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Old Jan 18, 2006, 04:55 AM
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Lipo Battery Concerns - HELP!

Hi,

I know there are many post about lipo battery problems / safety issues etc, however I was hoping that you guys could give me some feedback to my particular issue:-

I purchased a hydrofoam over ebay. This came with a 3 cell - 11.1v - 18mah LIPO battery.

This didn't come with a charger, however I purchased one for 15.99 from the local model shop same as this model:-
http://www.shiremodels.co.uk/index.a...&productid=699

This doesn't have a mains plug, so have to connect to my car battery.

When I first got the boat/plane whatever you want to call it, it was shipped with battery but not connected so when I connected it it had power. I then took it for a flight and after xx mins that motor started to run slower as if the battery was running out.

When I got home I tried to put this on charge (on my car battery in my boot). I set the mah to 1500 and the cells to 3, however I soon as I press start it beeps fast informing me there is a problem. I took this to the model shop and they put this on a voltage meter and its only reading 8v (all 3 cells). My charger wont seem to accept it unless you hold the start button for 3 secs and then it starts to charge and then re-checks the battery after 2 mins and if still incompatible, rejects it. I can't start the charge off the standard way, however when I use this advanced start and re-checks it doesnt seem to reject it (is this dangerous)?

The model shop plugged a more advnaced charger in and confirmed it only reported 8.xx volts and it was charging but very very small amounts 0.175 mah (i think).

I then started to learn how dangerious these batteries are and started to panic.

Should I attempt to charge this battery of my car battery in the boot (using the lipo charger)?
Should I try and get the voltage back over 9.9v (3.3 per cell) using my advanced charging method (descibed above)?
Or should I throw this battery?

I have also read that these can be safely charged in a pirex jug with some sand in. Does this need a lid? or is the open jug acceptable/safe'ish?

Can you store these in a pirex jug when not used (the pirex jug im think of it the pouring jugs used in kichens (or for water the house plants).

I think the main problem come from the hydro foams speed controller not detecting when the battery goes below the minimum safe voltage (overdischarging it)?

If I was to continue to use the hydrofoam (maybe with a new battery), should I take a voltage meter to the field with me to measure it every 10 mins or something to ensure that is not going below min voltage?

Should I charge a new battery before first use?

When is a lipo battery likely to swell and burst into flames. I last attempted a charge on these 2 nights ago - are they safe now? Is it during or just after the charge when they are dangerous (other than after a crash)?

If I need to dispose of the old battery, is it acceptable to sink in salt water and then put out with the trash?

Sorry for all the questions, I know some of them have been answered by the sticky note on lipo batteries but feel I should check with you guys and share your knowledge.

Thanks
Mark
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Old Jan 18, 2006, 05:20 AM
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You are right in what do You think.
I think You should charge that pack, but start at low current (250mA) in force mode, then after approx a hour, disconnect it and charge normally at 1500mA. (I did assume that Your pack is 1800mAh, not 18.) . Do it in a place where You can safely launch small pyrotechnic firework. (I do not know what is pirex jug )
More advanced approach is to charge pack cell by cell after such issue - if You can reach single cell terminals.
You should have at least any cheap dvm, just to check voltages. No load voltage have to be within 3.7 and 4.20V each cell, so pack have to be over 11.1 and below 12.6V. Quite sharp.. Under load voltage should never drop below 3.0V.
You should look for manual tor that esc, maybe it can be switched to higher LVC (9.0V or up to 9.9V, depends on load and pack quality) - or buy some voltage monitor (microscreem or so), otherwise You will destroy any Lipo pack.
Yes You should charge new batery before use.
Charge is dangerous during, if anything fails, but also after, if overcharged (cell will swell after few hours).
Salt water is used to discharge pack slowly, as it is conductive. It takes a long time.
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Old Jan 18, 2006, 06:45 AM
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coro thanks for prompt reply.

Can you confirm what should be the min voltage for all 3 cells and the max when fully charged?

I don't think I would let a firework off in the boot of my car, so had better think of an alternative charging method - would this work:-

http://www.aldi.co.uk/special_buys/product_31.html

I don't really understand the section below that you wrote, does this go on the plane etc..-

"You should look for manual tor that esc, maybe it can be switched to higher LVC (9.0V or up to 9.9V, depends on load and pack quality) - or buy some voltage monite Yor (microscreem or so), otherwisou will destroy any Lipo pack."

