Here's a circuit I built for my friends young lad to look after his bike battery, and to top up his dad's car when he's away. It also charges his NiCad battery packs,
I was really impressed with it, constant current,constant voltage ,I was able to turn this thing down to 10ma at 13.8 volt.. and crank it up to 25volt at 5amp. or 13.8 at 5amp and then 7volt at 5amp..
If you have an old automotive type charger (iron core transformer) this circuit could be built so a guy could hook the battery charger to this circuit and charge your batteries..
It reverts to constant voltage when the battery is full,and constant current when the battery needs a recharging or top up.
I added two extra pass transistor's(4 in total) and inserted TIP3055's in place of the 2N3055 ,increased the heat sink..
Most parts were scavenged ,, the heat sink came from the local scrap yard at scrap price.. some old computer power supplies.a case from a local thrift shop (it started out life as a cassette deck.)
Hopefully some of you guys will find it handy as an add on, to turn your old buzz box into a mulit use charger..