12v -> 12v charger

[5Z]

I currently charge the (hard to remove) batteries in my ASH-26E with a
solar panel and charger installed on/in my trailer. During a contest,
the plane may not spend much time in the trailer during daylight hours,
but it does spend most nights in there.

The solution would be to use the solar panel to charge a battery in the
trailer, which would then be used to charge the glider overnight. Best
would be to use this system all the time with two chargers in the
trailer and a single cable to hook up to the glider.

So... does anyone know of a charger that will accept 12v input to
charge a 12v/18ah SLA battery? I've found some charger chip
application notes, but I really don't want to build one of these.

Thanks,

-Tom

[Walter Kronester]

> So... does anyone know of a charger that will accept 12v input to
> charge a 12v/18ah SLA battery? I've found some charger chip
> application notes, but I really don't want to build one of these.


Hi Tom,
the airplane model builders are using chargers with 12V input.
You best look in Google for a supplier of airplane model equipment
in your aerea.
Walter

[Udo Rumpf]

http://www.hobby-lobby.com/chargers.htm

I recommend Graupner Ultramat 12
Regards
Udo



> So... does anyone know of a charger that will accept 12v input to
> charge a 12v/18ah SLA battery? I've found some charger chip
> application notes, but I really don't want to build one of these.
>
> Thanks,
>
> -Tom
>

[5Z]

Udo Rumpf wrote:
> http://www.hobby-lobby.com/chargers.htm
>
> I recommend Graupner Ultramat 12

Thanks - that looks like the ticket. I had thought about RC model
chargers, but thought there might be issues using one on a lead acid
battery for prolonged trickle charging. The specs at the Graupner
website: http://shop.graupner.de/webuerp/servlet/AI?ARTN=6412.67 seem
to indicate this will not be a problem.

-Tom

[Mottley]

check on http://www.strobl-solar.de who is specialised in Buffer
Batteries Systems

Regards

[5Z]

Mottley wrote:
> check on http://www.strobl-solar.de who is specialised in Buffer
> Batteries Systems

Very nice, but a bit outside my budget. The Graupner R/C charger is
looking like the best option so far. Now If I could find one with
fewer options - like just works for Lead-Acid the price might be even
better...

-Tom

[Eric Greenwell]

T o d d P a t t i s t wrote:
snip
>
> One option, if you want to keep your current 12 volt solar
> cell system would be to buy a 12 volt DC to 120 volt AC
> inverter and plug in a regular 12 volt charger. It's not
> elegant or efficient, but it should work.

It depends very much on the particular inverter and charger, because
they are often marginally compatible; for example, I have a 300 watt
inverter that powers my 1 amp charger to about half output. So, test
before you buy an inverter, if you can.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[JS]

Tom:
Even though my entire house runs that way, I wouldn't recommend
inverting and using a standard 120V charger. Eric points out that it's
not efficient. Better to do that in a larger system (the home is 1260W
solar, 400W wind, 48V grid tie inverter and battery backup, about 95%
efficient).
For someone with a hangar, use PV and a grid-tie inverter to run the
meter backwards during the daytime. Then plug your normal charger into
120V. This may or may not be "legal" where you live.
I've just started aquiring bits for a similar system. Perhaps with a
big enough "trailer" battery (less voltage drop as you charge the
glider) you could use two of the same charge controllers, one for the
trailer battery, one for the glider battery.

PV Panel -> Solar Charge Controller -> Trailer Battery -> SCC -> Glider
Battery.

There are solar charge controllers for around $40. But their weak
point will be whether the controller can deal with only 13-ish volts on
the supply side. PV panels generate well above their rated 12V. The 48V
array at home puts out about 100V open circuit! For an extra $50, the
model charge controllers like Udo pointed you to will work great.
There's another DC to DC model charger I've seen for $75 US. It will
do Sealed Lead Acid.
http://www.modelflight.com.au/rc_model_chargers/swallow_battery_charger.htm
But it's in Australia.

