Strange behavior of mintyboost

[Oby One]

If i remember correctly this chip has a max input of 6 volts.
These Ni-Mh are just temporary and my main batteries will be a li-ion with 1.5V
While the 1.5 is the nominal voltage... when they are fresh they will have more... so overshooting the max limit of the lt1302 chip.
Am I correct?

However... this doesn't explain the weird behavior of my mintyboost.
I tried again this night... and even with the two additional diodes it has the same graphic for charging.
It starts very slowly to charge... and then it discharges my phone.
WHy??????

[adafruit_support_bill]

These Ni-Mh are just temporary and my main batteries will be a li-ion with 1.5V

Yes, 4 of those in series would be risky, but 3 in series would work very well with nothing wasted in keeping your diodes warm.

However... this doesn't explain the weird behavior of my mintyboost.

But you say that MintyBoost is putting out 5v as designed. Your phone is likely interpreting the state of the usb data lines to determine the charge mode. I don't have any experience with the htc phones and their charging protocols.

[Oby One]

Htc is sensing the usb/ac connection via the data lines.
If the data lines are free(not connected).. it believes that is has an ubs connection and only gets 500ma from mintyboost.
If the datalines are in short... the htc will think that is has an AC wall charger connection and it will get 1000ma.
I already tested this and I know it is true.

I will test tonight ,after my phone is empty again, in this way:
I will disconnect the battery pack from the mintyboost and connect instead the USB Li-Po Charger.
(that charger works ok ....and I have tested it already)
So I will provide a steady constant 4.2 V to minty boost.
If my mintyboost is constructed ok and it has no problem with its circuitry then it will charge my htc desire battery without a problem.
Correct?

[Oby One]

As for your recomandation to use a serial 3x batteries.
I have read successful stories here on this forum from people that have used 4x batteries or htc desire.
I have no doubt that I will be able to make mine work OK... it's just a matter of time and of understanding what is wrong.

I needed this mintyboost+ its solar pack ..because I go very often into the mountains and do geocaching or just mark my track via gps. Two times in my life I survived because of my phone.... and in both occasions the battery was almost depleted
As you know the gps consumes a lot of power so my phone becomes unusable very fast.
As my life and my well-being depends on this phone and its mintyboost companion ..... I need to be sure that I have a relaible power source.
I am thinking to use nothing less than 4x .... or maybe even 6x batteries so I would very much appreciate your guidance.
Thank you!

[adafruit_support_bill]

As my life and my well-being depends on this phone and its mintyboost companion

I hope you are carrying a map & compass too. I love my electronics, but I never go into the back-country without the "10 essentials" http://www.survival-center.com/dl-list/dl11-ess.htm

I have no doubt that I will be able to make mine work OK... it's just a matter of time and of understanding what is wrong.

The MintyBoost is a relatively simple device. It will supply 5v at up to 500 mA - provided that it has sufficient battery voltage and current to do so. The real question is what does the phone do with that output. If your phone attempts to draw 100 mA, the MintyBoost voltage will sag. How your phone deals with that is anybody's guess. (My iPhone 3G would go into a mode where it would not accept a charge from ANY charger until I re-booted it.)

Your best bet is to make sure you have a battery pack with sufficient voltage and current capacity to allow the boost chip to operate efficiently. And check with other users of the MintyBoost and htc phones about how they have the data lines configured.

[Oby One]

of course I go with the map and compass.. in certain situations due to a cloud descending on the top of the mountain... or very dense snow or other bad/extreme whether situations... the visibility drops to a few meters.... and it's impossible to orient yourself just using map/compass.
Not being able to point myself on the map...and visually see the route I may get lost.... remain without food,water, resources. Once I was almost to fall from a cliff because the visibility was less than 3 meters.
So in this cases I use the gps with the map.... and everything is Ok....as long as I have battery
Here comes the mintyboost in picture...

Until I do the test with the usb Li-Po charger tonight... tell me a simple/efficient way to put 4x or 6x batteries without loosing half of the actual power through the damn diodes.

