Solar Boost 3024iL and Dolphin 1 Settings

[2Wind]

I would appreciate advice with respect to the charging settings for my mains battery charger and solar charger.

System:

3 X 205AH 12V Bosch N200 batteries FLA type
Dolphin Series 1 120-240V charger
Solar Boost 3024iL Solar charger controller
2 X 250W Solar Panels

Limitations:

The old generation Series 1 Dolphin has only two switchable settings
"Free" - 13.9V Charge, 13.2V Float
"Gell" - 14.4V Charge, 13.6V Float

The Solar Boost is multi-switchable
Charge - 14.0V through 14.8V in 0.2V increments
Float - 13.2 through 13.8V in 0.2V increments

Application:

For all but 2-3 weeks of the year coastal or at anchor, the boat does weekly to fortnightly day sailing with an occasional overnight. Otherwise it sits at the marina on the charger.

I have noted that the batteries go through what seem like a lot of water - e.g. 10 litres in 6 months.

Considerations:

The limitation of the Dolphin is that it has only the two programs, and I suspect that FLA batteries should sit on float using the lower 13.2V "Free" program, even though its Charge/Acceptance is at a lower than ideal 13.9V level. (as compared to its "Gell" program). BTW Until I recently noted this it had been on the "Gell" and I wonder if this is why it uses much more water than I would have expected.

With the Dolphin set as above, how should I set up the Solar Boost. Currently it is as default, being Charge/Acceptance 14.4V and Float 13.2V.
I could dial it down to 14.0V as its minimum Acceptance voltage to "near match" the Dolphin's 13.9V. In practive, at the dock, it is not needed specifically unless the mains dockside circuit breaker trips (a monthly issue on average ensuring I visit the boat at least once a week given the fridges are running).

Thanks for any advice you can offer.

[noelex 77]

Firstly I am surprised your 500w of solar is not enough to keep up with your fridges in sunny Brisbane especially as the door will not be opened, or warm goods added while you are away

In Brisbane in the worst month you should be getting 100-120 AHrs per day on average. If you can disconnect from shore power it reduces the risk of stray current corrosion which can be very rapid and attack expensive components like saildrives. This risk is not high, but few boats are fully protected with an isolation transformer and the lack of previous problems in this regard is no guarantee that it won't occur in the future.
As well it removes the unreliability problem of shore power as you noted. It is one of the advantages of a large solar array that you are not taking advantage of.

Obviously from your comments this is not possible, but maybe some extra insulation, another solar panel, or turning the fridge temperature up slightly would enable you to disconnect from shore power. Making your life easier and providing some added protection for the boat.

On to your question:
It is worth asking the battery manufacturer, but if you cannot do this the common settings for cyclic use (while you are using the boat) for flooded batteries are 14.8-14.6v absorption and 13.8-13.6 v float.
While you are away from the boat I would lower these settings considerably especially if your charger/ regulator resets to an automatic absorption cycle every 24hrs even if the batteries are fully charged. Say 14.1v absorption and 13.2 float.

So use the "Free" setting on your charger and adjust the solar regulator to the above voltages. This will mean changing them when you leave the boat.

If you are paying for electricity most people set their solar array a tiny bit higher than the charger so this is providing free power where possible.

Most flooded lead acid batteries also benifit from a periodic equalisation charge so you might like to incorporate this if your battery manufacturer recommends this.

[2Wind]

Noelex
Thanks.

I'll look at reducing my current draw at the marina, by positioning the boat more optimally for the current winter sun angle and turning off the freezer. Should halve the current draw and increase the solar output, and perhpas come off the grid. Whilst the older Dolfin does not do an equalize, the Solar Boost can be set to do this either every 30 days or manually. Will need to check how the auxillary starting batteries are connected in all this. ? charged from both sources?

Thanks again.