It's great to get our electric power from the sun. Like centering a
nice thermal.
Jim

[bumper]

Check out

http://www.solarconverters.com/

they make, or will custom make, pretty much any DC to DC converter. They
also make stock MPPT solar charge controllers that are small in size, so
suitable for use in gliders with solar panels. An MPPT controller can gain
as much as 30% more battery charge current from a given PV panel.

all the best,

bumper
Minden, NV
"JS" > wrote in message
oups.com...
> Tom:
> Even though my entire house runs that way, I wouldn't recommend
> inverting and using a standard 120V charger. Eric points out that it's
> not efficient. Better to do that in a larger system (the home is 1260W
> solar, 400W wind, 48V grid tie inverter and battery backup, about 95%
> efficient).
> For someone with a hangar, use PV and a grid-tie inverter to run the
> meter backwards during the daytime. Then plug your normal charger into
> 120V. This may or may not be "legal" where you live.
> I've just started aquiring bits for a similar system. Perhaps with a
> big enough "trailer" battery (less voltage drop as you charge the
> glider) you could use two of the same charge controllers, one for the
> trailer battery, one for the glider battery.
>
> PV Panel -> Solar Charge Controller -> Trailer Battery -> SCC -> Glider
> Battery.
>
> There are solar charge controllers for around $40. But their weak
> point will be whether the controller can deal with only 13-ish volts on
> the supply side. PV panels generate well above their rated 12V. The 48V
> array at home puts out about 100V open circuit! For an extra $50, the
> model charge controllers like Udo pointed you to will work great.
> There's another DC to DC model charger I've seen for $75 US. It will
> do Sealed Lead Acid.
> http://www.modelflight.com.au/rc_model_chargers/swallow_battery_charger.htm
> But it's in Australia.
>
> It's great to get our electric power from the sun. Like centering a
> nice thermal.
> Jim
>

[JS]

bumper wrote:

> An MPPT controller can gain
> as much as 30% more battery charge current from a given PV panel.
>

Their 3W MPPT controller is only 70 bucks. A good deal.

[bumper]

For anyone ordering these, their "stock" models come with the LED status
lights in the box, mounted with hot melt glue on 'em. Not very useful for
the typical glider installation as the box will likely be buried behind the
instrument panel somewhere.

If you call them, I believe they will install the LEDs with longer leads.

bumper
"JS" > wrote in message
oups.com...
>
> bumper wrote:
>
>> An MPPT controller can gain
>> as much as 30% more battery charge current from a given PV panel.
>>
>
> Their 3W MPPT controller is only 70 bucks. A good deal.
>

[[email protected]]

The combination of a 12V inverter and 120VAC battery charger need not
be inefficient - it is dependent upon the efficiencies of the two
parts.

I am charging my batteries using a solar panel and voltage regulator.
Usually, I can recharge the batteries after landing using the remaining
daylight. If not, it easily recharges in the morning. I use this
combination of solar panel and regulator:

Affordable Solar
PO BOX 12952
Albuquerque, NM 87195-0952

800.810.9939 Toll Free
505.244.1154 Direct
505.244.9222 FAX
Web: www.Affordable-Solar.com
"Independence You can Afford"


Name Code Qty Each Options
------------------------------------------------------------
Morningstar SunSaver 829 1 69.00
10L-12V Charge Controller
SunWize OEM20, 20 Watt 1142 1 165.00
Solar Panel
Subtotal 234.00
Shipping 25.20
Tax 0.00
Total 259.20

[5Z]

Any thoughts about putting one of these between the storage battery and
a charge controller?

http://store.l-f-l.com/prod/DC-DC-ADAPTER/51F1439494-

What would be the best voltage setting?

-Tom

[[email protected]]

I assume you are talking about charging your glider battery from a
storage battery, which you charge with a solar panel during the day.
This would probably work with the solar charger I mentioned, but I
offer no guarantees (there is nothing obviously wrong). I would NOT use
this without a charge controller, however. I would experiment with
output voltages to find which one was most efficient. To do this you
will need to measure both discharge current from the storage battery
and charge current into the battery you are charging. You probably can
use 18V safely. Be sure to measure voltages at both batteries to sure
something isn't going wrong (the battery under charge shouldn't measure
more than 15V unless it is cold (I did this when it was 26 deg and it
measured over 15V).

Tom Seim
DG-400
Richland, WA

[5Z]

wrote:
> I assume you are talking about charging your glider battery from a
> storage battery, which you charge with a solar panel during the day.

Yes. Basically, I want a setup that looks like:

a) Solar panel
b) Charge controller
c) Storage battery
d) charge controller
e) Glider battery

I currently have (a) & (b) rated at 12v. So in my case, I need a
solution for (d) that does 11v+ -> 12v SLA charge.

