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Sorry not to have replied sooner. I did get to talk with friends regarding noise on the mains from an ET charger system. I was unaware of such possibility and still don?t know how to eliminate such. Is there a ready-made filter for this problem? Regarding Sparkfun product #SEN-09028 90 Amp voltage & current sensor: If the Picaxe command "readADC10" is used the 90-amp current is read out as a 10-bit digital number. Thus the 90 amps are divided into 1024 parts; or 0.09 amps per division. This seems sufficiently sensitive for a charger system. And the breakout board spits out a digital reading of a max voltage of 52 volts; which also can be divided into 1024 bits. It would seem that this is an ideal item for our purpose ? except that it reads current in only one direction. So for amp-hour tracking this has to be overcome. One of the many nice features of using a microprocessor is that the self-discharge could be handled by periodically checking the ?idle? battery voltage and applying a ?booster? shot. After all, I am after the automated feature[s] of using a microprocessor. One member of this forum voted for ?don?t bother ? just use the existing charger?. But for good battery care this, in my estimation, requires manual checking in some manner. I have been doing this but would like to have some degree of automation. And the existing timer, I feel, is insufficient. If GE had microprocessors available, would they have incorporated them in their design. I think so. Regarding amp-hour tracking sampling speed: Even the inexpensive Picaxe operates at some 10,000 commands per second. And there are ?X models which may be faster. I hope that any algorithm would still be fast enough. They offer a datalogging board, which I bought. Will explore sampling rates on this. Memory capacity seems to be the limitation. I welcome any thoughts. Cheers, David
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