Leaving Solar panel to charge for long periods
I have a 120 watt solar panel with a charge controller connected to a 110 amp leisure battery. Once the battery is fully charged the controller maintains a holding voltage 14.4v. Obviously there will be times when the voltage goes to zero (during the night
etc) but I wonder if it would be better for the battery to disconnect the SP and use a smart charger when the caravan is not being used for a 2 or 3 months in winter. Any thoughts please
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Good question, Tirril. I thought my controller ‘dumped’ excess power and behaved much as a ‘smart’ charger does, responding to the needs of the battery, but have never checked to see what actually goes on. It’s so easy to forget something that’s out of sight
and seems to work OK. I’ve no idea how the ‘dumping’ is performed, I assumed it just opened the circuit.0 -
I would have thought one of the basic functions of any controller is not to over charge a battery. Surely all controllers would be intelligent enough to switch to maintenance mode once the battery is fully charged. Check the spec and if in doubt you can
always cover the solar panel for how ever long you think necessary.peedee
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Both my PWM Morningstar SunSaver and SunSaver Duo are actually "smart chargers" as when they have respectively the battery or batteries fully charged they switch the supplied current down to zero. These I have no hesitation to, and I do, leave continuously connected up day after day. [Measured to one hundreth of an Amp.]
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Further to the above, my checks show the max voltage from the panel is 22v of which it delivers a max of 14.4v to the battery. If the daylight is dimmer the max volts for the panel obviously reduces but it will still deliver 13 to 14 v to the battery. Even when the battery is fully charge the panel appears to be delivering a holding charge of about 14 volts hence my question is this ideal or would it be best to use my CTEK smart charger. From what you say ocsid your SunSavers are a bit smarter than my controller.
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You really need to be looking at the current flow Tirril which should be zero or very little into a fully charged battery. What you are probably seeing is the battery volts?
peedee
Write your comments here... Maybe I am not doing it right peedee but if I disconnect the battery the control charger shows two readings (measured by my multimeter). First reading is what the panel can produce which can be up to 22v. Second the amount it
is pushing to the battery which is a max of 14.4v so it seems that the charger is reducing down to around 14 volts but I never see a figure less than this unless the light level is low.0 -
Tirril, as "PD" and I are saying your interest should be in the "current" ie the Amps, rather than the "volts". If there are no Amps then nothing is being pushed into the battery.
You say you have never seen less than 14 Volts. But is this after the smart charger has been connected, un interupted for a few hours so has assessed the battery as charged and backed down from trying? Or after it has been recently connected and is attempting to ascertain the battery's state of charge?
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I can only think you are looking at the open circuit voltage from the regulator and in full sunshine 14.4 volts or thereabouts is what you would expect to see. Like OC and myself are saying the only way to check the regulator is behaving itself is to check
the current flow. You can do this on a permanent basis by fitting a>
BM1< meter or similar. I think Merve has fitted a BM1 mini and is quite pleased with it.peedee
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The panel needs a regulator to cut off the charge current once the battery is fully charged. I would check with the supplier to establish just what you have.
Write your comments here... HI Wildwood - it has a charge controller fitted which is said to control the amount delivered to the battery. I think from what is being said I am measuring the volts rather than the amps so will set about making the necessary
checks.0 -
Thanks too ocsid and peedee - I realise I am measuring just volts rather than amps. I have a decent multi meter which can measure amps so that is my next task. Thanks too for the BM1 link which alhthough expensive seems worth having as it can always be switched
to any future installation. The information provided would be usefull and appeals to my liking to know what is happening.0 -
Hi Tirrill my old son! I have had my SP connected to my batteries for almost 3 years and my batteries have been kept in tip top order all that time so I'm happy. Yes, the BM1 is an extra check on battery life etc. Certainly my controller seems to work as
a smart charger.0 -
Many thanks Merve and good to know. I think the BM1 is my next purchase apart from its usefulness I am one of those who likes to see how the kit is working. For the last few days until yesterday we had an inch of frosted snow covering the panel yet it still
supplied power although the amount of light was reduced.0 -
One of many things I thank the inventor of SPs for is the fact that it has stopped me running backwards and forwards with freshly charged batteries! I happened to have to go today as I had to change the battery in the keyfob (Bailey valencia) and it hadn't had enough power to put the alarm on the last time I was there. I checked the batteries and as usual they were fine. The other money saving tip was from my technician at service. He advised not leaving the blinds shut as eventually, they will not push down and fold up into their housing as well as they should and will start to fail. So I cut cardboard to shape and covered all the Windows with it. Took no time at all. All Windows blockedbout so sun can't fade the fabrics. Also he mentioned tyres. Fortunately I keep my tyres covered from UV light at all times. Apparently, it's UV and not the great British roads that destroys tyres. Another money saving tip!!
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Thanks Merve regarding the window blind tip as I have been closing mind to prevent fading. I do keep the tyres covered to combat UV. I used to jack a previous single axle onto axle stands to take the weight off the tyres but now having a t/a and using it
during the winter I no longer bother. The Bailey key fobs a pain as they activate too easily when carried in a pocket.0 -
14.4 volts is the correct voltage for recharging the leisure battery and if the output was unregulated then it would not do any good to keep pushing current into the battery (as others have said above). It might be useful to measure the current but if it
is a smart charger it could be difficult - it may be pulsed etc. and anyway you would need a high impedance multi-meter. Best is to get information from the manufacturer.0 -
14.4 volts is the correct voltage for recharging the leisure battery and if the output was unregulated then it would not do any good to keep pushing current into the battery (as others have said above). It might be useful to measure the current but if it
is a smart charger it could be difficult - it may be pulsed etc. and anyway you would need a high impedance multi-meter. Best is to get information from the manufacturer.Write your comments here... Much obliged Hitchglitch. I am currently monitoring with a multimeter and all seems ok.
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