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Old 02-01-2021, 16:50   #1
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Does this seem right?

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.
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Old 02-01-2021, 17:33   #2
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Re: Does this seem right?

I have a very similar setup. Refrigeration is probably drawing 5-7 amps per hour. At peak time your 300w of solar is likely producing 12 amps per hour but for a lot of the day it will be producing 7-10 amps per hour. So your solar is keeping up with what is running during the day but it isn't really putting a lot back in the batteries. You need to double your solar which is what I'm doing shortly.
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Old 02-01-2021, 17:59   #3
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Re: Does this seem right?

Quote:
Originally Posted by wryanddry View Post
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.
What you have not done is add up the daily loads on your batteries and the daily input from the solar panels.

Take each of your items and observe the amp load (you may need a clamp meter or other means of measuring) times the hours per day it is running. This is your total amp hour load.

Then observe the number of amps your solar system is putting in per day.

You will quickly see why your refer is cutting out in a few days.

My guess is that the danfoss and the waeco are together using at least 100amp hours per day. Add in the other uses and it's probably over 150 AH per day.

Your 300 watts of solar will likely produce less then 15 amps at the peak, tapering off to very little. So figure 90-100 AH from the solar.

You'll have a deficit of 50 AH per day, and your 500AH of batteries can actually only deliver 50% of that, so 250 AH. That is why you are exhausting your batteries in 5 days or less.
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Old 02-01-2021, 18:59   #4
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Re: Does this seem right?

Quote:
Originally Posted by wingssail View Post
My guess is that the danfoss and the waeco are together using at least 100amp hours per day. Add in the other uses and it's probably over 150 AH per day.

Your 300 watts of solar will likely produce less then 15 amps at the peak, tapering off to very little. So figure 90-100 AH from the solar.

You'll have a deficit of 50 AH per day, and your 500AH of batteries can actually only deliver 50% of that, so 250 AH. That is why you are exhausting your batteries in 5 days or less.
That's the figures I saw too when I read the OP.
(Although peak will quite possibly be around 20A on a good day)

Hitting the batteries with a 1/2 hour of engine time with a decent alternator first thing in the morning when they are most depleted could just about make it self sufficient
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Old 02-01-2021, 19:02   #5
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Re: Does this seem right?

300w is not enough to run a boat. In the sun.

More batteries just extends the time between needing more charging. (Motors or dock). But then requires more charging. Like 7hrs by motor to recharge the 500ah bank.

Get your self a battery monitor like a victron 712 so you know what’s going on.
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Old 02-01-2021, 19:05   #6
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Re: Does this seem right?

Here I go again

> I have a very similar setup. Refrigeration is probably drawing 5-7 amps per hour. At peak time your 300w of solar is likely producing 12 amps per hour but for a lot of the day it will be producing 7-10 amps per hour.

> Then observe the number of amp hours your solar system is putting in per day.
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Old 02-01-2021, 20:19   #7
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Re: Does this seem right?

Quote:
Originally Posted by StuM View Post
Here I go again

> I have a very similar setup. Refrigeration is probably drawing 5-7 amps per hour. At peak time your 300w of solar is likely producing 12 amps per hour but for a lot of the day it will be producing 7-10 amps per hour.

> Then observe the number of amp hours your solar system is putting in per day.
Thanks Stu.
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Old 02-01-2021, 20:39   #8
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Re: Does this seem right?

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.
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Old 02-01-2021, 20:56   #9
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Re: Does this seem right?

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Originally Posted by George_SD View Post
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.
I haven't heard this. Can you point out any source literature? Thanks.
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Old 03-01-2021, 10:44   #10
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Re: Does this seem right?

500 AH flooded lead acid batteries is 250 AH usable. As said above, find out how much you actually use.

How is the insulation on the fridge? May be better to add more insulation than charging capacity.
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Old 03-01-2021, 10:59   #11
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Re: Does this seem right?

Please note that the inverter uses batteries electricity even at rest, i. e. when no item is using 220v!
So, you may save some amphours if you will shut down the inverter when you do not use it for the charging of the laptop.
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Old 03-01-2021, 11:10   #12
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Re: Does this seem right?

