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Model Forum / Radio Controlled / Air Models / April 2007



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Electric Tote/Field box options and charging lead batteries?

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markm75 - 20 Apr 2007 16:00 GMT
I've narrowed down my choices to these two totes.  I will be doing the
charging of Lipos too.

I'm trying to eliminate carrying TX cases and jump start batteries
(for charging at the field) combined with the chargers etc.. an all in
one solution (though in some cases where i'm in a hurry and not going
for long, i will probably just throw the TX in a single TX field case
with the batteries and go)..

Here are the two I've found:

ElectroTote:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXLXB5&P=FR  $54.99
The dimensions on tower hobbies are wrong and can be found here :
http://www.carlgoldbergproducts.com/electrotote.htm   (22 by 9.5 by
14.25)

Ultra Tote:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJBU2  (18.6 L, 9.1
W, 12 H)

It appears they both support 2 chargers.. but the Ultra tote is a bit
smaller (better in my case with a 2 door car and often a stroller in
the trunk plus a big 54" plane (in pieces)) or so i think.

I guess to really do 2 chargers with the electro tote I would need to
not use a power panel (which i have) and go for a TritonJr?  IE:  i
will now be using a lead acid 7ah battery for charging, but to charge
that battery I have a 600mah AC wall adapter with alligator/leads on
it.. those leads plug into the power panel and then charge the lead
battery if I'm right.  But.. does the TritonJR have inputs to do
this.. it says it can charge lead batteries but I dont see how,
without those inputs?  I only see outputs.

My current charger is a CellPro 4s.. it will charge the Lipos until i
replace the power panel with a Triton JR (?)..

The Electro tote offers a fan to cool the lipos while they charge (is
this really needed, vs making sure its ventilated)?

The ultra tote doesnt have a fan, but I should still be able to charge
the lipos in a compartment on the unit.

In either case.. I am going to line the lipo charging compartment with
ceramic tiles which should make things safe should they catch fire.

Any thoughts on charging of the lead batteries with a TritonJr vs
power panel and the need for a fan?

If the fan isnt really that important then I'm leaning towards the
smaller Ultra tote as of now :)

Thanks
Fubar of The HillPeople - 21 Apr 2007 21:09 GMT
Does it have to be an actual "Flight box"? A couple of years ago I went to
Orchard Supply Hardware and purchased a plastic stacking toolbox with
wheels.  In the bottom I installed a Die Hard lawn tractor battery. I had a
second 7Amp flight box battery installed also but removed it later.
I mounted several pairs of power outlets (banana plug type) into the side of
the box to allow for multiple chargers to be used at once.
The box has enough room with the different stacking trays to carry chargers,
various leads and adapters, flight packs, tx, video receivers, small B&W 12v
TV, butane soldering pen, and plenty of other crap.

Signature

Dan
AMA605992
KE6ERB
http://www.fubar1.net
"I've heard the screams of the vegetables..."
Take out the "trash" to reply

> I've narrowed down my choices to these two totes.  I will be doing the
> charging of Lipos too.
[quoted text clipped - 49 lines]
>
> Thanks
markm75 - 22 Apr 2007 02:48 GMT
On Apr 21, 4:09 pm, "Fubar of The HillPeople"
<fub...@trashsocal.rr.com> wrote:
> Does it have to be an actual "Flight box"? A couple of years ago I went to
> Orchard Supply Hardware and purchased a plastic stacking toolbox with
[quoted text clipped - 5 lines]
> various leads and adapters, flight packs, tx, video receivers, small B&W 12v
> TV, butane soldering pen, and plenty of other crap.

I'm not sure what ya mean by actual flight box?  For a 3200mah battery
pack (say 3.2 amps).. is it reasonable to assume that if completely
depleted (which lipos never are).. a 7amp battery (lead acid calcium)
would only be able to charge it about 2.1 times or so, but probably
alot more in reality? (Debating whether to go bigger batter or just do
a PSU and hook up to the car battery while the car is running.  I dont
really want to touch the car, but I'm not sure, I'm also thinking i
probably wont charge more than maybe one or two times at the field
anyway)

I ended up picking up the Ultra Tote, as its smaller and i figure i
can line one of the drawers with ceramic tiles for fire proofing the
drawer that ill use to charge the lipos in at the field or at home on
the kitchen counter.  I'm also betting i can easily throw a fan in
there to keep things from getting hot in the sunlight.

Cheerio
BCRandy - 22 Apr 2007 13:19 GMT
Why not save the drawer and just charge the lipo's outside
of the tote?  A small Pyrex bowl/measuring cup or a piece of
the foil backed insulation used to build furnace ducts can
safely hold the battery while charging.

