Quick query

[oldish hippy]

Approx how long for battery to charge on solar through ctek ,! / It is winter ,yes know sun is lower, 2 /It was completely flat .Just gong to leave it as long as possible before checking it. Thanks in advance.

 

[harrow]

I don't think it will.
In peak summer maybe a week or more.

 

[mfw]

If battery too flat it may not charge at all you may have to loop a charged battery into it

 

[trevskoda]

If its very flat it will never recover to full or not charge at all, at this time of year a mains charger is the only way.

 

[Tezza33]

My batteries are usually ok even at this time of the year but yesterday I had to plug the EHU cable in because both sets of batteries were down to 12.1v

 

[Phantom]

It depends on solar panel size.

 

[trevskoda]

How many watts of panel have you got up top.

 

[molly 2]

I have a100 w for the last 2 weeks been getting nowt if I fitted another 100 w I would be getting 2 times nowt

 

[Wooie1958]

I have 160w solar on the roof for the leisure batteries and a separate portable 20w panel that i use in the windscreen to keep the engine battery topped up.

Just been and checked ( still dark out there and raining ) the leisure batteries are sat at 12.75v and the engine battery is sat at 12.65v.

 

[Admin]

Approx how long for battery to charge on solar through ctek ,! / It is winter ,yes know sun is lower, 2 /It was completely flat .Just gong to leave it as long as possible before checking it. Thanks in advance.

At this time of year (December 21st being the worst day) you will get between 10% - 20% of your panels output in direct sunlight. There is approx 8 hours of sunlight at this time of year.

I am going for 10% but multiplying by the full 8 hours.

10% of 175 watts = 17.5 watts

17.5 watts x 8 hours = 140 watts (max and I doubt it is this much)

140 watts divided by the 14.4v bulk output that the CTEK will be trying to reach is approx 9.72 Ah per day. Let us call it 10 Ah

The charge efficiency of lead-acid batteries between 60% - 90% depending on the state of charge and battery type. I shall assume 75% to make things easier.

75% of 10Ah is 7.5Ah per day.

I think your battery is 85Ah so from flat it would take 12 days to recharge if there were no other loads on it and it was a healthy battery.

Now the fact is that the battery has been left in a discharged state and this will have caused sulfation and there is a good chance depending on how long it has been left that way that it will never recharge and is scrap.

 

[Markd]

Bottom line sounds to be that if you use your batteries at this time of year you'll need something other than solar to recharge them.

 

[Admin]

Bottom line sounds to be that if you use your batteries at this time of year you'll need something other than solar to recharge them.

Tilting panels can really help.

 

[Markd]

Agreed

 

[oldish hippy]

Thanks phil it cost me nothing to try and the ctek with the five stages might help a little

 

[Wooie1958]

Tilting panels can really help.

If they are fixed horizontal to the roof would parking the motorhome on a very steep hill facing the sun work

 

[Admin]

If they are fixed horizontal to the roof would parking the motorhome on a very steep hill facing the sun work

At this time of year, they need to be at almost 90 degrees as the sun is so low on the horizon.

 

[Markd]

At this time of year, they need to be at almost 90 degrees as the sun is so low on the horizon.

Now there's a business opportunity - a set of winter props to allow vans to be stored on their sides

 

[r4dent]

At this time of year 150 w solar will give a daily output of about
Aberdeen 5ah / Liverpool 8ah / Brighton 10ah.

If you have 50% (flat!) 200 ah battery you will need 100 ah to charge it to full

Therefore Aberdeen 20 days / Liverpool 12 days / Brighton 10 days.

Of course if you have more solar or smaller battery or live in Benidorm it will take less time.

 

[Admin]

At this time of year 150 w solar will give a daily output of about
Aberdeen 5ah / Liverpool 8ah / Brighton 10ah.

If you have 50% (flat!) 200 ah battery you will need 100 ah to charge it to full

Therefore Aberdeen 20 days / Liverpool 12 days / Brighton 10 days.

Of course if you have more solar or smaller battery or live in Benidorm it will take less time.

You need to factor in charge efficiency (60% - 90%)

 

[trevskoda]

I have a100 w for the last 2 weeks been getting nowt if I fitted another 100 w I would be getting 2 times nowt

Thats strange as i have 200w and getting 14.2v on bright days, no idea of amps in, always starts and does what it says on the tin.