🚀 go-pugleaf

Ramesh, the effort you're making to answer criticisms of this product
seems to show that you sincerely believe that the solar charger is
useful.  However, you clearly don't know anything about electricity
or about batteries, and Durell isn't providing the information you need
to understand what it is and is not capable of.  This could be because
you're talking to non-technical people at Durell who also don't understand
the device's limitations, or it could be because they are telling you
only the good side of the story and deliberately ignoring the weaknesses.

No matter where the misunderstanding is coming from, a device with the
specifications you listed simply won't do most of the things you say it
will.

First, some background information (obtained from battery data books):

1. Lead-acid batteries do slowly lose charge over time as they simply
   sit there, neither being charged or discharged by an external
   device.  This phenomenon is known as "self-discharge", and is
   probably what the marketingese phrase "internal loss of power"
   refers to.

   However, self-discharge is very slow.  At room temperatures,
   a battery stored on a shelf needs to be recharged once every
   6 months to keep an acceptable charge level.  In automotive use,
   if you start your car just once a month and drive it for a while,
   you don't really need an external charger of any type.

2. For batteries that are very seldom loaded but which must remain
   at full charge indefinitely (i.e. emergency lighting batteries),
   it is possible to use a trickle charger.  This supplies a small
   current continuously to compensate for the battery's internal
   self-discharge.

   For a 50 Ah (ampere-hour) battery, which is about the size of a
   typical car battery, the Mallory battery databook states that an
   appropriate trickle charge rate is 100 to 250 (C/500 to C/200 rate).
   This rate will also return a partially-discharged battery to full
   charge over a very long period.  But remember that this is 100 mA
   supplied continuously, 24 hrs/day.

   The solar charger is rated to put out 40 mA under optimum conditions.
   Since it's dark half the time, and there are clouds sometimes during
   daylight, and the charger doesn't rotate to track the sun, I doubt
   if the charger's average output over the long term is more than
   10 mA.  An average charge rate of 10 mA is enough to slow down the
   battery's self-discharge, and it might even hold the charge state
   constant under the right conditions, but it is so far below even
   the recommended minimum trickle-charge rate of 100 mA that it is
   unlikely to ever put significant charge into a partially-discharged
   battery, no matter how long you wait.

Now, let's look at some of the claims that Ramesh makes:

>The figure of 40 mA is right.  The unit is a trickle charger.  It is
>designed to be used in a fashion where you could leave it connected when
>the car is not being driven. The charger shall maintain the level of battery
>charge constant all the time and also help prevent internal loss of power.
>The purpose of the unit is to replenish the naturally discharged electricity.

This is consistent with the charger just overcoming self-discharge.

>Question No. 2
>--------------
>The claim that the solar charger will jump start the battery in seconds
>is false.
>
>Answer 
>-------
>The term "within seconds" was used only as a phrase and does not imply
>in any sense whatsoever that it will jump start the battery in 1 or 2 or
>3 or ... seconds.  However, if the charge level of the battery is not
>very low, yes it will jump start it in a "reasonable period of time."
>( this is a function of the level of the battery charge  )

To "jump start" a car, you connect it to a second battery or other high-
current power source.  Ideally, the source can provide several hundred
amps, sufficient to start the car while the car's own battery is still
discharged (e.g. another car's battery).  Less ideal but still workable
is a source that can provide on the order of 50 amps - not enough to
start the car directly, but enough to charge the car's own battery
to the point where it can start the car in a few minutes.  Another
car's alternator will do this, for example.

If you have only a 10-amp battery charger, you could also connect it
and wait a half hour or an hour, which might put enough charge back into
the car's battery to start the car.  But this could hardly be called
"jump starting", because of the long delay.

The Solar Charger's output is a factor of 1000 below what is necessary
to jump start a car.  It is so low that it is unlikely to be able to
significantly charge a discharged battery at all, even given a year.
This is not a "reasonable period of time".  Saying that this charger
can jump start a car or a battery is ludicrous.

