Lithium-ion batteries - some hands-on experience

[whatlep]

I've recently acquired a 12 volt "block" lithium-ion battery from one of the innumerable Chinese supplierts on eBay. My experience to date is summarised in an article here:
https://sites.google.com/a/gardenra...s/lithium-ion-battery---some-hands-on-testing

Hope this is useful to the battery buffs!

 

[nicebutdim]

That's very interesting, especially the run time. Thanks for the info, I may have a go at them myself.

 

[Westcott]

I have a similar battery, but it's used to power my 2.4GHz RC transmitter, for more than a month on one charge.
My latest L-ion battery is for loco power, it's a 22.2V 5200mAh block, replacing 3 x 7.2V 3500mAh NiMh packs, and more than doubling run times.

 

[tramcar trev]

I notice that lithium ion batteries need to be flattened the first few time they are used to get the best life out of them....
A trick to rejuvenate NiCad batteries... These as we all know develop a "memory" caused by cadmium dendrites "growing" through the cell and "shorting" the battery. The cure is to rather than do the discharge recharge thing is to give them a deep charge over voltage. This has the effect of burning off the cadmium dendrites and rejuvenating the battery..... Not that anyone uses NiCad these days but they are used in portable solar devices and some people still use them in some "personal" items....

 

[whatlep]

To add to the original posting as requested in a couple of PMs, my supplier on eBay was "keyzone". Here is an identical listing to the one I used: http://cgi.ebay.co.uk/12V-DC-Rechar...20645075335?pt=UK_Gadgets&hash=item1c1701c187 and here is an even cheaper one which I found this evening, but is untested: http://cgi.ebay.co.uk/12V-Rechargea...rElectronics_Batteries_SM&hash=item45f93d92f0

I've ordered one of the second items just to see how it works.

In terms of my battery power controller that's simple. It's a Cliff Barker system. It is the Poodle's Privates as far as I'm concerned. Compact, sensitive and 100% satisfactory. Please see: http://www.cliffbarker.me.uk/ and look under "speed controller" for details. Perhaps I should add that there are other Barker users on GSC who have also been very pleased with their systems.

 

[whatlep]

Having advocated Lith Ion batteries for quite some time...I rest my case - despite being shot down a few times by one or two people who knew very little about them and who only went on heresay from the aeromodeller world.

Incidentally the second battery shown - (the blue one) in Whatlep's post , I have three of these for sometime (4600mA types). The chargers of both types of battery seem to be the main one that Chinese dealers send out irrespective of the make of Lith Ion batteries.

FOR THOSE WHO KNOW LITTLE ABOUT THESE BATTERIES.​

USE ONLY THE LITHIUM ION CHARGER TO CHARGE THEM NOT A LITH POLY BATTERY CHARGER OR ANY OTHER CHARGER.​

Spot on with that last line Ross. Absolutely vital.

Testing will continue today and subsequently I will report back on the recharge time. There is no substitute for real-life testing!

 

[Westcott]

As a follow-up to my earlier post about getting a new http://en.wikipedia.org/wiki/Lithium-ion_polymer_battery < Link To Lithium Polymer (LiPo) battery, here's the Ebay links -

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=150440339189&ssPageName=STRK:MERFB:IID < Link To 22.2V 5200mAh LiPo battery

You mustn't let an individual cell's voltage drop below 3V, otherwise it is permanently damaged, so I got a voltage display that plugs into the balance socket -

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=370457479210&ssPageName=STRK:MERFB:IID < Link To Battery cells voltage display

Not forgetting the special charger for up to 6 cell L-ion batteries -

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=200581938252&ssPageName=STRK:MEAFB:IT < Link To iMax B6 charger

Usual disclaimer: no connection with these 'shops', other than as a satisfied customer.

 

[whatlep]

Thanks for those bits and pieces Hamish.

Testing has now been concluded. The loco came to a halt after a total of 8 hours 25 minutes running time. When I checked the battery voltage, my meter showed 2.97 volts. I presume that this means that the battery's onboard circuitry has shut it down when a minimum of 3 volts was detected.

Charging is now underway. I'll post how long it takes.

 

[Westcott]

When I checked the battery voltage, my meter showed 2.97 volts. I presume that this means that the battery's onboard circuitry has shut it down when a minimum of 3 volts was detected.

I rather hope that the internal electronics shut off first to protect the cells from undervoltage damage!
This is probable a 3 cell battery, a fully charged cell being about 4.2V, giving the total of 12.6V that you measured.
Looking at your voltage/time figures, your battery cut off at about 10.5V, 3.5V per cell.
A good safety margin.