> On Apr 21, 4:09 pm, "Fubar of The HillPeople"
> <fub...@trashsocal.rr.com> wrote:
[quoted text clipped - 45 lines]
>
> Cheerio
stone_axe - 22 Apr 2007 14:26 GMT
I've been looking at the same solution too.

For me, 20aH would be ideal for a field charger battery.

If you go the Tower route, you can do 2 7aH batteries and get 14aH fo
a decent price.

If you do the math though, 14aH ain't much.

The other question I have is how to properly keep the field box o
float charge so it is always at the ready

--
stone_ax
Robert Reynolds - 22 Apr 2007 14:51 GMT
> I've been looking at the same solution too.
>
[quoted text clipped - 7 lines]
> The other question I have is how to properly keep the field box on
> float charge so it is always at the ready?

Harbor Freight sells a float charger, #42292.
Morgans - 22 Apr 2007 20:13 GMT
> I've been looking at the same solution too.
>
[quoted text clipped - 7 lines]
> The other question I have is how to properly keep the field box on
> float charge so it is always at the ready?

To me, the gel cell batteries have such low self discharge, charge them
after you get home, and if you want that extra 1/2 amp hour, then you can
put it on charge a half hour before you leave.  Really, that is all it
takes.
Signature

Jim in NC

markm75 - 23 Apr 2007 16:53 GMT
> > I've been looking at the same solution too.
>
[quoted text clipped - 14 lines]
> --
> Jim in NC

Is it not safe to put a lead calcium battery on its say 600mah to
1000mah AC power adapter and let it trickle charge after fully
charged..

Are you saying the gel cell batteries are better suited for continuous
charging?
Morgans - 23 Apr 2007 23:42 GMT
> Is it not safe to put a lead calcium battery on its say 600mah to
> 1000mah AC power adapter and let it trickle charge after fully
> charged..

I would not consider 600 miliamps a trickle charge, at all, for a 7 amp hour
battery.  7 milliamps would be a trickle charge.

> Are you saying the gel cell batteries are better suited for continuous
> charging?

No, not at all.  You are not understanding what I am telling you, or I am
not understanding what you are asking.

It is safe to charge with an AC adapter, as long as you stop it after the
correct time.  Not continuously, at the rates you suggested, though.

That is the trick; knowing the correct time to stop the charge.  If you
guess wrong, overcharging it will kill it dead as a doorknob.  No joke.

If you charge it at one amp, and it is drained, it will take a hair under 8
hours.  Figure capacity x time, or a 7amp hour battery charging at one amp =
7 hours.  You need to add a little, around 10%, because no battery charges
completely efficiently.

Now, let's say your battery is not completely dead.  How much capacity is
left in it?  You have to guess.  If you guess it is half dead, and charge it
for about 4 hours at one amp, no problems.  If it was only a quarter dead
and you charge it for 4 hours, it has taken one more step into the trash
can.

That is why you need a float charger; so the charger can read how the charge
is progressing, and then stop the charge at the appropriate time.

I think there is still a problem with your understanding.  You do not need
to continuously charge it to keep it ready to use.  If you fully charge it
when you get home from the field, and let it sit for a month, it is not
going to be discharged enough to even be able to notice.  Really.  Even for
two or three months.  They hold a charge while sitting around, even better
than a car battery; much better.  If you want to put that last little bit
back in, put it on charge for a half hour, but not much more, or else you
are over charging it, and it has taken that first step into the trash can,
again.

Long to short, go buy a float charger, and keep from killing your batteries.
You will end up killing them (multiple batteries, if I remember correctly)
if you do not use a float charger.  Pretty foolish to save the 20 bucks or
less for the float charger, and instead buy twice as many batteries over a
period of time, don't you think?
Signature

Jim in NC

markm75 - 24 Apr 2007 04:38 GMT
> Long to short, go buy a float charger, and keep from killing your batteries.
> You will end up killing them (multiple batteries, if I remember correctly)
[quoted text clipped - 3 lines]
> --
> Jim in NC

Excellent point.  Reason why I asked in such a way was because here in
the house I will have my ultra tote with the lead acid battery and the
cell pro charger.. Someone in another forum said they charged their
lead battery while using the cell pro (off of the same lead acid
battery) safely and all the time, this way they could charge their
lipos in house and on the field have a fully charged battery ready for
action, perhaps he left out the fact he was using a float charger :)

I checked on the float mentioned before and yeah.. its only $7 plus
shipping.. very nice.

I wont be using a PSU to power the cell pro in house, hence all the
questions.. I'm trying to keep things as simple/ready for action as
possible.

