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Very Inexpensive 12V Li-Ion Battery pack

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#1 bassplayer142

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Posted 07 February 2013 - 07:55 PM

I stumbled and bought a pretty cheap battery pack that packs 9.8Ah, overcharge/discharge protection, and simple charging from ebay. I recieved it yesterday and unfortunately the charger is just a 12.6VDC charger that operates at 350mA. That yields a charging time of roughly 28 hours!!! (It's been charging since yesterday).

I'm hoping to have it tested in a while to see how legit the real AH rating and discharge protection work. Also, a higher amperage battery charger would be ideal. For this price this thing is a steal. It would easily power everything on my rig in a small, lightweight and inexpensive package.

I'll update later if anyone is interested.

http://www.ebay.com/...&_trksid=p39...

#2 mitaccio

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Posted 07 February 2013 - 08:52 PM

if it is actually 12volt and the amperage stated, that is a great deal and a good way to.run the scope. but I thought with lipo it was 3.7volt per cell.

#3 Gene7

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Posted 07 February 2013 - 09:57 PM

Very top voltage is 4.2 v per cell down to about 3.5 v. Use discharge care and do not take below about 3 v. per cell, or you could end up with 787 type fire. I have been into LEDs and the 18650 type cells. The best are only about 1/2 the advertised capacity. Keep us updated please. Gene

#4 ccs_hello

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Posted 07 February 2013 - 10:07 PM

Per its marking, it's a 3-cell Li-Ion 9800mAh battery pack w/o per-cell lead wiring (to be used by a balanced charger). The charger wiring is a very basic power supply, not really good for Li-Ion charging. The battery pack does not have its own protection circuit board.

P.S. Li-Ion cell is native 3.7V, when fully charged, it's 4.2V. But will quickly drop down to 3.9V approx.
You multiply the number by 3 (3 cells), you get the numbers shown in its label.

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{edited} to high light cautions

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#5 Jaimo!

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Posted 07 February 2013 - 11:21 PM

Might be very good way to run the fans on my Dob...

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#6 Mark Peterman

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Posted 08 February 2013 - 09:48 AM

You might want to check this one out. Runs my fan for days. Small and lightweght.

http://www.amazon.co...P120A-1/dp/B...

#7 Gene7

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Posted 08 February 2013 - 09:58 AM

Do go to Battery University and read about Lithium Ion batteries and charging. I would charge no higher than 4.1 V per cell. Gene

#8 tezster

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Posted 08 February 2013 - 11:36 AM

I use a very similar 6800mAH battery pack to power my dob fan and wireless DSC (also purchased through eBay) - I think most of these batteries are supplied by the same distributor. Given my modest power requirements, the battery has served me well so far.

When I first tested the battery at home, I had it running my fan and BETI for 8 hours continuously without running out - my observing sessions rarely go for longer than ~4-5 hours. I've never tried draining it completely. Recharging does take some time to complete, however. I can't really speak to its longevity, as I've only had mine for about 8 months. I'm certainly happy with mine, given its low cost.

I think these are a good option if you only have one or two low-consumption devices to power.

#9 Midnight Dan

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Posted 08 February 2013 - 11:47 AM

You just have to be careful about how sensitive your particular equipment is to battery voltage. I bought a similar unit and it would not power my Nexstar 8SE for very long because the voltage quickly dropped below what the mount needed.

A lead acid battery provides normal voltage of 13.8 to 11v as it discharges. This battery, like any LiIon will provide voltage from 12.6 to 10 volts. Many devices will work fine with that voltage, some will not.

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#10 Markovich

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Posted 08 February 2013 - 01:24 PM

I had terrible experience with these same batteries. First one arrived DOA and the seller in China refused to send me a new one unless I shipped the first one back at my expense. The second one , from a different eBay seller, worked for a month and then died. I stumbled across a website by a electrical engineer who examined these batteries and found the circuitry and charger to be very dangerous. The possibility of overcharging and subsequent fire was quite eye opening.

#11 Project Galileo

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Posted 08 February 2013 - 01:37 PM

I use this battery pack to run my dob's 12v fan and 9v tracking platform.

