Alternator to LiFePO4 charging

[swampbush]

The Victron multiplus has a storage mode which seems to fixed at 13.2v. After a few hours of float it will drop to storage if that is enabled. It will periodically return to absorption. The time between recharges (days or weeks) and the length of the absorption(in 15min increments) is programmable.

I think the charging can be set to turn off using a switch and a programmable assistant to vary the charge depending on the voltage being input. I haven't tried yet, perhaps someone else has done this?

[Dockhead]

Originally Posted by swampbush

The Victron multiplus has a storage mode which seems to fixed at 13.2v. After a few hours of float it will drop to storage if that is enabled. It will periodically return to absorption. The time between recharges (days or weeks) and the length of the absorption(in 15min increments) is programmable.

I think the charging can be set to turn off using a switch and a programmable assistant to vary the charge depending on the voltage being input. I haven't tried yet, perhaps someone else has done this?

I've used a Victron Multiplus for nearly a decade.


I don't know about other charger/inverters, but this one, at least using the normal control panel, cannot be set to pass through AC power but shut down the charger. It has three operation modes --



1. "Off", which is no charging, no inverting, and no AC power passed through from shore or generator;


2. "On" -- charging on (automatically going through the charging modes, subject to forcing into any mode). And AC power is passed through from shore or generator. The current limiter control limits the amount of power taken from shore or generator by the charger, to stay within the set current limit if possible, by reducing charging current.



3. "Invert" -- charges when there is an excess of shore or generator power, and takes power out of the batteries and inverts it to make AC power when shore or generator power is absent or insufficient to meet AC loads.





There is no mode which allows you to stop charging, however you can force it into float at any time. You can program the float voltage so presumably could force it to float at a voltage which will not charge the batteries.

[swampbush]

Originally Posted by Dockhead

I've used a Victron Multiplus for nearly a decade.


I don't know about other charger/inverters, but this one, at least using the normal control panel, cannot be set to pass through AC power but shut down the charger. It has three operation modes --



1. "Off", which is no charging, no inverting, and no AC power passed through from shore or generator;


2. "On" -- charging on (automatically going through the charging modes, subject to forcing into any mode). And AC power is passed through from shore or generator. The current limiter control limits the amount of power taken from shore or generator by the charger, to stay within the set current limit if possible, by reducing charging current.



3. "Invert" -- charges when there is an excess of shore or generator power, and takes power out of the batteries and inverts it to make AC power when shore or generator power is absent or insufficient to meet AC loads.





There is no mode which allows you to stop charging, however you can force it into float at any time. You can program the float voltage so presumably could force it to float at a voltage which will not charge the batteries.

Do you have the usb cable to program it and the latest firmware? Using veconfigure software you can run through all the different configurations. You can't do much without using veconfigure. Google veconfigure, or have a look at the victron forum. Hours of reading there! https://community.victronenergy.com/index.html

[Dockhead]

Originally Posted by swampbush

Do you have the usb cable to program it and the latest firmware? Using veconfigure software you can run through all the different configurations. You can't do much without using veconfigure. Google veconfigure, or have a look at the victron forum. Hours of reading there! https://community.victronenergy.com/index.html

The DIP switch programming is fine for lead batteries. I will use a Color Control GX panel when I install my lithium bank.



I am fairly conversant with the programmable capabilities of the Multiplus but AFAIK it is not possible to program it to operate with the battery charger shut down.


However, you definitely can program a low float voltage and you can definitely force it into float, so this could probably be made to work with lithium.


But as you say there are hours of reading there, so if I've missed something I would be grateful to be corrected.

[mikedefieslife]

Originally Posted by swampbush

The Victron multiplus has a storage mode which seems to fixed at 13.2v. After a few hours of float it will drop to storage if that is enabled. It will periodically return to absorption. The time between recharges (days or weeks) and the length of the absorption(in 15min increments) is programmable.

I think the charging can be set to turn off using a switch and a programmable assistant to vary the charge depending on the voltage being input. I haven't tried yet, perhaps someone else has done this?

Forgive my ignorance What a multiplus, which is an inverter and 230v AC charger got to do with charging LFP batteries from an alternator?

[Dockhead]

Originally Posted by mikedefieslife

Forgive my ignorance What a multiplus, which is an inverter and 230v AC charger got to do with charging LFP batteries from an alternator?

He's responding to thread drift in Post #15.

[swampbush]

Originally Posted by Dockhead

He's responding to thread drift in Post #15.

Sorry about the thread drift. I have been going through the same thoughts for handling all the charge sources for LiFePO4. For my alternators I have used a victron citrix voltage sensitive relay that activates at 13.7v. The positive wire that turns on the relay runs through a victron bmv700 and manual switch. So the alternators only feed the house bank if the switch is on and the bmv relay is closed based on state of charge or voltage range. Solar is my main charge source, but I want to be able to have some engine charging if required.

