5 or 2.5 or 1.5 watt solar trickle charger?

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NAC

Golden Member
Dec 30, 2000
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I have an old pickup that I use about 2-10 times a month, but perhaps even less in the winter months. I try to take a long trip every month with it, but often don't. It needs a new battery again, this one lasted I think 3 years, maybe less. I think a solar trickle charger would be a good investment. I'll leave it plugged in all the time and just sitting on the dash. The truck is in the shade.

Question is - what capacity in watts would you recommend? Harbor Freight has a 1.5 watt version for $15, up to about $50 for a 5 watt version online. If I attach this to a new battery, is a low watt version sufficient? Or do I really need x watts for it to maintain the battery?
 
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dbcooper1

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May 22, 2008
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It may not matter because you might not get sufficient voltage depending on how little direct sunlight is available.
 
tortillasoup

tortillasoup

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Jan 12, 2011
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Yeah you might want to just plug it in and get a Batteryminder 1500. It's temp compensating and it will desulfate the battery. They have battery desulfating chargers that are solar powered but they cost a bit more and you need a lot of sunlight. Also, you also have to keep in mind that it might not work well during cloudy days or at night.
 
disappoint

disappoint

Lifer
Dec 7, 2009
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Well let's see. Say you wanted to charge the battery at 2 amps. I think car battery trickle chargers like the above mentioned BatteryMinder are around 1 - 2 amps, probably around 1.5 amps.

If you want to charge at 2 amps, 2A x 12V = 24 Watts

1.5A x 12V = 18 Watts

So a 5 Watt solar panel won't be enough. An 18 Watt panel would be considered the minimum in my opinion. Don't forget the voltage regulator and fuse!
 
tortillasoup

tortillasoup

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disappoint said:
Well let's see. Say you wanted to charge the battery at 2 amps. I think car battery trickle chargers like the above mentioned BatteryMinder are around 1 - 2 amps, probably around 1.5 amps.

If you want to charge at 2 amps, 2A x 12V = 24 Watts

1.5A x 12V = 18 Watts

So a 5 Watt solar panel won't be enough. An 18 Watt panel would be considered the minimum in my opinion. Don't forget the voltage regulator and fuse!
Click to expand...

Yeah a basic battery tender setup with solar panel won't desulfate the battery and can overcharge the battery as well. It's not an ideal setup at all. I'd go with solar if there was no way for me to run an extension cord and hook up a batteryminder.
 
T

thomsbrain

Lifer
Dec 4, 2001
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I want to say there are solar chargers with over-voltage protection.

That said, these only work if your vehicle has an always-on 12v outlet. If your car (like many) turns the outlet off when the car is off, it won't do anything unless you connect it directly to the battery (or some other always-on power connection).
 
razel

razel

Platinum Member
May 14, 2002
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Consumer bought solar panels won't be able to keep your battery charged. It might barely enough power to power your alarm and offline electronics. Perhaps in the DIY world you could build one that's good enough. You will also need more than 12volts to charge the battery. You'll need at least 14 volts or better yet, 14.4v (alternator) or more. Most car batteries with no load is 12.6 - 12.9v. Even then if you figure out both problems, you'll need to line probably half your front window with panels. Might as well cover your entire front windows cause then you can use it to shield your dash from the sun. :)
 
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disappoint

disappoint

Lifer
Dec 7, 2009
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NAC said:
Thanks for the input. So it seems that something like the below would work?

I need to decide if I will be willing / remember to plug in the truck regularly, or just want a solar unit which I don't really need to remember - I just set it up on the dash when I leave the truck. It seems that the similar AC battery minder unit is only about $50.

http://www.northerntool.com/shop/to...SWUo7YbEq-Gxj30C7Q3wEjo6t1xn4f6uG-hoCcEHw_wcB
Click to expand...

Yeah that will work, but keep in mind that is not something you would want to use to charge a nearly dead car battery, only to keep one that is already charged topped up.
 
bryanl

bryanl

Golden Member
Oct 15, 2006
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The watt rating is optimistic and applies only when the charger is facing straight into the sun, at best. But 1.5W at 12V is only about .120 amp, which may barely be enough to overcome the parasitic draw from any post-1980 truck's computers. If you have a 120VAC source available near the truck, get a regular trickle or automatic charger and hook it up monthly.
 
tortillasoup

tortillasoup

Golden Member
Jan 12, 2011
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The batteryminder 1500 is a better charger because you can safely charge a fully discharged battery from as low as 3V. Yes it will take a while to charge but it can charge that with no issue. It will also desulfate a battery, restoring lost capacity lost from sulfation.
 
A

Auric

Diamond Member
Oct 11, 1999
9,591
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After muy research of chargers awhile back, CTEK seemed the best and I've been happy with the most popular MUS 4.3. They are $60 on amazon and ebay but warranty requires an authorizied dealer such as tnrbattery for $70. At first, I was looking at low amperage for tender use only but the extra cost was worth the ability to recondition and charge relatively quickly as well (also replacing an obsolete one).

http://forums.anandtech.com/showthread.php?t=2406469
 
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Brovane

Brovane

Diamond Member
Dec 18, 2001
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2,332
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NAC said:
I have an old pickup that I use about 2-10 times a month, but perhaps even less in the winter months. I try to take a long trip every month with it, but often don't. It needs a new battery again, this one lasted I think 3 years, maybe less. I think a solar trickle charger would be a good investment. I'll leave it plugged in all the time and just sitting on the dash. The truck is in the shade.

Question is - what capacity in watts would you recommend? Harbor Freight has a 1.5 watt version for $15, up to about $50 for a 5 watt version online. If I attach this to a new battery, is a low watt version sufficient? Or do I really need x watts for it to maintain the battery?
Click to expand...

Or Van Conversion which is or 3rd vehicle sits out in front of or house and sometimes it can sit between 4-6 weeks between uses. I use one of these on my vehicle and it seems to keep the battery in-shape without issue between drives. Of course it might help that I live in Southern CA.

http://www.amazon.com/gp/product/B004ZC3TFC?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
 
tortillasoup

tortillasoup

Golden Member
Jan 12, 2011
1,977
4
81
Auric said:
After muy research of chargers awhile back, CTEK seemed the best and I've been happy with the most popular MUS 4.3. They are $60 on amazon and ebay but warranty requires an authorizied dealer such as tnrbattery for $70. At first, I was looking at low amperage for tender use only but the extra cost was worth the ability to recondition and charge relatively quickly as well (also replacing an obsolete one).

http://forums.anandtech.com/showthread.php?t=2406469
Click to expand...

ctek one sucks ass.
 
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