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Does solar charger really make any difference?
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05-04-2013, 10:26 AM | #1 |
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Does solar charger really make any difference?
It has been two hours and it hasn't make a dent on my Kindle. Wondering if it even worth hooking up to the car
BTW, I think the Kindle battery is 1.5Ah, BMW is 850Ah and the charger is 5w and 250mAh peak |
05-07-2013, 07:57 AM | #6 |
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W=IV
I=W/V You can do the math if you like.... If it's 5w, and your battery is 12V, (actually if you measure it with a voltmeter you'll actually find it's higher,) you'll get .4 amps. I don't think that'll do anything for your car battery. 1.5 amp Schumacher from Walmart for $20 and a long extension cord.... Last edited by jzchen; 05-07-2013 at 07:58 AM.. Reason: clarify the formulas |
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05-07-2013, 01:52 PM | #7 | |
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Thanks for the info. How does it compare to Battery Tender? Just want to make sure it has all the "intelligence" and won't over charge the battery.
My car is parked on someone else's drive way, so connecting a power cord is kind of intrusive. I left the car with 12.3v and today is the first day with half sunshine, rain later during the week ... Not very optimistic I have to admit. I'll give it a try. If doesn't work, maybe I'll just plug it in twice a week for a few hours. Quote:
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05-07-2013, 02:37 PM | #8 | |
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The thing is that you said it is limited to 245mA, which I am not sure how that plays into things. If it is true, then that would be even less than the 400mA that the equation works out to.... |
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05-07-2013, 09:45 PM | #9 |
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A company called Granite Digital sells the one I have. Google saveabattery.com and you'll find it. They have a unit sized to keep an auto battery. The Granite unit is smarter than the Deltran Battery Tender. I've used both.
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05-10-2013, 04:59 AM | #10 |
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My BMW branded Deltran didn't even work.... The one from Walmart works just fine on the jump start points. (Glad at least someones' worked!!! ) Called Deltran up and realized it would be a waste of effort/money to get it fixed under their warranty. Went to Walmart and bought another. (I have six of those now...)
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05-10-2013, 06:59 AM | #11 | |
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05-13-2013, 07:21 AM | #12 | |
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05-13-2013, 01:33 PM | #13 | |
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But charger should not have a reverse draw on battery when outlet goes out, right? |
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05-13-2013, 05:38 PM | #14 | |
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I agree, I think they work fine as long as the battery has sufficient charge already, and not dead, although some as Efthreeoh mentions have a function for bringing back almost dead ones. (I honestly don't think you can bring back a real dead one, having studied this chemical reaction in some science classes... You need a "seed" of non-oxidized lead to be able to reduce some back, or something like that... It's been a long time since I've studied it...) |
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05-31-2013, 11:24 AM | #15 |
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Today is a good sunshine day on east coast. I estimated that the panel can charge an iPhone 4S in about 3-4 hours.
Does anyone know how to do the math? How is charging iPhone vs BMW? Assuming there's sun half of the time, is this enough to maintain the battery? Of course, there imply the question, how much does a parked E60 consume? |
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