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David, Thanks for the prompt and through reply. I too am not an EE and took to microprocessors only after retiring; and only those programmable in Basic. I took to them at first for use in datalogging strain gage data [never completed]. The Picaxe especially is inexpensive [the 08M2 costs some $4] and has many features [ie. built-in analog-to-digital conversion]; as well as an extensive forum. If interested smoke out their site. http://www.picaxeforum.co.uk/ My main reason for trying to get some group design help is twofold: Design the circuit for the 36-volt battery bank Come up with the best algorithms using the available logic features of the Picaxe/Pbasic. The Picaxe [-M2] accepts a Vdd voltage ranging from 1.8 to 5.5 volts. Using 5.0 volts the ADC input has an upper limit of 5 volts. If the battery bank upper limit is, say 50 volts then the voltage divider should consist of, say, a 10k and a 1k resistor pair. Correct? A pot between them sounds good. The other way is to program in a conversion variable. A thermistor could easily be inputted; but there are linear temperature ICS that, I feel, would do a better job. Need the equation however. And need to go to a bigger Picaxe IC for additional ADC inputs. The cost difference is a dollar or two. See the two US distributors for availability and costs. I like the 18M2. The ?sleeping? time or times [as a function of battery voltage?] is up to us. Need a contributor here too. For an initial design should we consider the use of the existing on-board charger with a set of good capacity flooded lead acid 6-volt golf cart batteries? The available processing power is well beyond the referenced article design. Charging current: My ET uses a 20-inch length of #6 gauge copper wire to sense operating current. But "Sparkfun" offers a 100+ [have to look it up] amp current sensor for some $20. Is that worth it? And, again, someone to draft the algorithm ? thinking Basic. So, again thanks for your input. I think it would be neat to come up with a group design. Thoughts? Cheers, David |