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Old 15-06-2012, 11:14   #1
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Thumbs up A Question Regarding Excess Charge....

In the throes of setting up some decent solar panels and i wondered is it possible to send any excess charging current that the batteries don't need to an invertor that then uses that excess to either heat the HWS or De-sal automatically? (Pre-setting were we want to channel that extra power prior)

I can see there will be many situations where our solar is topping up the batteries same time as we are motoring or simply generating excess current so we may as well store the energy as water or heat.

This would have to be i guess a PLC working in conjunction with the regulator?

Hope someone can give some ideas. Cheers Frank.
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Old 15-06-2012, 16:37   #2
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Just connect the invertor into the battery circuit as normal.

Dave
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Old 15-06-2012, 17:03   #3
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Re: A Question Regarding Excess Charge....

See: Southeast Marine Services :: Solar, Wind and Water Power :: Charge Regulators :: NCHC-12-60 12V Systems, 60A Max. Charge Current, with load divert

These are 12VDC regulators that will monitor the charge state of your batteries and if they indicate full will close a relay and "divert" the charge to some other place. That place may be a 12VDC water heater element or dissipation resistors or something else.

But I believe in the case of solar panels if you have a good solar regulator it will effectively "throttle back" the panels so that you do not overcharge the batteries.
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Old 15-06-2012, 21:38   #4
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Re: A Question Regarding Excess Charge....

I wouldn't spend the money on an automatic shystem, but it is easy to do manually.

I have a cruising buddy with a 400 watt array. If he is sitting at anchor and by noon the panels have topped up his batteries, he will turn on the inverter and heat up the hot water tank for 30 minutes or so. That takes about 80 amphours which can be replenished in an afternoon on a sunny day.

David
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Old 15-06-2012, 22:50   #5
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Re: A Question Regarding Excess Charge....

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Originally Posted by djmarchand View Post
I wouldn't spend the money on an automatic shystem, but it is easy to do manually.

I have a cruising buddy with a 400 watt array. If he is sitting at anchor and by noon the panels have topped up his batteries, he will turn on the inverter and heat up the hot water tank for 30 minutes or so. That takes about 80 amphours which can be replenished in an afternoon on a sunny day.

David
Dave we do it manually now, however when we are ashore or busy sailing it would be more efficient to have our system dump the excess power into storage i.e. Hot Water or Fresh Water without any input from me. Cheers Frank
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Old 15-06-2012, 22:55   #6
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Re: A Question Regarding Excess Charge....

Quote:
Originally Posted by osirissail View Post
See: Southeast Marine Services :: Solar, Wind and Water Power :: Charge Regulators :: NCHC-12-60 12V Systems, 60A Max. Charge Current, with load divert

These are 12VDC regulators that will monitor the charge state of your batteries and if they indicate full will close a relay and "divert" the charge to some other place. That place may be a 12VDC water heater element or dissipation resistors or something else.

But I believe in the case of solar panels if you have a good solar regulator it will effectively "throttle back" the panels so that you do not overcharge the batteries.
Ok i'll look there i guess the regulator senses gradual resistance from the batteries as charge builds so what i'm after is probably something based on sensing 'state of charge' and then switching on the pre-chosen item either HWS or De-Sal.
If this had an upper switch on point and a lower switch off it would be ideal.
I guess i'm trying to use the "throttled back" portion of the charge so we get greater effeciency from our panels.

I'll check out the sites cheers Frank
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Old 15-06-2012, 22:57   #7
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Re: A Question Regarding Excess Charge....

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Originally Posted by goboatingnow View Post
Just connect the invertor into the battery circuit as normal.

Dave
Dave we do that now, i'm looking at using all the power we generate more efficiently rather than wasting excess. Cheers Frank
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Old 16-06-2012, 00:35   #8
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Re: A Question Regarding Excess Charge....

I guess to bring the question back to dead basics:-

What we need is a sensor that detects when the battery bank is in it's say 90% charge position that it then turns on a selected circuit that will consume battery power (EXCESS CHARGE), in our case an Inverter that will then power up our HWS or our De-Sal.

Cheers Frank
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Old 16-06-2012, 03:42   #9
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Re: A Question Regarding Excess Charge....

Some solar regulators have the ability to dump current to a load.
This could be a water heating element
Made to your specs
Eg 12, 24,volts
Almost any amp you would likely need

This by virtue of its design would be very slow
At heating
But none the less possible at a somewhat
Reasonable cost
ie.the cost of the element & wiring
When you buy your solar regulator choose
The right one
Your may even be able to run your
Wind generator through your solar
Regulator thus use it excess energy
As well
Choose wisely


Talk to your solar supplier
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Old 16-06-2012, 04:00   #10
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Re: A Question Regarding Excess Charge....

