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Chris,
I appreciate that you race RC cars, and obviously that they most often use LIPO cells. I'm quite familiar with charging rates and BC1.2 Also I understand what C stands for. What others may not know about C is that it's the rate of charge based on the maximum rated capacity of the battery in mAh (milliAmperes). This means that if a battery such as the Moto X, which has a capacity of 2,200mAh is charged a the rate of 1.5A, it's being charged at the rate of 68%, or C.68 of its rated capacity. This means it may be able to charge to 100% of its capacity in less an hour and a half. That is FAR TOO FAST for a cell phone battery and if done on a regular basis will cause the battery to become essentially beyond life in a very short period of time, less than a year in fact. By contrast the charger supplied with the typical phone is a much lower mAh rating of typically from 750mAh to upwards of 900mAh, or C.34 to C.41.
The stock charger from the manufacturer - the one supplied with the Moto X phone outputs 1,150 mAh, or C.52 (Thanks MotoXGirl! :biggrin
. Even the manufacturer's "Rapid Charger" (see link below), is only 1.2A which is C.55, all far less than the C.68 you referred to as a "maximum BC1.2 charge rate of 1.5A", or 2A which is C.91;http://www.motorola.com/us/accessories-batteries-chargers/Duo-Rapid-Charger/duo-rapid-charger.html
Without intention of insulting our friends in the RC world I'd like to separate them from the cellular phone world for lots of reasons. The main one is because there are no functional current limiting circuits in most RC batteries - and instead are contained in three external charger. And RC enthusiasts in the greatest percentage are by and large the most demanding of LIPO batteries by the very nature of their purpose, pushing them often beyond their intended limits...some deliberately, some mistakenly, but most as a whole.
RC is by design intended to use all the power of the battery at a high current rate, and in a very short time, over one or a few short periods of racing - we're talking minutes here, not all day like our cell phones. Discharging at that high rate causes the anode of the batteries to be stressed and that reduces their lifespan. Also it's the goal of enthusiasts to charge the batteries as quickly as possible so they can race again sooner. Again unfortunately charging these batteries quickly also dramatically reduces their lifespan. Another thing many RC enthusiasts do is over-charge (or bump-charge), the batteries to get more "juice" and therefore more run time from them each time they race...it's all about having an edge over the competition that gets you to the finish line sooner and win the race. And again...you guessed it...this dramatically shortens the batteries' lifespan. In fact, it's not uncommon for an RC Racer to charge at rates in multiples of C, such as C2 or even C3 or more, to get a lightning fast charge and be back in the race quickly. Those batteries die very soon when charged at those rates.
This is all the exact opposite of cell phones. We are looking for batteries to provide low current draw over long periods of time - preferably all day and until we go to bed, we want our batteries to last the usable life of the phone - about 1.5 to 2 years, and although we do like faster charging, if the battery can last all day we can simply charge overnight and that gives us plenty of time to charge slowly.
The manufactures of our phones know this, and so they deliberately use a different chemistry in the batteries of our equipment designed to provide slow drain over long periods, and they use a much more sophisticated charging and metering circuitry than most RC enthusiasts use. The intention of course is to charge slowly so that the battery is not stressed, not to charge the battery in excess so its not stressed, to release the power over a long period of time at slow rates, again not to stress the battery, and ultimately to provide a battery that lasts for the length of the expected life of the phone which is from one and a half to two years or typically 500 complete charge cycles (0% 10 100%).
What I'm trying to impress are two things. 1, Cell phones are completely different animals than RC vehicles and so the batteries have to be designed and handled completely differently if you want them to perform the way we hope they perform. And manufactures know this so they take great care in designing the batteries, the phones, and the chargers to maximize the long-term output of the battery and provide great long runtimes.
