1. Home
  2. ⚙ Stationary Engines - UK
  3. Magneto charging circuit

Magneto charging circuit

On my little boat I have no means of recharging the battery....but I do have a 5hp outboard engine! I removed the flywheel and inside was the coil providing the spark with a vacant space opposite. With some steel sheet and copper wire from a motor rewinders I made a coil! Someone donated me a gadet which converts the AC to DC. Guess what, at about

75% revs I got 2 amps at 12.5 volts perfect.

The problem is I've started to think this is too easy something must be wrong. As you increase the revs the volts increase, as you decrease the revs the volts decrease what will the battery think about the differrent voltage ? or is the current so small it won't be bothered? Does the battery still get some benifit when the volts are low?

This can't be rocked science our garden grass cutter charges a battery with no problem..... do I have to go out and but a widget or somthing ?

Any thoughts anybody

Regards,

Poorfruitcake

Reply to
Poor fruit cake
Loading thread data ...

The Dynamo on an old car works in the same way except a regulator box is put in the circuit to stop overcharging and regulate the voltage to around 14 -

15 volts otherwise the battery will boil dry. If the voltage drops below that of the battery it will not accept any charge. The alternator works in a similar way except it is made to spin at higher speed at idle to overcome the low voltage and it generates AC which is converted to DC.

Martin P

Reply to
campingstoveman

The battery voltage can go up to 14.50 for an hour or so without damage, less if the ambient is above normal.

If that voltage you gave is without a battery connected, then you may find that fitting a smoothing capacitor across it will increase it substantially, or the battery if close enough will do the same thing. Depends also on the type of meter you measured it with.

The thing to do is give it a try and see what it does, monitoring battery volts and current into it.

12.5volts won't charge the battery at all, a good battery will sit at 13volts if charged.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

formatting link

Reply to
Peter A Forbes

hi... No its that easy, you often find on outboards that there is a space for a charging circuit, the only thing is to make sure that when the revs drop that the current doed not flow from the battery to the coil, this should be achived with rectifier that your mate gave you, i would not worry about boiling the battery a coil that size will never produce enough current to sustain a high voltage on the battery.

Regards bob

Reply to
Bob

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.