A Battery Guide
Note: This list is in progress, still updating periodically.
***If you have any info to add please go ahead and post it as a reply. I will add a link in this list to your reply and give you credit. Thanks in advance!***
Some info to help you understand batteries (yes I've done my homework, and I know this is dense, sorry about that). To help navigate this list, type [ctrl] + [F] and enter battery type.
-Can do about 2C max
-Have a relatively high internal resistance (when compared to lead-acid), this means a high voltage drop under load
-Require a BMS (battery management system) to protect from over discharge, over charge, and discharge rate
-Very dangerous if mistreated http://www.valence.com/battsafe.asp
-Require a special charger designed to charge Lithium-ion cobalts
-Have a limited life even if you don't cycle them
-Survive about 300-400 100% DOD cycles
-Can be charged quickly at 1C
-Very high nominal specific energy, specific energy in EV use unknown
-Price is rapidly falling, but appears to be able to compete with lead-acid in real-world use when considering battery price alone. This does not include time & materials for pack construction, a BMS, special charger, and pack maintenance including finding bad cells and replacing them throughout pack life.
-Power density is high, but batteries can not safely peak a high multiple of their rated capacity at only 2C. This means you need a high energy pack to get a lot of power.
Lithium-ion A123 Systems "Nanophosphate technology"
- Probably the highest specific power battery commercially available
-As these become more available they will likely be used a LOT for smaller PEVs (personal electric vehicles)
-Do your own research http://www.a123systems.com/html/technology.html
-Spec sheet: http://site.buya123systems.com/ANR26650M1specs.pdf
-Low internal resistance, and extremely high power
-Can peak an extremely high multiple of their rated capacity, i.e., you don't need a high energy pack to get a lot of power
-Not a lot is know of them in real-world use for EVs
-Price is very high at this point. Consider buying Drill packs from ebay. Additionally the drill packs will have a BMS installed.
-Much safer, longer life, more power, less energy, and lower nominal voltage than lithium-ion cobalt, but still very high energy density
-Cycle life moderately effected by discharge rate http://www.a123systems.com/html/tech/life.html
-Can be charged extremely fast
-Capacity moderately effected by temperature
Lithium Manganese "Spinel" by NickF23
Valence Lithium-ion U-Charge XP series
-Longer life than cobalt lithium-ion
-Do your own research: http://www.valence.com
-Designed to be integrated into lead-acid applications. Can be charged from lead-acid chargers (huge advantage)
-Lower specific energy than cobalt, but still very high
-Moderate specific power
-Come with integrated BMS (another huge advantage)
-Can only peak about 3C
-Come in standard BCI lead-acid battery sizes U1, Group 24, & Group 27
-Capacity effected by temperature
-like cobalt, can be very dangerous if mistreated
-Very high specific power, are popular for RC craft
-Specific energy can very, typically appears to be less than Cobalt, but still very high
-Need a special Li-Po charger
-Generally used for applications requiring high power in small battery size. A123 will likely replace them as A123s become more available as they have a higher specific power, and are safer
-Cycle life similar to that of Cobalt
-Also need a BMS, especially in a large pack
-Need a special charger designed to charge NiMH or NiCad
-Safer than Li-ion under abuse
-NiMH survive about 300-1000 100% DOD cycles to 80% capacity depending on discharge/charge rate, quality of battery, heat, if they are used with a BMS, etc.
-Can usually last much longer than the above # of cycles with reduced capacity, if they are treated well, i.e., NiMH might last 1500 cycles to 60% capacity
-NiCad can survive 2x or more as long as NiMH if they are treated well
-Most NiMH/NiCad don't last very long in real-world use because they are used without a BMS and over charged/discharged
-RC Car 6-cell sub-C NiMH/NiCad generally survive 300 cycles, this is under very high discharge (<5 min rate)
-In general lower internal resistance than cobalt lithium-ion, but still not very good in large cells (D & F)
-Not effected by cold temperature nearly as much as lead-acid
-Efficiency is poor 66% for NiMH, a little better for NiCad depending on charge rate
-SOC (state of charge) drops quickly, 30%/month, however they can sit in a discharged state OK
-Maintain voltage well throughout discharge cycle
-Specific energy in EV use varies depending on discharge rate and internal resistance: ~20whrs/lb for NiCad, 25-30 for NiMH
-May be less expensive in real-world use considering their longer life than lead-acid when considering battery price alone. This does not include time & materials for pack construction, a BMS, special charger, and maintenance to find bad cells in pack throughout its life
-Specific power varies a lot depending on cell internal resistance, and may be moderate for larger D and F cells, and very good for smaller sub-C cells (those generally used in power tools).
