Battery state of charge

[Stu Jackson]

That's a very good way to look at it.

[sailorboy1]

[QUOTE=Dockhead;

I follow the same 50% rule as everyone, and like others didn't vote in Don's poll, since I charge not at some particular SOC, ............ I will not start up the generator specially to charge batteries unless the SOC falls to 50%,

.[/QUOTE]

To me that's a vote for 50% as that is what you are willing to allow the batteries to get to before you charge.

I mainly charge by just the time I motor in/out of mooring fields and anchorages. But sometimes I haven't done this in a while and have tended to charge when I get down to 80% on my monitor.

This is why I started this as I was wondering if I really was doing something beyound needed by using the 80% SOC instead of something lower. I probably am doing this because in my mind this was cost effective to maintain the batteries for longer life. But I started questioning whether this was a false enomony to save on battery costs while increasing engine run time.

[tartansail]

Originally Posted by Maine Sail

Actually solar does quite well in Maine, if installed well. If you base it on solar insolation maps our average is Portland is 4.51. NY City is 4.08... Our winds in the summer are also light and solar very often beats wind on daily performance. I have nothing against wind but find solar, more reliable, longer lasting, less expensive, and quiet...

Wind gens are fine but do require more maintenance. I just this winter re-built a 7 year old wind gen. It has had two sets of blades in 7 years and required all new bearings, a bead blast and re-powder coat. The solar panels on this customers boat are 13 years old and show no signs of age and have required zero maintenance since installed (other than wiping bird crap off them). They still have not yet re-installed the wind gen and with their Kyocera panels they are finding they really don't need it. They can run their boat for multiple weeks in Maine on just the solar and this includes running a Frigoboat that stays cold enough to have ice cream.

Properly installed and sized solar works well here in Maine.. For taking batteries from 80% state of charge to 100% SOC, for mooring sailed boats, it is tough to beat solar...

Many thanks. That's a very helpful perspective as I try to decide which way to go. The 70-100% with the boat on the mooring is exactly the situation we're in. (It will be 80-100 once I improve the insulation in the fridge. That is the biggest energy hog on the boat, but the admiral won't consider doing without.)

[Jim Cate]

Originally Posted by Maine Sail

Actually solar does quite well in Maine, if installed well. If you base it on solar insolation maps our average is Portland is 4.51. NY City is 4.08... Our winds in the summer are also light and solar very often beats wind on daily performance. I have nothing against wind but find solar, more reliable, longer lasting, less expensive, and quiet...


Properly installed and sized solar works well here in Maine.. For taking batteries from 80% state of charge to 100% SOC, for mooring sailed boats, it is tough to beat solar...

G'Day all,

Mainesail, I bet that you guys up there don't have to worry about solar charging during the winter because your boats are not in the water being used then. For those of us who sail and live aboard year-round, solar gets pretty thin during the low sun angle/short day times of the year.

During the summers we have no problem surviving on our 240 watts of fixed mount solar panels, but right now (winter here) it is woefully lacking, and we're forced to add diesel hours to keep up. Our wind generator helps at times, but being anchored in protected spots (to survive nasty wx like the past few days) this isn't reliable.

What would help some is aimable panel mounts so as to better use the low sun angles, but even that wouldn't be enough, I fear. A few more panels would help too...

And for Don (the OP) the reason that I didn't "vote" is that there is no fixed state of charge that gets the engine started. Really, I doubt if many full time cruisers have a fixed value for this... more an ad hoc sort of decision based on a lot of variables.

Cheers,

Jim

[Dockhead]

Originally Posted by Don Lucas

To me that's a vote for 50% as that is what you are willing to allow the batteries to get to before you charge.

I mainly charge by just the time I motor in/out of mooring fields and anchorages. But sometimes I haven't done this in a while and have tended to charge when I get down to 80% on my monitor.

