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Old Nov 30, 2005, 09:16 AM
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Twin Falls, Idaho
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Quote:
Originally Posted by bjpaul
Charles has given you the solution multiple times, just follow it.

Brad
And around and around we go!
rc
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Old Nov 30, 2005, 09:35 AM
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Proposed saftey change for ASTRO 109

Much has been made of the potential of the ASTRO 109 to bump the cell count when charging an already charged low series cell count (2S,3S) pack in stage 1.

The limiting factor has always been described as the microprocessor has no control over the current level set by the manual pot.

SO WHAT!!!! The microprocessor controls the duty cycle of the charge current. At present stage 1 it sends a 50% duty cycle to the pack, in stage 2 it is 59 seconds on, 1 second off, in stage 3 the duty cycle pulses get further and further apart.

WHY NOT HAVE THE MICROPROCESSOR IN STAGE 1 WHEN IT INITIALLY DETERMINES IT HAS A LESS THAN 4S PACK TURN OFF THE DUTY CYCLE?

That may be simplistic, but you could through testing apply different duty cycles that are appropriate without causing the low cell count series pack to jump a cell count, even if the pack was fully charged.

All in software.

Brad
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Old Nov 30, 2005, 10:37 AM
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All I have to say is that it is a good thing that laws are in place to stop people from smoking while fueling their cars at the gas pump. How many people do you see set the pump on and then walk away into the store or go wash the windows. I can not believe that we are expected to stand there while the gasoline in pumped! I would not go to a filling station that expects me to do that. What? Turn off the engine? LOL You guys great.
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Old Nov 30, 2005, 11:22 AM
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United States, CA, Norwalk
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Quote:
Originally Posted by bjpaul
Much has been made of the potential of the ASTRO 109 to bump the cell count when charging an already charged low series cell count (2S,3S) pack in stage 1.

The limiting factor has always been described as the microprocessor has no control over the current level set by the manual pot.

Brad
The problem is not limited to low cell counts. The Astro 109 can bump up to the wrong cell count with high cell counts as well.

To the best of my knowledge there are 3 things that can lead to a 109 bumping to too high a cell count;

Charging an already charged pack. It appears that a pack in good condition would have to be "topped off" more than once to cause this to occur, but this condition may become more common as more people transport all their batteries, charged and discharged, in battery bunkers or similar. The safest thing to do would be to check the batteries as you pull them out, and put them into a "charged" pile, and a "discharged" pile but, of course, many people just put them all on the charger, and those that are already charged only take a few minutes.

Charging at too high a current; This probably occurs most often when a person forgets to reset the current when going from a large pack to a small pack, but it could also be caused by just setting the wrong current.

Charging a damaged pack; It may be possible (I don't know for sure) for the voltage of a damaged pack to rise more rapidly than normal, causing the 109 to detect the wrong cell count in stage 1.


Quote:
Originally Posted by bjpaul
Charles has given you the solution multiple times, just follow it.

Brad
The solution given by Charles is a good one, and I wish that everybody would follow those instructions, but in fact, only a few people have even seen them. My concern is not for me since I don't own a 109, and I keep my distance from any 109 being used at the field. I'm also not terribly concerned about you guys, since everyone contributing to this thread is aware of the potential for their 109 to bump to the wrong cell count and start a fire. I am concerned for the other 99% of 109 users that aren't aware of this "feature". Most flyers don't participate in RCGroups, and even people who do don't necessarily check the Chargers and Batteries forum, so the vast majority of 109 users have not seen my repitative, whiny droning about this issue.

The direct cause of all "bump and burn" accidents using a 109 is failure by the user to follow the procedures outlined in the instructions, but if a simple change to firmware that does not adversely affect the operation of the charger could prevent 90% of those fires, what is your argument against implementing that change.

I am not willing to concede that it's okay to burn a man's house down because he is too lazy to read the instuctions, or too ignorant to understand them.


