I thought people may like to see how I make these, as I have now finished the first half of my last batch of 20 chargers. Six are already spoken for. I'll post a schematic shortly but you can see from the pics how they are made.
They are all hand made my me personally and tested before despatch on a real IMA battery, price is £200 postage paid worldwide in case anyone wants one. I'm confident enough in the design and assembly now to give a 2 year RTB warranty. You return faulty charger to me, I send you another simple as that. This warranty also now applies to the chargers I have already supplied
so that's good news for the 10+ current owners as well.
Parts for 10 chargers on bench ready for assembly.
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Charger power supplies fitted into ABS case.
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Parts for the charging leads and vehicle socket/connections. note the diodes at the battery connection points to prevent power travelling back from the IMA battery to the socket.
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The voltage indicator circuit. This is attached across the output of the 48v constant current power supply and illuminates when the voltage of the supply rises above 43v. It is on when the charger is turned on but not plugged into a battery as the supply is unloaded and rises to it's full 48v output voltage. It is off during the main charging phase as the battery pulls the supply voltage below the led trigger threshold. It comes on as charging nears then end as battery voltage rises. It's basically a 43v zener diode, 330R resiistor and led in series. The led only lights when voltage rises above zener conduction point.
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Inside a completed charger. The power cables are knotted inside the case and hot glued to prevent them being pulled out. The cable joints are all soldered and heat shrinked. There is plenty of room inside the case for ambient cooling which is one of the reasons I choose a decent size case to give some surface area.
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Packed ready to go with label and charge socket bundle.
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The specs are universal AC input 100-250v, Output DC 173-175v 350ma CC. Good effciency as well around 80% or so.
My grid chargers
and can go off/dim when the cells are really full as they dip in voltage slightly when full.
Best Tank: 
