Configuring chargers and battery charge

[Asinnobooks]

Hi everyone,

Just got my first system installed - big thanks to everyone who has helped out on this forum!

I'm configuring my Victron MPPT, DC-DC charger and battery monitor and need to give them information about my batteries. I've got most of this from the manufacturer, but what I'm not sure about is whether or not my chargers and monitor will know how much charge is in the batteries at present, and therefore when to stop charging them. I have 2x180Ah AGM batteries connecting in parallel.

How can I determine this, plug it in to the Victron connect app, and ensure that I don't overcharge/damage my batteries when I start feeding current into them?

Many thanks in advance, oh solar deities.

 

[rmaddy]

Start with the battery monitor. Run VictronConnect and get the Battery settings all setup. That is the primary component that knows the SOC of the batteries.

Once that is working as expected then run VictronConnect for the SCC. Get the Battery settings setup for that with correct battery type and all of the correct voltages. Same for the DC-DC charger.

Setup VE.Smart networking for all of the Victron components and they will talk to each other.

You now have a system that will do what needs to be done to treat your batteries well. Of course that assumes you’ve entered correct values for everything.

 

[mikefitz]

Same for the DC-DC charger.

Setup VE.Smart networking for all of the Victron components and they will talk to each other.

The Victron dc to dc charger has no networking capability.

I have 2x180Ah AGM batteries connecting in parallel.

the specification for the batteries will advise of the correct charging voltages , somewhere between 14.4 and 14.7 absorption voltage and 13.6 to 13.8 float.
Charge the batteries and keep the absorption voltage at the specified value until the current falls to 3 amps, the batteries are now fully charged. If you don't have a AC charger and only use solar its a little more difficult. Allow the charger to complete the charge cycle and drop into float mode. The battery wont be completely charged but near enough. At this point set the battery monitor to 100% state of charge. The setup of the Victron battery monitor, (the default values need altering when charging from solar)

Battery capacity, your actual capacity, (capacity at the 20 hour rate)
Charged voltage, the charge voltage your chargers are set to, minus 0.1 or 0.2 volt, example charge voltage 14.4, BMV setting 14.2
Puekert Exponent 1.25
Charge efficiency factor 94%
Tail current 1%
Charge detection time 5 min

The BMV syncs to 100% when the voltage is above the charge voltage and the current is below tail current and both the conditions are valid for the charge detection time.

No battery monitor remains accurate over a period of time as small errors accumulate. Keep a watch on the operation of the system and if the monitor seems to be in error, force a sync to 100% when you are confident the batteries are fully charged.

Dont worry about overcharging the batteries, lead acid batteries are quite robust and will automatically accept less and less current as they are charged. AGM like to be charged at 0.2C, thats 70 amps for your batteries. They will accept this current up to somewhere between 50% and 80% SOC, then the current will fall . At 100%SOC the current will be less than 1% of capacity, around 3 amps.

Mike