Battery Power

Also: Super Capacitors +

Because battery voltage varies with charge, it must be regulated with some type of DC to DC Converters

PIC Specific Battery Backup Power Supply

Automotive power systems

Cordless Tool Battery Systems

Battery characteristics

"Battery characteristics" from _Portable Design_ 1998 July article by Jim MacDonald

Size vs Capacity

Battery capacity (in Ampere·hours) is described by the letter C. A battery with a C rating of 1.2 A·hr is capable of supplying a 1.2 A load for 1 hour. Also, when charging this battery at a C/10 rate (120 mA charging current), it takes a little over 10 hours to charge it.

Load vs Time

The Eveready data book lists the following loads vs. hours, to a cutoff voltage of 1.0 volt for AA Alkaline batterys:

• 1500 ohms = 1850 hours
• 300 ohms = 340 hours
• 150 ohms = 160 hours
• 75 ohms = 82 hours
• 50 ohms = 54 hours
• 30 ohms = 32 hours
• 10 ohms = 7.8 hours
• 4 ohms = 2.3 hours

[*] number of recharge cycles until only 80% of initial charge capacity is available upon recharge. These figures are /very/ best case and probably double the real world value.

Lifetime cost comparison

From http://www.batteryspace.com/li-ionsinglecell.aspx (Thanks to Russell McMahon)

The environmental impact of batteries can be vastly reduced by responsible recycling. The cost of LiFePO4 may be overstated, but is still valid in comparison. E.g. all the cycle life numbers are best case, but the relative low cost of LiFePO4 remains if all cycle life figures are reduced.

Lance Allen

The internal resistance of any power source is a representation of that batteries ability to provide power to a load. This can be thought of as a battery capable of delivering infinite current at no voltage drop in series with a resistor, that resistor being the internal resistance. So a small 12volt battery will have a higher internal resistance than a big 12volt battery and a damaged battery will have a higher internal resistance than an undamaged battery.

You can determine internal resistance by loading the battery and watching the voltage drop across its terminals. If a 12 volt battery drops 1 volt under a load of 1 amp then its internal resistance is 1 ohm. Internal resistance will vary with the state of charge so compare batteries at a common condition, such as full charge.

Manufacturers data is usually comprehensive on a batteries ability to deliver power at different rates, temperatures etc.

A lead acid battery is fully charged at a terminal voltage of 12.6 volts, 25% discharged at 12 volts and flat at 10.8 volts. DO NOT discharge a 12 volt Lead Acid Battery below 10.8 volts or it will be damaged over time.

So (from manufacturers data) a Hitachi 12 volt 7 Amp Hr Lead Acid battery has a fully charged internal resistance of 25 milliohms and can supply a maximum current of 40 Amps for 5 seconds. The maximum charging current is 2.1 Amps.

Don Hyde says:

The non-rechargable (primary) batteries are easy to get your hands on and easy to use. They can be dangerous though, because they will deliver several amps at 3V, which will heat up a wire hot enough to burn your hand.
Don't ask how I know this.{ed: <GRIN> been there, have that scar. Many people have experienced this as a result of carrying batteries around in a pocket, then forgetting and tossing in loose change. Very serious damage can and has occured.}

As for the rechargables...

I mentioned exploding and catching fire... Lithium rechargables have a serious problem with thermal runaway while charging. As they charge, they warm up, and as they warm up, they draw more current, which makes them even warmer...

Lithium rechargables are usually "smart battery" packs, and the plastic and stuff includes temp sensors and usually part of the charger circuitry.

There just might not be any available as individual components since there is such an intimate relationship between the charging circuitry and the stuff in the battery pack, with a serious liability issue if it's not right. They are light, and have lots of capacity, otherwise the laptop and cellphone guys wouldn't be going to all the trouble and expense.

Replacement cellphone and laptop battery packs are readily available. Perhaps the easiest way to get one to play with would be if one of them sold an offline charger. They are expensive, though.

