Simple Solar For A Simpleton

[VirtualVagabond]

Originally Posted by belizesailor

WOW, that's a lot of run time! I agree that is crazy for a typical cruising boat. What's the amp rating of your battery charger? I'll check. What is the age/condition of your batteries? Old batteries, or batteries in poor condition, near the end of their service life will absorb charge for a very long time...and never achieve full charge. The batteries are about 18 months old, according to the previous owner, and seem to be in good condition. What are your normal loads in Amp Hours per day? Not sure. Did a spot check on the neg from battery bank and it was 14.2, mid morning.

On both my boat, and at my house, both 12V, I have about 450AH house battery banks. I don't typically need to run the engine/gen driven charging system more than about 1 hour per day depending upon usage. House has a 40A charger and 365W of solar, boat can do max of about 135A from alternators and currently only has about 150W solar, but boat alternator system typically steps down to about 60A within a matter of minutes. In either case I don't typically need to run the genset/engine more that 1-2 hours per day depending upon usage.

Sounds like to me that you have some other energy system issues you should resolve before adding solar.

I do need to resolve the energy consumption issue, but I'm running the genny so much I figure a good reduction in the mean time would be a step in the right direction.

With the boat recently bought, I have a long list of other projects I'm tackling, so this is a 2 step deal. Solar panels to reduce genny time now, and reduce consumption as step 2 down the track a little.

[rtbates]

Have you given ANY thought to reducing your electrical needs??

[foggysail]

Originally Posted by VirtualVagabond

Thanks Tom,
Do you know if 6v 242 amp batteries are a universal size or if they're unique to US Battery. We won't be back in US waters for a long time and I don't really want to install something that is only available here.
The 105 Trojans are only about 18 months old. Is it not possible to add a few more of them?

Vic

Your present batteries are rated at 225 ampere hours. Upgrading to 242 ampere hours buys you little.

[VirtualVagabond]

Originally Posted by Greg4cocokai

Just for starters. 10-t105's is 5 x 220 ah's which equals 1100 ah's! Sounds to me like you need a lot more current from your charger. We have 10 -t105's, have a large refer and separate freezer using around 200 ah's a day and run our gen at most 1 hour a day. A Xantex freedom 30 puts out 140 amps or our Outback inv/charger puts out 100 amps. We also have 3- 85 watt panels. We're at anchor 99% of the time. Hope that helps.

Greg

Hi Greg,
Not sure I understand the math here. I thought that 10 x 6v 105 amps, wired to deliver 12v would only deliver 525amps and not 1050 amps.
Have I got this wrong?
We also have an Outback Inv/charger. It will be their export model because we're wired for 12v DC and 230v AC. From the User Guide I can't find what the charger amp rating is. Would it be the same for all their inv/ch models or would it vary?
The boat also has a Xantrex Link 2000 that I haven't got my head around, but I use it to tell when I need to run the genny.
I don't let the reading drop below 12.2v and I charge until it reads between 14 - 14.25v

It's my dream to run the genny only 1 hour per day!

Vic

[VirtualVagabond]

Originally Posted by Jimbo485

Vic,

Solar is so cheap these days, that you just stick on as many panels as will fit on your boat. You should be able to fit on plenty. If you run out of deck real estate, look at an MPPT, but you will generally find that it is cheaper to buy another panel or two than buy an MPPT. Check the maths and $$. I've got an Outback Inverter/charger and the diagram showing a 'Typical Outback Power System' shows the unit as having 'two Outback MX-60 PV MPPT charge controllers', so I guess I've got an MPPT already.

(We produce 100% of our energy from panels, with no generator and no MPPT magic box and a 6A alternator. Two thirds of our panels just go direct to the battery bank thru two breakers in the cockpit, without any sort of controller. No engine battery, just one bank for everything. No need to complicate your life.) This sounds like heaven!

You are using your generator so much, you have another problem somewhere. I agree. I'm wondering if that permanently hot Balmar alternator is sucking out more current than I realize.


Rules of thumb, proven satisfactorily to us from our experience over the last 2 years in the tropics:

Work out your daily Ah usage. Multiply by 4 and install that amount of W in terms of solar panels and about the same in terms of Ah battery capacity. That's it, nothing more to do. Maybe throw your generator overboard or sell it to another cruiser with too few panels and not enough noise in their lives? Know of any takers?

Best of luck, mate!

Thanks. I like the simplicity.

Vic

[VirtualVagabond]

Originally Posted by atoll

sounds like you are starting at the wrong end of the equation when working out your power needs.

first replace all domestic and nav lights with led bulbs House lights are leds, nav lights not yet.

,re-engineer your fridge and freezer with thicker insulation,top opening if possible.
replace fan driven or pump driven cooling condensers with a sea water cooled skin fitting type condenser. Sounds major at this point when we have so much else we have to get through by November

replace cabin fans with low draw hella fans,or better get some wind scoops to keep the boat cool. Good idea.

if you are running a big inverter,get a back up small 250w unit for computers and chargers for every day use ,and only turn on the big inverter when needed. We do have a big inverter but don't use it much, except when the generator is running. Computers etc we can run directly off the 12v system using cigar lighter sockets and some mini inverter gadget we got at Radio Shack for about 50 bucks.

consider putting in a 24v battery bank for running fridges,inverters etc with a top range high amp smart charger. Again, too much to tackle in the short term, but may well look at it down the track.

if you are going to be spending a lot of time underway a wind gen is essential,as a lot of the time your panels will be in the shadow of the sails on east west passages.