-Some can peak a high multiple of their rated capacity while other cells can not.
- A very important difference between NiMH and NiCad is that NiMH do not maintain a charge/discharge memory and may be charged without a full discharge. NiCad batteries suffer from a charge/discharge memory and must be fully discharged to maintain their run time. If they are not discharged the discharge time will slowly shrink to almost nothing, rendering them useless.
Lead-acid VRLA (valve regulated lead-acid) AGM (absorbed glass matt), deep cycle type:
-Low internal resistance, low voltage drop
-Need special charger designed for lead-acid
-Require battery balancing of some type, usually done by battery regulators (much less complex & cheaper than a BMS), during charging
-Cells appear to be "matched" in capacity much better in production than those of NiMH/NiCad. They also appear to very in capacity less than NiMH/NiCad throughout their life.
-Survive 300 100% DOD cycles to 60-80% capacity, Enersys may survive another 100 or so. After this, available capacity drops very quickly with cycles.
-No. of cycles vary more or less linear with DOD, i.e. 600 cycles at 50% DOD. However, appear to have a slight to more significant advantage with lower % DOD, depending on DOD, manufacturer, and type. There seems to be no "sweet spot" DOD like with flooded lead-acid, instead they always appear to offer more life the lower the DOD cycles
-Cycle life moderately effected by a high discharge/charge rates, but severely effected by over discharging/charging
-Effected more by cold weather than NiMH/NiCad
-Likely the safest batteries available.
-Don't require maintenance of any sort, other than checking the terminal bolt tightness
-On the flip side to how they are effected by cold, if you live in a hot climate and/or heat the batteries via fast charging they can provide significantly more energy/power
-Can be used in any orientation as opposed to flooded lead-acid. This means they can be shipped via UPS, Fedex, ect.
-Very efficient, as high as 95% depending on charge/discharge rate.
-Can sit a long time without significant loss in SOC (state of charge)
-Maintain voltage well throughout discharge cycle, except the voltage drop is more and happens sooner than NiMH/NiCad
-Must be charged after use. Can sit discharged, but they will sulfate, and this can shorten life (depending on how often, how deeply discharged)
-Specific power in EV use (this is not the nominal specific energy!) is about 10 whrs/lb, might be little higher drained slowly, and slightly lower if drained very quickly.
-More resistant to vibration than flooded lead-acid
-Contain a catalyst to recombine hydrogen/oxygen during charging, this means they rarely vent hydrogen, and are safer than flooded lead-acid
-Are 2-3x cost of flooded lead-acid
-Specific power depends on manufacturer, and type. Generally high for those designed for SLI applications (Hawker, Exide, Optima), and good for generic use.
-Can generally peak a very high multiple of their rated capacity
Lead-acid flooded deep cycle (golf cart, semi-industrial, not marine or starter)
-Poor internal resistance, high voltage drop
-400+ 100% discharge cycles, capacity drops rapidly after this
-Appear to have a "sweet spot" DOD for maximum life. Some say this might be about 50% DOD, i.e., if you always charge them after 20% DOD then you will get less life than waiting until they are at 50% DOD.
-Efficiency is low at 70%
-Vent hydrogen when charged, must be in well ventilated area
-Can spray acid when shorted/discharged too fast, or charged too fast.
-Must be kept upright, cannot be shipped via UPS, Fedex, ect.
-Require checking acid level & adding water.
-Acid eats clothing, meaning floodeds are a PITA to work around
-Cheapest battery type
-They tend to smell
-Usually balanced by occasionally purposefully overcharging at a low rate. They will benefit from battery regulators nonetheless.
-Do not maintain nominal voltage well through discharge cycle, and tend to really "sag" in voltage the last 30% SOC (state of charge)
-Specific power in EV use varies depending on discharge rate, can be considerably less than 10 whrs/lb if drained quickly, >15 whrs/lb if drained more slowly. This makes them much more suitable for less-demanding EVs such as forklifts and golf carts.
