Victron solar controller: Battery settings


#1

Hi everyone,

First post here. We’ve just hit the road! Day 3 in a different country and loving it.

We have a 280W solar panel on the roof, a Victron Energy 100/30 SmartSolar controller and 2x Leoch 130Ah AGM batteries in parallel.

I have the data sheet of the batteries, but not finding it very clear when trying to derive settings for the solar controller. Can anyone with a bit more battery experience have a look and let me know if you can decipher it.

By the way, I’m and electrical engineer by trade, but a totally different discipline within the industry, never touched batteries, so any recommended reads would be greatly appreciated.

Regards,
Insta: @doginavan


#2

i’ll run this through a friend of mine who knows alot about these things and get back to you

The .pdf seems pretty helpful, where did you get it from?


#3

When I was looking for a battery I had in mind the fact I’d need something pretty detailed. Came across Alpha Batteries who seemed to have more detail than others.


#4

Like many manufactures, especially overseas (china) the charts do not match reality. At average temperatures of 72F. The chart recommends 14.7 volts for Maximum! of 2 hours per day (or is it .2 hours) then 14.4 volts for continuous charge. Then a boost charge 14.1a, that doesn’t make any sense. They lost something in translation.
I would set my controller the the Controllers Setting for AGM batteries, then pray for rain.
You Do want to limit the charging amps to about 25 amperes per each battery. As you have two batteries, no more than a 50 amp rated charger. But any 3 stage name brand charger can be set for your batteries. Pick the settings for <14.4 or .5 volts boost (initial), then <14.4 float. Or find another standard AGM charging parameter and use that. Do not use any high volt/amp charging on AGM battery. Here is Maine Sail on charging AGM battery. https://marinehowto.com/how-fast-can-an-...e-charged/


#5

Yes ignore the timings, but not necessarily the V levels.

And max charge ratings are BS, never mind about them, especially in a solar context.


#6

Those preset settings are useless. They work if you got nothing else. But I notice there is always voltage drop between the controller and battery.

The further your battery the more voltage drop. And the controller usually won’t take heavy gauge wire unless you can somehow get it to fit in the small openings.

Measure the voltage at the actual battery terminals and go from there. If the controller reads 14.4 volts and then you go to the battery and it reads 13.9 volts, thats a .5 volt drop. Its what I was getting on my battery for years. I was under charging the batteries by .5 volts, they were pratically on float voltage for all that time.

Now I set the bulk/absorb to 15 volts and float to 14.4 volts when charging lead acid. I think voltage drop is more common then people realize. , I tried changing wires etc to fix the voltage drop and couldnt fix it, I just compensated by raising the charging voltage on controller. This will keep the controller on bulk longer feeding your battery high amps when it needs it the most.

More damage will occur from undercharging your batteries then overcharging the batteries with solar. As long as the voltage on the terminals are within specs your good to go.

Keep the float voltage high, with solar you run out of sunlight before the batteries can finish the absorb cycle. It won’t damage the batteries, lead acid like that type of voltage all the time.


#7

The manufacturers sheet is very poorly translated, this is what I would conservatively set the batteries too:

Set the Victron to
Absorption voltage 14.40V
Maximum absorption time 6h 0m
Float voltage 13.60V (up to 13.8 if needed)
Equalization voltage 15.00V
Automatic equalization Disabled
Temperature compensation -24.00 mV/°C ***(SEE NOTE BELOW)
Low temperature cut-off Disabled

These are the numbers I would use, it is the best interpretation I could get from that poorly translated bad spec sheet from the manufacturer.

You need to have the solar controller as close to the batteries as practicable, < 3 feet is good with a minimum of 12 gage wires going to the battery (I would use 10 gage, but the wiring calculators say 12 is plenty). ***I based to temperature compensation off the poorly made graphic chart, which is -40.00mV/°C but it is not a smooth linear correction they just have 2 drops, however most manufacturers use something closer to -24.00mV/°C, I would use this instead.

If you have undersized wiring or a long distance from the controller to the battery, measure the voltage at the battery and compare it to what the Victron controller says it is to (as another poster said) if there is more than a .1volt difference than you will need to raise all the controller values up higher by that amount to compensate for the voltage sag. For example, if the main readout screen under Battery - Voltage says you have 13.2 volts but your manually connect voltmeter hooked to your battery terminals say you have only 13.0 volts then you will need to adjust all the numbers I gave you for the settings higher by that amount, in this case add 0.2 volts to all settings i.e. Absorption voltage to 14.6 volts instead of 14.4

You do not have a large enough solar to over current the batteries so no worry there.

Don’t use equalize mode at all unless you think the batteries are really bad and as a last ditch effort to revive them.


#8

Great help everyone. Thanks very much, much appreciated.