 

[Neil Robinson]

Interesting stuff, thanks for posting.
I'm intrigued by that special charger for up to 6 cell L-ion batteries -. It claims to charge 20V Li-ion/Poly and 15 Ni-MH/NiDd cells yet has a maximum input voltage of 18.
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[/size]

 

[don9GLC]

Interesting stuff, thanks for posting.
I'm intrigued by that special charger for up to 6 cell L-ion batteries -. It claims to charge 20V Li-ion/Poly and 15 Ni-MH/NiDd cells yet has a maximum input voltage of 18.
[size=14pt]
[/size]

I'm intrigued as well. Could it be the input is 18V AC, 25.4V pk-pk?

 

[Westcott]

This type of charger is designed to run off a 12V car battery.
It must have a DC converter in it, cos my old one can charge 18 NiMh cells in series at 5A from an old car battery.
The mains car battery charger is running at 10A while this happens!

 

[whatlep]

A quick update for those who have expressed interest.

The test train finally ground to a halt after 8 hours 25 minutes of running (albeit with 4 breaks for the weather). The battery was then placed on recharge. I confess to forgetting about it this evening, so all I can say is that the charger automatically shut off somewhere between 6 hours and 10 hours (when I remembered about it!). All completely without fuss.

The battery remained cool throughout recharging, though the charger got pretty warm, albeit no warmer than other chargers I have for NiMH cells. After charging, the battery was back up to 12.63 volts.

So, Lithium-ion batteries. No fuss, high capacity and cheap. Like 'em!

 

[Bram]

What is the dimensions of the battery pack Peter?

 

[whatlep]

What is the dimensions of the battery pack Peter?

The black block I have is 107mm by 64mm by 25mm. Half of the rocker switch protrudes beyond that by about 3mm, but obviously only in a very small area at one end of the battery, varying by how the rocker is set.

 

[Westcott]

An update on my 22.2v 5200mAh LiPo pack.

After going on about not over-discharging them, I managed to do just that!
In fact before it even had its first charge.
Disaster I thought - one ruined pack.
However, measuring the individual cells' voltages via the balance plug, only 2 of the cells were too low a voltage.
Confirmed by the charger as an error when (in vain hope) I tried to recharge in LiPo balance mode.
However, a quick Google found that some users had recovered their cells by charging slowly in NiCad mode instead, until the low cells came up to 3V, when Lipo charging mode should work again.
An anxious evening of testing this method eventually resulted in an apparently fully recharged battery.
Just to check that the battery is really OK, I've been forced to test-run the long ABBA train, that pulls 3 Amps, all morning.
Battery cell voltages are holding up well, and remain balanced.

So hopefully disaster is averted.
This time, touch upvc.

 

[Westcott]

Ross,
I trust your alarmist postings are intended as humour, or perhaps http://en.wikipedia.org/wiki/Schadenfreude < Link To schadenfreude?
At no time did I use the 'wrong' charger, nor was there the slightest danger.
The charger in question is an http://www.amazon.co.uk/Digital-iMAX-Battery-Balance-Charger/dp/B003N0VXNW/ref=pd_rhf_shvl_1 < Link To iMax B6, which performed perfectly, and helped me safely recover an accidently over-discharged battery.

 

[whatlep]

An update on my 22.2v 5200mAh LiPo pack.

After going on about not over-discharging them, I managed to do just that!
In fact before it even had its first charge.
(snip)

Hamish - An interesting warning story, but, as a numpty on battery technology I'm confused. I thought all Li-ion batteries had a cut-out circuit built in specifically to avoid over discharge? So how did you manage to over-discharge before the battery had its first charge?

 

[Westcott]

Ross, when I said 'anxious', I meant that I was anxiously hoping to recover an otherwise un-rechargeable battery.
I was not anxious about the method itself.
The battery could not be recharged in LiPo made because 2 cells were low voltage.
So the choice was to dispose of it responsibly, or use a proven method to recover it.
I chose the latter, and it was successful.
During the recovery process I constantly checked the individual cells' voltages, the total voltage, the battery temperature and squishyness, all at a charge current of 0.1 Amps.
I saw no risk, observed only normal battery conditions, and would repeat the process without hesitation, if needed.

A bit like running a live steamer, but safer...

 

[whatlep]

Re: Lithium-ion batteries - some hands-on experience

A quick update on my experiences with Li-ion batteries. All is very much OK with the battery in the initial postings, but it now has a friend. Basically the same battery but without the hard plastic shell. That makes the battery significantly smaller at 103mm x 53mm x 20mm, though the wires which exit the latest battery effectively add a few millimetres in both length and width unless you feel very confident about bending them sharply. The new battery is sufficiently small to fit in the cab of a Stainz, but I think it's just too long with the wires to get into the bonnet of my battery Schoema diesel. You'll notice that like the first battery, the new one has a built in on-off switch and a tiny LED close by which illuminates when the battery is on.

One warning if you do get one of these batteries. On the blue model, there are two external connections. One is intended to allow charge into the battery via the supplied charger, the other to feed whatever the battery is powering. However, the two wires are both live when the battery is on and if you connect them they will blow up the battery! I will (very carefully) remove the feed wire plug and hard wire the battery to my radio control receiver/ controller, insulating everything appropriately.