will this work? low voltage disconnect

I have installed a outdoor music system on my work truck. I have the amp running to a switch so i can turn it off and on. The switch is installed in my "custom switch panel". I want to use this amp when the truck is off.

I am planning/thinking about installing a low voltage disconnect device

https://m.ebay.ca/itm/321416391361

before the amp. so if im listening to music with the truck off the device will kill power to the amp when it reaches a desired level of voltage. So i can set device to kill power at 11.7 volts and my truck will still start.

But im wondering if i can install it before im switch panel and it will work for all my accessories at the same time? I have beacons, cargo lights, lift gate, etc

Then it will also work if i left an led toggle on for the night?

Is there relays you can buy that do this that might be even easier?

Just looking for any ideas you guys have thanks.

You can, but...

That Peak BDI controller looks fine. It has a relatively low standby current (ie 1.5mA compared to my occasionally recommended $20 MW728 which has 10mA standby and is not programmable).
If you need to switch higher loads (eg, >300W amplifiers etc) then have it control another relay.


But the desired battery cut-out voltage depends on the load current. For example, 11.7V with a (toggle switch) LED means the battery is well & truly discharged whereas for a heavy load (maybe 10A or higher) 11.7V may may mean the battery is only 10-20% discharged. (General rules are not to discharge cranking batteries below 80% and deep cycles below 50%. That equates to open circuit (recovered) voltages of about 12.4-12.5V and 11.8V-12.2V respectively.)

Also keep in mind that the battery will usually drop to below 10V during cranking.

I'd be curious what delays are used - they are essential for voltage sensing switches. For similar dual-battery switches they are applied to (before) reconnecting the load, but other low voltage cut out controllers may apply the delay before cut off - hence riding thru cranking and other voltage dips.

I wonder if the unit's behavior can be reprogrammed? (It's probably a PICAXE or similar controller and probably not a mask (ie not a permanently burned program).)   

oldspark wrote:

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You can, but...

That Peak BDI controller looks fine. It has a relatively low standby current (ie 1.5mA compared to my occasionally recommended $20 MW728 which has 10mA standby and is not programmable).
If you need to switch higher loads (eg, >300W amplifiers etc) then have it control another relay.


But the desired battery cut-out voltage depends on the load current. For example, 11.7V with a (toggle switch) LED means the battery is well & truly discharged whereas for a heavy load (maybe 10A or higher) 11.7V may may mean the battery is only 10-20% discharged. (General rules are not to discharge cranking batteries below 80% and deep cycles below 50%. That equates to open circuit (recovered) voltages of about 12.4-12.5V and 11.8V-12.2V respectively.)

Also keep in mind that the battery will usually drop to below 10V during cranking.

I'd be curious what delays are used - they are essential for voltage sensing switches. For similar dual-battery switches they are applied to (before) reconnecting the load, but other low voltage cut out controllers may apply the delay before cut off - hence riding thru cranking and other voltage dips.

I wonder if the unit's behavior can be reprogrammed? (It's probably a PICAXE or similar controller and probably not a mask (ie not a permanently burned program).)   

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So do you think every time i start my truck the device will kill the power to all my accessories

Probably, unless it has a disconnect delay.

The best solution would be a dual battery setup.

I was going to suggest that, but the LVD (LoVolt Disconnect aka Battery Protector) is a separate else first step.   
A 2nd battery can be added later whether to provide engine crank independence (both its voltage dip to 2nd battery loads like PCs or audio), and ability to crank irrespective of how discharged the 2nd battery is) or extended reserve (whilst isolated of course!) for a large sound system (eg, IMO say >100W assuming >10 minutes operation).