#12 ccs_hello

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Posted 08 February 2013 - 07:25 PM

I edited post #4 to highlight the " NO" words.

Li-Ion without proper charger can be dangerous (same reason for the airline caution on this type batteries). Same story for recent Dreamliner issues (its Yuasa Li-Ion batt pack.)

Example of a reasonably good charger:
http://www.hobbypart...80-charger.html

Not those cheapie power supply adapter re-purposed.

Clear Skies!

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#13 ccs_hello

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Posted 08 February 2013 - 07:30 PM

You might want to check this one out. Runs my fan for days. Small and lightweght.

http://www.amazon.co...P120A-1/dp/B...


I felt the vendor playing the number game on its battery rating. The mAh figures are using individual cell's then adding them up, while these cells are in series. If it is showing the battery pack's output voltage, then the mAh value should be just one cell's rating, not three.

#14 bassplayer142

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Posted 09 February 2013 - 12:11 PM

I've been using my IMAX B6AC charger instead anyway. I guess it shouldn't surprise me that the charger is just a wall wart rather than a real charger. I left it on some of the day yesterday but unfortunately someone turned it off while I was gone and I didn't get a good test reading on how long it lasted. I'm running it through with a .7Amp load for testing. I'll repost when I know how it functions.

CCS Hello. How do you know that there is no battery over discharge circuit inside??

Markovich. Thanks for the information. Since I'm using a quality charger I presume I won't have any overcharging issues.

#15 ccs_hello

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Posted 09 February 2013 - 12:30 PM

Oh, I may be wrong. The fleaby item description says
- over-change/discharge protection
(I thought it's just a 3-cell prime-cell pack.)

So I do hope it has the proper circuit.

Clear Skies!

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#16 Gene7

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Posted 09 February 2013 - 05:23 PM

Anyway, I suggest keeping a close check on the charge voltage with a digital voltmeter and not over charge over 4.1 volts per cell. Gene

#17 Markovich

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Posted 09 February 2013 - 07:04 PM

There are many links about the fire hazard of Li-Ion batteries, but here's a decent review. http://www.dvxuser.c...p/t-283393.html

#18 ccs_hello

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Posted 09 February 2013 - 11:01 PM

Thanks Mark for the link.

The linked article's original poster opened up the pack and described the design.
Based on that review, in my book, it does not have the proper charger. The output protection is sub par.

IMO, don't buy it.

Clear Skies!

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#19 mmclure

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Posted 09 February 2013 - 11:40 PM

LiPo batteries need to be treated with great respect. If the batteries do not include a built in charging circuit, you must use an intelligent charger that can do the appropriate constant amperage/constant voltage charge cycle, and if more than one cell is involved the charger must be able to "balance" the cells to bring them up to the same voltage.

The electric r/c flying community switched from NiMH to LiPo a few years ago and LiPo fires were a not uncommon experience until there was enough data about them to know how to treat them properly. Things are a lot safer now, but fires still occur.

#20 TopherTheME

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Posted 10 February 2013 - 02:43 PM

I'd stay away from that battery. A Li-any type battery with that capacity and cost isn't going to live for very long. I'd give it 50 cycles max before its capacity is cut in half.

If you still want to use Li batteries I recommend HobbyKing.com for batteries. They're not great, but for the money they perform fine for astro stuff and usually live a couple years before a cell goes bad. I like to use the 4s1p 5000mAh lipoly packs connected up to a LDO 12V regulator that I built.

#21 bassplayer142

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Posted 10 February 2013 - 03:51 PM

I opened the charger and verified myself that it is just a 12.6 static output. Not the correct type for charging Li-Ion but since I already had a charger that is not a big deal on my side. I just got done charging it and ended up with 12.3 Volts which is the ideal (4.1*3) = 12.3 Volts.

On a side note. These are Li-Ion and not Li-Polymers like many are posting. Not sure where this misconception came through.

Also, the battery pack has a led and switch built into it. I have not and probably won't open it up unless it dies. But assuming that it does have this extra circuitry rather than just a few cells. My plan is to to test it and measure the current when and if the voltage drops. If it does drop to zero, it should be safe to say that over discharge circuitry is present.

