So is owning a multimeter critical for safety for use with unprotected li-ion battery use at high voltage in a P.V. ? If so shouldn't people be warned in advance and strongly advised to purchase a multimeter when buying such batteries from suppliers AND instructed how to use them with their P.V.?
Strikes me that most people would be ignorant of these issues. I certainly was.
Well personally, I would not use any "unprotected" battery. First link below is to a thread on the CandlePower forum. In my opinion and other more knowledgeable people, using a digital voltmeter is considered a smart recommendation for both safety and in knowing if your battery charger is "overcharging", as well as in prolonging the life of the rechargeable batteries. Whether consumers should be "warned" or "advised", well it's still a "buyer beware" world out here, as well as a lot of misinformation, so the more information and knowledge you gather, the better chance you have of making an educated decision on what you choose to buy and use. Hope this helps, not confuses. If instructions are followed there is no reason NOT to use rechargeable batteries, but since just about every site that sells these batteries mentions the potential hazards, there are certainly good reasons for doing so. Below are some links and excerpts to help anyone interested in learning more get started, but there is certainly much more information out there depending on how deep you want to go.
Photos of Protected Lithium Batteries - CandlePowerForums
EXCERPT:
"It's a very good and important question. When we say "Protected" we mean a separate computer chip that is added and gives a cutoff (breaks the circuit in the battery from completing) if the voltage goes too low, the voltage goes too high, the current amperate goes too high, and the cell temperature rises too high. There is a difference between a "PTC" "Positive Temperature Coefficient" vent holes, and this electronic voltage/amperage circuit protection which is put on a computer chip. Many hear PTC as "Protection Circuit" which it is not."
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Lithium-ion polymer batteries, polymer lithium ion, or more commonly lithium polymer batteries (abbreviated Li-poly, Li-Pol, LiPo, LIP, PLI or LiP) are rechargeable batteries (secondary cell batteries).
Lithium-ion polymer battery - Wikipedia, the free encyclopedia
EXCERPT:
The voltage of a Li-poly cell varies from about 2.7 V (discharged) to about 4.23 V (fully charged), and Li-poly cells have to be protected from overcharge by limiting the applied voltage to no more than 4.235 V per cell used in a series combination. Overcharging a Li-poly battery will likely result in explosion and/or fire. During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 V per cell (used in a series combination), or else the battery will subsequently no longer accept a full charge and may experience problems holding voltage under load.
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Lithium-ion battery (sometimes Li-ion battery)
Lithium-ion battery - Wikipedia, the free encyclopedia
EXCERPTS:
Safety requirements:
Li-ion batteries are not as durable as nickel metal hydride or nickel-cadmium designs, and can be extremely dangerous if mistreated. They may explode if overheated or if charged to an excessively high voltage. Furthermore, they may be irreversibly damaged if discharged below a certain voltage. To reduce these risks, lithium-ion batteries generally contain a small circuit that shuts down the battery when it is discharged below about 3.V or charged above about 4.2.V. In normal use, the battery is therefore prevented from being deeply discharged. When stored for long periods, however, the small current drawn by the protection circuitry may drain the battery below the protection circuit's lower limit, in which case normal chargers are unable to recharge the battery. More sophisticated battery analyzers can recharge deeply discharged cells by slow-charging them to reactivate the safety circuit and allow the battery to accept charge again.
Other safety features are also required for commercial lithium-ion batteries:
▪ shut-down separator (for overtemperature),
▪ tear-away tab (for internal pressure),
▪ vent (pressure relief), and
▪ thermal interrupt (overcurrent/overcharging).
These devices occupy useful space inside the cells, and reduce their reliability; typically, they permanently and irreversibly disable the cell when activated. They are required because the anode produces heat during use, while the cathode may produce oxygen. Safety devices and recent and improved electrode designs greatly reduce or eliminate the risk of fire or explosion. These safety features increase the cost of lithium-ion batteries compared to nickel metal hydride cells, which only require a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve. Many types of lithium-ion cell cannot be charged safely below 0 °C.
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Lithium-ion cells are charged with 4.2.±.0.05.V/cell,except for military long-life cells where 3.92.V is used to extend battery life. Most protection circuits cut off if either 4.3.V or 90.°C is reached. If the voltage drops below 2.50.V per cell, the battery protection circuit may also render it unchargeable with regular charging equipment. Most battery protection circuits stop at 2.73.0.V per cell.
For safety reasons it is recommended to stay within the manufacturer's stated voltage and current ratings during both charge and discharge cycles.
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lithium iron phosphate (LiFePO4, or LFP) battery
Lithium iron phosphate battery - Wikipedia, the free encyclopedia
EXCERPT:
The LiFePO4 battery uses a lithium-ion-derived chemistry and shares many of its advantages and disadvantages with other lithium ion battery chemistries. The key advantages for LiFePO4 when compared with LiCoO2 are improved safety through higher resistance to thermal runaway, longer cycle and calendar life, higher current or peak-power rating, and use of iron and phosphate which have lower environmental impact than cobalt.
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