reacting to what it thinks is a "short circuit". This would display error "E1"

The very first paragraph of the manual states:
Voltage drop over a long or undersized cable between the battery plus and the SBP may result in a short circuit alarm when starting-up the load, or unexpected shutdown.

How does that relate tou your problem?
Well, most Audio Amplifiers have a very high inrush or startup current when switched on. This inrush current will cause the battery Voltage to suddenly dip momentarily and the SBP will interpret this as a short circuit and it will disconnect.

Adjusting the shutoff Voltage setting may have no effect on the short circuit detection especially if the actual battery Voltage is dropping well below 8V during that instant of high inrush current to your amplifier.

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daveinfl answered ·

Thanks for the response.


There are no error codes. The only message I receive is when I am using the Bluetooth app and can observe “Reconnecting.” This shutdown only lasts for 5 seconds so I am not sure it’s short circuit protection?

Also, the Audio Amplifer is on a separate cable run not passing through the Battery Protect. The Battery Protect would have no way of seeing the current; only the voltage drop.

The only theory I have is since the Audio Amp is about 8 inches away from the BP, perhaps the amplifier is causing too much interference on startup via the transformer? In other words, the field the amplifer is creating interferes with the circuity of the BP?

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