Does this seem right?

[hill2sea]

As others have stated, you are short amps., as were we with 800w solar, etc.. our problem is inadequate aged insulation for fridge freezer. Project for the future. Before solar we had to run genset 1 hour per day + two hours once a week for watermaker at 100 gallons, to safely keep up. After solar, one hour every three days running fridge and inverter 24/7. Fridge is 110volt, wish it was 12volt! What we found is that if we turn off the inverter and fridge/freezer at night, we would could keep up with genset running two hours once a week and make our 100 gallons of water. Have AGMs now, and considered lithium for charge acceptance, but maybe in the future. Charge acceptance with solar or even genset for lithium is huge over AGM. I understand that btus are btus but until we reinsulate it works for us for now. We have holding plates. Just a suggestion but if you don’t need an inverter, not as much help as with our setup. We also always try to float batts once a month as well.

[ForeverDes]

Originally Posted by George_SD

Often an overlooked item is that the MPPT controller is is designed to work with something like 200w panels and limited voltage range, but people add bigger or more panels, which causes the controller to cut charging.

A long shot, but may be worth a look.

300 watts / 15v = 20 amp. Any controller rated for 20 amp or more shouldn't cut out with 300 watts of solar. A 15 amp controller would be limited to a little over 200 watts of solar.

[Adelie]

Originally Posted by wryanddry

We have a Moody 376 in Greece. We bought the boat in November and spent the winter in the marina living aboard and refitting her to sail for the next season. On plugging her in to shore power on the hard in preparation for splashing we discovered the Victron charger was pooched, cooked all the house batteries. So replaced the charger with a Sterling charger and all the house bank (4x 100Ah wet cells). added 2x 150W solar panels and an MPPT charge controller. changed all incandescent lamps for LED's.



Once we set off sailing we found that after 3-4 days our fridge was turning off, we traced this back to a battery protector which was shutting off the fridge as the battery bank voltage fell below the pre set limit to prevent the bank being damaged by over discharging. This was despite the solar panels dumping charge into the bank all day in the strong med sun. We added a 5th 100Ah battery to the house bank, now sitting at 500Ah.



During me rewiring the main panel I blew the battery protector on the fridge circuit and replaced that with a new one.



So we have a 500Ah house bank serviced by 300W solar on MPPT charge controller for on the hook/cruising. We still are forced to run the engine after 5-7 days or head in to shore to top up on shore power.



In terms of draw we only have 2 items that draw 24/7:



One Danfoss refrigeration compressor running a standard evaporation plate and a second Waeco system with a holding plate. Both evaporator plate and holding plate are in the same insulated box.



The rest of the draw is intermittent and used sparingly:



all lamps are LED's

Autopilot ST4000 autohelm

B&G Zeus 9 chartplotter

Navman 7110 VHF

Furuno Navtex

AIS receiver

Windlass

200W pure sine wave inverter (emergency charging of laptop only)

12v USB charging for all tablets/phones/handheld VHF etc



With 500Ah and 300W solar we anticipated being able to be able to go for more than a week or so without having to run the engine or hook up to shore power. I see others on this forum doing more with less.



Is it a lack of solar? We had the batteries load/stress tested as we had them down below 11.4v a couple of times and we were told they were fine.



Suggestions to improve/troubleshoot the system/make the vessel more self sustaining WRT power?



Thanks in advance for suggestions/advice.

WRT?

You were probably fine for bank size to begin with. Bigger bank is still better.

Each cold plate is probably drawing about 50Ahr/ day, so 100Ahr/day.

Rule of thumb for MPPT controllers is daily output in Ahr is 1/3 nameplate production by panels in Watts. This assumes panels are laid flat.

300W of panels is probably producing about 100Ahr/d.

If you tracked the sun you’d produce a lot more.

The autopilot is also a significant demand, probably averaging 2-3A. So if you run the autopilot for 8hr between anchorages that’s 16-24 Ahr. So you are probably losing ground ever time you use the autopilot.

The other loads are probably nickel and diming you to death. You need to find out what those loads are. Trying to estimate usage is going to be very approximate. Best thing to do would be to get a power meter with a shunt from Amazon. $20 plus shipping. Assuming the panels feed directly to the batteries, mount the shunt between the batteries and the panel so you are only measuring the demand.

If you want to check production get another meter and mount the shunt between the battery and the panels.

I would add at least another 150W of panels.

I would also get a small MPPT controller for each new panel. This does 2 things.
A. It minimizes shading effects. When panels are in parallel or series shading on 1 panel will drag down the production of all the panels. A small controller on each panel means shading on 1 panel only affects the production by that panel.
B. Redundancy. If 1 controller dies, you can always get wire that controller’s panel to another controller. If all the panels go thru 1 controller which dies then you aren’t getting any power out of any of the panels.

If you have to run an engine or generator to help charge the batteries the best time is first thing in the AM. When batteries are significantly discharged they are willing to take a higher charge current. As they approach full they are willing to accept less and less current. Starting at 50% it may take 60-90min to get the bank up to 75% then it will take another 4.5-6hr to get to full. Engines and generators are good at high current. Panels are good for the long slow charge getting to 100%.

At the very least install a voltage meter on your bank so you can monitor how deep you battery has been drawn. There is a relationship between voltage and state of charge.

