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2018-10-19, 22:50:04
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Author Topic: Solar & batt questions about present set up  (Read 895 times)
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Long time no see...we've had a lot of financial and family stuff going on.
However, especially on seeing Grum's and TinMan's recent vids, I wondered if folks might have some advice about my present solar and battery set up.

About 5 or 6 years back, I bought 2x 1lb bags of solar bits...solar panel pieces with some actual full sized cells.  Those 7 cells went on the back of an old mirror and sat around. Instead, I was using the other bits to make 1A 18V panels.
Fast forward to a month or so back and I bought a 100W DC/DC converter...ideal for hopefully boosting the 4V output at 8A to something useful for a car battery.
It turns out that the output is very confusing !
As seen in the pics below, at 17.75V it's putting out apparently over 4A  ^-^
So let's see....each cell is 0.55V and each when new was rated for 8A = 4.4W per cell
4.4 x 7 = 30.8W
It should be a 30W panel, then after the booster should maybe leave a 23W or similar setup, able to charge a 12V car battery.
However, as corroborated with a Uni-T multimeter, the actual wattage coming out is apparently more like 75W  8)
Presumably the switching frequency is upsetting both meters.
Anyhow - decent wattage whatever it truly is, well past the usual combined 10W or so from the other broken bits panels, am quite delighted with it.

But am not delighted with the Alum converted car batteries and they are what i'm looking for advice about.
Both batts are former failures from our car. 1 was struck by lightning and the other likely didn't do much better in its former life.
Both used to charge to approx 11.5V
The lightning one sits at 5V and refuses to budge.
The other has very slowly gained from 5V to 9.5V over the past few days of charging on this panel.
It'll top out at about 11.5V and then drops back by the next morning, to be about 1/2V higher than the day before.

I suppose it would be best to scrap the very very bad one.
Would you suggest ######'ing the other ? sharp spikes to try and bring back the possibly knacked out cells ?
A top down inspection of the batt cells seem to show them to be quite clean, but years have passed of no use.



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ʎɐqǝ from pɹɐoqʎǝʞ a ʎnq ɹǝʌǝu
   

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Posts: 1247
Slider,
Both of your batteries exhibit lower than normal voltage at
rest and are unable to hold a stable higher voltage after
being charged.

This indicates that both are suffering extensive internal
deterioration and are undoubtedly beyond rejuvenation.

Your solar setup is quite nice.


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"Truth: the most deadly weapon ever discovered by humanity. Capable of destroying entire perceptual sets, cultures, and realities. Outlawed by all governments everywhere. Possession is normally punishable by death." - John Gilmore (1935- ) Author
   
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Cheers muDped.
Yeah, normally a lead-acid would be absolute toast, but with being Alum converted it formed thoughts on what normally happens to them after 'extended resting'.
As such I guess it doesn't matter what happens to them and both are ripe for some experimenting. Running a high spike setup through the totally duff one was planned for today...just to see, but as seen in the attached pic it's all warped and twisted up. Might empty it out and put 18650's inside.

The better batt is at 10.85V this morning, so it looks like something may be happening inside it, very slowly, day by day. That one is much cleaner and ship shape looking from what can be seen top down.


Indeed, am mightily impressed with the DC/DC converter.
It's this one: https://www.ebay.com/itm/100W-DC-DC-Boost-Step-Up-Converter-3-35V-to-5-35V-12V-24V-9A-Power-Supply-Module/201947726698
$2.76 !!!
I mean, why is this not more of a thing ? to put a few cells in a much smaller area and with less soldering etc involved, then use a booster. Particularly if a salvaged or second hand panel has a few damaged cells.
The panels wires now run inside a back window of the house, after making a cable from old mains cords yesterday and I have it hooked up to a 9V desk fan. It ran until gone 5pm yesterday, which at this time of the year is really good. The fan started spinning at 7.30am today, with heavy clouds outside. As soon as the panel goes over 3V the booster starts outputting whatever mA it has and the 17.75V is quite solid through cloud cover or sun (which is how it arrived, I didn't need to turn the setting pot screw).

It would be good to make a UPS for this PC using the seemingly OK battery, being that we get microblip power cuts once a week or so. The lights dim and the PC resets. All it would need to do is cover for 1/2 second and would be a waste of a good quality battery.
 


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ʎɐqǝ from pɹɐoqʎǝʞ a ʎnq ɹǝʌǝu
   
Group: Moderator
Hero Member
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Posts: 1331
... .-.. .. -.. . .-.
Btw, near the bottom of Page 211 of the battery handbook, which is an excellent read and thanks -
"keep the charged batteries at ambient temperatures of not higher than 0 degrees C"  ???

The author must live in Minnesota !


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ʎɐqǝ from pɹɐoqʎǝʞ a ʎnq ɹǝʌǝu
   
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