So I basically wont need the existing charger I have.. the 600mah
one.. unless I need fast charging and I check the voltage periodically
to see if full (what would full be considered on a 12v battery.. ie:
13.50 volts etc?)  or use the formulas to guestimate at when its
nearly full etc.

Any idea how fast the float charger charges (i'm guessing over night,
like 14 hours full charge?)  The one from harbor freight doesnt list
many specs on it.
Although the speed with this one isnt really that important, as it
will just remain plugged in 24/7 pretty much, unless I take the box
out to the field.

Sorry for the misunderstanding.. I dont think I was fully explaining
my "vision" of things either.
Morgans - 24 Apr 2007 22:21 GMT
> So I basically wont need the existing charger I have.. the 600mah
> one.. unless I need fast charging and I check the voltage periodically
> to see if full (what would full be considered on a 12v battery.. ie:
> 13.50 volts etc?)  or use the formulas to guestimate at when its
> nearly full etc.

Good plan, with using the extra power to the battery, only when you have
high drain.  As far as what the voltage should be, I don't recall.  Perhaps
someone can jump in with that, or go over to Red's battery clinic and ask.

> Any idea how fast the float charger charges (i'm guessing over night,
> like 14 hours full charge?)  The one from harbor freight doesnt list
> many specs on it.

Perhaps up to two amps, but you could check it pretty easily.

> Although the speed with this one isnt really that important, as it
> will just remain plugged in 24/7 pretty much, unless I take the box
> out to the field.

I would not leave it on all of the time, as it could still over charge,
slightly.

Try charging it with the float charger, take it off the charge and check the
voltage a couple hours later.  Then wait a week and check the voltage.  I'll
bet it is high enough that you will not be concerned with having to keep it
on charge all of the time.

After you charge it, get a 24 hour timer, (and plug the charger into that)
and set it so it turns on once a day for one hour.  That will be plenty long
to keep it charged, and will not overcharge, that way.
Signature

Jim in NC

Doug McLaren - 24 Apr 2007 15:22 GMT
| It is safe to charge with an AC adapter, as long as you stop it after the
| correct time.

To be fair, that's true of almost any charger.  Even charging LiPos
with a NiCd charger is safe if you pick an appropriate charge rate and
stop it at the correct time.

The magic is in stopping at the correct time.  Alas, even if you can
do it 95% of the time, that still leaves 5% of the time that you ruin
your battery (and maybe start a fire.)

| That is the trick; knowing the correct time to stop the charge.  If you
| guess wrong, overcharging it will kill it dead as a doorknob.  No joke.

Well, it takes a lot of overcharging to burn off the electrolyte -- a
little won't ruin it, just damage it a bit.

| Now, let's say your battery is not completely dead.  How much capacity is
| left in it?  You have to guess.

No, you don't (have to guess.)  You can measure it.  Unlike NiCd and
NiMH cells, you can determine the charge status of a gel cell battery
by simply measuring it.

I forget the exact values, but I think it's around 13.0 to 13.5 volts
for fully charged and 11.0 to 12.0 volts for mostly discharged.
(These values are measured when the battery is not on a charger or
load.)  And it's pretty linear -- a voltage halfway between the fully
charged and fully discharged voltages indicates a battery that is
approximately half charged.

I'd have to take some measurements to know the exact values, however.

| That is why you need a float charger; so the charger can read how the charge
| is progressing, and then stop the charge at the appropriate time.

Yup, you want a float charger.  Or you can charge it with a charger
like the Triton, if you have another power supply for the Triton.

But float chargers are cheap.

| Long to short, go buy a float charger, and keep from killing your batteries.
| You will end up killing them (multiple batteries, if I remember correctly)
| if you do not use a float charger.

I also forget the specifics, but gel cells are somewhat different than
car batteries, and a float charger for a car battery may not be
exactly right for a gel cell -- I think they'll charge it slightly too
high.

Signature

Doug McLaren, dougmc@frenzied.us
"One in a million odds happen eight times a day in New York." -- Penn Jilette

markm75 - 27 Apr 2007 15:33 GMT
| That is why you need a float charger; so the charger can read how th
charge
| is progressing, and then stop the charge at the appropriate time.

Yup, you want a float charger.  Or you can charge it with a charger
like the Triton, if you have another power supply for the Triton.

But float chargers are cheap.

After reading around in other forums I am now confused on this whol
float charger or not concept..

Other forums say its perfectly fine to keep the 12v lead calciu
battery on an AC trickle charger (600mah on a 7amp hour battery
continously.. in fact, the local hobby shop had no idea what a floa
charger was and said that they always use the trickle charger even al
the time.

--
markm7
 
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