-Specific power is moderate to good
-Can generally peak ~5C
-Similar to traditional lead-acid
-Offers numerous advantages when compared to lead-acid, including low temperature performance, ability to sit discharged, and slightly longer cycle life
-Included in the E-max originally, not sure if they still are
-Have a different charging voltage and profile than traditional lead-acid
-Not sure if anyone could get any, except by buying an E-max.
"Differences between Lead and Silicone" by chas_stevenson
-I don't think you can get them anymore, please correct me if I'm wrong and provide a source
-Initially looked promising at about 2x the specific energy of lead-acid, and longer life
- http://www.electricmotorsport.com used to carry them
- http://www.nizn.com/ appears they have just quit
Thats about all I know. In general much more is known about lead-acid in EV use than other types of batteries. Some things are not well established, or I just need to find more info about:
-How do lithium-ion handle vibration when compared to lead-acid at a cellular level? How about at a larger level, i.e., how reliable will the cell interconnects be?
-What will happen if a lithium-ion battery is punctured and/or exposed to high heat? Will it explode and cause the rest of the cells to explode as well?
-If lithium-ion are shorted, will they explode, and how will they explode?
-How are lithium-ion effected by temperature? Will high external temperature in combination with high internal temperature caused by rapid charge/discharge adversely effect life/safety?
-How reliable will a large BMS be constructed to monitor thousands of cells? How likely is a catastrophic failure causing battery explosion?
-How likely is an internal short in the advent of an accident of a large thousand plus cell pack? Will this cause explosion, and how quickly from the short until explosion?
-Where do you take hundreds of pounds of NiMH/NiCad/Lithium-ion to have them recycled/disposed of properly, and how much will this cost? (Please don't throw them in the garbage)
-How likely are individual cell failures, and how will this probability change through the life of the pack?
-What will happen at the end-of-life? Will most cells fail at nearly the same time, or will this vary considerably?
-How do you design a large battery pack allowing easy replacement of bad cells?
-Does temperature effect sealed lead-acid more than flooded lead-acid?
-Discharge may cause considerable rise in temperature of NiMH/NiCad/Lithium-ion. Will they need to sit a while before charging? Will a cooling system be required?
-Can a cheap constant voltage or constant current charger be constructed with a temperature cutoff for NiMH/NiCad which still allows for a fair number of cycles?
-How much energy must be left in NiMH/NiCad/lithium-ion packs in order to prevent taking the voltage too low to possibly cause cell reversal? Will this adversely effect capacity? How will this change throughout the pack life?
A few additional things to consider:
-With a lead-acid system a battery replacement is easy. If you construction your own pack from cells of NiMH/NiCad/Lithium ion, then you will have to construction a new pack for each replacement.
-NiMH/NiCad/Lithium-ion with tabs may have poor quality connections at the joint to the tab, which may not handle high current, and fail under vibration
-If you or your battery charger damages your batteries then you will likely need to buy new batteries. (Lead-acid are cheap to replace)
-A BMS system may cost as much as the price of the cells for NiMH/NiCad/Lithium-ion
-A charger for a pack of large cells will need to be custom made (including the a BMS), and as such, will not be as reliable as chargers/battery regulators that have been on the market for lead-acid
- Known sources for batteries:
Cheap Generic(low quality):
SAFT (high quality NiMH/NiCad)
Panasonic/Sanyo (good quality)
Sealed Lead Acid
B&B Batteries (good quality, good power)
Enersys (Odyssey, Cyclon, Genesis) (Very high quality & Power)
Exide 34XCD (Very high power)
Optima (Very high power)
Battery Regulators (Powercheq recommended)
http://www.trojanbatteries.com check with local battery supplier
Lithium-ion Cobalt BMS/Chargers
http://www.ebay.com (search for lithium-ion Dewalt packs)
Battery Info Resources
This is not a complete list or guide. I tried to cover the most practical information, including the most promising battery technologies. There are lots and lots of other battery technologies.
In addition, this guide only covers batteries for energy storage, and does not include other technologies for potential energy storage (including fuel cells, flywheels, electrostatic (capacitors), etc.), or energy transfer (induction, electromagnetic, etc), or energy harnessing devices (solar cells, wind generators, etc.) which may become practical for EV use.
Good summary Andrew.
A few points.