This is why I started this as I was wondering if I really was doing something beyound needed by using the 80% SOC instead of something lower. I probably am doing this because in my mind this was cost effective to maintain the batteries for longer life. But I started questioning whether this was a false enomony to save on battery costs while increasing engine run time.

I see. I didn't understand your question that way. But in any case, I would charge the way you do if I could do it without a lot of unnecessary generator runs. If you can do that without a lot of effort, then more power to you. Certainly the shallower the discharge, the less wear and tear on the batts. If it requires a lot of generator time to keep the batts above 80%, on the other hand, query whether that is really efficient or not.

[Hudson Force]

OK, I decided to place a vote. I did this even though my constant fultime liveaboard cruising results in charging my system by many means without my active decision. I decided to select the recharge at 80%; however, the posted intervals include two different selections for 80%! So, I randomly selected one of the two. Everyone who votes on this poll and selects any 5% interval has two possible places to post their vote. Why does the scale have all these redundant selections?

[Tropic Cat]

Originally Posted by Maine Sail

...Properly installed and sized solar works well here in Maine.. For taking batteries from 80% state of charge to 100% SOC, for mooring sailed boats, it is tough to beat solar...

Don't know about this.

Bought a pair of group 27 cheapie Walmart deep clycle batteries in June 2008.

Have a 75 watt solar panel and a small 10 amp MPPT charge controller. No battery charger / no dock power at all. Batteries have never been deep discharged..and actually have never been cycled at all.

The boat's in Florida and gets very light use. After 4 years one of these Walmart batteries looks like it's charged but almost immediately drops to 8.5 volts when you actually put a load on it.

I'm thinking solar panels aren't the way to go??? The batteries are obviously sulfated..yet really haven't ever been used.

[Jbaffoh]

Originally Posted by Tropic Cat

Don't know about this.

Bought a pair of group 27 cheapie Walmart deep clycle batteries in June 2008.

Have a 75 watt solar panel and a small 10 amp MPPT charge controller. No battery charger / no dock power at all. Batteries have never been deep discharged..and actually have never been cycled at all.

The boat's in Florida and gets very light use. After 4 years one of these Walmart batteries looks like it's charged but almost immediately drops to 8.5 volts when you actually put a load on it.

I'm thinking solar panels aren't the way to go??? The batteries are obviously sulfated..yet really haven't ever been used.

I'd guess that one of your "cheapie" batteries is defective, or your solar controller isn't working properly.

A few years ago, my controller stopped controlling and the crappy Group 27 Kirklands that came with the boat boiled dry from the 17.1 volts they were being fed. After replacing the controller with a PWM unit, and replacing the crap batteries with 6v Trojans, everything has been perfect.

[onestepcsy37]

i went the solar route two years ago and am pretty happy about it. here in florida/bahamas there's always enough sunshine to keep the batteries up. the fridge is, as usual, the biggest draw. i think that anyone full time or even part time cruising should have solar panels. once installed they are practically maintenance free for the next dozen years or so.

i've thought about wind gens but don't see the need for one yet. too much 'stuff' in a wind gen to go wrong or need maintenance.....

[Tropic Cat]

Originally Posted by onestepcsy37

i went the solar route two years ago and am pretty happy about it. ...i think that anyone full time or even part time cruising should have solar panels. once installed they are practically maintenance free for the next dozen years or so......

yeah but are you going to be replacing batteries every 4 years charging off solar panels like I am?

[Jbaffoh]

Originally Posted by Tropic Cat

yeah but are you going to be replacing batteries every 4 years charging off solar panels like I am?

More like every 15 years if he uses quality batteries and sets it up properly. Solar is not your problem--something else is.

[Maine Sail]

Originally Posted by Tropic Cat

Don't know about this.

Bought a pair of group 27 cheapie Walmart deep clycle batteries in June 2008.

Have a 75 watt solar panel and a small 10 amp MPPT charge controller. No battery charger / no dock power at all. Batteries have never been deep discharged..and actually have never been cycled at all.

