Output Coils

[Jimboot]

Thanks synchro1. I have been looking at the circuit diagrams for the  bendini engine. There is a 12v drive battery and a 12v charge battery. There is no transformer etc. so how do the people who make these know they are getting a 12-14 volt output to charge the battery and not some silly voltage that will fry the battery??

If they fried the output battery they would be happy. I would start with some cheap meters that will start you getting used to the concepts etc. Hook one up to your output before you hook it to the battery just to see what it is. I had some output coils that were pushing out 1kv on a simple pulse motor. The amps were quite low though so total wattage out, was about 2/3 of what I was putting in, so efficient but no cigar.

[MileHigh]

Thanks synchro1. I have been looking at the circuit diagrams for the  bendini engine. There is a 12v drive battery and a 12v charge battery. There is no transformer etc. so how do the people who make these know they are getting a 12-14 volt output to charge the battery and not some silly voltage that will fry the battery??

The answer to your question is that the output that charges the charge battery is not a voltage source, it's a current source.  A discharging coil is a current source.  The output voltage of the coil is primarily determined by the voltage of the charging battery itself.  The voltage going into the charging battery is not determined by the coil.

You should try Googling "What is a current source?" and "Voltage source vs. current source."

If you can understand the concept of a current source and how it works then you will be ahead of 98% of all Bedini motor enthusiasts.  I can't explain why, but literally there are Bedini motor enthusiasts that play with their Bedini motors for years with no understanding whatsoever that when the charging battery is being charged it's being charged by a discharging inductor that is a current source.

[MileHigh]

Hook one up to your output before you hook it to the battery just to see what it is.

If you are suggesting that you should connect a voltmeter to the unloaded discharging coil you should never do this.  The current source output from the discharging coil will generate an unknown high voltage that may fry the voltmeter and/or give the experimenter a very nasty shock.

[nathanj99]

What do you suggest? Would a 1 ohm resister help?

[Farmhand]

When charging a battery with a switched coil discharge. If the charging battery is in bad condition and has a high internal resistance then the voltage observed at the charging battery terminals may get quite high (even showing large spikes on a scope) and not much current will flow through the battery. that will eventually break down the sulfates if the battery is just sulfated. But if the charging battery is in good condition with low internal resistance then the voltage at the terminals of the battery will not get high and the battery will experience more current for a longer time and the battery will take charge from that.

If you open circuit the leads of an old transformer based battery charger or a car alternator (not recommended) the open circuit voltage is for my charger around 20 volts for a 12 amp charge and about 17 for a 6 amp charge ect. the car alternator on my old car gave about 18 volts at idle open circuit. The amount of current produced through the battery from a transformer charger or an alternator is determined by the "applied potential". If a regular transformer charger is applied to a sufated battery then the battery terminals will only go to about 20 volts or so (car alternator has active regulation).

But when a switched coil charger (ala bastardized boost converter with no output regulation) is connected to a sulfated battery with high internal resistance then the voltage can rise much higher for well known reasons, the higher resistance reduces the ability of charging current so it raises the voltage instead to overcome the resistance. and it does. Safe or not. 

They can serve a purpose to try to restore really bad batteries but to get good capacity back in my batteries I use a 4 stage - 6 amp current pulse charger I bought from ebay it has a refresh function and analyses the battery before charging to determine the best algorithm it can for charging that battery, the fast charge portion uses a pulsing current that can build a higher voltage fast on a sufated battery, but when that happens and the charger stops prematurely I simply apply an appropriate load of around 4 to 6 amperes  to drain the battery and force the battery to cause it's own current which also helps to desufate the battery. Then when it's discharged I put it back on the charger which does the refresh cycle again and re analyses the battery.

If I want to reclaim a badly sulfated battery I usually use some magnesium sulfate (epsome salts) saturated solution in each cell then maybe a coil switching setup for a while to get some charge into the battery so it can be discharged through an appropriate load. Discharging the battery appropriately does as much to desulfate the battery as charging it does.

Similarly a 1 amp trickle charge will restore a sufated battery if left for long enough.

Reality bites.