Hi Alex,

Much of our sailing will be east/west. We're thinking 2 panels on the davits, and one each side on the rigid doghouse. Similar doghouse to the boat you saw with us in Holland. That way we're guaranteed to always have some in the sun... and shade!
Cheers,
Vic

[VirtualVagabond]

Originally Posted by Don Lucas

Vic

Just what is is your daily amp-hr load and what percentage of battery state of charge have you been trying to mantain?

Both panel sizing and battery capacity is going to be based on your daily loads. There's no upper limit to the panels, just a lower limit of what will recharge your batteries.

I feel I'm a power hog, but if I'll willing to not recharge the batteries above 90-95% I can recharge with my engine in 1.5 hours/day. So your generator run time really has me confused as that's a lot of power.

Hi Don,

I really do have to get a handle on what I'm using. I guess I'm using whatever I'm having ro replace by running the genny.I need to contact manufacturers of the equipment on board, particularly fridge/freezer gear to get their consumption figures.

Maybe I'm trying to charge them up too much so running longer than I could get away with.
I turn on the genny when we're showing the batteries at 12.25v, or as low as 12.10v. I run it until the volts are showing 14v - 14.2v.

Vic

[VirtualVagabond]

Originally Posted by rtbates

Have you given ANY thought to reducing your electrical needs??

Yeah... that is step 2.
I know it's a cart before the horse approach, but we have a big upgrade program in a lot of other more vital parts of the boat, so I'm looking for improvement, not perfection in this area at the moment.

Vic

[noelex 77]

A battery monitor would be a big help Vic. Knowing the amps going into the battery and net amp hours will give you a much better idea when to start and terminate the generator.

[VirtualVagabond]

Originally Posted by foggysail

Your present batteries are rated at 225 ampere hours. Upgrading to 242 ampere hours buys you little.

Foggy,
Good point.
What is the calculation to get to the amp hours rating from 10 x 6v 105amp batteries?

Vic

[VirtualVagabond]

Originally Posted by noelex 77

A battery monitor would be a big help Vic. Knowing the amps going into the battery and net amp hours will give you a much better idea when to start and terminate the generator.

I've just pulled out the owner's manual for the Xantrex Link 2000. I suspect it's the key to understanding all these dark forces on the boat.
So far I've just been doing what the previous owner showed me with the display in volts.
Would you happen to know this unit and if it will display amps going in and net amp hours?

Vic

[noelex 77]

Yes. Get those dark forces on your side. The manual in electronic form is here BTW.

http://www.xantrex.com/documents/Dis...-1(Vendor).pdf

[sailorboy1]

Originally Posted by VirtualVagabond

Maybe I'm trying to charge them up too much so running longer than I could get away with.
I turn on the genny when we're showing the batteries at 12.25v, or as low as 12.10v. I run it until the volts are showing 14v - 14.2v.

Vic

When what gets back to 14-14.2V? If I start at 12.2 and start my engine to recharge I will get to 14.4V almost right off, but that desn't mean I put any charge in. Voltage when charging only tells you that you are charging at a high enough voltage, nothing about state of charge.


But this doesn't match the amount of time you are running your generator. You need to know the amps in to compare to your battery capacity and if possible your amp-hours in/out.

It kind of sounds that you aren't really getting your batteries charged even though you have a massive amount of generator run time.

[Dennis.G]

The run time on your 4 kW generator does not make sense. There is likely something wrong. Are you able to read actual AC or DC amps output when generator is on? If you have an AC generator outputing to a charger, your charger should be putting out max DC amps (say 120 A or whatever charger rating is) when generator is first started up (allowing some time to ramp up to max output).

One possible generator issue is low speed which will give less than 60 Hz AC power. The generator regulator will automatically reduce voltage output if speed/frequency is low. Charger will in turn reduce its output seeing low AC input voltage. End result can be generator/charger system charging battery system at 40 A or less resulting in the long run times. Check that your generator is giving 115 to 120 volts AC output under load as it should. If generator voltage drops below 110 your charger will not give rated output to battery bank.

[Dsanduril]

I was replacing the oil cooler on the engine on the weekend and found that the Balmar alternator was pretty warm. Something is not right there. It must be drawing current from somewhere so that's next on the hit list.

Don't know if you have a clamp-on amp meter, but if so, check the field current on the alternator. This can be 5-6A on a good sized alternator. It should be shut off by the ignition switch and the regulator, and probably comes from the starting battery. But I've seen some strange wiring in my time. It used to be quite common to use the Lewmar "controller" on alternators, it was just a big rheostat that was used to manually adjust the field current. I still have, and still use one on my boat connected to a Balmar alternator. But you have to have a way to disconnect the field when the engine is not running, otherwise the alternator will sit there and draw current 24 hours/day and do nothing for you (except maybe eat up your zincs). The alternator then basically becomes an ~70W heater (and thus could feel warm).

If you don't have a clamp on ammeter, but can check the total draw (as you said above) then check the total draw, then disconnect the wiring from the alternator and see if it drops. That should tell you if you have a field current draw on the alternator (at least it will if the field is connected to the same battery bank).

The way I read the T-105 specs they are 225Ah (20 hour rate) at 6V. That means you have 2250Ah at 6 volts => 2250 * 6/12 = 1125Ah at 12V.