A way To Save Charging Time

[Sailmonkey]

Originally Posted by Kenomac

Doesn't the battery bank want to see 100% float status every few days? Otherwise, it seems like the max charge goes down, down , down until I plug into shore power to get back up to 100%



Will solar improve this situation, or will I not see much of a difference?

Solar will completely solve this problem, it will charge all day every day, while your generator only charges for an hour.

Even though your AH counter shows 100%, I'd bet your actual SOC is closer to 85-90%. The last bit will take all day. This is what solar does exceptionally well.

[Kenomac]

Originally Posted by Sailmonkey

Solar will completely solve this problem, it will charge all day every day, while your generator only charges for an hour.

Even though your AH counter shows 100%, I'd bet your actual SOC is closer to 85-90%. The last bit will take all day. This is what solar does exceptionally well.

Will 250w of solar be enough to top things off? I don't want to purchase more than is necessary, but I only want to do this once and get it right the first time.

There will be some shading at times.

[Sailmonkey]

Originally Posted by Kenomac

Will 250w of solar be enough to top things off? I don't want to purchase more than is necessary, but I only want to do this once and get it right the first time.

There will be some shading at times.

The more the merrier, but a lot of this depends on your bank size as well as your daily consumption.

IE, if your average daily daylight consumption is 100AH and your panels produce 120AH during the same period you'll put 20AH (perfect world) back into the batteries. That means that the overnight losses are what you'll need to make up for with generator run time. Bigger solar arrays can offset the losses even more, until you no longer need the generator.

[Fuss]

Originally Posted by Kenomac

Will 250w of solar be enough to top things off? I don't want to purchase more than is necessary, but I only want to do this once and get it right the first time.

There will be some shading at times.

No it won't top things off and never will unless you have a huge array. The best it will do is make the generator run time that is dedicated to battery charge shorter.
Sorry, but that's the reality.

My advice is don't spend any money until a competent marine electrician has given you his opinion on how to optimise your systems.

Maybe write a pm to mainsail.

I guess you have 500ah of 24v batteries, 150ah alternator, 8kw generator, 100ah battery charger, air con, dc watermaker 150lph, inefficient fridge freezer using more than 80ah in 24 hrs, gas cooking and BBQ for meat fish, wash machine, hair dryer with run time restrictions.

So solar will never get 100% for you

My advice, make sure your alternator and charger run bulk at 29.6 if lead acid or whatever batt manufacturer says if agm or gel for example.
Install 400 watts of solar, you are not a catamaran, more solar will spoil your lines.
A victron multiplus charger/inverter will help manage batt charging and a/c loads in case you have only a charger.

Preference most generator run time to early morning as solar will be most efficient over the rest of the day.

[Kenomac]

Can someone provide the coversion factor for estimating the Ah produced by 450w of solar?

Our daily consumption is outlined as follows:

Frigoboat fridge (well insulated) keel cooler type also with cooling fan.

Frigoboat deep freezer well insulated with triple Frigoboat compressors, one keel cooler and one with water pump cooling.

Two Spectra 380 watermakers utilizing four pumps which run one hour per day while genset is running.

All galley appliances are electric and run only when genset is on.

All lighting is LED with very little draw.

Washing machine used maybe once every other day.

Battery bank is a damaged 450 Ah lead acid Trojan type allowing 377 Ah at present 24v.

Remember, we expect to run the generator one hour per day during meal prep making water at the same time. The solar really only needs to take care of the refrigeration and bringing the batteries up as high as possible.

[Sailmonkey]

Originally Posted by Kenomac

Can someone provide the coversion factor for estimating the Ah produced by 450w of solar?

Our daily consumption is outlined as follows:

Frigoboat fridge (well insulated) keel cooler type also with cooling fan.

Frigoboat deep freezer well insulated with triple Frigoboat compressors, one keel cooler and one with water pump cooling.

Two Spectra 380 watermakers utilizing four pumps which run one hour per day while genset is running.

All galley appliances are electric and run only when genset is on.

All lighting is LED with very little draw.

Washing machine used maybe once every other day.

Battery bank is a damaged 450 Ah lead acid Trojan type allowing 377 Ah at present 24v.

Remember, we expect to run the generator one hour per day during meal prep making water at the same time. The solar really only needs to take care of the refrigeration and bringing the batteries up as high as possible.

100-150 AH......depending on a variety of factors from the 450 watt array (24 volt system).

450/24=18.75 amps instantaneous.

18.75 amps for 6 hours= 112AH.

[Fuss]

Originally Posted by Kenomac

Can someone provide the coversion factor for estimating the Ah produced by 450w of solar?
.

In the med in summer...100ah at 24v

[Kenomac]

Thanks

[Fuss]

On the very best day 450 watts of solar with the very best mppt controller on a monohull you will add 110ah to your battery bank in 24 hrs and not more.

[a64pilot]

Originally Posted by Fuss

On the very best day 450 watts of solar with the very best mppt controller on a monohull you will add 110ah to your battery bank in 24 hrs and not more.

12V??

[capitangiorg]

Ken, on Creuza I had a very similar setting.
I had to run the genset 2-3 hours por day, then I installed 520 W of Enecom (4x130W) flexible solar panel on the bimini.
After the installation 1 hour por day running the genset while we were producing water and hot water was enough and some day I didn't need to run the genset.
In my experience the flexible panel are less efficient that the rigid one though they are nicer and easy to install on a bimini.
So if you in any case are going to run the gen for breakfast and supper 450W should be enough for refrigeration, lights and for topping up the batteries.

[StuM]

Originally Posted by Sailmonkey

100-150 AH......depending on a variety of factors from the 450 watt array (24 volt system).

450/24=18.75 amps instantaneous.

18.75 amps for 6 hours= 112AH.

I'd say that is too ambitious.

24V systems don't charge at 24V. More like 27?
So 450/27 = 16.7 Amp

6 hours equivalent of rating is only applicable in good conditions (such as sunny tropics or mid summer, mid latitudes). 5 is much more appropriate for planning purposes. So more like
16.7 x 5 = 83Ah for a 24V system.

[Sailmonkey]

Originally Posted by StuM

I'd say that is too ambitious.

24V systems don't charge at 24V. More like 27?
So 450/27 = 16.7 Amp

6 hours equivalent of rating is only applicable in good conditions (such as sunny tropics or mid summer, mid latitudes). 5 is much more appropriate for planning purposes. So more like
16.7 x 5 = 83Ah for a 24V system.

I'll admit your numbers are far more realistic, I had hoped that I was just demonstrating the simple math needed to determine power produced.

The really hard part to state with any certainty is the amount of electricity produced on any given day on a boat at anchor where trade winds don't keep the vessel orientation fairly consistent.

[Fuss]

Originally Posted by Sailmonkey

I'll admit your numbers are far more realistic, I had hoped that I was just demonstrating the simple math needed to determine power produced.

The really hard part to state with any certainty is the amount of electricity produced on any given day on a boat at anchor where trade winds don't keep the vessel orientation fairly consistent.

No it's not hard, the certainty is that properly installed 450w of solar in the med in summer will put on average 100 ah back into your 24v battery bank over 24 hrs.

Let's not get complicated here, the guy wants to know roughly what goes back into his battery bank in the med when he has 450 watts of solar. And the answer is 100ah. Let's leave it uncomplicated and not over discussed... it's the problem with these forums, things get over discussed on here until no one can tell what's right and wrong any more.

[senormechanico]

Interesting.
That's basically what we get in the PNW in the summertime on nice days with 440.