[sailorboy1]

Originally Posted by wryanddry

With 500Ah and 300W solar we anticipated being able to be able to go for more than a week or so without having to run the engine or hook up to shore power. I see others on this forum doing more with less.
.

You don't have enough solar. Most specifically don't have have enough if you expected to last a week on the batteries. I spent my first 3 years cruising on 290W solar and 440AH batteries. They needed extra every few days. Now I have 640W solar, still need more charging every few days normally unless I feel like dragging down the batteries, which just means I will have to supplement the solar longer later.

[wryanddry]

This is great, thanks for all the input. The wet cells are Numax 105Ah cells X5, we have installed a Victron battery monitor, the MPPT charge controller is an epever unit. Images of all attached. I figured we needed more input to the house bank, hard to find space on the Moody 376 for more panels, on top of the bimini is one option but the boom is so close. Hydro generator like Watt&Sea or wind gen. Second alternator could be an option ( I have a spare). We have to return to shore every couple of weeks as the tankage on the 376 isn't amazing (250L of water) so plugging in to shore power tops up the house bank nicely, just don't like pushing the house bank below 11.5v! Maybe LifePO conversion.

[LLCoolDave]

Whoa, FLA batteries should not be discharged that far. Discharging below 12.2v (50%) is likely causing damage. 11.8v is a fully discharged battery.

[Adelie]

11.8v resting is 70% DoD.
11.5v is 90%.
Capacity test ends at 10.5v which is OK very occasionally. Battery needs to be charged as soon as possible to avoid sulfation.

Their 11.8v was probably under load so they were more likely at 55-60% DoD.

[smac999]

with the victron you should be able to see the loss. both real time in amps, and then daily on AH.

IE you might see +10a for 8 hours during the sun (say 20a solar - 10a load)

and then say you have -10a for 16h all night

that means you have a avg loss for the day of 10a for 8h or 80ah daily loss. so you would see the ah meter go down 80ah each day. -80,-160,-240ah etc.

this example would give you 3 days on the boat. as your 500ah battery bank should not be below 50% or below 12.0v which would be -250ah.

to break even daily in this example you would need +20a during the day which is 50% more solar. and even more to make up for days that are not sunny.

[sailorboy1]

12.2V is a normal FLA reading under house loads with the batteries at around 80% SOC based on my experience of 3 sets of 440AH on my boat

the OP needs a Honda. It is going to me much cheaper and useful than second alternator (which would only help below 70-80% SOC) etc.

[wingssail]

Originally Posted by wryanddry

This is great, thanks for all the input. The wet cells are Numax 105Ah cells X5, we have installed a Victron battery monitor, the MPPT charge controller is an epever unit. Images of all attached. I figured we needed more input to the house bank, hard to find space on the Moody 376 for more panels, on top of the bimini is one option but the boom is so close. Hydro generator like Watt&Sea or wind gen. Second alternator could be an option ( I have a spare). We have to return to shore every couple of weeks as the tankage on the 376 isn't amazing (250L of water) so plugging in to shore power tops up the house bank nicely, just don't like pushing the house bank below 11.5v! Maybe LifePO conversion.

An option you are overlooking is daily (or less frequently) operation of the main engine and allow the alternator to put in the bulk of the daily needs. One hour a day would be sufficient. We've done this for 25 years of cruising. It is fine.

Save your money for a watermaker (perhaps a small one) and run it at the same time. You will extend your cruising.

[Adelie]

Originally Posted by sailorboy1

...

the OP needs a Honda. It is going to me much cheaper and useful than second alternator (which would only help below 70-80% SOC) etc.

OP is trying to figure out how to avoid using his engine or buying a generator.

[Baronkrak]

Originally Posted by LLCoolDave

Thanks Stu.

No need to be sorry, most people will understand that you are quoting Ah energy.

The correction to A is meaningless A is just A. VA is power in direct current and Ah is a unit of energy.

[guyrj33]

Originally Posted by Baronkrak

No need to be sorry, most people will understand that you are quoting Ah energy.

The correction to A is meaningless A is just A. VA is power in direct current and Ah is a unit of energy.

Sorry, but amp hour (Ah) is a measure of battery capacity. Watt hours (Wh) are a measure of energy.
Ah is a frequently used term, but is dependent on battery voltage to convert to a measure of energy.

Power (Watts) = Voltage * Current = vi or for boaters volts times amps.
Energy (WattHours) = Watts * Time or for boaters amps times volts times hours.
So if your lamp draws 1 amp at 12 volts. It is a 12 watt lamp and if left on for an hour consumes 12 Watt Hours.
Your 12 volt 100 Amp Hour battery has a energy storage capacity of
12V*100A*1H or 1,200 Watt Hours.
If you leave your 12 Watt lamp on for 10 hours it will use 120 Watt Hours or about 10% of your battery's stored energy.

[Baronkrak]

Keep it simple; Ah is a unit of energy.

For other, Techtarget
An ampere hour (abbreviated Ah, or sometimes amp hour) is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour.

[guyrj33]

Originally Posted by Baronkrak

Keep it simple; Ah is a unit of energy.

For other, Techtarget
An ampere hour (abbreviated Ah, or sometimes amp hour) is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour.

ok, then it should be easy to convert amp hours to watts.
How many watts in an amp hour?