I'm looking to implement a way where as the EZ-B moniters the LiPo battery voltage, it will trigger a script to say "Low battery. Robot is powering down" when the low battery warning activates, and proceeds to switch the EZ-B off, possibly triggering a relay so it breaks the connection between the battery and EZ-B, and then I can charge the battery without disconnecting it from the EZ-B.
The problem I run in to trying to figure this out is re-initialising the relay to re-establish the power connection, as I would need the EZ-B to operate the relay which at this point would be in its "Off" state so it wouldn't trigger the relay. I'm normally pretty good figuring this sort of thing out, but I can't get my head around this one.
Has anyone done something similar to what I'm looking to do? If so, I'd love to hear your solutions.
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My only concern is how much of a battery life hit will you take keeping a digital pin high and the relay energized.
If you expect the robot to be unattended so fully discharging the batteries is a real worry, than probably worth figuring something out.
Alan
rs media has this.he says all systems powering down or
the batt in my feet needs changing
As for powering down the EZ-B with a low battery, a solidstate relay can be connected to a digital port. Using EZ-Script, you can use the GetVoltage() command to get the most recent voltage from the EZ-B v4
Here is one from SparkFun, but it only does 8 amps - which is not enough juice for a Revolution robot: https://www.sparkfun.com/products/10636
I'm aware about the safety of recharging a LiPo battery unattended and I use a Ballance charger with an auto cut of feature which reduces the chance of "bad things happening".
The amperage is actually something I didn't fully take in to account while thinking about this so thanks for the heads up DJ. So it does look like a relay is the way to go. Just to be clear, when I was asking about the auto power cut off, I wasn't asking about having it added to the EZ-B, as you really have done an amazing job designing the v4 to be as powerful and as compact as it is, and know that adding a relay to the board to carry out this fiction would take up to much real estate. No, this is something I want to add myself for the possibility of designing a "dock and charge" on my current and future projects.
I suppose what I'm ultimately looking for is a convieniant and safe way to recharge a LiPo battery that is still connected to an EZ-B, much like a laptop or mobile/cell phone does (The device can still have the battery connected, and even be used). Maybe this could be a future EZ-Robot product module, that could be designed to connect to the EZ-B's power base connector that could be that could be added to the product range and sold in the shop. Just an idea.
But for now, my current project has a Roomba for a drive base, so when the LiPo gets to 6v or so a final script is triggered to say" I'm going to recharge", and send a "dock" command to the Roomba which I know how to do, then powers off the EZ-B as the Roomba seeks the docking station. Once I get this figured out Incan build on it from there.
Anyway thanks again for your input guys.