Induction coil

[Nowhere-Man]

Explosions with batteries are a known phenomenon on boats. I think it was the gel, sealed batteries that were often charged at over voltage. The fault was the use of controllers for fast charge. For lead acid about 14 volts was the ideal. In my line these days charging is a fundamental issue. The deep cycle batteries you can discharge but the key is to attain as full a charge as possible. Below 12.7 volts is on the flat side. This is why when they fit diode isolators on battery banks so the motor start battery is isolated from domestic, the small diode drop has to be compensated. Battery sense regulators supplied the solution.
I keep meaning to build a battery repair device. It uses high voltage pulses to dislodge sulfer on the plates.

[ppppenguin]

Lead acid batteries don't, in themselves, explode. However the charging process gives off hydrogen which is a very real hazard. Conventional lead acid batteries give off hydrogen when charged. In an SLA the hydrogen is only be vented when overcharged.

[Nick]

I'll also need to find an SLA charger - car battery chargers aren't ideal for SLAs.

One I designed earlier:

   

   


  SLA Charger Schematic.pdf (Size: 26.44 KB / Downloads: 14)

[ppppenguin]

Thanks. I may have an SLA charger around somewhere. Otherwise for the sort of occasional use this will get I'll just do it by timed charge from a bench PSU in current limit.

[peter scott]

Jeffrey, your coil is a very lovely device but I acquired a much more modest version from dregs of MBL's collection when I went to get the CRTs.

With careful adjustment and about 5 volts primary I can get about 3.5 cm of spark that for needle points apparently corresponds to about 37kV.

What can your coil do with needles?

   
   

Peter

[ppppenguin]

Very nice. I'm sure you paid a lot less than I did.

I've never pushed mine to the max as I don't want an accidental failure. Gap between points is about 6cm as I said in the OP. Must try a Jacob's Ladder one day.

[peter scott]

I think your coil is a very desirable object. Mine is very definitely not and 6 cm represents something like 55kV. Much more spectacular.

Thanks,

Peter

[peter scott]

With a 12 volt 18 amp supply I can get 5.5 cm but not with the constancy of the lower voltages and rather heavy arcing at the contacts.

   

Peter

[ppppenguin]

I think the 12V SLA on mine is overdoing it slightly, judging by the amount of arcing at the contacts. I think a fraction of an ohm in series (longer wires!) would help.

[peter scott]

I was wondering about the health of the capacitor across my points. I might see if paralleling it might help.

Peter