Understanding my solar power and batteries

[motion30]

I do not have a problem I just have some questions. So i have a 44 my with a hardtop on my flybridge holds 1100 watts of solar panels. I have almost 1300 amps.hrs Of golf cart batteries. Today was my best solar production ever what's up production of 360 amp hours of power. I have my absorption voltage set at 14.8. I rarely make it to float voltage. When I wake up in the morning my battery voltage is seldom lower than 12.4. Everything seems to work well for me. My question is would I be better off with a smaller battery Bank that would get the float charge more often. Or is what I have just fine. I am a full-time live aboard on the hook

[smac999]

do you know what your daily usage is?

removing batteries may screw you in periods of bad weather.

[Unity]

Batteries take higher charge when batteries are less full. For most batteries, above 80% charged is both unnecessary and inefficient. Basically the solar charger will stop sending current (meaning you are wasting available power) as you go to absorb and then even more so at float. Your configuration sounds awesome!

[Bleemus]

Originally Posted by Unity

For most batteries, above 80% charged is both unnecessary and inefficient.

Please provide data for the above statement.

[motion30]

No I do not know my daily usage, I would like to have a battery monitor. I did have one on my last boat but this will take a major battery wiring as the batteries are spread all over the Bildge

[ozsailer]

G'day Motion,
I would love to know a lot more information if possible.
1) Your current location.
2) Hours of premium sun for highest panel efficiency
3) Type of solar controllers.
4) Did you set the controller for the manufactuers recomended charging rate.
5) Age and size of panels.
6) Are you operating on a 12 or 24 volt system as the theoretcial power current output of the panels is approximately 91 amps at full efficiency. Based on your 360 AH of power being delivered this apears well short of maximum output via the panels unless you have very littel draw down on your batteries daily.
7)What is the current daily power consumption of your vessel.





Greg H

[john61ct]

Originally Posted by Unity

For most batteries, above 80% charged is both unnecessary and inefficient

Total hogwash, unless intentionally buying cheap batts and replacing them much more frequently.

Need to get to 100% Full as per endAmps, ideally most cycles, 2-3 times per week minimum

to get good longevity.

[john61ct]

Really the smaller bank size is not relevant, you need to use less than 85% of what goes into your bank most days no matter its size.

Once you have that under control, more AH gets you a bigger buffer for poor insolation.

But if not under control, average SoC keeps dropping and the bank reaches EoL way too early.

If you have the ability to charge at higher ICE amps early in the AM for an hour or two, you may be able to get to that 100% Full via solar, again a few days per week is all, not needed every day.

Monitoring gear helps, certainly need an ammeter you trust, a good SoC guage and/or AH counter even better.

[john61ct]

Originally Posted by motion30

as the batteries are spread all over the Bildge

that in itself may be a problem needs fixing.

[Unity]

Originally Posted by john61ct

Need to get to 190% Full as per endAmps, ideally most cycles, 2-3 times per week minimum to get good longevity.

Did you accidentally say “190%”? Did you mean 90%?

If so, do you really mean float is important or just that we need to fully charge from time to time? 2-3 times per week seems ... difficult for most cruisers and inefficient from a power generation perspective. An occasional equalization I thought addressed that challenge, no?

Like all boating, it’s constant trade offs. Perhaps slightly less battery life in return for far less generation time / more efficient power storage? All of which also costs real dollars...

[Stu Jackson]

Originally Posted by motion30

No I do not know my daily usage, I would like to have a battery monitor. I did have one on my last boat but this will take a major battery wiring as the batteries are spread all over the Bildge

Actually, one of the easiest things to do is to figure out what you use every day, even without a monitor.


How?


You make an energy budget. Like this:


The All-Important Energy Budget:
Energy Budget


Interestingly enough, a good budget properly constructed, is remarkably predictable, within a reasonable range of daily use.


What many of us have found is that we are very, very good at doing budgets and that the monitors simply CONFIRM our good budgeting.


What goes out is easy, it's linear: amps times duration.


What's harder to know, and where monitors (coulomb counters) really shine is showing you what goes back in. Because of battery acceptance, like this:


Battery Acceptance by Stu Battery Acceptance


Good luck, nice rig you have, I'd never remove a battery. What you have sounds awesome.

[john61ct]

Originally Posted by Unity

Did you accidentally say “190%”? Did you mean 90%?

Thanks, fixed it

> Need to get to **100% Full** as per endAmps, ideally most cycles, 2-3 times per week minimum to get good longevity.


If so, do you really mean float is important or just that we need to fully charge from time to time?

I mean the above. A quality charge source properly adjusted does not drop to Float until 100% is reached.

> 2-3 times per week seems ... difficult

Ranges from a piece of cake, to slightly inconvenient, to impossible in some cases.

However important to do best we can, improve the situation if possible, not just give up on tge goal. If longevity is important to you.

> An occasional equalization I thought addressed that challenge, no?

No, monthly if all's well, the more PSOC abuse the more frequent, helps a bit but for sure no cure.

Many use banks that can't be equalized.

> Perhaps slightly less battery life in return for far less generation time / more efficient power storage?

It's not a slight difference. Can mean a quality bank could last 10+ years gets murdered in a season.

I certainly am not advocating using ICE generation for the long tail.

> All of which also costs real dollars

Yes, as I said intentionally buying cheap lead and replacing more frequently can be a rational economic choice.

But those that spend thousands on a quality bank will save money by treating it well.

[john61ct]

Originally Posted by john61ct

that in itself may be a problem needs fixing.

http://www.cruisersforum.com/forums/....php?p=2722093

[a64pilot]

Decreasing your bank size will make it worse.
Reason is your saying your seldom getting to Absorption voltage, making the bank smaller will only deeper discharge it, power removed will be the same.
Ideally you need to run a generator first thing in the morning when the banks acceptance is high and can take everything your shorepower charge can feed it, then let your Solar polish the charge off, that will get you to 100% SOC. I do this a couple times a week

Unless your South of the Equator, it’s only going to get worse not better as time progresses as we are losing Solar time every day.

If it helps I see exactly the same thing you do, I have 1,000 W of Solar and a 660 AH bank

[a64pilot]

Originally Posted by Bleemus

Please provide data for the above statement.

He is right about it being inefficient, unfortunately it’s necessary though for battery life, but the closer to full charge a lead acid battery gets, the less efficient the charging is.