Tomorrow’s Best Battery Solution—Today

simply the sum of the individual 10- or 20-member battery set. Table 8-3’s summary data is laid out in much more usable format.

Your choices are actually quite simple and logical at this point. Notice the 6-volt options give you from 26.0 to 29.3 kWh of energy-total on-board battery kilowatt hours. The two 12-volt choices give you either 14.0 or 19.8 kWh. Looking at the weight column, the 6-volt choices weigh from 1,220 to 1,420 lbs., while the 12-volt choices weigh either 600 or 860 lbs. In total cubic feet, although this figure would obviously translate to a larger actual mounting space required, the 6-volt batteries require from 9.6 to 9.8 cubic feet, while the 12-volt batteries need either 4.9 or 6.1 cubic feet.

Cost is another matter. Some figure had to be used here, so the manufacturer’s suggested list price as of August 2008 was plugged in, discounted 30 percent (70 percent of list), and multiplied by either the 10 or 20 number appropriate for the battery string. As mentioned earlier, your costs will vary from these figures, so look at the cost here only for comparative purposes.

With the cost disclaimer out of the way, we can proceed. If you want the best range, choose the highest on-board energy. If you want the most acceleration, choose the lowest weight. If cost is a factor, choose the lowest cost. As all of these usually are factors, dividing energy and cost by weight is usually a good way to see what gives you the most for the least. Table 9-4 does this and gives you two clear winners: the T-125 for the 6-volt group, and the 27TMH for the 12-volt side. Notice the T-125 gives you about 1 kWh less energy, saves you 100 lbs., and costs you $750 less than its bigger T-145 brother—it’s the best deal in the 6-volt group and the best choice for Chapter 10’s pickup conversion. On the 12-volt side, the 27TMH gives you 40 percent less energy at 14.0 kWh, but saves you 260 lbs. and costs less than half that of its bigger 5SHP brother. It would be the ideal solution for a lighter-weight vehicle. Or if you just wanted to tool around your neighborhood in Chapter 10’s pickup truck and win all the local drag races, then ten 27TMH batteries weighing in at 600 lbs. save you a cool 720 lbs. over the 20 6-volt T-125 battery solution.

If you pick up a battery book (or read a battery chapter in any book) from any decade of the 1900s, it’s interesting to note that every one states the best battery of the future is “just around the corner.” The reality is a little different. The reality is that things move very slowly in the battery world—events are usually measured in decades, not years. So while this section will talk about the latest and greatest in batteries, don’t expect any of these at your battery dealer soon—if at all.

Trojan Total Total Battery Model kwh/lbs Energy Decision Criteria $/lbs Cost Decision Criteria T-105 21.34 1.237 T-125 21.36 Highest 6-volt energy/lb 1.227 Lowest 6-volt cost/lb T-145 20.62 1.669 27TMH 23.40 Highest 12-volt energy/lb 1.247 Lowest 12-volt cost/lb 5SHP 23.02 1.795

Table 8-4 Trojan Battery Final Trade-Offs