Strange behavior of mintyboost

[oby_one]

schema2.jpg (34.56 KiB) Viewed 2596 times

I know for sure that the phone is taking 5V and 400ma from the mintyboost...
that has been measured by me many times and it is 100% true .

We can say that the phone is consuming 2W while charging.

If there was no need for mintyboost... you could say that I was drawing 2W from the battery pack.


Howerver there is a mintyboost and it was an efficiency of about 83% at 5Volts.
So I calculated that it will take another 0.34W from the battery pack.
That means I should have a current consumption of about 0.5Amps.... far far different from the actual 1.18 Amps I have now.

[Snipeye]

First off, you've been rather rude to both adafruit and arduwino, and while I can't force you to apologize or anything, I would like to point out that they're only here to help, and getting angry and/or rude at them solves nothing.

Second, this quote:

I understand what you say about my phone power consumption when charging. However the tests I have done shows that that idle power is very small. it doesn't quite matter in this equation.

I also understand (and know) very well what you say about actual battery power. Howerver this is not relevant .. because my mintyboost is drawing to much power out of them anyway. It should suck way less.... like 0.6 Amps.. not 1.18 as it is doing now.( also check oPossum's table)

The problems are very clear ( seems that only in my opinion) :
1.that mintyboost is consuming way to much power from the batteries
2.The consumption graph is in reverse.... it means it is consuming way too much power at 5V ... and way too less at 3V.... it should be the opposite..

Please consult oPossum's table that shows the correct comportment of a mintyboost.
After you consult both his and mine, you will notice the problem more clearly.

I see that you're expecting 0.6 Ah draw on the battery pack running at 4.8v, correct? Unfortunately, I was unable to find an input voltage vs efficiency graph on the datasheet, however I know that as the input voltage nears 5v, the efficiency decreases. For the sake of simplicity, we'll state that at 4.8v, the lt1302 attains 90% efficiency (it's probably worse). The next thing to consider is current draw: Even at ideal input voltage, roughly 3v, efficiency at 500mAh is only 86% - 86% of the already 90% efficiency, leaving us with about 77% efficiency. Now, 4.8v multiplied by what YOU expect the current draw on the batteries to be, .6Ah, gives us 2.88Wh. 2.88Wh*77% efficiency = 2.22Wh, which at 5v = 444mAh, at best. Now, if your phone tries to draw OVER 500mAh AT ALL, the efficiency of the lt1302 drops even further, and as the temperature of the lt1302 increases due to poor efficiency, the efficiency worsens even further.

I would suggest:

1. Getting your battery pack as close to the idea voltage as possible - I'm not 100% sure what that is right now, though I believe it's somewhere around 3, 3.5v. This will help to increase the efficiency of the mintyboost.

2. Test the mintyboost with a different device - if it charges just fine (which is the case with every single device I personally have ever tried to charge with it) then it's NOT THE MINTYBOOST'S FAULT. Your phone probably activates some 'charging' mode when plugged in, where it stops 'caring' about current draw on it's own batteries - as would make sense if it were plugged in to a wall. When plugged in to the mintyboost, however, as soon as the batteries on the mintyboost are unable to meet the current/voltage demands of the lt1302, and the efficiency decreases, blah, blah, the lt1302 CANNOT provide enough current, and even though your phone still thinks it's charging, it fails to replenish the battery it's using, leading to a discharge. Adafruit and arduwino stated earlier that 50% is a commonly-reported charge rate with the mintyboost and your particular model of phone. If average isn't good enough for you, design your own circuit.

Fact of the matter is that arduwino and adafruit both went out of their way to accommodate you - they offered you a refund without you returning the product. For FREE. They cannot do more than they have done. The lt1302 the mintyboost is based around simply IS NOT CAPABLE of performing better. If it matters that much to you, get a phone that the mintyboost better supports, or TAKE THE REFUND THEY OFFERED YOU AND DO LITERALLY ANYTHING YOU WANT WITH YOUR MINTYBOOST - for pete's sake, you could smash it with a hammer at NO loss to you except the time you wasted because you weren't satisfied with what most people were able to get out of the mintyboost under the same circumstances you are.

Sorry if I seem a little PO'd, but when I see somebody dissing on people like adafruit - the kind of person who has done so much for the opensource community and electronics hobbyists/enthusists - even after receiving all the help she has to offer (and then some, from other sources) AND dissing on the community here, which includes me (with your comments like "the problem seems clear to ME", (as if you were somehow better than all of us)) I get a little PO'd. I feel that you were dealt with in a very professional and sincere matter, but you just wouldn't let it go. You were offered a complete refund, that's as good as it's going to get.

[oby_one]

Fact of the matter is that arduwino and adafruit both went out of their way to accommodate you - they offered you a refund without you returning the product. For FREE. They cannot do more than they have done. The lt1302 the mintyboost is based around simply IS NOT CAPABLE of performing better. If it matters that much to you, get a phone that the mintyboost better supports, or TAKE THE REFUND THEY OFFERED YOU AND DO LITERALLY ANYTHING YOU WANT WITH YOUR MINTYBOOST - for pete's sake, you could smash it with a hammer at NO loss to you except the time you wasted because you weren't satisfied with what most people were able to get out of the mintyboost under the same circumstances you are.

Sorry if I seem a little PO'd, but when I see somebody dissing on people like adafruit - the kind of person who has done so much for the opensource community and electronics hobbyists/enthusists - even after receiving all the help she has to offer (and then some, from other sources) AND dissing on the community here, which includes me (with your comments like "the problem seems clear to ME", (as if you were somehow better than all of us)) I get a little PO'd. I feel that you were dealt with in a very professional and sincere matter, but you just wouldn't let it go. You were offered a complete refund, that's as good as it's going to get.