Next, manufacturers put current limiters in the phones for just the reason we're debating. They know that users will want to "push the envelope", and try to charge faster than intended. They also know that if allowed to the batteries will become weak in a very short period of time, likely before the 1-year warranty is up. They therefore deduce that they will ultimately suffer the costs for the damage done to the batteries by the end user when the phone is returned for a "bad battery". Truth is, in approximately 90% of the phones returned for "bad battery", the batteries test out as in proper working condition. In those instances it's the charging circuit that has been abused by attaching it to a poorly designed charging block which damages the charging circuitry and then performs improperly during charging, resulting in batteries that are improperly charged and don't last as long as spec'd to. This is also why in most manufacturer's phone's warranties there appears a disclaimer that using a non-manufacturer spec'd charger MAY void your warranty.
Directly from page 60 of the Motorola Moto X user's guide (https://motorola-global-portal.cust...irect/1/filename/Xfon_UG_Vzw_68017470001A.pdf):
Safety, Regulatory & Legal
Battery Use & Safety
Warning:
Your mobile device contains a battery that should only be removed by a Motorola
approved service center or recycler.
• Don’t try to remove or replace the battery yourself. Attempting to remove or replace the
battery may damage the battery and may cause burning and injury.
• Don’t try to take apart or fix your phone. Attempting to take apart or fix your phone may
damage the battery and may cause burning and injury.
• Don’t crush, bend, or expose your phone to heat or liquid. This may damage the battery
and may cause burning and injury.Safety, Regulatory & Legal
Battery Charging
Notes for charging your product’s battery:
• During charging, keep your mobile device and charger near room temperature for
efficient battery charging.
• New batteries are not fully charged.
• New batteries or batteries stored for a long time may take more time to charge.
• Motorola batteries and charging systems have circuitry that protects the battery from
damage from overcharging.
Third Party Accessories
Using third party accessories, including but not limited to batteries, chargers, headsets,
covers, cases, screen protectors, and memory cards, may impact your mobile device’s
performance. Using a non-Motorola battery or charger may present a risk of fire, explosion,
leakage, or other hazard. Motorola’s warranty doesn’t cover damage to the phone caused by
non-Motorola batteries and/or chargers. For a list of Motorola accessories, visit
Accessories
(in English only).
I've disassembled dozens of different CELL PHONE chargers (and also have explored RC Battery chargers), and in almost every case, if the charger is made by a cell-phone manufacturer it is robust, contains lots of regulation and filtering to provide the most pure DC current it can, and likewise in almost ever case aftermarket chargers of all types are miniscule in design, have little regulation, little filtering (if at all more than simple capacitors), and put out DIRTY current which stresses the charging circuit. Also, current limiters are only so good at protecting the remaining circuity immediately down-line and the battery at the other end. Current limiters do get weak and eventually fail when put in a situation where they must resist current draw in excess of their rated capacities.
Using high powered charging blocks with these phones puts them in harm's way, and for no real good reason. The phone will only allow the battery to charge at the rate the manufacturer has set as a limit and no faster (as long as the current limiter is functioning normally). So using a 2A charging block for a phone that's spec'd to charge at a maxim rate of 750mAh will do NOTHING to speed up the charging process, but could put the phone at risk of damage. It's perception that appears as reality for many. On the other hand, if the phone has a fast charging limit, perhaps as high as 1.2A (not 1.5A), then using a higher powered block will yield a faster charge, but it will also result in a shortening of the battery's life and eventually poor run-time performance...dying earlier and earlier in the day with full charges. Again, using a 2A charger even for a phone that can charge at 1.2A is excessive. I have chargers that have two ports as well. One is 1.2A and the other 2A. I will NEVER plug my phone into the 2A socket - plain and simple. There's no reason to. The phone can't charge faster than 1.2A and so that's all I give it.
So if you want to get the most out of your battery, and prevent damaging it, you will heed the manufacturer's recommendations and use ONLY the FACTORY SUPPLIED Charger on your phone, you won't exceed the current output rating that is on that OEM's (Original Equipment Manufacturer), charger, and you will avoid succumbing to the temptation of overdoing it.
I rest my case.
There is far more informative information on BatteryUniversity.com that backs up my claims from the undisputed battery experts there, the ones who make the industry's most highly regarded CADEX chargers for military, emergency and other mission-critical radio and safety equipment.
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