It seems that for MPPT Voc is the important rating/limit

A discussion on this forum:
https://www.cruisersforum.com/forums...gs-225071.html

Victron page that talks about overpaneling

https://www.victronenergy.com/blog/2...ge-regulators/

Victron also publishes max V,A values for their charge controllers and why they have different models. For example MPPT 75/10 MPPT 75/15 have 75v and 15amp max, anything over that may cause trip or cause a malfunction.


Renogy:
https://www.renogy.com/blog/solar-ch...o-choose-one-/

Quote:
if an MPPT Controller can accept 100 volts of input, it will then take this (up to) 100 volts and step it down to your 12V or 24V battery. Let’s say you have 4 x 100 Watt panels in series, each with an open-circuit voltage of 22.5V. Those 4 in series will be 4 x 22.5 V = 90 Volts, which the controller can accept.

Here, especially in total voltage and watts section.
https://oceanplanetenergy.com/2020/0...ers-for-boats/


it may be more relevant to PWM controllers not, MPPT
https://www.coastalclimatecontrol.co...tallation.html


Quote:
What happens if I connect too much solar to the Board?

The answer somewhat depends on if its too much voltage or too much power— Too much Voltage can damage the unit. Over 50 volt for Apollo and 54 volts for Sól but less than 60 volts the board will display “Err” then “001” or “O.L.” depending on which version you have.

Above 60 volts will cause PERMANENT DAMAGE and is not covered under warranty.

Hooking up too much power (Over the STC Rating) can cause either the current limit to activate or an over temperature “Hot” shutdown. This will not damage the charge controller but you will not be getting the full available power of your panel at that point during peak conditions around solar noon.

So its important to stay within the Charge Controller specification limits.
Apollo = 280 / 560 Watts STC for 12 / 24 volts respectively V2.xx version
Sól = 350 / 700 Watts STC for 12 / 24 volts respectively on the 20 amp V1.04 version
https://www.diysolarforu.com/faq.html


But then again, my understanding of solar electric components and their workings is very rudimentary at this point.
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Old 03-01-2021, 11:13   #13
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Re: Does this seem right?

I assume you have an icebox type fridge not a front door opening one? See what more you can do to insulate that refrigerator - there are diminishing returns but as a standard installation I bet you are nowhere near that yet.
You might also think about a wind generator mounted on a pole at the stern. If so I suggest you try to get one you can somehow shut down (stop turning) remotely as in my experience the vibration resonance from a wind generator can be quite disturbing at night when sleeping in an aft cabin as on the Moody 376. I got rid of it altogether for that reason. Mine was mounted on a mizzen mast though so may be different on a pole.
Persistent engine running to charge batteries is not good for the engine as you know - the bores can glaze under light load - Bore glazing and polishing in diesel engines – Cox Engineering.
Engaging reverse gear at anchor (to load the engine to avoid glazing) is very likely to cause problems due to prop walk taking over & swinging your boat around the chain - depends how crowded the anchorage is & how strong the wind I guess.
By the way your current situation (sorry) is killing your batteries. Are they cheap truck type (say £100 each) or high cost real deep discharge batteries?
Quote from YBW.com One thing I would add is that about the most cost-effective improvement you can make to a boat's electrical system is to increase the size of the domestic bank. Having a bigger domestic bank enables the available charge current to be used more efficiently. A bigger bank also experiences a lower depth of discharge for a given usage, and it's the depth of discharge which ruins batteries prematurely.
Cant you just fit another 100 amp battery in & get a 120 amp alternator & run the engine for an hour or more every few days on passage somewhere?
BTW you can get 110 amp batteries now about the same size as 100 amp - all helps.
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Old 03-01-2021, 12:04   #14
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Re: Does this seem right?

Quote:
Originally Posted by George_SD View Post
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.
This statement was made without knowledge of the actual controller being used by the OP, which makes this statement irrelevant at best.
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Old 03-01-2021, 12:08   #15
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Re: Does this seem right?

I agree with the earlier post suggesting using your engine for an hour or so early in the day, which will let the alternator supply bulk current to the batteries and then solar can bring them up closer to 100% during the day.

Also think you'd benefit from a battery monitor properly installed on your house bank, then you'd have actual data to work with.
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