Do you my battery would be safe now after the problems it has had and the last attempted force charge being 1.5 days ago?

Thanks again
Mark
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Old Jan 18, 2006, 07:09 AM
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Excuse my mistypes, please... maybe the batteries in my keyboard are going off
The voltage over 11.1 is sure. It is no load voltage, the rest, measured couple of minutes after flight. This let You use allmost all energy in a pack while keeping the pack in perfect condition.
Voltage under load goes down as low as 9.0V, and it is not exact, as it depends on pack health, temperature, and the power required.
Max voltage is 12.6V is absolute and should never been outreached.
Yes, it is about plane esc, that did allow too deep discharge of Your pack.
Many of new smart ESCs can be programmed some way, at which voltage they will shut engine off. Maybe Yours too. If not, there are some devices on market, which start beeping or lights a led, or even cuts throttle signal from RX to ESC when voltage falls too deep. It is hard to avoid overdischarge without some helping device - but counting the time of flight can help.

There is only one issue with Your batery - possibly it became unbalanced. While You will check only summary voltage of 3s pack, the maximum voltage while charging could distribute nonequally -example: 4.2V, 4.0V, 4.4V , sum=12.6V . In this occasion, third cell hets to 4.4V and will be damaged, swell and so on.
While discharging, the same issue takes place. With voltages 3.8, 3.8, 3.5 sum is 11.1 This is not so critical, but reality can be worse than this example.

Any 12V Pb batery can be used to power Your charger anywhere. I do not know what kind of batery is used in the unit at Your link - but it should be sufficient. Maybe just a small cheap 40Ah or less, car batery is enough, if You have car batery charger.
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Old Jan 18, 2006, 09:48 AM
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I understand what you mean about unbalanced. Is there a way to check this. I have only two wires that come out of the battery and am a little nevous about trying to get further in to the battery. Is there a way to charge specific cells?

The reason I looked at this charger from Aldi is for the portability and ease of charging the charger! This means that I can charge the lipo batteries in a safer location and also means that I won't require an additional charger to charger a car battery as this product from Aldi plugs into the mains to recharge - have I made this understandable?

Thanks
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Old Jan 18, 2006, 02:09 PM
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Yes, i said before that i think You are right in what do You think, all in all.
It is good that Your charger can charge maximum of 3s, so there is no probability of incorrect charger settings (no higher cell number is possible) - foolproof.

Checking balance is discussed often.. After such deep discharge it seems to be good idea, however You will need to open the pack to access cell terminals. Do it if You can.
But if You have no experience in electronics, it is not so good idea
There are 3 cells, each have + and - terminals. the cells are connected in series, so there are 2 joints (+cell1 to -cell2, and +cell2 to -cell3). You may atach a crocodile or solder short wires with balance connector onto that pack - search this forum for howto add taps to pack, to see what it means, and estimate whether You can do it safely. If Yes, then every cell should be charged separately as 1s (to 4.2V). After that the pack will be usable in ordinary way. Doing that on different charger displaying voltage and charged mAh (at that shop?), You could see the health of separate cells.
Or ask for help somewhere, maybe at the shop where You did purchased it.. What more can I say...
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Old Jan 19, 2006, 04:23 AM
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Thanks again for your info coro.

Bit of a general question now then:-

Where do you all charge your batteries?
Where do you all store your batteries after charging and when not in use?

Thanks
Mark
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Old Jan 19, 2006, 01:10 PM
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One more quick question...

Coro,

I purchased one of those power stations from the link I posted.

I have posted the specification of this below and was hoping if someone can confirm if i am ok to connect my lipo charger to this:-

- Output Voltage = 12V
- Peak Starting Current = 900A
- Battery Capacity = 17.2 AH

This is obviously used to be able to jump start a car.

I have measured the DC volts that it is suppling and they are at 12-13v. This is about the same as my car battery reads (when not running).

Please let me know if it is safe to plug my lipo charger into this to charge my 3 cell lipo batteries. The Peak Starting Current of 900A is concerning me a little so would like clarification if this is compatible??

HELP.