[Oby One]

I will test tonight ,after my phone is empty again, in this way:
I will disconnect the battery pack from the mintyboost and connect instead the USB Li-Po Charger.
(that charger works ok ....and I have tested it already)
So I will provide a steady constant 4.2 V to minty boost.
If my mintyboost is constructed ok and it has no problem with its circuitry then it will charge my htc desire battery without a problem.

Ahaaaa so it has a problem.
I tested as described above... and find out that even with the healthy/constant current from my Pc--->mintyboost ... the phone is still discharging.
So I must have done something wrong when constructing my mintyboost.
Please look at the first pictures I posted and try to find my mistake. I already checked again and didn't notice anything different from the instructions.

[adafruit_support_bill]

I will test tonight ,after my phone is empty again, in this way:
I will disconnect the battery pack from the mintyboost and connect instead the USB Li-Po Charger.
(that charger works ok ....and I have tested it already)
So I will provide a steady constant 4.2 V to minty boost.
If my mintyboost is constructed ok and it has no problem with its circuitry then it will charge my htc desire battery without a problem.

Hang on there. Just because the input is a steady 4.2 volts does not make it a good power source for the MintyBoost. The charger puts out a limited current (200mA I think) and the MintyBoost can't put out any more than what comes in.

You need to test with a real battery, and you need to be looking at the interface between MintyBoost and Phone.
What is the voltage output of the MintyBoost (while attached to the phone)
How much current is the phone pulling from the MintyBoost?

[Oby One]

Hang on there. Just because the input is a steady 4.2 volts does not make it a good power source for the MintyBoost. The charger puts out a limited current (200mA I think) and the MintyBoost can't put out any more than what comes in.

It should be good because it was used before with mintyboost by other users..

You need to test with a real battery, and you need to be looking at the interface between MintyBoost and Phone.
What is the voltage output of the MintyBoost (while attached to the phone)

4.0 Volts at the usb connection point.
1.49->1.5 Volts if you mesure the voltage at the supply point of minty boost
( see the picture )

How much current is the phone pulling from the MintyBoost?

500ma

[adafruit_support_bill]

It should be good because it was used before with mintyboost by other users..

Without batteries?

Not surprisingly, with a current limited supply, the output voltage sags. Now try it with batteries.

[Oby One]

ouu. correct
With the li-ion battery I have a voltage of 3.9 V at the input and 5 volts at the usb connection point.
The phone seems to be charging...

So the problem should be in the diodes or battery pack.
I think the next stage will be to try to power the mintyboost with the 4x NI-Mh battery pack but not using the diodes.
Correct?

[adafruit_support_bill]

I think the next stage will be to try to power the mintyboost with the 4x NI-Mh battery pack but not using the diodes.

That sounds like a good plan.

[Oby One]

Is it safe to run them without the diodes?
The batteries should be identical... but I measured different voltages in each of them( not a big difference).
Being rechargeable I shouldn't worry if some current is transfered between them.
Correct?

[yeoj4151]

I wouldent be worried about it. Everyone else on the fourms says "oh my gosh you can do so much damage", and you can if you have one are dumb, or mistaken and have one set of batteries compleatly dead and the other set charged. But if both sets are charged your fine. There shouldent be any problems.

[Oby One]

Please take a look at the bellow graph.

I started the test at about 1:30 with the battery at about 33%
The 4xNiMh where charged perfectly and mounted without the diodes.All the voltages I checked were OK.

So in Zone A you may see the phone correctly charghing until about 4:30..
in Zone B the charge from the mintyboost seems to have stopped and now the phone is constantly discharging until 8:30 in the morning when I woke up and disconnected it from the mintyboost.
In Zone C you will see the phone not discharging.... or doing it very slowly.
In Zone D I decided to connect the mintyboost again .....and noticed the same rate of discharge.... leading me to believe that the mintyboost is actually discharging my phone when connected.
In Zone E you may see that the discharging of the phone stopped because I again disconnected the mintyboost.

After this very clear analysis, please tell me:

1. Why does the charge from a freshly charged 4x NiMh 2500mah batteries is not enough to charge 50% of my idle (Htc Desire with 1300 mah battery)

2. Why the phone is rapidly discharging when connected to mintyboost? (as you can clearly see in zone B and D)

3. How can I repair this incorrect behavior of my mintyboost?

Thanks.