The boat's in Florida and gets very light use. After 4 years one of these Walmart batteries looks like it's charged but almost immediately drops to 8.5 volts when you actually put a load on it.

I'm thinking solar panels aren't the way to go??? The batteries are obviously sulfated..yet really haven't ever been used.

Hmmm I also have "cheap" Johnson Controls / Wal*Mart batteries, no dock, on a mooring and they have been cycled LOTS. They are now in their sixth season and have been maintained by an 80W solar panel and for 4 years a PWM controller and for the last two a Genasun MPPT. I am sitting next to the DC panel right now typing this looking at the 4.7A load that has been on them now for about 8 hours and they are still at 12.66V..

They underwent a full battery of tests this winter which you can read about here:

5 Year Wal*Mart Battey Observations

The batteries are performing EXCEPTIONALLY well. I install a LOT of solar and my customers batteries always test better and last longer when compared to what they had. In general I find my customers with solar consistently getting longer life than my customers plugged into shore chargers 24/7...

Also keep in mind that you are in the land of heat and should ideally have a temp compensated solar charge controller. Batteries dislike heat as heat drastically shortens their life span. I suspect your failure may have more to do with a faulty controller, stratification due to the lack of use or possibly battery temp...

[Mr B]

280 watts of solar panels. 4 of them,
913 Rutland wind gen,
MPPT controller. 10 amp
Marlec HRSi charge controller,
Sunsaver 10 amp.
1800 watt invertor,
Battery charge moniter,
House batterys, AGM Not sure of the amp hours, But lots of them,
Engine battery, lead acid, PITA,
When I first got the boat, I was bit heavy handed on power, the house went down to 25%
Ran the main engine for 20 minutes, Full power again,
The main engine has a bigger alternator on it than standard,

This system is fully self contained and Automatic, I dont need to even think about it,
I dont need shore power under any circumstances,

I only need to change the angles of the solar panels twice a day,

Even on cloudy days, power is still going in,

PO had a generator, but never used it, So he sold it,

PO had set it up for permanent living on it and also ran his office off the boat,

Most of the above got drowned,

My new system below,

MPPT controller, 20 amp
Sunsaver 20 amp
240 volt invertor, 5000 watt, 10000 max, Pure Sine Wave,
Marlec HRSi for Rutland 913 wind gen,

Above cost $720-00 AUD

New Battery charge monitor, not purchased yet,
New engine battery, supplied by insurance company,
New AGM's about $400-00 each, X 3

[Tropic Cat]

Originally Posted by Maine Sail

....Also keep in mind that you are in the land of heat and should ideally have a temp compensated solar charge controller. Batteries dislike heat as heat drastically shortens their life span. I suspect your failure may have more to do with a faulty controller, stratification due to the lack of use or possibly battery temp...

Don't think the charge controller is 'bad' per se. It's a small one that fits in the palm of your hand. It has just one LED which is 'on' when charging and rapidly blinking when in float mode. I believe I picked it up at West Marine.

I'm not familiar with the term 'stratification' when talking batteries. Does this mean the battery electrolyte has broken into layers? If so, will shaking the battery un-stratify it?

Battery temp is pretty much out of my hands, as Florida is what it is.

Yet I recall one of these group 27s dying on me last year when at anchor when it shouldn't have. I borrowed an upscale battery charger from a dock mate and charged the heck out of it the next day (read overcharge and watching the electrolyte bubble) and this seemed to fix it as a borrowed load tester showed it to be in good shape after the treatment. Today this battery is no trouble...it's the other one that is causing trouble.

I'm going to get to the boat sometime today and pick the trouble battery up. Time to abuse it and see if I can 'fix it'

I know you don't hear this enough but I really appreciate the work Maine Sail has put into the boating field. Terrific effort!!

[stevensuf]

I now have enough solar so that i dont need to worry about power when at anchor or tied up, on passage i wait till 50%, I don't like using the engine to charge the batteries, but find under passage im closer to240AH per day while on the hook closer to 150AH a day.