Drop-in Lithium Engine Start Battery?

[mikegunn]

I use a “hello-sailor” remote boat monitor to keep an eye on battery bank (engine/service) voltages and bilge alarms. If any of the voltages drop below 11.8 V I’ll be advised by SMS message on my phone, as will a bilge pump actuation. However, I don’t have to wait to be advised, as the voltages and bilge alarm status can be interrogated at any time by using SMS. It is also possible to control a relay remotely, again by SMS. No contract is necessary and using a pay as you go Sim the cost is literally a few pence per month. The ability to remotely control a relay could be used to actuate a high current latching relay to disconnect the engine battery. I’ve no connection to the company, just a very satisfied user of a system that doesn’t require the complexity or cost of an internet connection.
Mike

 

[William_H]

One approach might be to separate the power supply to the ECU and feed this via a voltage sensing relay (battery protector) such that with any significant drop in voltage say to 12v it will open and reduce current drain.NB the VSR will have a small current wastage when open. You would need a bypass switch so that ECU could be powered again if hopefully there is enough charge remaining to crank the engine to start. ol'will

 

[Graham376]

Two easy options, either small solar panel or, if boat ls left plugged in to shore, a small charger/maintainer such as CETEK.

 

[PaulRainbow]

What a palaver !!

Just fit a loud buzzer. Connect the buzzer negative to the battery negative. Connect the buzzer positive to the load terminal of the engine isolator, via a normally closed relay. As soon as the main isolator is turned on, the buzzer will sound.

Connect the relay coil connections to the battery negative and the charge warning light connection of the alternator. When the engine starts the buzzer stops. When you stop the engine the buzzer sounds until you turn the main isolator off.