#22 ccs_hello

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Posted 10 February 2013 - 04:45 PM

The battery pack's label says
"Super polymer Lithium-Ion Battery".

That's Li-Po (Lithium Poly).
Li-Ion (the cell is in sealed metal can, since the electrolyte is not molded in polymer form) cell costs more.

Clear Skies!

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#23 ccs_hello

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Posted 10 February 2013 - 05:05 PM

Add a picture:
Left Li-Ion (metal can, Samsung)
Right: Li-Po (plastic pack, Tenergy)

Both are dead with pressurized gas inside.

Attached Files



#24 FlorinAndrei

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Posted 10 February 2013 - 07:07 PM

Do go to Battery University and read about Lithium Ion batteries and charging. I would charge no higher than 4.1 V per cell. Gene


With Li-ion, do NOT attempt to do anything manually. Get a specialized charger, and let the charger cut off the current when the battery is full.

Also, when in use, a special circuit must be used to either cut off the battery when it's empty, or at least give you a visual or audio warning.

Basically, never manage a Li-ion battery yourself, you'll end up frying it. Let the electronics do it.

A Li-any type battery with that capacity and cost isn't going to live for very long. I'd give it 50 cycles max before its capacity is cut in half.


If properly managed, a Li-ion battery can last a very long time, through many many charge-discharge cycles.

But I agree that high capacity + low price = there must be a catch somewhere.

If you still want to use Li batteries I recommend HobbyKing.com for batteries. They're not great, but for the money they perform fine for astro stuff and usually live a couple years before a cell goes bad. I like to use the 4s1p 5000mAh lipoly packs connected up to a LDO 12V regulator that I built.


Hobby King is a great supplier for Li-ion stuff. Make sure you get an appropriate charger for the batteries. Li-ion are very fussy with charging. If charged appropriately, a Li-ion pack will last a long time.

Another issue is that Li-ion batteries for RC projects, like the ones on Hobby King, are generally not protected, which means the battery does not shut down automatically when overcharged or overdischarged. If you don't cut it off in time, you'll damage it. For this reason, many RC projects use buzzers to warn you when the battery is close to the low point, and then it's up to you to stop. This works well for an RC project such as a mini-helicopter, but may or may not work well for other applications.

Here's a 12V Li-ion battery for RC projects. It is NOT protected:

http://www.hobbyking...idproduct=11927

Here's a good charger for such batteries, it includes protection:

http://www.hobbyking...?idproduct=6478

Here's a buzzer for unprotected batteries:

http://www.hobbyking...?idproduct=7223

Here's a protected battery:

http://www.hobbyking...idproduct=31315

---

Another route to take is the 18650 cells. These are Li-ion cells used in laptop batteries, but can be purchased separately, and chargers as well. I use 18650 for flashlights, I purchased a charger, several cells, and 3 flashlights, one of which is installed on my bicycle.

http://www.amazon.co.../dp/B004L7D8SY/

http://www.amazon.co.../dp/B004OADU22/

The flashlights are extremely bright, last a very long time, yet are very small.

Make sure the 18650 cells you purchase are protected.

Here's a couple links, but I'm sure you could google more:

http://www.batteryju....com/18650.html

http://www.batteryju...onchargers.html

I intend to use 18650 cells for a telescope fan combo, I'll post the results when it's done.

---

Bottom line is this:

Li-ion provide more energy per weight than lead-acid, but require some care. If the battery is protected, and a good charger is used, then it should be fine.

#25 ccs_hello

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Posted 10 February 2013 - 08:25 PM

Li-Po has the nominal voltage of 3.7V and fully charged at 4.2V.

Li-Ion is tricky, depends on the Electrolyte used, the voltage will be different. The are two popular types:
- Nominal 3.6V Fully charged at 4.1V
- Nominal 3.7V Fully charged at 4.2V

Detailed Li-Ion batt spec. will have this info. Charging 3.6V type to 4.2V (0.1V higher) is slightly off-spec.

Clear Skies!

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