Charging 12V Power Tools

System

At my holiday cottage I have two solar panels charging up 4x12V batteries (sorry I don't know any more than that). The system is wired up so that it operates lights, a fridge and a couple of sockets that allow charging of mobile phones and running a portable DVD player through a 12V car cigarette lighter adaptor. I also have a 12V Bosch drill driver with the usual 240V mains battery charger but I would love to be able to charge the drill via the solar power. Does anyone know if there is an adaptor on the market that would let me do this?
Thanks
Andy

niel

Re: Charging 12V Power Tools

if you use a sinewave type inverter you can just plug into that with your chargers and run the inverter off of the batteries. some chargers can be used with the cheaper modsine inverters, but some will not like it to the point of it being damaged by it so you'd have to stick with the sinewave type. not real familiar with some of the available inverters you'd have available in the uk and maybe nigel could pipe in on this one.

my first thought was to run dc to the chargers' circuitry, but not all are setup easily to tap into the right spot to do this and not all are able to work with 12v as a base voltage making the inverter the better choice for the variety of tools and chargers out there. you will need to evaluate all of your loads including the inverter loads to the battery in addition to the present dc loads and also revisit the ah capacity of your batteries to know if it can handle all of the loads they will need to provide everyday without being drained back to the 50% dod point. you'd have to be sure the inverter chosen can handle all of the loads you'd present to it at any given time so the wattage rating of it won't be exceeded or blow out fuses.

once you've reached this point you can then figure on feeding the batteries their needed current for charging everyday. the general rates of charge will range between 5% (low) and 13% (hi) and possibly higher with some battery types of the battery ah capacity total. ask the manufacturer if you don't know the specs of the batteries, but definitely get their approval for any charging rates above 13%. it can get somewhat complicated figuring what controllers and pvs to get as there are variables like mppt or pwm controllers, wire run distances, odd pv voltages, j box or mc connector on pvs, warrantees, etc. i suggest you read more while you are figuring out all of your loads to familiarize yourself with some of the options you could have.