@WB, sorry, your right. I forgot the EZB will shut down it's ports when that warning goes off. It's been a while sense I fought that issue. The only solution if your using batteries in your robot is to run your custom script. New and inexperienced Revolution customers probably wont know how to do this. The way this forum and the EZ Robot business plan is structured is that it's up to more advanced users to point these things out and help the young and newbies . We have all found ways to work around the built in and hard coded safety features of the EZB. I don't think your going to see any of that change unless EZ Robot redesigns the EZB and comes out with a V5 version.

Although EZ Robot is space aged advanced I think it's sometimes too idiot and kid proofed. Personally I think it would have been a better to just be able to disabled the warning and shutdown features. This would be better for people responsible or advanced enough to watch the battery levels some other way or those of us running power supplies below the 6.6v but above EZB's min power requirement. Let a few people kill a battery or two and they will learn to keep an eye on it or turn on the protection feature. Personal responsibility.

I do understand that EZ Robot's future is in the kids who are just becoming interested in robots. However when they designed Revolution and the V4 around it, (in some areas) EZ Robot kinda forgot about the older and more advanced custom builders. It's an old grip I have and one that is really over shadowed by the rest of the mind blowing features of the EZB. I also do understand that there is only enough room on the EZB and what you can pack into it. However the focus of EZ Robot on it's new and mostly unskilled Revolution customers is still obvious to this day and probably rightly so. There was a thread asking for a separate area of this forum for custom built robots and more advanced builders. The answer was a polite "no, go start your own forum for that". My interpretation of that "no" was that DJ wants the more skilled to watch over the new kids and unskilled and answer the many simple and repetitive questions coming in. He also said he wants the advanced builders to inspire" the new comers. I'm not sure I really by that last one. I cant really blame him for this approce as it's a brilliant customer service solution. And like I said above, the kids are EZ Robot's future. The more advanced will find a way to make it work if the product is good enough. And it is.

EDIT: After thinking this through a little more I think that you can disable Battery Monitoring in ARC. I think (but not sure) if you disable Battery Monitoring you can drain your lipos down to nothing. If that is the case what I said above about not having control of this feature is incorrect. blush I also want to make it clear that I do feel that DJ has worked to assist and help the more experienced builders. He has in many cases jumped to give us features we asked for or needed. I just wanted to point out that I feel that the focus group that EZ Robot is aiming at now is the younger crowd.

i know there is probably no room in the Revolution robots or other small builds but something like this may help. It provides a soft shut down when your battery gets to low:

LipoShield intelligent lithium cutoff

@Dave.

How would something like the LipoShield connect to an EZ-B? I had a look at it and how to connect it to an R/C controller, but I'm a lil baffled as to how to connect it up to a v4.

@Steve, I'm not really sure how to interconnect the lipoShield. From the description it sounds like it's stand alone and operates independently. They say that when you see the device your controlling start to act and respond sluggishly you will have time to maneuver it to a safe resting position. I would think you still would have to have a script looping and watching the voltage. When the voltage drops to the point where the LipoShield kicks in that's when an alert could be sent to you and that is when you would start bringing your bot to a rest position. Of course if you get an alert you may not even need the LipoShield but it would automate the shutdown procedure better then the sudden cutoff that the EZB would do.

After thinking this through a little more I would think that if you use any of your own scripting to monitor the battery and use the LipoShield you would also want to disable Battery Monitoring in ARC. I think (but not sure) if you disable Battery Monitoring you can drain your lipos down to nothing. If that is the case what I said in one of my other posts about not having control of this feature is incorrect. blush

@Steve G. There are devices that will totally isolate your EZ-B from the 12V battery yet allow you to track voltage from the 12V source on an ADC port. They are called linear optoisolators. Most of the circuits shown with them are complicated and require opamps. However, for your situation, I think just 2 or 3 resistors and maybe a capacitor would do the trick. Perhaps a diode also to prevent burning out the optoisolater from reverse voltage. They come in 8 pin IC packages such as the Texas Instruments TIL300. The advantage is that they would provide absolute isolation between the 12V supply and the ADC port input. No chance of burnout. Might take a bit of tinkering to choose just the right value of resistors to get things in the right range but it should work.

Thank you for the advice gentlemen.

@Dave.

As it stands, I have the ARC battery warning disabled and I'm going to write a warning script to monitor the EZ-B's 6 cell 7.2 NiMH that triggers at 6v, so as you mention, I would have to do the same for monitoring the 8 cell 12v NiMH with another script but setting the warning for 8v (eventually this will all be part of an "auto dock & charge" control as well). So maybe the LipoShield will do the trick, if I can figure out how to hook it up. As for draining a LiPo with ARCs warning disabled, the secondary EZ-B's warning would kick in at 4.5v (unless that was disabled too), although at this point will more than likely be too late and LiPo damage would be done.

@WBS.

The TIL300 does sound like a good option as well. As for the linear optoisolater, that's a little bit beyond me as circuitry is a weak point for me and something I really havn't taken the time to learn. So me throwing something like this together is something I'm not really comfortable doing just yet. I appreciate your response explaining that though, and was an interesting read. Just shows I've got a quite a bit more to learn in that regard.

Anyway, thanks again guys. I'm grateful for both your input.

As for the Digital volt meter mentioned in the earlier post, this might be something I might get to try it out. The 12v batteries output voltage won't be going anywhere near the EZ-B, just the signal wire and common ground to an ADC port, so it should be pretty safe to play with (unless anyone thinks or knows otherwise). The only problem I see would be converting ADC values to an understandable, and fairly accurate 12v NiMH voltage reading.

@Steve G There will have to be at least 2 wires going from the digital voltmeter to the EZ-B. Nothing will happen if just the signal wire is connected to the ADC input pin. You may get some noise on the input pin to the ADC port, but that's all. When you run 2 wires, however, you have the possibility of burning out the ADC port. Especially if the voltage between them is more than 5 V. But even beyond that there could be complications from the separate power supplies being connected together via the digital meter.

There is still a possibility of using a simple voltage divider to do the job using 3 resistors instead of just 2 (for isolation between the batteries). I would have to run the idea by DJ first however, to be sure there are no problems I have not foreseen. He already uses current limiting resistors in the EZ-B to protect the inputs and this method relies on the same principles.

@WBS.

Quote:

just a signal wire to an ADC port

Lol, let's try again. I just read your post and re-read mine, and I just realised my mistake. It should have read "just a signal wire and common ground from the 12v ground, to an ADC port".

It'll be interesting to hear what DJ would have to say about the voltage devider idea.