Solar power and batteries

Sooz52

Sooz52

Joined
Jan 13, 2020
Posts
143
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Location
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
Hi, I’m after a little help, trying to find a mechanic today but I had a load of issues working yesterday, only powering a laptop. I’ve got it down to three possibles.

1. This sun control thing - I’m in full Spanish sun - is it normal that the lights flash on and off and it clicks? If that normal working great.

2. the solar panels were a little dirty so I cleaned them, however they’ve really old and might only pair up to make 100w (is this watts per hour). If my laptop alone (without using anything else but water pump) draws maybe 60Ah (the mains power supply says output 20v 2.25A), I am using a 12v to 19v charger for it; I’ve not yet used my main 12v to 240v inverter). Am I asking too much? Considering a new panel to add, I’ve plenty of space.

3. I have 2 large agm batteries, 95Ah each. Bu they’re 3-4 years old. I thing I need to replace them at that age, and higher wattage new ones can go in the space. Thoughts? Can I test their abilities with my multi-meter.

Thanks mhf brains.
 

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Have you got a hand held voltmeter? If not buy one, a cheapy at the chinese supermarket will do.

Check your battery voltage. Report back.

If charging voltage will be over 13,. If it has been over 13.8 for several hours it is probably charged.

This will establish if the solar system is charging.

Rough guide, 100watt panel in good sunshine may generate 65 watts so about 5 amps at 13v
Rarely get full output unless at equator, clean panels, battery needs charging, good controller etc etc

At night what does voltage drop to?
Imsure others will chip in with info.
 
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What problems with your laptop? If it was not charging properly then I would firstly try your inverter and mains charger. Plug the charger into the inverter. If that all works then you need to look at the 19v charger. We have had problems with these not being up to the job.
Look at the battery voltage at night with only minimal stuff on. It should read ~12.6v after a full day in the sun. Similarly first thing in the morning, before the sun hits the panels, approx 12.5v after a decent day before and not much telly or heating.
Google the manual for your solar controller. It will indicate what the lights mean.
Switch the inverter off when finished, they draw a noticeable standing current doing nothing.
Jon
 
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Unless the panels are really old (10-15 years+)they should be fine, this time of year in Spain around midday you will only get around 40-45% out of them with a good controller, with your controller probably quite a bit less.
A laptop on average takes around 4 amps when charging from a 12v adaptor.
With only 100 watts of solar I doubt if you will replace the energy you are using at this time of year.
I suspect your batteries are well past their best, my last van the AGM's lasted 18 months.

Best way to test is to do a controlled discharge like this:-

You need to separate the batteries and test them individually as a duff one will drag the other one down.

Fully charge the battery and leave to stand for an hour then take your 1st voltage reading.

Then if it's a 95a/h battery load it with a 5 amp load and run for 4¾ hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged but not recommended for wet cell batteries to do it too often.

1584093778306.png


If the batteries are past it I would as you have an Elektroblock I would replace them with 80a/h Gels they will give you more useable power than the AGM's and have a very long life.
 
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The NDS Controller manual is available on the RoadPro website:

The LEDs flash during normal charging and also to indicate problems.

The charging for each battery is in 4 'phases', because it's a smart charger. The LED sends out one, two, three or four flashes to tell you which phase it has reached. If it's continuous rapid flashing, a fuse has blown.

Your laptop power supply is 20V 2.25A, so that's 20 x 2.25 = 45 watts. The power supply working off 12V is likely to be about the same. If the laptop was completely flat, it would probably take about 2 hours to charge it up completely.

So 45 watts for 2 hours is 90 watt-hours, which in 12V battery terms is 90/12 = 7.5 amp-hours. The laptop probably lasts at least 7.5 hours on a single charge, so on average it's using about 1 amp-hour of charge per hour of usage.

The problem with inverters is that they take a constant drain when they are on, even with no load. For example, a 2000 watt inverter can waste 20 watts all the time it is on. If it's powering a 2000 watt hairdryer, that's negligible, but if it's powering a 45 watt laptop power supply for 8 hours, it's a lot of wasted power. Better to buy a small 150 watt inverter specially for that, if that's what you need. But even better is a good 12V to 19V converter.
 
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pappajohn said:
Your test timing is very specific Lenny but turning on a few lights and TV is very hit and miss for 5 amp load.
It needs a known 5a load, not a guess.
Something like a 60watt headlamp bulb is perfect.
Click to expand...
Not hit and miss at all you turn on enough appliances until 5 amps is being drawn or if not exactly 5 amps adjust the time to suit.
 
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Lenny HB said:
Not hit and miss at all you turn on enough appliances until 5 amps is being drawn or if not exactly 5 amps adjust the time to suit.
Click to expand...
But how do you know its 5a without an amp meter in circuit or if the appliance wattage is unknown?
Lights could be 10w, 20w or even LED and if your electrical knowledge is practically nil you'll never know.
 
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This site contains affiliate links for which MHF may be compensated.
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It really depends on how much you are using your laptop as it can take quite a while to recharge if the battery is very low or flat, also if you are constantly using it whilst trying to charge it you'll struggle to put anything in it at all.
 
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Ok I’ve been using my multimeter then been to two electrical mechanics, and the score is, I’ve not got enough solar for what I need, plus one of the batteries is pretty much defunct and the other not great. I’ll be spending a bit of money over the next few days.
In the sun regulator it says that Maximum peak power for each input is 150WP. Does this mean I can’t stick a panel of more than 150W on it? The other 2 panels are both plugged into input 1.
 
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I’ve just found the solar panel forum; I’ll head over there now..,

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Sooz52 said:
I’ve just found the solar panel forum; I’ll head over there now..,
Click to expand...
New thread here:

www.motorhomefun.co.uk

New system needed

Hi, I’m in a Hymer and underpowered, working from it with my laptop and only lasting up to 2 days without driving, so I need an emergency refresh. After a reasonable amount of research I’ve found how complex this is - I’m hoping not to have to become an expert on this before I buy as I really...
www.motorhomefun.co.uk www.motorhomefun.co.uk
 
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Thank you ?
 
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