Dan
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Old Nov 30, 2005, 11:52 AM
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Haralson County GA. USA
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Approximately seven months ago I was contacted and asked for my suggestions (wish list) for possible changes to the 109.

Two of my suggestions were:

Quote:
I would like a momentary push button switch to enable jumps to stage 2 and stage 3.
This would eliminate the 3 minute wait for stage 2 to start which some seem to hate and would also make stage 3 easily available for very slow charging ,as in over discharged cells.


Quote:
I would prefer a locking pot or one which you pull out to set and when pushed in turns freely but does not change setting.
There have been reports of the charge rate being changed accidentally during the charge. A few have placed a guard around the pot's knob which would serve the same purpose.

Charles
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Old Nov 30, 2005, 12:50 PM
resU deretsigeR
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Quote:
Originally Posted by TGoodwin
All I have to say is that it is a good thing that laws are in place to stop people from smoking while fueling their cars at the gas pump. How many people do you see set the pump on and then walk away into the store or go wash the windows. I can not believe that we are expected to stand there while the gasoline in pumped! I would not go to a filling station that expects me to do that. What? Turn off the engine? LOL You guys great.

Not to sure where you are going with this one.

in the 60's and 70's when i worked in service stations we always started the pump lifted the hood checked the oil and cleaned the windows. (remember full service)

As to turning off the motor you would be suprised just how many middleclass smart people run into the station drop the nozzle and never turn off the motor while the run into the am pm to grab a cup of coffie.

These are smart people all kinds but they lack a basic concept of a car catching fire at the pump.. It happens but not often.

These are the same ones that are in too much of a hurry and drive off with that same nozzle still in thier car. (Of course even nascar drivers and pit crew make that mistake)


My point is this intelegance ans smarts is not the point. smart people make mistakes all the time... just go to an abortion clinic some time alota smart people most made a mistake..


Mistakes happen we are human and we get in a hurry.

If a simple fix could be imployed to prevent this problem from occuring then why not impliment it.

Manual and rules are only good if your 100% dilagent we are human were are not diligent.

None of this is to start a flame war it is just to make the point that smart people make mistakes and those can be minumised by

1) Folowing the direction 100% of the time (proven we dont)
2) making the device less smart so that we have to think about what we are doing

while Hal Woo's idea is not atractive to most you do have to think about what you do before you do it so complacancy does not creep in as easy..


Just my pennys worth

Thank Paul V
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Old Nov 30, 2005, 01:43 PM
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Would using a cell balancer, connected to the battery tap lead, along with the 109 prevent it causing damage if the cell count jumps up during the charge cycle?
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Old Nov 30, 2005, 02:00 PM
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Haralson County GA. USA
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That would depends on details such as the charge rate,balancers ability to bleed (sink) the excess charge current and the balancers display and or audio signaling and if it also has the ability to stop the charge.
All balancers which I am aware of would indicate that the battery is being overcharged at least one would give a visual and audio indication and one would stop the charge when any cell reached 4.3 volts.

Charles
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Old Nov 30, 2005, 02:21 PM
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My solution would not cover 100% of the cases but it would cover the vast majority. It would save the day for all the <4S flyers out there. As for high cell count packs...........

Remember there are equivalent failure modes for manual cell count chargers also.

Take a (x)S pack reading 28v on a good DVM.

Select 8S and proceed to charge....... By the way that was actually a almost fully charged 7S pack. In this case the ASTRO would probably save the day.

So which instruction should we expect high cell count users to always get right?

- Don't charge already charged packs?
- Always choose the right cell count?

Brad
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Old Nov 30, 2005, 03:46 PM
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Quote:
Originally Posted by bjpaul
My solution would not cover 100% of the cases but it would cover the vast majority. It would save the day for all the <4S flyers out there. As for high cell count packs...........

Remember there are equivalent failure modes for manual cell count chargers also.

Take a (x)S pack reading 28v on a good DVM.

