18650 Led Torch Batteries And Chargers

[rick1970]

I currently use a older EDI-T P15 torch and have a couple of 2500mAh 18650 Li-ion batteries and a single port 240v charger. I currently am waiting on a Ultrafire TH-T60 HAII XM-L and a couple of extra Ultrafire 18650 Li-ion batteries from Dealextream as well as a Solarforce M8.

Now, whats the go with Li-ion vs Lithium batteries and are their charges different? What charger do I order from Dealextream to get a 2 x port charger, and the option of 12v charging from the 4x4 would be nice as well. The dealextram site can be a tad hard to work through....for me at least.

Cheers

Rick

[Duncs]

Lithium batteries aren't rechargeable - they're the ones you buy off the shelf at the supermarket and chuck out when they go flat.

Lithium-ion ("Li-ion") are the rechargeable ones. I'm guessing though that if DX has a "lithium charger" then it'll really be a Li-ion.

I'm not certain but I think all batteries are recharged in DC so a 240v recharger is converting back to DC anyway. Not sure how that helps but it seemed relevant. Anyway, point being that a car recharger should be simple enough to find. Either that or get an inverter for the car or just a lot of batteries to last the duration

[rick1970]

Ah, that makes sense......bit of confusion in the translation maybe. At the prices DX charge, 1/2 a dozen spares may not be a bad idea..

[Duncs]

The solarforce batteries come with over-charge protection built in and good run time compared with some others (I'm told - I haven't done a comparison myself but the mAh advertised isn't always ahhhh "accurate").

[Adios]

_{Lithium ion cells are a differnt volatge per cell than other batteries so they need a special charger . Also they have to be charged to a certain point and then the charger has to cut off or damage will result . Although they do exibit a rise in internal resistance as they charge up that throttles off the current but the voltage needs to be shut off before each cell goes over about 3.8 volts ( 4.2 absolute max) They are the only cells that last longer if you under charge them.}

_{Here is some charging info from the net .}

Charging and discharging batteries is a chemical reaction, but Li-ion is claimed as an exception. Here, battery scientists talk about energies flowing in and out as part of ion movement between anode and cathode. This claim has merits, but if the scientists were totally right then the battery would live forever, and this is wishful thinking. The experts blame capacity fade on ions getting trapped. For simplicity, we consider aging a corrosion that affects all battery systems.

The Li‑ion charger is a voltage-limiting device that is similar to the lead acid system. The difference lies in a higher voltage per cell, tighter voltage tolerance and the absence of trickle or float charge at full charge. While lead acid offers some flexibility in terms of voltage cut‑off, manufacturers of Li‑ion cells are very strict on the correct setting because Li-ion cannot accept overcharge. The so-called miracle charger that promises to prolong battery life and methods that pump extra capacity into the cell do not exist here. Li-ion is a “clean” system and only takes what it can absorb. Anything extra causes stress.

Most cells charge to 4.20V/cell with a tolerance of +/–50mV/cell. Higher voltages could increase the capacity, but the resulting cell oxidation would reduce service life. More important is the safety concern if charging beyond 4.20V/cell. Figure 1 shows the voltage and current signature as lithium-ion passes through the stages for constant current and topping charge.

Figure 1: Charge stages of lithium-ion. Li-ion is fully charged when the current drops to a predetermined level or levels out at the end of Stage 2. In lieu of trickle charge, some chargers apply a topping charge when the voltage drops to 4.05V/cell (Stage 4).

Courtesy of Cadex

The charge rate of a typical consumer Li-ion battery is between 0.5 and 1C in Stage 1, and the charge time is about three hours. Manufacturers recommend charging the 18650 cell at 0.8C or less. Charge efficiency is 97 to 99 percent and the cell remains cool during charge. Some Li-ion packs may experience a temperature rise of about 5ºC (9ºF) when reaching full charge. This could be due to the protection circuit and/or elevated internal resistance. Full charge occurs when the battery reaches the voltage threshold and the current drops to three percent of the rated current. A battery is also considered fully charged if the current levels off and cannot go down further. Elevated self-discharge might be the cause of this condition.

Increasing the charge current does not hasten the full-charge state by much. Although the battery reaches the voltage peak quicker with a fast charge, the saturation charge will take longer accordingly. The amount of charge current applied simply alters the time required for each stage; Stage 1 will be shorter but the saturation Stage 2 will take longer. A high current charge will, however, quickly fill the battery to about 70 percent.

Li-ion does not need to be fully charged, as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge, because high voltages stresses the battery. Choosing a lower voltage threshold, or eliminating the saturation charge altogether, prolongs battery life but this reduces the runtime. Since the consumer market promotes maximum runtime, these chargers go for maximum capacity rather than extended service life.

Some lower-cost consumer chargers may use the simplified “charge-and-run” method that charges a lithium-ion battery in one hour or less without going to the Stage 2 saturation charge. “Ready” appears when the battery reaches the voltage threshold at Stage 1. Since the state-of-charge (SoC) at this point is only about 85 percent, the user may complain of short runtime, not knowing that the charger is to blame. Many warranty batteries are being replaced for this reason, and this phenomenon is especially common in the cellular industry.

Avoiding full charge has benefits, and some manufacturers set the charge threshold lower on purpose to prolong battery life.

Edited June 15, 2013 by Happy Jack