It is now clear to me that we have very different views about the same subject. This might happen due to a different style in thinking, communication, environment. I know this because I have asked some of my friends to read this thread and they all agree with my opinion.
When 2 people see the same apple in two different colors, it should be a gentlemen agreement to agree not to agree, it's not wise to continue the discussion anymore, so after this post I will stop.

Just for you to know, I don't consider being rude to arduwino or adafruit, I was mad at them for not providing any real help but not rude. Were you considered that I have received help, I consider to receive almost none because nothing involved actually debugging the device.

You keep saying about the refund. It is a good option and I am grateful for it but it is not what I want. I wanted just a simple simple thing ...and that is to charge my phone on my long & dangerous mountain trips.

(with your comments like "the problem seems clear to ME", (as if you were somehow better than all of us))

That statement was put in the post because everytime I felt I explained the problem with 100% clarity, It didn't reach the target....
It is not a problem of me being better then anybody.... it is a problem of communication and the hard task of transmitting clearly one piece of information. ( here I failed miserably)

The thread got to diluted and information from previous posts didn't make it into readers fresh memory. many of the statemes or possible problems... or incertitudes were explained by me in older posts.. but nobody is remembering them. While I don't expect anybody to memorize my thread.... you can imagine how I feel when I am asked 11 times what is the voltage of my power source... or how does my phone do the charging.... and so on.

This thread goes nowhere as I can see so I will stop it here. Just don't delete it ... maybe other readers will have something to learn from it.

Once again I appologize to arduwino and adafruit if they felt bad because of me, trust me it was not my intention, it is a different approach on problems... caused by different cultures.
Sorry!

sorry.jpg (5.33 KiB) Viewed 2580 times

[Snipeye]

If there's one thing that can bring Americans and Europeans together, it's lolcats. I apologize for my extremely rude post, I'd like to explain it away, but even justification would be an insult to your kind apology. Good luck with your mintyboost, and I would suggest testing it with other devices to see if it's the mintyboost or your phone.

[chronoverse]

I saw this in my situation too. With no load, the V(D-) = V(D+) = 1.97V and V(out)=4.97V, this looks fine. The unsettling part is that input current is 0.01A, with no load. This is the lowest number on my Fluke 73 and it does not seems right. When I first use the unit right after the assembly, the chip turned very hot. It has not been that hot ever since.

I am willing to un-solder a few parts to check if any one got burned. Which one I should pick first?

[adafruit_support_bill]

Hi Chronoverse. Best to start a new thread for this and post photos of the front & back of your Mintyboost.

[Donziboy2]

Edit.
Reread a large portion of this thread.
One thing I should mention about NIMH batteries is there rated mAH is not always correct. If you pull large currents from them quickly they have a habit of dying far faster then if you pulled less over a longer period.
They also take a few charges to normalize all batteries in a group.
Also most manufacturers will give you a padded number greater then what can be achieved.
End Edit....


The LT1302-5 as used in the mintyboost is designed to step up low voltages to 5v. The problem is that the closer to 5v you get the less efficient they are, anything above 4.6v and these thing leak power like there is no tomorrow. The second problem is your using 4 NIMH batteries. Yes they say 1.2v but they can get close to 1.45v fully charged. If you have run the LT1302-5 above 5v for any amount of time you have probably damaged it.
Try going down to just 3 fully charged batteries. If that does not fix the issue then there is a damaged component in your minty, most likely the LT1302 itself.


I spent a week researching and designing my own LT1302-5 minty with a solar cell and a 3battery pack with a relay coil charge controller, I found that the only way to safely go above 5v at any time was to add a 10 ohm resistor as shown in the LT1302 data sheet, the problem is that the resistor just burns off the extra power, so I opted for 3batts instead of 4 in series.

[john444]

Hi Donziboy2,

I only picked up on this thread today so there is probably no opportunity to address Oby One’s questions. You make some good points and for those like myself that are interested in these things, here are some comments:

These were three good points made by others:
1 Oby One’s phone is consuming current as the minty-boost is trying to charge the phone battery. This is leaving less current available to charge the internal battery.
2 The phone charge configuration seems to be asking for more than the Max756 can provide. This is causing the minty’s output to be low resulting in lower effeciency.
3 The phone does not revert to a low-power mode when minty’s cells are dead but still connected.This causes Oby One’s phone to discharge the internal battery faster that it should.

There are a couple of fundamental issues that seemed to have been overlooked during the earlier discussion.

#1 - It is unrealistic to rely on the manufacture’s cell ratings for widely varying conditions. The cell rating is the 'discharge' rating for the cells.

#2 –Oby One was confusing the 'discharge' rating of the phone’s battery for the 'charge' rating. The charge rating for cells is much worse than the discharge rating. This means it takes much more current for a longer time to charge than to discharge cells. Charging batteries (regardless of type) is not very efficient. A reasonable expectation is to put in 2x to 4x what you pull out.

#3 - The voltage converter (minty boost) does add its own losses to the system. However, these losses are small in comparison to the cell losses.

[marilenc]

I have mintyBoost v3 and I also noticed the strange discharging with a HTC Desire phone. After some measurings and looking at the boost converter specs. If you look at the converter efficiency diagram you see that at lower input voltages the randament decreases very fast as the current is higher. Thus as the batteries discharge under a certain value the randament goes very low since the phone draws a high current, even in usb charging mode. I improved somehow on the situation with a 3xAA setup and by creating an app which monitors the charge and emits a high sound when (if) the phone is discharging. Search for mintyCharger in the Android Market, if it might help.