See also

• Linear Technology make what they call Micropower switching regulators (LT1073)
  • LTC1559-3.3/LTC1559-5 Backup Battery Controller with Fixed Output
  • LT1239 Backup Battery Management (charging / step-up converter) and Main Supply Regulation
  • LTC1479 PowerPath Controller for Dual Battery Systems
• Exide Handbook for Gel-VRLA-Batteries: Explains battery design, plate sizing to dictate end point chemustry, gas evolution and recombination etc, effect on cycle life of temperature overcharge %, depth of discharge, more ... AGM versus Gel factors., plate growth during lifetime and implications, valve aspects, service life and cycle life, acid stratificatin, thermal runaway, ... Majors on Sonnenschein' A400/500/600/700 series batteries but far more widely useful.
  • http://www.sonnenschein.org/PDF%20files/GelHandbookPart1.pdf Part -1 Basic Principles, Design, Features.
  • http://www.sonnenschein.org/PDF%20files/GelHandbookPart2.pdf Part-2  Installation, commissioning, operation Self discharge, charging regies, trickle charging, much more.
• http://www.duracell.com/oem/Pdf/others/TECHBULL.pdf 23 page Duracell summary on Nickel metal Hydride seems better than most.
• http://www.stefanv.com/electronics/using_nimh.html Not overly techo but potentially useful article on practical NimH use. .
• http://www.panasonic.com/industrial/battery/oem/chem/nicmet/index.html Panasonic NimH stuff
  • http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NIMH_Precautions.pdf Panasonic: Precautions for designing devices with NimH batteries
  • http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NiMH_ChargeMethods.pdf Panasonic: Charge methods for NimH batteries:
• http://www.eneloop.info/home/why-eneloop/low-self-discharge.html Sanyo on Eneloop self discharge compared to stc NimH
• http://www.stefanv.com/electronics/low_self_discharge.html Comparison of 8 x low self discharge AA NimH brands. Note that quoted voltages are at 1C load.
• http://ka7oei.blogspot.co.nz/2013/05/lithium-iron-phosphate-lifepo4.html Cell imbalance issues in a multicell battery and a circuit to prevent it.
• http://www.mpoweruk.com/life.htm#arrhenius Battery cycle life and factors
• http://www.nachhaltigwirtschaften.at/results.html/id4477 Vanadium Redox self discharge mechanisms (Roger?)
• http://www.panasonic.com/industrial_oem/battery/battery_oem/batteries_oem_home.htm
• http://www.yuasa-jpn.co.jp/maine.html
• http://www.powercache.com/
• http://data.energizer.com/datasheets/_partof/splash.htm
• http://data.energizer.com/batteryinfo/application_manuals/nimh_application_manual.htm
• http://www.4gdo.com/batfaq.htm
• http://www.duracell.com/OEM/Rechargeable/Nickel/nickel_metal_tech.html
• http://www.mahaenergy.com/products/consumer/mhc204f.htm CHARGE YOUR AA & AAA NiMH & NiCD BATTERIES IN ABOUT 3 HOURS! $27.00 US
• http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1964 Li-Ion power pack 7.4V 8800 mAh $67.

Archive:

• List post "Battery Capacity" They don't really have an internal resistance... +
• List post "How to read Battery voltage with PIC" +
• PICList post "Monitoring battery status." +
• PICList post "Lithium Ion Batteries" (and NiCad memory) +
• PICList post "Cell Phone NICAD Battery Conditioning"

See also:

• https://docs.google.com/spreadsheets/d/1Pk2dOzy6_Os_MRMNCAoiN81tqECrH8EbxnYlpBUQVGI/edit?pli=1 Updated battery comparison+
• http://www.ti.com/lit/sg/slyt420c/slyt420c.pdf Table of Contents Battery Management System Applications
  
  3 Overview
  4 Energy Harvesting and Nano Power Solutions
  5 Electric Bicycle Solutions
  6 Wireless Power Devices
  7 Handheld Consumer Medical Equipment
  8 Portable Industrial Solutions
  9 Automotive Power Solutions Battery Management Products
  10 Battery Chargers
  22 Battery Charger Protection
  23 Battery Fuel Gauges and Monitors
  26 Battery and Peripheral Authentication
  27 Battery (Li-Ion) Protection
  28 Wireless Power Solutions Design and Development Tools
  32 Resources+
• http://ka7oei.blogspot.co.nz/2013/05/lithium-iron-phosphate-lifepo4.html Cell imbalance issues in a multicell battery and a circuit to prevent it. This is for batteries, but may apply to multi-cell supercap power storage as well.+
• http://www.smartgauge.co.uk/batt_con.html When stacking multiple batteries in parallel for greater current capacity, always use a "star" pattern where each battery is individually connected back to a single set of terminal posts. If you just string them in a "ladder" the lead resistance will result in the battery farthest from the load providing less current than the one nearest the load. Alternatively, you can connect the batteries in sets of two, then connect those sets together to form two sets of two batteries, and so on.+
• http://buchmann.ca/ Online book - Batteries in a portable world

Questions:

• wdtoo at KILLspammsn.com asks: " looking for a replacement for a vinnic L1028 Alkaline Battery 12V 23A. Any suggestions where to find one? Thanks"

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