Charging Lipos in models

[robc_wa]

Ho Ho and Merry Christmas all.

I am about to install a Lipo battery in a model for the first time.

I am familiar with installing NiMh batteries and arranging for a charging socket. The Lipo needs both the power and balance leads connecting up.

Is it simply a case of arranging that the power side is accessible via a socket
and having the balance lead connector discreetly stowed so that it can be connected up at charge time?

Regards
Rob

[MVL Bridges]

Hi Rob,
From what I know of radio control aircraft, charging lipos in models is generally not advisable unless you have a clear view of the battery and it is easily accessible if you need to remove it in a hurry. Lipos need to be treated with care and if a charging goes wrong it can quickly reduce a detailed model aircraft to ashes. I would imagine a loco wouldn't suffer as badly but the result would not be very nice. My personal advice would be always to remove the battery and charge it where you can see it.

Best wishes
Michael

[LNR]

Hi Rob,
I now run a 3S 2200ma Lipo in my petrol mech. loco, and am aware of the points that Michael has made.
I charge my battery in the loco via a charging socket, and by connecting the balance lead to the charger, always using the balance charge cycle of the charger. I believe a 3S to be fully charged at 12.6volts, however I only charge to 12-12.2 volts not straining the battery to gain a few extra mins. of running.
I remove battery regularly and inspect for swelling etc. (it sits in a felt lined steel case in the loco as it's a soft pack) and have had no trouble with it. The loco sees lots of hard work and would often be charged three to four times a week.
I would add that I am NOT recommending this procedure, merely pointing out what I do.
Grant.

[Enginehouse]

Hi Rob,
From what I know of radio control aircraft, charging lipos in models is  generally not advisable unless you have a clear view of the battery and it is easily accessible if you need to remove it in a hurry. Lipos need to be treated with care and if a charging goes wrong it can quickly reduce a detailed model aircraft to ashes. I would imagine a loco wouldn't suffer as badly but the result would not be very nice. My personal advice would be always to remove the battery and charge it where you can see it.

Best wishes
Michael

I use these 18650 batteries in pairs and in threes in half a dozen different locos. I always remove the battery boxes, then remove the batteries and charge them in pairs on a steel tray, using the specific wall wart type Lipo charger. Red flashing when charging, green when fully charged. Having seen the results of one of these batteries which suffered a spectacular breakdown, I am careful to follow precisely the same routine and have never personally had any sort of problem whatsoever (yet). I also have a couple of the blue protected multipack types which again are charged by removing them from the loco and changing them with the correct auto charger. Two fully charged 18650 batteries producing 7.4V will easily push my small r/c quarry stock around the garden layout with a short (10 or so) rake non stop for well over four hours which is about my average gardening stint. then usually recharge immediately after use.

Cheers.

Roy H

[ge_rik]

I concur with all the advice which has been given so far. I now use mostly 18650s but I also have three locos equipped with lipos (in silver pouches). I charge them all inside the locos but use an intelligent charger (iMax B6). I don't always balance charge them - but do regularly check the cells to ensure they are balanced. I set the iMax to charge at 0.5A - well below the max they can take. A lot of the problems with lipos and li-ions come from trying to charge them too quickly. I never leave them on charge unattended and charge them in a well ventilated (north facing) conservatory well away from anything flammable. I also use protection boards in all my lithium equipped locos to ensure that the cells do not become overly discharged and are protected from short circuits.

I have had an 18650 which I accidentally short circuited when making up a battery pack. It went into thermal runaway and vented quite spectacularly. However, it did reassure me that cylindrical li-ions are indeed less volatile than lipos and so, in time, I plan to replace my lipo powered locos with li-ions. I now buy decent branded li-ions - in my experience the cheapo ones which can be bought on eBay and elsewhere are of dubious quality with exaggerated capacities (eg ones which claimed to be 2800mAh were really only 1600mAh and one of them packed in after only one year's use).

To answer your question. I use a DC socket as the main charge socket and tuck the balance charge socket away so I can access it for checking the charge of each cell and when I need it for balance charging.

Rik

[LNR]

I think Rik has mentioned two very important points here.
Lipo's typically used in cars and aircraft are often being charged at very fast rates for repeat operation, often generating lots of heat.
Also many battery capacities are grossly over exaggerated, everyone wants endurance from the battery, so capacity is a great selling point.
I should point out that I also use an intelligent charger (Imax B6) not trusting those little black wall box things.
As I mentioned elsewhere, I basically treat it as a fuel tank, sometimes after heavy work, the loco goes on charge during lunch to be ready again for the afternoon. Chassis mounted charge socket, with the balance lead tucked up in the open engine bay (just looks like engine wiring)behind the radiator.
Grant.

[robc_wa]

Thank you everybody. Unfortunately the loco has restricted access so I think I will have to leave the battery in. It seems that slow charge using the balance plug on a good charger ( I have a B6) will be the least risk, if not necessarily the recommended method

Once again thanks to all for the advice . Once I get a few bits from ebay and banggood I will write up the installation of power and control

Regards

Rob

[ge_rik]

I never leave them on charge unattended and charge them in a well ventilated (north facing) conservatory well away from anything flammable.
Rik

Rob
Just realised, for "North" read "South" (t'other side of the equator) ....  ;)

Rik

PS - The latest version of the B6 (v2) won't let you charge Lithium batteries in 'Charge' mode without the balance charge lead connected. I assume this is because H&S somewhere in the world told them that it's a good idea. Daft thing is they've still kept 'Charge' and 'Balance Charge' as two separate options even though they both now are one and the same (unless, of course, they're not - and 'Charge' doesn't actually balance charge them even though the lead has to be connected .....)