Five Trojan Battery Solutions

to the acceleration and top speed performance your EV can get out of its batteries. • Energy Density (Orgravimetric Energy Density)—Also known as specific energy, this is the amount of power available from a battery for a certain length of time (under optimal conditions), measured in watt-hours per pound of battery weight. It translates directly to the range performance your EV can get out of its batteries. • Volumetric Power Density—This is a factor more of interest to the technical battery community working across different battery chemistry types. It is power density measured in watts per gallon or watts per cubic foot volume rather than weight. • Volumetric Energy Density—Ditto here. This is energy density measured in watt hours per gallon or watt-hours per cubic foot—again volume rather than weight.

You will find these useful both for this section’s comparisons as well as those made in the “Future Batteries” section. Now let’s look at the winning batteries.

Five Trojan Battery Solutions

The Trojan Battery Company has been innovating golf cart battery solutions since the 1950s; their appearance here should not surprise you. Electrical vehicle batteries today are substantially superior to those of only a decade ago. You can pick from 6-volt or 12volt solutions, and the distribution network has evolved to give you more service at better prices.

We’re going to look at three 6-volt and two 12-volt alternatives from Trojan. The Trojan T-125 model—one of the 6-volt alternatives—is shown in Figure 8-4. Notice its

Figure 8-4 Trojan T-125 6-volt deep-cycle battery.

Figure 8-5 Trojan 5SHP 12-volt deep-cycle battery.

rugged construction, and the stud-type terminal posts with bolts and nuts. This case and construction is common to all family members in this 6-volt line. Figure 8-5 shows you a 12-volt unit, the 5SHP model case mockup previewed by Trojan at the September 1992 Burbank Alternate Transportation Expo. You might (or might not) have the EV label on the batteries you buy from your distributor.

Table 8-2 gives you the details of this lineup of five recommended EV battery choices from Trojan. Other than suggested list price—an area that we’ll save for special discussion—this is all from published data that you can get from your local dealer.

It lays out everything you need, but doesn’t quite give it to you in the form you need it—yet. Figure 8-6, also drawn from published data, shows the actual capacity versus time performance charts; notice the similar performance of the 6-volt and 12-volt data groups. You can use this data to determine the results of applying actual loads to any of the batteries you choose.

Figure 8-7 is from actual Trojan data on the T-105 model battery calculated 6/29/92. It is the real-life example of an equation shown earlier: Battery Life Cycles 5 Kd/Depth of Discharge In

In this figure Kd is around 28,000, so it shows that Trojan technology is pushing its deep-cycle batteries into the industrial battery area. In other words, the T-105 model and its other family members are heavy-duty deep-discharge batteries.

To figure out how many batteries you need, first determine the voltage at which you are going to operate your EV conversion. This voltage is established from your chassis, motor, and controller trade-offs, and heavily influenced by ultimate use, longest range, or fastest acceleration.

Our objective here is to pick the best battery for Chapter 10’s actual pickup conversion, so the operating voltage of 120 volts has been selected. Assuming you want all your batteries of the same type, and also that you’re not going to use any tricky series-parallel wiring combinations, this means you’ll either require 20 of the 6-volt batteries or 10 of the 12-volt batteries, all wired in series to obtain the 120 volts. When you wire your batteries in series, the total capacity available—the total ampere-hours— is the same as that available from any one battery. The total watt-hours is simply the total voltage times the total ampere-hours. The total weight, cubic feet, and cost is

Trojan Minutes Minutes Weight Energy Battery Nominal 20 AH @ @ 3 AH in Density Suggested Model Voltage Capacity 25 Amps 75 Amps Capacity Pounds watt-hours/Ib Length Width Height List Price T-105 6 volts 217 419 107 161 61 15.5 10.375 7.125 11.1875 107.76 T-125 6 volts 235 477 125 174 66 15.6 10.375 7.125 11.1875 115.67 T-145 6 volts 244 530 145 181 71 15.0 10.375 7.125 11.5 168.85 27TMH 12 volts 117 200 50 87 60 15.2 12.75 6.75 9.75 106.86 5SHP 12 volts 165 272 78 122 86 14.2 13.5625 6.75 11.5 220.50

Table 8-2 Comparison of Recommended Trojan Electric Vehicle Batteries

Table 8-3 Comparison of Trojan Electric Vehicle Battery Trade-Offs

Trojan Battery Nominal Quality in Vehicle Battery Total Battery Total Battery Total Battery Total Battery Total Model Voltage Vehicle Voltage AH Capacity Watt-Hours Weight Cubic Feet Cost @ 70% T-105 6 volts 20 120 217 26040 1220 9.57 1508.64 T-125 6 volts 20 120 235 28200 1320 9.57 1619.38 T-145 6 volts 20 120 244 29280 1420 9.84 2369.90 27TMH 12 volts 10 120 117 14040 600 4.86 748.02 5SHP 12 volts 10 120 165 19800 860 6.09 1543.50

Figure 8-6 Trojan 6-volt and 12-volt deep-cycle battery family time versus current curves.

Figure 8-7 Depth of discharge versus expected life cycles for T rojan T-105 battery.