question

A standing loss of 10% per month?

What the hack is this?

I have SOPzS Batteries and I do not loos this in two month.

And no, even with a SolarCharger connected (without Solarpanels) it would not suck such big batteries empty.

You must have definitively forgotten to disconnect something.

Do you have a GX device connected?

I see in the cell datasheet:

@ 100 Hour Rate 733 AH 7.33 A

If the Battery loos realy 10% a day, this would be after 3 month then roughly 513Ah and if your batteries are flat, then something must have drawn 5,7Ah a day or 0,23A in an hour. The SmartSolar MPPT 100/30 can not draw this current.

And if you say, that one month ago (you had already 50%) the battery started draining, than it would be even more worse because it would mean at least 11Ah a day.

Maybe you should think about what may be able to drain 0,45A (or even more) an hour over 30 days...

I have support ticket open with Rolls Batteries regarding the (what I would call) catastrophic discharge. Yes the new Rolls batteries with carbon nano technology (marketing BS) has extended the available cycles so the battery lasts longer at the expense of loosing 10% charge per month. With the isolator switch open there is nothing connected to the battery so I can’t understand what has consumed the power.

Could a diode on the solar panel turn it into a consumer of power at night ? My solar panels are no longer working. I see voltage but no amps. When the major drop in the battery occurred, that is when the panels stopped working

The only other thing connected was the output of a SmartSolar 100/30 MPPT controller. The MPPT controller itself did not have power. When looking at the Victron APP I can see that even though the controller was not powered, the solar panels have powered it enough to have the histogram of the battery state

I don't understand this.

You say that the MPPT was still connected to the battery.

But then you say that the MPPT did not had power (from the battery). Only some power from PV panels.

You say that the PV panels remained connected to the MPPT, but barely produced any power. Were they covered? Or why would the PV panels not produce power during the day?

Sorry for the confusing detail. The SmartSolar MPPT controller was connected but no longer charging (so showing as off) because the solar panels were producing 0 amps.

This is current state of the batteries and what I learned from Rolls Batteries technical support. The batteries are back to 100% SOC after days of charging. Rolls’ said even though the batteries were discharged to 3V that they were recoverable and would be undamaged by the event but I needed to adjust the charging regime of the Victron charger. Basically Rolls’ technical said the batteries (and other industrial batteries like my 6CS-17P’s) required and can take more rugged charging options. Now my charging is FIXED (not adaptive or battery safe), no STORAGE option, 15V for absorption charge, 6 hours, repeated every 4 days with a 5 hour cycle. If you know VE.Configure this is a blunt (not smart) charging regime and the Rolls batteries like that hard charge.

The batteries are back to a full temperature adjusted specific gravity of 1275 which is a true 100% SOC for these batteries with near 100% capacity. All cells are at near the same reading so there are no damaged cells. That’s the good news.

Regarding the unexpected discharge over 3 months. Rolls said these batteries self discharge @ 10% per month at 25C. As the boat (black underwater, dark blue topsides) stored on the hard it was 30C plus each day the insides of the boat was more than 35C on average so the monthly loss was more 20%. So that coupled with the fact the SmartSolar was connected but the solar panels stopped providing charge, the SmartSolar MPPT was a daily discharge load of around 3.6A (or 100A per month) that is what lead to the full discharge of the batteries.

The outcome was the Rolls Batteries are extremely tough, I have adopted a more appropriate charging regime, I need to replace the solar panels so they can keep the batteries charged while I am away. The last is I will attempt to incorporate a Cerbo-S GX controller so I can monitor the state remotely and take remedial actions earlier. I hope this now makes more sense.

The idle current of the MPPT you have is 30 mA on 12 volts and 20 mA on 24 volts. That's about 21 AH/month (12 volts). So this is unlikely the source of your loss.

If you have any sun on the panels, the charging you get will easily offset any loss. So leave the MPPT connected to both battery and solar panels. If you have no solar exposure at all, then you could disconnect the MPPT from the battery but again the loss is not very significant.

So some more detail that others may find useful. My boat is in the Aegean Sea. During summer here they experienced extreme temperatures. My solar panels were 2 x 100w and what I thought good quality semi-flexible panels on a 3mm aluminium base. They were 10 years old. The panels are fixed directly to a hard bimini on the stern providing shade over the helm and part of the cockpit. The bimini is made like a surfboard with strips of balsa wood epoxied on edge glued with thickened epoxy to a curved shape and after shaping is covered with layers of epoxy soaked fibreglass mat and vacuumed into place. It’s very strong and light and seemed like the perfect place for semi-flexible panels which are marketed to deck fix and so you can walk on them.

Well it seems in the extreme heat of a Greece summer this year, hard fixing such panels allows heat to build up to a level the panels can’t cope. A reliable off grid supplier in Athens warned me when replacing my panels I must have an air gap between the deck and the panels or if the solar panels reach in excess of 75C they short. That is what has happened to my panels. In one hot summer all panels are shorted, kaput, pining for the fiords, demised.

So it seems the extreme heat of this summer when the boat was not monitored, the Rolls batteries self discharged at above 20% per month (Rolls think more like 25-30% in above 35C) and the solar panels all shorted. That is what happened.

The good part is Rolls Batteries are so tough that they recovered from dead flat 3.45V and are now back at 100% SOC and Rolls believe based on specific gravity reads around 100% capacity with no damage.

All that said I now have a Cerbo-S GX in place monitoring the solar charge remotely over VRM portal. I hope to not have this knowledge be of disaster again.

Thanks for your replies.