The old battery dilemma....
2010 - MightyBoyEV was upgraded to a Li-Ion battery pack please follow this
upgrade on this site at
February 2009 - Over the next few years I will update these views to reflect on the technology of the day….
Yes, it’s still an issue in 2009, let’s hope 2010 brings some changes for the better. It’s not that better battery technology is not available - the issues are centred on price and quality. When I started this project one of the main aims was to use Li-Ion technology and I never remotely considered older lead acid technologies . Well guess what! I have just purchased a 72 volt charger and it will be profiled to charge non state-of-the-art AGM (Absorbed Glass Mat) SLA (Sealed Lead Acid) batteries…..
So why change now?
Firstly cost, Li-Ion cells have just not become common enough. This can be attributed to lower EV demand then projected. When petrol (gas) prices were extremely high around the world everyone needed an EV but prices have slumped and EV demand from the public has as well. The demand is still there from the green movement but most consumers are dollar driven. The world financial situation has also played a large part, investment money for new projects such as battery development and production is very difficult to find and most likely will not improve in the short term. For those of us in Australia, the poor exchange rate is another consideration. In my case I had budgeted for $5,000 Australian (with Battery Management System or BMS ) but this not possible and I want to use the car first quarter 2009.
The second issue is with the semi affordable Li-Ion cells that are currently available to the public. Most of these (Thundersky being the most popular) are made in China. Many are of questionable quality and to get REAL independent test data on these is next to impossible. I also favour having the BMS incorporated into the pack and correctly designed for the battery pack and battery chemistry. A few home EV builders have chosen to go with these cells and are very happy with the outcome to date. Unfortunately none of these battery packs have been in service for more than 3 years so projected life in the real world is still unknown. Up-to-date information on this subject is regularly covered on the podcasts @ www.evcast.com . It is interesting to note that the new Toyota “Plug in Prius” model to be released in 2009/10 is actually staying with nickel-metal hydride battery technology. Is Toyota wrong??
So what will I do to get this baby on the road?
Firstly, I have decided on the type of SLA battery that I will use - my choices came down to AGM or Gel Batteries. After reading for hours, sending numerous emails and talking to a number of electro chemists I picked AGM batteries over Gel batteries. I will not go into the research behind this decision here but in the end there was not much in it. AGM’s basically still offer a reasonable number of cycles (but not as good as Gel batteries), they are slightly smaller and lighter for the same Ah rating, they handle higher discharge currents for short periods and recover better. They are also slightly more tolerant of a bad charge or two. But overall I wanted to spend the least amount of money to get me through 2 to maybe 3 years. At that time hopefully Li-Ion (or the next favour of the month) will be more mature and I can make the move away from lead. Six Power Sonic PG-12V103 AGM SLA batteries (Spec sheet actually quotes these as 111Ah) cost me $250 each, so for the Mightyboy I will be up for $1,500. A second battery holder for the rear of the ute has now been made keeping the original Li-Ion battery box for future development. A good technical reference is downloadable at http://www.power-sonic.com/index.php?id=98 for those that would like to read more on SLA batteries.
Choosing a suitable battery charger was my next issue. Because I plan to upgrade cell technology, I was hesitant to buy a $1,700 Zivan NG3. Also it seems Zivan don’t encourage the user to re-profile their chargers. I could be wrong here but this is the information that I received? So the search was on for a well proven “On road Charger”. Once again after looking at all the options, including 6 separate chargers, I discovered the QuiQ Electric Vehicle Battery Charger from Delta-q in Vancouver Canada. It filled my requirements perfectly – designed for “On road” use, will charge my pack overnight and it is microprocessor controlled with the ability of the user to change the profile to suit the battery chemistry of choice. Downside.... It doesn't handle Li-Ion charging. I will use a different charger anyway if I go Li-Ion in a few years. There is an Australian agent (http://www.advancetrident.com.au/deltaQcharger.html) they seem very knowledgeable about the product. The cost is currently $840 and the company has been in this business for years.
Going with these batteries means poorer performance and less range but it will be fine for my current limited use......