Select 8S and proceed to charge....... By the way that was actually a almost fully charged 7S pack. In this case the ASTRO would probably save the day.

So which instruction should we expect high cell count users to always get right?

- Don't charge already charged packs?
- Always choose the right cell count?

Brad
Most modern chargers (not all) that have manual cell count also check to make sure you have selected the correct cell count before the charging commences. The Apache 2500 has a fairly narrow voltage range. If you over discharge a battery, it simply will not charge.

I personally do not want to throw away the idea of auto detection, as long as it works properly. I have tried to fool my Electrifly Polycharge 4 by charging an already fully charged pack at 2C 5 times in a row, and it catches me every time. I don't like the fact that it also does a 5 minute charge sometimes (although at a very low rate) before it decides on the cell count, but it doesn't tell me the cell count until it has decided, and it has never missed yet, even when abused repeatedly.

Again, what would be the problem with having the 109 work exactly as it does now, except that it would stop if it increases the cell count, and wait for confirmation by the user?

Dan
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Old Nov 30, 2005, 04:14 PM
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Dan, the valid voltage range for:

7S 22.4v to 29.4v
8S 25.6v to 33.6v
9S 28.8v to 37.8v

So if a pack reads 28V how does the charger confirm the cell count?

Brad
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Old Nov 30, 2005, 04:37 PM
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Quote:
Originally Posted by bjpaul
Dan, the valid voltage range for:

7S 22.4v to 29.4v
8S 25.6v to 33.6v
9S 28.8v to 37.8v

So if a pack reads 28V how does the charger confirm the cell count?

Brad

Exactly as it does now. The only difference I am advocating is that the user has to confirm the new cell count if the charger changes it.

As I understand it, the voltage ranges used by the 109 are

7 cells 25.8-30.0
8 cells 30.1-34.3
9 cells 34.4-and above

Which is why stage 1 charging is necessary to bring high cell counts up to a voltage within those ranges. The charger would recognize 28 volts as 7 cells, but wouldn't you want to be consulted if it decided to bump it up to 8 cells.

Dan
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Old Nov 30, 2005, 05:06 PM
**I'm Battman**
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Dan, Paul V and Charles, Now you are making some serious SENSE. I love it!

rc




Now here is a man that really makes some sense............

pgitta
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Join Date: Mar 2005
Posts: 40 Oh my God, this thread is hilarious. I keep flashing on Little Joe and Hoss cradeling sticks of nitro and moving like Pandas.

You'd think you're working with Nitro-glycerine or something.

Personally, I charge my Lipos in a pile of hay under my bed.

Never had a problem.
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Old Nov 30, 2005, 06:15 PM
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Now that's a great idea.

Quote:
Originally Posted by Dan Baldwin
Again, what would be the problem with having the 109 work exactly as it does now, except that it would stop if it increases the cell count, and wait for confirmation by the user?
Dan
In spite of my support for the 109, I can see that your idea seems to be a very good one. I guess I missed this if you posted it before. I'd send mine in for an update for this feature if it was to become available, because even though I'm as careful as I can be, I'm not immune to the same kind of errors others have made.
Dave
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Old Nov 30, 2005, 07:23 PM
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Quote:
Originally Posted by davecee
In spite of my support for the 109, I can see that your idea seems to be a very good one. I guess I missed this if you posted it before. I'd send mine in for an update for this feature if it was to become available, because even though I'm as careful as I can be, I'm not immune to the same kind of errors others have made.
Dave
Quote:
Originally Posted by Dan Baldwin
That would be better than what it does, but I think it should stop the charge if it changes the cell count, start beeping, and wait for the user to do something.

Dan
The quote above is the the first time I mentioned it in this thread, but I've been pushing for that mod for many months, on several threads. If Bob were willing to make the change, you wouldn't even have to send your charger in. All you would have to do is buy a $10.00 chip and change it yourself. As I have said in another thread, if Bob were to make that change, I would buy a 109 even though I don't need one.

Dan
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