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1. 05:58 AM - Re: A brown-out alternative? (zwakie)
2. 09:05 AM - Re: Re: Battery (Robert L. Nuckolls, III)
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Subject: | Re: A brown-out alternative? |
Update: yesterday I tested to see how well the DC-DC converter does its job with
a battery in less than optimal condition (12.1 Volts without any loads on it).
I saw that the output voltage of the DC-DC converter dropped to 9.85 Volts initially
and quickly (well below 1 second) recovers to the set point of 12.5 Volts.
This 9.85 Volts is well above the brownout point for my EFIS so it still is no
issue for me, but I thought it would be worthwhile to share, so others are aware
that the DC-DC converter takes some time to reach the set point voltage when
battery voltage is lower than normal.
--------
Marcel Zwakenberg
Europa XS TG || 912ULS || PH-SBR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487097#487097
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> >All for a couple of dollars delivered.
> > ebay item 183558004137
> > It looks like this particular one works with a solar input of 6
> to 18 volts. There are definitely some cheap viable options
> available for the Do-It-Yourselfer. Even more are available for
> Lithium batteries.
>
>
>A little digging reveals some concerns about this charger. The IC
>used on the module is the Consonance CN3767 (datasheet here
>(http://www.consonance-elec.com/pdf/datasheet/DSE-CN3767.pdf)).
>While it *is* a true MPPT charger (a rarity on eBay at this price
>point), it's probably not going to function as you would like, for a
>couple of reasons.
>
>First, the seller's claim that the module can accept solar panel
>inputs between 6 and 18V, while true, is misleading. The CN3767
>uses a buck topology, not buck-boost. This means that it can only
>*reduce* the input voltage. Any time the solar panel's output falls
>below the battery voltage minus a diode drop, the battery will not
>be charged at all. So to charge a battery that's sitting at 12V,
>the minimum solar panel output will be >12.7V.
>
>Second, the photos of the module show that the maximum power point
>voltage (Vmpp) is set lower than it should be for a low-power
Good put Eric. I would like to qualify my
earlier assertions about 'solar chargers'
in that my comments targeted the generic
solar arrays some with built in isolation
diodes and NO active electronics. I've got
a couple of panels laying around here that
I was considering for use on farm equipment
that sits idle for long periods of time . . .
generally allowing battery(ies) to self-destruct.
Usually very EXPENSIVE batteries I might add.
Popular devices like this
https://tinyurl.com/y7x2wbfu
which is better than nothing but too small
to be a serious charger . . . and if it were
larger like this one
https://tinyurl.com/y9zy4zjs
perhaps too big to be allowed un-controlled
access to the battery in maintenance.
I have one of those '18w' devices . . . and
it's really closer to a 10 watt. Yeah, it
will put 1+ amps into an SVLA battery in
full, direct sunlight . . . but output falls
of markedly with changes in sun angle and
clouds.
To be sure, solar arrays CAN be adapted to
charging and maintaining batteries but
they require the addition of electronic
'smarts' to competently craft a set-it-and-
forget-it maintenance system.
The eBay item cited is interesting. I've
ordered a couple. I'll team one up with
a pair of my not-quite-18w panels and
put a data acquisition system on it.
MEASUREMENT will tell the story. Thanks
for the heads-up!
Bob . . .
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