First things first, what you are buying in any LiPo battery is a controlled explosion in a wrapper. Sounds over the top? well take a look at google video with the search "Lipo Battery Fire" or go direct to videoplay?docid=3690260570423705609  to see what happens if one is overcharged. Now that you are suitably shocked at what can happen (and remember these things are in EVERY mobile phone and laptop, but at much lower charge and usage rates) I'll tell you what to look for when buying and using these amazing devices.

The LiPo battery is indeed an incredible bit of engineering containing anyware from 3 to 5 times (3 average but up to 12 in cases) the "energy density" of a NiCad or NiMh rechargeable battery, bearing in mind that your average radio controlled car battery, if shorted, is able to melt through cooker power wire with ease and you begin to see the need to treat battery's with 3 times this power with great respect.

LiPo batteries have a rating measured in C where C is the current rating for the battery, 1200mAh for example, this 1200mAh stands for Milli Ampere Hours and is the standard used to measure the capacity of batteries. A single (1mAh) is 1 Milliamp for 1 hour, you get 1000 Milliamps to 1 Amp. A 1200mAh LiPo may have a continuous discharge rating of 12C meaning 12 times its mAh making our example battery capable of 12 x 1200mAh or 14.4Amps and a peek drain (15 seconds or less usually) of 15C giving a peek drain of 18Amps. One more C figure remains and that is the charging C, this can be upto 1C (i.e. only charge at the rating of the battery, 1200mAh in our example case), some newer technology is around the corner that will allow unbelievable charging rates but that’s for a future guide.

When buying a used LiPo battery it is rare that it will not have been used at high current drain, this is not a problem so long as the user of the battery did not over drain it. If the battery was over drained beyond its design limits the battery will "Puff Up" as each little pocket of battery expands under too much load, so check the pictures carefully and ask for extra ones to be taken from the side showing the layers of the battery so you can be sure no expansion has taken place. Also of great importance is the integrity of the battery, by this I mean its outer casing (usually a plastic material) UNDER NO CIRCUMSTANCES purchase a LiPo with "slight cracks", "splits", "grazes" or ANY other form of physical damage. I cannot stress this enough, if you buy a LiPo battery with a ruptured outer casing you run the risk of allowing (under high load) the creation of actual lithium and all of its associated toxic and irritant gasses. A normal healthy LiPo battery contains no actual solid lithium and will stay that way if treated correctly.

When charging your LiPo batteries please do so while you are there, do NOT walk away and leave them, BAD IDEA. Also find a suitably fire proof place to charge them on. Ideal places include a concrete paving slab or old kiln crucible, please do not use metal tin lids as the danger of short circuit is too great. At a push a "FROG" house brick is fine (ones with the carved out middle). Always use a computer controlled dedicated LiPo charger, NEVER use an old NiCad or NiMh one. I personally have a 12v LiPo charger with built in computer monitor(not expensive £15-£40). When at home I power it with a large heavy duty regulated 13.8v mains transformer(£17 from a local electronics suppliers though I am sure somthing equivilent could be found on ebay), when out in the field I use a car battery to power it.

Recently alot of, if not all, LiPo batterys have started having a second lead attached to them and you may be wondering what this is for, the extra lead ( a 3 or 4 pin connector unlike the 2 pin main connection) is for "Balanced Charging" what this means is that each cell inside the LiPo battery is charged seperatly. This method allows for the correction of possible under/over charging with multi cell LiPo batterys. If you have a 7.4v or perhaps an 11.1v  LiPo battery then it is made from either 2 or 3 smaller cells each added together to give the desired total volatge, it is possible for these cells to become charged or used to the point where each cell is at a different voltage, while this difference is small there is no problem, if the difference becomes larger over time it can lead to one or more cells becoming over charged and that is somthing we always want to avoid. If you are new to LiPo I advise you to purchace a "Balancing LiPo Charger" to take advantage of this feature, if you are an existing LiPo owner and you have a battery fitted with this extra plug it is well worth upgrading your charger to take advantage of it.

It is important to check the state of your batteries before charging them, even though most computer controlled chargers do this automatically, do not rely on a machine to perform a task that you should be doing anyway. Get hold of a multimeter or volt meter (again not expensive £2-£50) and check that the voltage of the LiPo to be charged is not too low. Low voltage for a LiPo battery is measured by taking the cell count (usually 2 to 4 cells) and multiplying by 3v so a 3 cell 1200mAh LiPo would have a minimum charge voltage of 9v if it is below this then something went wrong. Either you let the battery discharge too low by continuing to use the battery after it was already low or the battery has developed a fault. If you are 100% confident that the low voltage is due only to a slight over use, and I mean SLIGHT, then most chargers have a force charge mode which will put a little current into the battery for a limited time (usually around 30 seconds) and then stop and attempt to charge normally. If the forced charge for 30 seconds does not return the battery to a voltage above 9v for a 3 cell, 6v for a 2 cell and 12v for a 4 cell (cell count x 3v) then the battery has likely suffered damage and must either be disposed of correctly (check with your local council about battery disposal facilities in your area) or returned to the place of purchase for a check-up by a qualified engineer.

When using your LiPo battery make sure you do not regularly use it at maximum current drain, a LiPo battery used for most of the time at 50% or less of current drain will, and regularly do, provide years of 80%+ capacity service over many thousands of recharges. Some manufactures claim only to have 500 recharges before service degrades but I have found plenty of decent LiPo cells to last in excess of 1000 charges.

After using your LiPo battery check it for temperature it should never be "Ouch" hot to the touch, that’s a BAD sign and indicates that you need to use more batteries in parallel or reduce the current load on the single battery (changing motor, prop or gear ratio for example). Also check for damage to the external packaging of the LiPo battery and any packs that show signs of splits, cracks, “Puffing Up” or ANY physical damage should be discarded of in the proper manner.

At the start of this guide I said that a LiPo was a controlled explosion in a wrapper and indeed it is, but used correctly it is an explosion that will provide many hours of entertainment and power for months and years to come.

Play it safe and have fun.

Spencer AKA Foxabilo

If you did not find this guide helpfull, drop me a mail and let me know what I can do to improve it.