are there any electrical engineers out there listening: I was told today at an large alternate energy store that if you use normal gel cell, also called AGM, or standard deep cycle liquid acid batteries between 85 amps and 150 amps (size) you do not need a charge control on the solar panels if the solar panels are the low voltage type at 16.8 volts closed circuit or less. But this information is not true for the high efficient panel types with a close circuit voltage of 17.volts or greater. some do 21 volts he said
He gave these four reasons, but is he telling the truth ????? 1. With direct connection - - the battery can not be over charged because the charge rate will be reduced to what ever the battery voltage is holding at, it will automatically charge faster a low battery but unfortunately will never charge 100% full for the same reason. 2. With direct connection - - The internal resistance of the battery will increase as the battery gets charged higher 3. With direct connection - - the size of battery (mass, meaning amps capacity) will absorb long before any boil rate can be achieved. 4. The normal charge wires for the short distance on a small boat about 40 feet of number #12 tin coated with the resistance of two battery diode pack ( spilt/back feed diode) puts enough stress on the system to help provide any over charging The plan is purchase One (maybe two in parallel ) Each unit , Kyocera, 48 watt panels, charge voltage, 16.1 volts at 2.3 amps A two battery charge diodes to prevent back feeding the second battery and two 85 amp hour batteries , one for general use and one as back-up He also quoted that if you use a battery with an hour amp rating of greater than 200 amps with direct hook-up , again that is with the lower charging voltage, it would take many weeks to charge the battery for the same reason, the mass or the volume of the charge area. Because the closer it got to a full charge the slower it would take the charge. AND if you must buy a charge controller to pay the extra amount and buy the "constant voltage" ( like the one called Solar Boost ) type charge control. Meaning the device keeps the charge voltage constant and varies the amps and not the other way around used on cheap charge controllers. Any help here would be really helpful. _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
