Suggestions/Observation/Bug Reporting

Forum for announcements and discussion of beta firmware.
ukoda
Posts: 22
Joined: Fri Oct 11, 2013 3:28 am

Re: Suggestions/Observation/Bug Reporting

Postby ukoda » Tue Oct 29, 2013 2:38 am

If you are going to a bit of hassle here then maybe it's worth rethinking the whole approach? This problem has been dealt with in many existing chargers, and some do it better than others. The easiest ones to work with, and most common is where the negative terminal is spring loaded pushing along the center axis of the battery. Usually this a simple U shaped spring but one of my chargers has it as lever with a spring pushing against it. The reason they have done that is it allows the lever to have wide arc and shaped such that it makes flat contact on the battery at two different angles. In this way it works well with both AA and AAA cells and it is easy to get the batteries in and out.

If you were to also sense the angle the charger would know when a battery was present and what size cell it was, AA or AAA. I have seen a request for this feature discussed elsewhere in these forums. If engineered right it could be quite cheap. One risk/issue is the resistance of the pivot point could be significant with respect to the cell's internal resistance. An additional strap would fix that but adds more complexity.

Mark
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Joined: Sun Jul 28, 2013 6:47 am
Location: Brisbane, Australia

Re: Suggestions/Observation/Bug Reporting

Postby Mark » Tue Oct 29, 2013 3:04 am

That sort of style connection would suit most chargers, but I think in this case with the charger being a bare board, the current style of clips make sense - they really just need to be a little less strong.

The main problem with adding complexity is that it's often adding an extra point of failure. Personally, I'd rather have a micro switch that could fail than to add in something that could cause extra (and possibly inconsistent) resistance. The current clips seem to be very good in that regard - resistance seems to stay quite consistent between removing and reinserting the same cell.

As far as detecting AAA cells, if you look at the C9000, it appears to have separate connectors for the negative end of AA and AAA cells (from memory of looking inside one though, it's the same piece of metal however) With separate connectors, then that would allow for detection of different cells electrically, but it then just adds extra complications on the electrical side of things. It could be done with a 0.1 ohm sense resistor between the AA and AAA connector, but that then would require an extra ADC channel for each charging channel.

Paul.Allen
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Location: Utah, United States

Re: Suggestions/Observation/Bug Reporting

Postby Paul.Allen » Mon Nov 18, 2013 9:06 pm

I am testing out 0520 and was wondering if a forced charge for cells that come up bad on all settings not just on charge could be done? For example if it has already come up purple, the cell wasn't removed and yet the same button press option was selected it just goes for it? That being said I still think if the cell is Really bad, it maybe could have an option where it does a 150mA timed trickle charge while monitoring the temperature and that is it, even if the user selects to override.

Mark
Site Admin
Posts: 411
Joined: Sun Jul 28, 2013 6:47 am
Location: Brisbane, Australia

Re: Suggestions/Observation/Bug Reporting

Postby Mark » Tue Nov 19, 2013 2:29 pm

Paul.Allen wrote:I am testing out 0520 and was wondering if a forced charge for cells that come up bad on all settings not just on charge could be done? For example if it has already come up purple, the cell wasn't removed and yet the same button press option was selected it just goes for it?


I like that idea!

That being said I still think if the cell is Really bad, it maybe could have an option where it does a 150mA timed trickle charge while monitoring the temperature and that is it, even if the user selects to override.


If the cell resistance is over 1000 milliohms (from memory), the code will automatically drop down to 200 mA if charging is forced. I've got some really bad cells where even that is too high and the voltage during charging goes over the maximum 2.048V of the ADC. I guess that it could continue charging and ignore the voltage during charging, but there would be no way to know if the voltage was getting high enough to permanently damage the ADC...

Tcepsa
Posts: 46
Joined: Tue Aug 06, 2013 5:26 pm

Re: Suggestions/Observation/Bug Reporting

Postby Tcepsa » Fri Nov 22, 2013 1:48 am

For something to stretch out the clips, folks could probably get a dowel from their local hardware store that's slightly larger than the diameter of a battery, saw it off to the same length as a battery, and push it in. Probably would be best to go with oak; I'm not sure how well pine would hold up against the clips ;-) (Obviously a no-go for folks who don't have a nearby hardware store with dowels, but figured I'd throw it out there) If I get a chance to try it I'll let you know how it goes.


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