Firefly Oasis Carbon Foam AGM Batteries

[john61ct]

Do you measure trailing amps at the bank before the SC transitions to Float?

Does it get to Float before mid-afternoon even when the bank got under 60-70% SoC overnight?.

Maybe just an adjustment extending absorb hold time will get you to 100%?

If you do hit that endAmps point, you could let the SG know, hit the 100% reset.

[Pete O Static]

Originally Posted by john61ct

Do you measure trailing amps at the bank before the SC transitions to Float?

Does it get to Float before mid-afternoon even when the bank got under 60-70% SoC overnight?.

Maybe just an adjustment extending absorb hold time will get you to 100%?

If you do hit that endAmps point, you could let the SG know, hit the 100% reset.

No, I don't measure trailing amps at the bank.

Float before mid afternoon? Yes and No. As you point out, the Absorption Phase is time limited. So the controller will go into float mode when one of two things has occurred. Either the battery charge rate has reached less than 2 amps during constant voltage charging ( ie fully charged the bank ) OR the time limit of the absorption phase has been reached. Many mistake the latter for a fully charged bank. ( which is why I assume you are measuring trailing amps at the bank )

My Victron measures the bank voltage at controller start up in the morning and based on the state of discharge, determines a maximum absorption time. Assuming a steady discharge over night, the maximum limit is 6 hours. ( I cannot change or adjust that time limit ) So yes, by noon I am technically in "Float Mode" but depending on how much sunlight I actually managed to harvest in that time, my bank may or may not be fully charged. This is where I see a difference in what the smartgauge is telling me vs the Victron App and it makes perfect sense.

This is also where the Firefly's really shine because I don't sweat it if they don't reach 100% SOC. If say the solar array gets me to 90% as per the smartgauge, the engine alternator easily gets me to 100% if needed.

I try to avoid resetting the SG whenever possible because I think over time, that defeats it's purpose of actually "learning" what bank health is.

[john61ct]

Hmm, I never imagined the 100% interfered with its learning, in fact assumed the opposite.

Apparently the Victron's pretty complex algorithm return it to Absorb quite quickly compared to other SCs, there was a thread someone speculated on the details but seemed pretty opaque, haven't done testing.

[a64pilot]

I think resetting it interferes with it, it is best just simply left alone.
However as I have found with mine that is is extremely sensitive to have good contacts, which of course is logical. The factory fuses mine came with were prone to corrosion, causing the SG to behave erratically. I first cleaned them off and applied silicone grease which helped, but in truth things didn’t get completely right until I cut them out and replaced with sealed fuses that had silicone grease on them from the beginning.

I know this is common sense, however the corrosion on the fuses and the female spade connectors used for the fuses was nearly invisible and was more of a dulling of the metal than anything else, but it was enough.

The acid test and what tipped me off was that the voltage reading of the SG didn’t agree with my Fluke when I measured at the battery terminals, it wasn’t out but about .1 or maybe .2, but it was enough to make it so that the SG wasn’t accurate.

[leftbrainstuff]

We've had 4 Fireflys for a year now. We have 1kW of solar and are able to heat hot water and recover all the previous 24 hrs consumption. Providing we have full sun for at least 5 hours per day.

We run 3 Victron 100/30 MPPT controllers. 1 per 350W panel. These controllers are very efficient and double our recovery compared to the old PWM controller we ran before.