*****Suggestions for Needed Updates to the Software****

[dragula]

Preface:

I run 2wd 1/10 electric dirt oval with 2S lipos and brushless motors. Its an extremely competative class I run, and we look for every edge we can find. I run the Extrema chargers because its very accurate and gets me the highest charge voltage when compared to other chargers. I also run them because they are software upgradeable. My Tekin ESC is, and the updates have been awesome, so I hope similar things happen with these.

Suggestion 1:
Our 2s lipos are typically run for 4-5 min when we race and we can take a battery down, depending on the size, nearly to its cut-off voltage. At that low, we risk damaging the battery, and the car is sluggish.

I have noticed my charger does not charge a lipo when in CV mode all the way down to 0mah....Instead it charges it down to 10% of the initial charge current setting. Meaning if I charged it at 5A, it will maintane the charge voltage all the way down to 500mah and cut it off and not 0mah. What I have had to do to top off the battery to attain a higher average discharge voltage over the length of the race and avoid hitting the cutoff voltage is charge at multiple lower amperages until I have it all the way down to 50mah rate and it cuts off.

Please offer an update to charge all the way down to 0mah with a ramp down based on the inital charge rate. I would suspect this would also be helpful in other applications such as flying and boats, but I really need this.....

Suggestion 2

We have talked a few times about allowing a slightly higher settable cell voltage of 4.25v/cell instead of the current 4.20v/cell limit in the chargers now. This we have found to be safe, and had no issues with doing so. Our only issue is finding a charger with the ability to set the voltage cut-off to slightly higher than 4.20v/cell. We have made some simple circuit board based ones, but they allow the user to put the voltage anyplace, and that can be bad for some users who will push them way too far. Currently in our class of racing, the rules allow us to 4.22v/cell and I would even be good with that, but I have tested far above that, and can say without a doubt the 4.25v/cell will more than fine for what we need.

It was mentioned that this causes an issue with either the BIM or the balancer, but if your still balance charging at that voltage, something else is wrong, as it should have balanced out well before then.

Again, I appreciate your time, and really love the fact the chargers are upgradeable and hopefully some or all of my suggestions can make it into the next update. Please let me know. I have a need to go fast, and to do it safely!

[dragula]

Still no replies?

[testpilot]

Thank you for your suggestions. Our initial experiments with setting the charge cutoff to 0mah proved that the law of diminishing returns was alive and well. You will only get a very tiny percent of extra charge (less than 1% C) for an extraordinarily long charge time. 10% is the best compromise and is used by most chargers.

The top off voltage voltage right after a charge is quickly discharged in idle time and even quicker after a load is applied. It has little relevance with the overall power (watt/hours) of the battery.

Many of our model airplane fliers are setting the voltage to 4.15  or 4.10 volts per cell in order to extend the life of their cells and do not perceive any noticeable loss in power.

We are still considering the 4.25 volt setting in our next release. Stay tuned.

[dragula]

Thanks for the reply.

I have been tinkering with low charge settings, and below 200ma its kinda a waste of time, but how about lowering the cutoff to 5% of the intial charge. That way I can still charge at 8amps and still get the current down to 400ma before shutting off. That would help some. We push these things pretty hard, and when the batteries last as long as they do, we aren't too worried about the total life span.

[dragula]

Any news of the update yet?

[dragula]

Anything yet on the higher voltage yet?