>Question No. 3
>--------------
>The claim that the charger will prolong the life of your car battery
>indefinitely.
>
>Answer
>------
>Durell International claims that this is true, provided you use it in 
>a particular way. If you leave the charger connected, even when your car is 
>parked and not in use.  The panel will trickle charge your battery 
>continuously thus helping maintain a constant level all the time.  It will 
>also help prevent internal loss of power.  Automatic cut-off will help 
>prevent over-charging your car battery.  The unit also has three built-in 
>solar cells that will help at dusk / evening times.

A slow trickle charge can prolong the life of a battery that is otherwise
unused, if you don't want to charge it periodically.  It would be useful
for any vehicle where the engine is not started for months at a time.
It's also useful if you drive your car for very short trips, not long
enough for the battery to be fully recharged after starting.

But for any car that is driven for a reasonable period after each
start, the battery is being fully recharged anyway.  The life of a
battery in such circumstances depends on how often and how deeply it
is discharged.  The solar charger will not change this in any significant
way, and thus I can't see how the battery life would be prolonged any.

>COUPLE OF SCENARIOS WHERE THIS CHARGER COULD BE USEFUL
>------------------------------------------------------
>
>1. You go to work on a very cold morning.  Its freezing.  Its sunny.
>   [ ... ]  At the end of the day's work,  when you are ready to go home,
>   your car just doesn't start.  It was very cold all day throughout.
>   So you call a tow truck and have your car battery jump started.
>   [ ... ]
>   How could you have avoided this situation using the solar charger ?
>   --------------------------------------------------------------------
>   Well, when you left your car in the parking lot and were headed for
>   work,  you could have left the charger connected.  What this will do
>   is continuously trickle charge your battery thus keeping the charge
>   at a constant level.  That way, when you came back from work,  your
>   car would be ready to start.

If it's so cold you car doesn't start with a fully-charged battery,
the solar charger won't help.  If your battery is old and has lost some
of its capacity, the solar charger won't help.  If the battery is OK,
but your alternator isn't working properly and isn't recharging the
battery, the solar charger *will* help - but it probably won't put enough
charge back into the battery in one sunny day to compensate for the
amount used in starting and driving.  And you'd better get your alternator
fixed before the next cloudy day anyway.  If your drive to work is so
short that the battery never gets fully recharged, the solar charger
may help a bit.

>2. Similar to above, but lets say the weather is fine.  However, when you
>   left your car, you forgot to turn off the lights.  Again, if the 
>   charger were connected, it would continuously trickle charge your
>   battery and so when you return, you car would be ready to start 
>   even if the lights were on for a long, long period.

Rubbish.  A pair of headlights left on draws 8-10 A.  To keep the battery
charged, the charger would have to supply the same amount of current.
A 40 mA charger would just slightly increase the amount of time required
before the battery is discharged - by about half a percent.  If it takes
4 hours for the battery to go dead. having the solar charger attached would
extend that time by about 1 minute.

Remember, 40 mA at 12 V is less than *half a watt* of power.  Leaving
just one light bulb on in the car (e.g. dome light, glove compartment light)
is enough to consume all of the power produced by the charger, and take
power from the battery as well.  The charger just doesn't have enough
output to provide any significant protection against this.
  
>   To the extent you use the charger as designed, it would actually
>   virtually ( notice, I say, virtually ) eliminate the need for a tow
>   truck or jumper cables.  Your car battery charge level will always
>   be constant.  This would also improve the functioning of air-conditioner
>   and other units in the car.  

As noted above, this charger provides no useful jump-starting capability.
You need jumper cables as much (or as little) as you did without it.

The air conditioner only requires power when the engine is running.
The alternator on the engine can supply 50-70 A of current, generally
enough for all electrical loads.  Even if it can't supply enough,
the output of the charger is 1/1000th the alternator's output, and
won't make any detectable difference.


Ramesh, I'd suggest that you learn something about electricity and
batteries before you start making claims about solar battery chargers.
The device would actually be useful to some people under some circumstances,
but when you post an ad that makes so many claims that are obviously
untrue, you lose all credibility.

	Dave Martindale