Thanks
Mark
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Old Jan 19, 2006, 03:13 PM
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Old Jan 19, 2006, 04:32 PM
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I thought this power station (see link below) was effectivly a portable car battery that you can use to jump start a car and also use as a 12v battery (its not powered by the mains, however you do have to charge it up from the mains when flat).... Does this make sense?

http://www.aldi.co.uk/special_buys/product_31.html

Anyway, you might be right because using my potentially damaged lipo battery that has been discussed on this thread I performed the following:-

1. Tested the volts that come from my car battery (when the car is not running) and this reported approx 13v

2. Tested the volts that come from this power station (link above) and this was also around 13v so therefore I figured it was just like a car battery

3. Plugged my lipo charger onto the power station and connected it to the lipo battery. Previously my lipo charger has rejected this battery due to only reporting 8.5v, however with an advanced feature I am able to force charge for two mins and then it re-tests, therefore I set the maH to 250 and used force mode and it didn't get rejected. After approx 1 hour I checked the voltage and it was reporting just over 9v and (analog meter - not very acurate tho).

4. Re-connected the battery to my lipo and set the 1500 mah and this time it started without issue (didn't need the force mode).

5. Kept checking every few mins and after around 30 mins it began to get warm and what could be discribed as very slightly puffy

6. It started to get warmer and warmer and then started swelling up a little so immediately disconnected and have put outside on the lawn in a ceramic plant pot.

What should I do with this battery now. I don't want to attempt to charge it again. I just want to dispose of it.

Can I plug it into my plane and just run the motor until it goes complety flat (my plane may actually allow this to happen as I dont believe it has a configured speed controller, which is why I am in this position)..

Should I leave the battery outside all night? Its in one plant pot with a drain hole and I have put another plant pot upside down on top of the other (also with a drain hole) to act as a cover. If it is a damp or wet night the battery is likely to get wet or damp

What are the chances that this could go up in flames? Could this happen if I connected to the plane to run the motor to run the battery down?

When is this battery safe to handle again? (but not to use properly)

What is the likely hood that this swelled due to the power station battery I am using? Please see the link above for the information on this product..

HELP HELP HELP

Thanks
Mark
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Last edited by mdavenport; Jan 19, 2006 at 04:40 PM.
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Old Jan 20, 2006, 02:07 AM
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That pack is safe only after complete discharge of all cells. This can be done by diving it ito salt water for quite long time (few days) as discharge current is low.

Next time You should purchase a pack with balance connector. You do not need balancer and You do not need neither callibrated expensive dvm to compare voltages, but it seems to be problem if You cannot reach cell terminals (without that connector). http://www.rcgroups.com/forums/showthread.php?t=457023

edit: Q: "What are the chances that this could go up in flames? Could this happen if I connected to the plane to run the motor to run the battery down?"
A: Very high. Yes, it could happen when You will try to discharge anyway using higher current (the pack is sensitive to overtemperature now.)
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Old Jan 20, 2006, 02:46 AM
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Quote:
Originally Posted by mdavenport
I thought this power station (see link below) was effectivly a portable car battery....
It is.

The only charging this power station does is with the big clamps. Do NOT hook the big clamps to your lipo-charger's input and you'll be fine. I know of a dozen of these type units in use locally. They are very popular to run chargers and other 12v stuff at the field.
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Old Jan 20, 2006, 06:55 AM
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Andy,

If I don't hook the clamps to the lipo charger how do I connect it? do i have to use the 12v cigarette charger that is on it? If so do you know where I can get the special connector?

Do the clamps push out a different voltage then to the cigarette charger?

Coro, is there any chance that the battery can do something unexpected whilst sunk in salt water. Would you advise doing this in the sink or a jug and leave it outside?

Thanks
Mark
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Old Jan 20, 2006, 07:23 AM
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[QUOTE=mdavenport]
Do the clamps push out a different voltage then to the cigarette charger?
I have no knowledge about that device, but as I did read the page on link You posted : t
They said that it can start a car (900A stated there). There was no word about recharging a car batery. In this case the clips should be connected directly to batery inside.
In case that it should charge car batery instead of giving high current for starter, there would be stepup electronics to create about 15V... perhaps, but I do not think so.


Coro, is there any chance that the battery can do something unexpected whilst sunk in salt water. Would you advise doing this in the sink or a jug and leave it outside?

It should do nothing, because the discharge current thru water is low, but warning, it is electrolytic reaction creating 2 H2 and O2 (hydrogen and oxygen) which are highly explosive (much more than any Lipo), and oxygen is considered as poison. Leave it outside.
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Old Jan 20, 2006, 07:52 AM
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Coro,

Sorry about my misunderstanding but it is my believe that this isn't a car charger just a car starter (if you car battery is flat)

Are saying that the clamps can be connected to the lipo charger successfully?

Thanks and sorry for misunderstanding again...

Mark
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