For $100 I can get a fancy model charger with lots of extra options,
but it will do the job.

For a bit less than $100 I can get the car adapter/voltage booster and
a regular charge controller. Two boxes, but maybe a little more rugged
than the model charger. Since I have 2 batteries in the glider that I
now alternate using/charging, this may be the best solution, as at a
later time, I can get a 2nd controller to keep both batteries topped at
all times. Since I use the batteries one at a time, I prefer to have
an independent charger on each instead of just charging them in
parallel.

If I were starting from scratch, I think I'd set up a 24v storage
system using 2 car batteries or large SLAs. Then use the 24v to drive
a 12v charge controller for the glider battery.

-Tom

[Eric Greenwell]

5Z wrote:
> wrote:
>
>>I assume you are talking about charging your glider battery from a
>>storage battery, which you charge with a solar panel during the day.
>
>
> Yes. Basically, I want a setup that looks like:
>
> a) Solar panel
> b) Charge controller
> c) Storage battery
> d) charge controller
> e) Glider battery
>
> I currently have (a) & (b) rated at 12v. So in my case, I need a
> solution for (d) that does 11v+ -> 12v SLA charge.
>
> For $100 I can get a fancy model charger with lots of extra options,
> but it will do the job.
>
> For a bit less than $100 I can get the car adapter/voltage booster and
> a regular charge controller. Two boxes, but maybe a little more rugged
> than the model charger.

What's not clear is that the output of the adapter is compatible with
the charge controller, since the adapter is likely to have output
characteristics much different than the solar panels the charge
controller is designed for.

> Since I have 2 batteries in the glider that I
> now alternate using/charging, this may be the best solution, as at a
> later time, I can get a 2nd controller to keep both batteries topped at
> all times. Since I use the batteries one at a time, I prefer to have
> an independent charger on each instead of just charging them in
> parallel.
>
> If I were starting from scratch, I think I'd set up a 24v storage
> system using 2 car batteries or large SLAs. Then use the 24v to drive
> a 12v charge controller for the glider battery.

This seems like a good scheme. Can't you switch over to it for a small
extra cost? Maybe sell your present panel to another pilot, or some such?

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[[email protected]]

I don't agree with that assessment. The step up converter has a
regulated output, driving the charge controller which will accept a
broad range of input voltages. Remember, a solar panel is modeled as a
battery with a series resistance; a regulated power supply is modeled
as a battery with a very small series resistance.

Tom

[dumass]

Does anyone have suggestions for a good (i.e good quality and good price) solar panel supplier for the charge system ?
Did anyone do calculations for required panel size ?

[[email protected]]

See my earlier post.

Panel size = charge rate
Charge rate (max) = battery size
Battery size = go look in your glider

Tom

[Eric Greenwell]

dumass wrote:
> Does anyone have suggestions for a good (i.e good quality and good
> price) solar panel supplier for the charge system ?

This is the panel and vendor I used for the panel mounted on my trailer,
and it seems to be good quality.

http://www.batterymart.com/battery.mv?p=VDC-SCC015

Amorphous construction panels, like this one, are typically much cheaper
than the crystalline panels. They are also physically larger per watt,
but generally this isn't an issue when mounted on a trailer or placed
next to the glider at a tiedown.

> Did anyone do calculations for required panel size ?

For an estimate, try this for estimating the minimum panel size:

[charging amphours required] = (your typical current drain) x (your
typical flight duration)

[hours of sunlight] = number of hours the panel will have for charging
the battery, including the hours after you land and the hours in the
morning before you take off.

[solar panel current] = amphours / (hours of sunlight before your next
flight)

For my glider:

..7 amps x 6 hours = 4.2 amphours
1 hour after landing + 4 hours in the morning = 5 amps (summertime)
4.2/5 = .84 amps

I have a 1 amp, 15 volt panel (also known as a 15 watt panel). I also
have a huge battery, so I don't have to have a full charge every day,
otherwise, I'd have a bigger panel.

Notes:

1) "Hours of sunlight" means any time the panel is out and charging, but
not the first or last two hours of the day when the sun is weak.
2) You have to align the panel with the sun every few hours to use the
calculated value.
3) If you don't want to re-align the panel with the sun, or it's mounted
on a trailer, or you want to charge during days with 50% or more cloud
cover, get a panel twice the size.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA