Victron 75/50 MPPT system not working!

[LETitROLL]

Only have the Mppt connected to one battery bank as even wiring them in series wont be enough to charge both the banks.

If you indeed have 12v 128ah batteries, then the 2 panels you have will not be enough to keep even 1 bank properly charged.
By wiring the 2 panels in series it will at least work and supply the full power from the panels to the batteries (your not even getting that now due to low voltage), but there will not be enough amperage to keep the batteries from meeting a premature death (c/10 charge rate).

[themacleanfamily]

My understanding of the way the battery banks were set up by the electrician is that the 4 x 128ah 12v batteries were connected in such a way as to give 256ah at 24v on each bank. If both panels are wired in series and only into that one bank am I still well short in terms of panel size?

[LETitROLL]

My understanding of the way the battery banks were set up by the electrician is that the 4 x 128ah 12v batteries were connected in such a way as to give 256ah at 24v on each bank. If both panels are wired in series and only into that one bank am I still well short in terms of panel size?

Yes, if indeed each bank is 24v 256ah you would need about 600w solar power for 1 bank, I was hoping you had 6v batteries (they are very common in your size/config battery banks).

[themacleanfamily]

Thats bad news. I may have to split one of the banks thereby making one large bank of 256ah and two smaller ones of 128ah each and have the panels feed that which would at least keep the bilge pump batteries topped up. Either that or try and get more powerful panels to give me the 700w that are no bigger area wise than the existing ones and swap them over.
I'm now also going to have to look into the Rutland wind generator as I have a horrible feeling that it wont be doing anything useful either!!

Many thanks for the help

[inetdog]

Thats bad news. I may have to split one of the banks thereby making one large bank of 256ah and two smaller ones of 128ah each and have the panels feed that which would at least keep the bilge pump batteries topped up. Either that or try and get more powerful panels to give me the 700w that are no bigger area wise than the existing ones and swap them over.
I'm now also going to have to look into the Rutland wind generator as I have a horrible feeling that it wont be doing anything useful either!!

Many thanks for the help

Wind generators actually can deliver good value on sailboats which are actually sailing. Relative wind speed and direction are consistently high even with low ground speed. That assumes that you found a good wind turbine. I am not familiar with the Rutland.

For a motor driven boat or for sitting at anchor the wind turbine is less likely to perform to what you might expect based on its specifications.
The law of physics that causes all of the problems is that the output of ANY wind turbine will be roughly proportional to the third power of the wind speed and directly proportional to the swept area of the rotor (a constant once you buy one.)

So a turbine rated at 100W at 20mph will produce only 12.5W at best at 10mph.

[themacleanfamily]

The one I have installed is the Rutland 914i which is rated as producing 143W at 24mph which like the panels will presumably have little or no effect on either of my banks due to their large size. I'm obviously going to have to rethink the entire setup based on all the advice provided her.

[inetdog]

The one I have installed is the Rutland 914i which is rated as producing 143W at 24mph which like the panels will presumably have little or no effect on either of my banks due to their large size. I'm obviously going to have to rethink the entire setup based on all the advice provided her.

If nothing else, the solar can provide a very good battery maintainer for long periods anchored without a shore connection.
The wind turbine less so.

[Living Large]

I'm late to the party, but what caught my eye is your Vmp of 23.6V is the giveaway that your panels are too low a voltage to charge a 24V battery bank. Vmp is the voltage at the maximum power point of the panel - and that is below your bank voltage. Not good.

[hangerbum]

I'm definitely a newbie at this game but wouldn't the amount of usage (discharging) of the batteries play a role in the size of the pv panels req'd. for charging batteries back up? I realize that the smaller wattage of the panels will not give optimum results for full use of the available amp hrs. but with compromising draw it might could keep batteries up to proper charge state. Just wondering...

[inetdog]

I'm definitely a newbie at this game but wouldn't the amount of usage (discharging) of the batteries play a role in the size of the pv panels req'd. for charging batteries back up? I realize that the smaller wattage of the panels will not give optimum results for full use of the available amp hrs. but with compromising draw it might could keep batteries up to proper charge state. Just wondering...

For FLA batteries at least, there are at least two separate considerations for sizing the panels.
1. They must produce as much power in a typical winter day (fewer sun hours) as you use during that same day, plus some more to make up for charging inefficiency and to allow recovery from several days of bad weather. If your usage is really low, you will be able to tolerate a smaller panel array.
2. When charging, at maximum PV power, you need to produce enough current to cause bubbling to mix the electrolyte. That will typically be in the range of C/12 to C/8. You should have at least this much panel power (rule of thumb for a 12V system is one watt of panel for each AH of battery capacity, if using an MPPT CC) regardless of how little energy you use each day.