Victron settings for new AGM battery

Omniphil

I picked up a Vmax SLR155 for our T@B 320. Our's already has the factory solar and the Victron 75/10 controller.

The standard battery was a group 24 regular flooded battery, Do I need to monkey around with the Victron controller settings for this new battery?

DougH

I've got VMax AGM batteries too, and wasn't sure what to use in the Settings area on the Victron app either.  I went to the VMax web site, and ended up with Expert mode off, an Absorption voltage of 14.65V, Float voltage of 13.90V, Automatic equalization off.

So far so good, but I'd love to hear if those 14.65 and 13.90 values should be tweaked.

Omniphil

Did a little digging around. Looks like the Vmax SLR155 wants Charging Voltage = 14.4-14.9 and Float Voltage = 13.5-13.8.

The Victron Smart Solar manual says that default Absorption Voltage = 14.4 and default Float Voltage = 13.8.

So I think I'll just leave everything as is, that should work from what I can tell.

DougH

I've had a couple VMAX SLR125 batteries in parallel in the back of the camper, and another battery up front since 2016, do a lot of rough roads, use them in sub 0F temperatures and TX summer heat, often go a little below 50% on the bank, use 2000-3000W inverters, and frequently run the A/C off them.  They're still going strong, though I only switched to a Victron MPPT 100/20 controller for more juice this past year. Your SLR155 should similarly give you 5-10 years of happiness.

Tundra57

Just an fyi. I also had the Victron 75/10 controller and factory panels. If you do the math in ideal circumstances you could have more available current to the battery from the panels than 10Amps. I contacted both my seller and Nucamp. Nucamp offered to send me a 75/15 to replace it. I had already done this so I did not take it.

Two days ago I was monitoring my solar panels and I saw 9.8Amps flowing to charge my battery. The sun was not fully bright and the rear of my tab was in shade. So it would seem to be very possible you could get some limiting with the 75/10. I suggest you contact your dealer or Nucamp and ask for a 75/15 replacement.

Omniphil

Tundra57 said:

Just an fyi. I also had the Victron 75/10 controller and factory panels. If you do the math in ideal circumstances you could have more available current to the battery from the panels than 10Amps. I contacted both my seller and Nucamp. Nucamp offered to send me a 75/15 to replace it. I had already done this so I did not take it.

Two days ago I was monitoring my solar panels and I saw 9.8Amps flowing to charge my battery. The sun was not fully bright and the rear of my tab was in shade. So it would seem to be very possible you could get some limiting with the 75/10. I suggest you contact your dealer or Nucamp and ask for a 75/15 replacement.

Very interesting. I didn't think a 130watt panel would go that high, but that is certainly something to think about for sure...  Thanks for the tip.

DougH

And in the Victron bluetooth app you can set the maximum charging current too, but I don't know if that alleviates Tundra57's concern.  If you had 1000W of solar panels but set the max charge current to 8A, could you still safely use a 75/10?

Darn these solar panel manufacturers nowadays for making such efficient units. It used to be you would consistently get half the spec value off a panel, but in the last few years some panels are now producing close to or even over the advertised power level.

Tundra57

Just to set the record straight. In my 2019 Tab 400 i have supposedly a 200watt factory solar. Which is fitted with the 75/10. If you get more energy than the victron will hanfle it just gets dumped. No damage just wasted. I spoke to a victron engineer who said  many RV companies go a size lower on controllers to save money. Most of the time they are ok. Not many of us get the tab located in full sun in perfect weather to get the most from the panels. But when you can the energy is wasted. Is that is why i upgraded. Apparently Nucamp agreed with my reasoning.

AnOldUR

DougH said:

So far so good, but I'd love to hear if those 14.65 and 13.90 values should be tweaked.

Doug, I have a VMAXSLR125 on the way and a MPPT 75/10 controller set to factory default:
(says it's for a Gel Victron Deep Discharge battery)
Absorption Rate 14.4
Floating Voltage 13.8
Equalization Voltage 16.2
Automatic Equalizer Disabled

As @Omniphil said above, that appears to be within the specs, but have you stuck with that or made changes? Have you done anything with the Automatic Equalizer? Any other setting changes that I should be thinking of?

Dutch061

Tundra57 said:

Just to set the record straight. In my 2019 Tab 400 i have supposedly a 200watt factory solar. Which is fitted with the 75/10. If you get more energy than the victron will hanfle it just gets dumped. No damage just wasted. I spoke to a victron engineer who said  many RV companies go a size lower on controllers to save money. Most of the time they are ok. Not many of us get the tab located in full sun in perfect weather to get the most from the panels. But when you can the energy is wasted. Is that is why i upgraded. Apparently Nucamp agreed with my reasoning.

This is not entirely accurate, you have to stay below the Maximum voltage - wattage on the input for the Solar Charge Controller. However, the Controller will reduce the wattage going to the batteries as they approach a 100% SOC.

Here is a link to everyone's favorite Will Prowse 

https://www.youtube.com/watch?v=C-k0WHJ4RxQ&ab_channel=DIYSolarPowerwithWillProwse

Brad