[Dockhead]

Originally Posted by swampbush

Sorry about the thread drift. I have been going through the same thoughts for handling all the charge sources for LiFePO4. For my alternators I have used a victron citrix voltage sensitive relay that activates at 13.7v. The positive wire that turns on the relay runs through a victron bmv700 and manual switch. So the alternators only feed the house bank if the switch is on and the bmv relay is closed based on state of charge or voltage range. Solar is my main charge source, but I want to be able to have some engine charging if required.

OK, so you disconnect the lithium bank from the alternator whenever system voltage reaches 13.7v, is that correct?


Presumably in your case the alternator is still attached to a starting battery, right?


That's a nice KISS approach (if I'm understanding it correctly), which would be fine if all you want to do is charge the bank while you're motoring, but I think it would not work well if you are consuming AC power from the inverter while motoring unless you are counting on loads pulling the voltage down and closing the relay again.


My alternator will not be attached to lead at all, so I couldn't do it this way, but I could power off the alternator via a relay inserted into the alternator start wire.

[swampbush]

Originally Posted by Dockhead

OK, so you disconnect the lithium bank from the alternator whenever system voltage reaches 13.7v, is that correct?


Presumably in your case the alternator is still attached to a starting battery, right?


That's a nice KISS approach (if I'm understanding it correctly), which would be fine if all you want to do is charge the bank while you're motoring, but I think it would not work well if you are consuming AC power from the inverter while motoring unless you are counting on loads pulling the voltage down and closing the relay again.


My alternator will not be attached to lead at all, so I couldn't do it this way, but I could power off the alternator via a relay inserted into the alternator start wire.

No, the victron vsr connects when it senses 13.7v from either the start or house battery. It then charges house and start in parallel, and disconnects when the bmv700 opens its relay. The victron vsr also connects when the house is charged by solar, which then charges the start battery from solar. I still have a lead acid house bank, but have experimented using either voltage or state of charge from the bmv to disconnect. Hard to get a true float but could cycle so that alternators charge when soc falls below say 90% and stops at 99%. Presumably the bmv relay could also disconnect the alternator field wire to stop charging.

[Dockhead]

Originally Posted by swampbush

No, the victron vsr connects when it senses 13.7v from either the start or house battery. It then charges house and start in parallel, and disconnects when the bmv700 opens its relay. The victron vsr also connects when the house is charged by solar, which then charges the start battery from solar. I still have a lead acid house bank, but have experimented using either voltage or state of charge from the bmv to disconnect. Hard to get a true float but could cycle so that alternators charge when soc falls below say 90% and stops at 99%. Presumably the bmv relay could also disconnect the alternator field wire to stop charging.

Well the "true float" would need proper regulation of the alternator (e.g. Balmar MC614), or else Sterling A2B charger.

[mikedefieslife]

Originally Posted by swampbush

No, the victron vsr connects when it senses 13.7v from either the start or house battery. It then charges house and start in parallel, and disconnects when the bmv700 opens its relay. The victron vsr also connects when the house is charged by solar, which then charges the start battery from solar. I still have a lead acid house bank, but have experimented using either voltage or state of charge from the bmv to disconnect. Hard to get a true float but could cycle so that alternators charge when soc falls below say 90% and stops at 99%. Presumably the bmv relay could also disconnect the alternator field wire to stop charging.

I have that very VSR, as well as another form BlueSea Systems. It will connect at 13.7, but it will allow 14.5v or whatever your alternator puts out to go through to the LFP bank. Surely you want to reduce that voltage to 13.8 somehow, then disconnect when close to full, or float at 13.2v.

[swampbush]

Originally Posted by mikedefieslife

I have that very VSR, as well as another form BlueSea Systems. It will connect at 13.7, but it will allow 14.5v or whatever your alternator puts out to go through to the LFP bank. Surely you want to reduce that voltage to 13.8 somehow, then disconnect when close to full, or float at 13.2v.

At rest start battery say 12.8v, house if LiFePO4 13.3. When you start the engine the start battery comes up quickly to say 14.0v. The vsr relay closes and the house bank starts charging. When the house bank reaches the desired voltage say 13.8 some hours later, the bmv relay opens, which disconnects the vsr relay and stops charging the house battery. The alternator continues to charge the start battery to 14.2.
It is also possible to use state of charge to open the bmv relay and may well be preferable with LiFePO4 as it can still be overcharged at lower voltage. In the bmv Bluetooth app set low SOC at 95% and high at 99%. Change the bmv setting to synchronize to 100% at 13.8v and 2.5% end amps and charging to the house will stop when the house battery is full and restart at 95%. Unfortunately this will mess up your displayed %charge as 95% will show empty. I prefer to just count amp hours down anyway.