Could you not use a charge diverter, the ones they use for switching battery banks when the first one is charged it switched over to bank two, just hook your load to it instead of the batteries
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Old 16-06-2012, 04:26   #11
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Re: A Question Regarding Excess Charge....

10 yrs of live aboard solar & wind
Spend your money on the 1 system that will charge
Your batteries the most ie solar 3-4 stage regulator
Use basic 240 &. Alternator charging

It won't matter that your batteries aren't 100%
Today because tomorrow your
Solar & wind will do it.
90% of the time or better

Yes you can dump your excess power
To a water heating element
Slow to heat by virtue of its design BUT POSSIBLE
Water heating elements can be made to
Your specs 12,24,110,240volt
At a somewhat reasonable cost
(talk to Woody hotwater systems Brisbane)
As can custom hotwater tanks

Watermaker would not be viable
As a automated use on dump loads
This needs to be manual system

Some solar regs have the ability to dump
Current
It may be possible run your wind generator
Through your solar reg, & use it's excess as
Well & most are user configurable

You have design your system from scratch
To do this so you can make sure
ie. buy the right regulator & wind gen

Get a system that is automatic it is
Very easy to fry you batteries with a
Manual control
Without fastidious monitoring

Over spec your reg by 20%+
They can run hot

GOOD LUCK
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Old 16-06-2012, 04:54   #12
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Re: A Question Regarding Excess Charge....

Sorry if my question wasn't clear, what i'm asking is :-
When batteries are nearing full charge is it possible for an auto sensing unit switch to turn the inverter on so then the HWS or DeSal is running whichever of the 2 i've selected the inverter to power for the event.
We have the Inverter, DeSal, controller, some solar (soon to be added to) and HWS on board now all i'm trying to do is automatically store hot water or make water ONCE batteries are topped up because always there is the possibility of excess power that goes to waste....
Cheers Frank
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Old 16-06-2012, 04:56   #13
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Re: A Question Regarding Excess Charge....

Quote:
Originally Posted by stevensuf View Post
Could you not use a charge diverter, the ones they use for switching battery banks when the first one is charged it switched over to bank two, just hook your load to it instead of the batteries
That's what has been suggested, i'd need to use it to activate the inverter switch through a solenoid i guess??

Cheers Frank
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Old 16-06-2012, 09:16   #14
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Re: A Question Regarding Excess Charge....

There was a skipper over on Sailnet about six months ago who was trying to do this. One of his ideas was that since he wasn't at the boat all the time (i.e., going ashore to shop, or going home for a week) that when he'd come back to his boat he'd have hot water. The group disabused him of this notion, suggesting that it would be safer if he did it manually and used his battery monitor to, ehm, actually monitor what was going on.

It takes all of fifteen minutes to heat a six gallon tank with a 120V heater element. While you can do the math, the aforementioned load of around 80A sounds right when heating with the inverter. If the batteries are topped off or over 90% soc and you have a good solar system, and a good sized house bank, this should be no challenge at all.

I simply don't understand the need or desire to do this "automatically." It would seem to be much safer to do it while you are there and monitoring the results. Sometimes I think we all may tend to overcomplicate things when trying the more sophisticated automatic approaches, which end up with more parts and more connections. Every electrical connection is a weak link in the chain.

djmarchand's answer was right on.

Your solar controller should step itself back anyway based on battery acceptance.
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Old 16-06-2012, 09:26   #15
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Re: A Question Regarding Excess Charge....

Quote:
Originally Posted by Stu Jackson View Post
There was a skipper over on Sailnet about six months ago who was trying to do this. One of his ideas was that since he wasn't at the boat all the time (i.e., going ashore to shop, or going home for a week) that when he'd come back to his boat he'd have hot water. The group disabused him of this notion, suggesting that it would be safer if he did it manually and used his battery monitor to, ehm, actually monitor what was going on.

It takes all of fifteen minutes to heat a six gallon tank with a 120V heater element. While you can do the math, the aforementioned load of around 80A sounds right when heating with the inverter. If the batteries are topped off or over 90% soc and you have a good solar system, and a good sized house bank, this should be no challenge at all.

I simply don't understand the need or desire to do this "automatically." It would seem to be much safer to do it while you are there and monitoring the results. Sometimes I think we all may tend to overcomplicate things when trying the more sophisticated automatic approaches, which end up with more parts and more connections. Every electrical connection is a weak link in the chain.

djmarchand's answer was right on.

Your solar controller should step itself back anyway based on battery acceptance.
Agree with some of your points however when we are not on the boat the systems are always reduced to a minimum.
To fall in line with your suggestion what read-out do you reccomend that accurately tells me that we have reached 90% charge so confidently we can startup the inverter?
We have a MorningStar RM1 and that gives only max and min voltages and voltage status along with battery temps. Cheers Frank
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