Charging batteries from alternator

[Col_T]

On your second point @nicknorman. My original question was raised because I haven't seen anything that suggests it can gradually take the load off an alternator when a lithium bank is deemed full - be that at 100%, or 80%, or whatever - so was wondering whether an immediate chop, even with LAs in circuit, would damage the alternator?

[WotEver]

2 hours ago, Col_T said:

On your second point @nicknorman. My original question was raised because I haven't seen anything that suggests it can gradually take the load off an alternator when a lithium bank is deemed full - be that at 100%, or 80%, or whatever - so was wondering whether an immediate chop, even with LAs in circuit, would damage the alternator?

The first part is difficult but not impossible to achieve. The second part has been answered: with an LA connected, no. Without a parallel LA, quite possibly. 

[Tony Brooks]

2 hours ago, Col_T said:

On your second point @nicknorman. My original question was raised because I haven't seen anything that suggests it can gradually take the load off an alternator when a lithium bank is deemed full - be that at 100%, or 80%, or whatever - so was wondering whether an immediate chop, even with LAs in circuit, would damage the alternator?

As I keep saying if you doctor the alternator so you bring the rotor feed or negative (earth) to outside the case you can then use some form of relay to disconnect the  rotor coil from the whatever is supplying it. That will reduce the output to zero as fast as the rotor field decays. It will be identical to that which happens many times a second as the regulator works and will not produce the output voltage surge related to disconnecting the load. Some alternators are easier than others. An A127 shoudl be very easy.

 

How you control the relay is up to you but whatever you are using to monitor the voltage and would otherwise disconnect the load could be used even though you may have to ensure the relay worked the correct way for the monitor output.

 

If you don't believe the above will do no damage then I can see no reason you could not use a hefty power transistor in place of the relay and then use a Pi or Andrion to produce a string of gradually reducing pulse width pulses so the output gradually drops until the off pulse is of infinite length and the alternator output is zero. I would just use a relay for simplicity.