Are you wary of Li-Po batteries?

Tony Walsham said:
Unprotected Lithium batteries should be banned. Period. To protect the idiots from themselves.
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I don't think so.

It would stop people making up their own packs with their own protection board.

If I was flying a model aircraft/quadcopter/helicopter etc I'm pretty sure I wouldn't want the motor to just stop because the battery was over discharged! I'd want to be able to land safely even if that did mean knackering the battery. One knackered battery is going to be cheaper than one mangled model.
 
You don't have to be an idiot (or does the exception prove the rule in my case?).

I was going to charge a bank of parallel connected, sealed LA batteries.

I always charge the four seperately by pulling off the spade connected wires. On this occassion, one connector was particularly tight and I struggled. Suddenly it released itself and several others came off too, causing a short.

Alarming display of pyrotechnics. Luckily, only the wiring suffered!

The moral of this one is always insulate the connectors ;)
 
I understand that "experienced" pack builders need access to a supply of Lithium cells. So maybe not an outright ban.
Perhaps a licence to buy them should be required.

RCS ESC's do not detect low voltage.
From now on any RCS ESC operators who use unprotected Lithium batteries, will void any RCS warranty.
 
Tony Walsham said:
RCS ESC's do not detect low voltage.
From now on any RCS ESC operators who use unprotected Lithium batteries, will void any RCS warranty.
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I stand corrected. Seems to me to be a useful extra safety feature for those of us who do prefer to use lithium batteries. I'll stick with Deltang, then.

Rik
 
What I don't get is what garden railway applications necessitate use of lipos anyway? Yes high performance cars, and things that fly- but surely most the time they aren't needed in a train, and in fact a bit of weight from a traditional nimh or nicad stick pack is all to the good in most locos.
 
Size In a small loco you can't beat them for capacity and size, no towing of battery wagon. In big locos with multiple motors you can get much longer running times for the size of battery. Lipos are the best. Also price for capacity is better.
 
So, just to get it clear in my head..... a specific question to Those Who Know - are there many documented cases of accidents (fire etc) with PROTECTED lith batteries, or are all the events discussed involving UNPROTECTED packs?

Jon.
 
It is always better to use protection. You have to remember that 50% of motorists are caused through accidents.

David
 
Thanks David, that raised a smile.... ;)

Would still like a serious answer to my question, though - as I'm trying to decide whether I need to work out a simple way of removing my (PROTECTED) pack from the 2095 for charging, or whether it is safe to leave it in the loco.....?

Jon.
 
My guess is 'hard-facts' will be impossible to come by..
Unless you have had it happen to you, or in your sight, then it is (well intentioned) hear-say.

There is obviously a risk associated with these if you either don't know what you are doing, have a fault, or abuse them.. - We possibly do all three with various things we do on our railways / in life??

I know of lead-acid batteries that have exploded, wiring that has burnt-out, and equipment that has been wrecked due to fault, or user-error.
Any technology that stores energy has the potential (sorry!) to release that energy in an uncontrolled way, causing damage or injury. - Even if it is a loco full of batteries falling off a raised track onto your foot! :o ::) ;)
 
Hi Rik, Deltang Rx/ESC's are terrific.
If David T ever makes an ESC that can handle 24 volts and 6 amps, I would stop making my own and feature Deltang Rx/ESC's exclusively.
 
Zerogee said:
Would still like a serious answer to my question, though - as I'm trying to decide whether I need to work out a simple way of removing my (PROTECTED) pack from the 2095 for charging, or whether it is safe to leave it in the loco.....?

Jon.
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Hi Jon
I suppose it's really down to personal preference and your tolerance of risk. I have nine locos with li-ions and I always charge my batteries in-loco. I use an intelligent charger, I slow-charge charge at 0.3A, I never leave batteries charging overnight or leave the house when I'm charging. Not all my batteries have built-in protection. For example, I've been unable to find protected 18650 li-ions with solder tags. Rather than risking soldering directly to protected batteries, I've wired-in external protection boards which monitor balance charging, low volts and short circuit - and as mentioned earlier, I use Deltang receiver/ESCs which include LVC auto-sensing for up to 4 lithium batteries.

For me, the benefits of li-ions outweigh the risks, many of which I've tried to minimise.

Rik
 
Zerogee said:
Thanks Rik, that's a very useful answer! :)
Jon.
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By coincidence, I've just finished converting one of my former track-powered locos to li-ion battery power. I've posted a description in another thread.

Rik
 
there still seems to be a mix up of Li-pos and Li-ions in this thread.
 
stockers said:
there still seems to be a mix up of Li-pos and Li-ions in this thread.
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IMO, for the sake of the discussion, I think the same arguments (ie safety) apply to both. To quote the Battery University website (http://batteryuniversity.com/learn/article/the_li_polymer_battery_substance_or_hype ):

As far as the user is concerned, lithium polymer is essentially the same as lithium-ion. Both systems use identical cathode and anode material and contain a similar amount of electrolyte.

Generally, Lipos come in floppy pouches (which are then often (but not always) housed in a more rigid case), whereas li-ions are more often now manufactured with more robust cases - often now in cylindrical formats. This can make them less prone to accidental damage but also means that they can't puff-up when they become unstable - hence they are more likely to vent.

However, as it's the electrolyte which is the most volatile component, they both need to be handled and electronically protected in much the same way.

Rik
 
ge_rik said:
IMO, for the sake of the discussion, I think the same arguments (ie safety) apply to both.
SNIP

However, as it's the electrolyte which is the most volatile component, they both need to be handled and electronically protected in much the same way.

Rik
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Which is the whole point of my original posting.
I know of no Li-Po packs Large Scalers may use that have any pcb protection.
There must be something about them that convinced Master Instruments (Australian Sanyo battery distributors) NOT to sell Li-Po because they consider them to be too dangerous for the general public in Australia to handle.
 
Hmmm.....this is a quandary...
I have three battery projects that are in limbo at present.
For one I will be using NimH packs but....
I have two of the older Aristocraft LiIon packs (with pretection) circuit board which I charge every now and then to keep them topped up.
I too wonder at the possibility of a 'unfortunate' occurrence.

I tend to do all my battery charging etc in the garage, which has more than its fair share of inflammable paraphernalia dotted about.
I do use a multi 'smart' charger that can do all battery chemistries and four different type of batteries at the same time and with the rate of charge controlled.

But, like Jon, I have been weighing up the pros and cons of Lithium v NimH. Yes the difference between LiIon and Li-Po is well documented.

I know that LiIon is safer than Li-Po but I still charge the LiIon batteries on their own, in a large metal tin, even though they are protected, are being slow charged etc. Oh yes and I am also always in the presence of the operation.....

As in life, it is all down to risk but having seen, many times, the aftermath of 'innocent' risk, and knowing that I take them myself on many an occurrence....another risk is maybe a risk too far.......?

At least with NimH you can leave the batteries charging and not worry (provided smart charger etc etc)
 
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