1 I've not seen any independent source confirming 'silicone batteries' are anything other than a normal lead acid batteries. I suspect they are purely a marketing gimmick.
2There are quite a few other lithium chemistries. One of which is lithium maganese LiMn2O4 cells. These are starting to be used by UK ebikes manufacturers. and also people hacking emoli milwaukee drill packs.I've heard they're going to be cheaper than normal li-ion cobalt once production gets going. Interesting thing about lithium is the sheer variety of chemistries, on top of this the managment systems, both electronic and thermal effects the longevity/performance of each of them. I read an EV world article in which automotive lithium guru Menahem Anderman spoke of the need to think of li-ion as an energy system rather than simply a chemistry per sea, which kinda made sense. I suppose unlike lead or nimh its going to be harder for EV enthusiasts to use lithium, though hopefully info will start to trickle out from the labs and manufacturers.
3 I've also heard that lithium batteries are not cost effective to recycle, though it can still be done. apparently nickle based batteries are cost effective to recycle. I hope recycling takes off soon especially with lithium as there are limiited supplies.
I've not seen any independent source confirming 'silicone batteries' are anything other than a normal lead acid batteries. I suspect they are purely a marketing gimmick.
There is a difference between Lead and Silicone batteries. Here is what I have found on these batteries from several sources.
Silicone batteries have the following advantages over conventional lead acid batteries.
Electrolyte Environmentally Friendly-Actually Recycled as Fertilizer
No Acid Mist emission when charging or discharging
Storage capacity as high as 1.75 times of international standards
Recharge acceptance capacity as high as 2.68 times int. standards
High current discharge, battery will not be damaged when discharging within 8 seconds at 30C deep discharge is allowed
Low self discharge: after fully charged the battery can be used within one year at a normal temperature
No Memory Effect for charging or discharging
Functions normally between -50C and +70C
No Pollution from the electrolyte
Maintenance Free; Sealed with a relief valve
Optimized for High Current Discharges
Low Internal Resistance
Long Life Span; over 400 times of recharging
Functions normally under 6000 meters of sea depth
The silicone powered, environmentally safe battery, where silicate salt is used as the electrolyte, is basically developed on the same theory as the lead-acid battery but they have the following specialty difference: using the silicate salt as electrolyte will produce absolutely no chemical pollution whether in production, usage or in disposal. This is a tremendous contribution for mankind worldwide. Furthermore, adding to the matured technology of the lead-acid battery production over the past 100 years, the quality of the silicone battery has advanced even further.
Read the entire article About Silicone Batteries for more information.
Other information from an Emax diary can be found at about the e-max batteries.
This may be a source for Silicone Batteries Dalin Trading Co., Ltd.
Here is another scooter which uses Silicone Batteries, the E-Runner 220.
Thanks for the links. I find that when I do a search "silicone battery" on google all I find is people is selling them, some of the sites seem a little dead aswell. The makes me a little skeptical. If we could find an independent source such as a trade magazine, an academic discussion or paper, or even an a substantial report by an EV enthusiast that backed up the specs but there's nothing,
The only independent information I have seen is from PJD on this site. Some claims, like the increased cycle life are a little tricky to check for but discharge rate, energy density and cold weather performance aren't, all it would take is someone with a drainbrain and a fridge. My guess is that if there was something special about these then someone would have tested them and reported back with there findings as they've been around a few years now. I hope I'm wrong.
Will do Andrew, I'll do a little research and go from there.
You forgot to include Lithium Iron phosphate batteries ( LiFePo4) offered by http://powerstream.com. :)
I know thing have been bad for silicone batteries. I hope maybe they will change as the lawsuit over the patent has now been resolved.
I have signed up to sell the silicone batteries in the USA and my first delivery of batteries will arrive at the dock in Long Beach on 7-9-07.
The batteries will go into a force electric car and an off grid house. I will be selling these batteries to at cost to anybody that wants to help me test them out.
See Community Marketplace/Sell Community Member Silicone Batteries.
Because of the importance of Silicone Batteries to our members, the above post was slightly edited, and the complete post was reposted in Community Marketplace/Sell Community Member Silicone Batteries.
In order to keep this thread close to topic, please post any replies, or inquires about purchasing these Silicone Batteries in Community Marketplace/Sell Community Member Silicone Batteries.
Thank's for your understanding,
Moderator Team Captain