7 3/8 x 9 1/4 T echnical / Build Your Own Electric Vehicle / Leitman / 373-2 / Chapter 8
Chapter 8: Batteries only kind of water you ever want to put in your batteries. Just cover the plates; don’t overfill the cells till the electrolyte overflows the battery top and causes a mess. Ideally, you want a tube from your water jug, or a small cup or glass with a pouring spout, or a clean funnel—something that makes it easy for you to pour without spilling. If any electrolyte is spilled, clean it up immediately and neutralize the spill area and its surroundings with baking soda per the next section’s instructions. Remember that the battery electrolyte is a strong acid that eats metal, upholstery, clothing, shoes, and people without discrimination. • Corrosion and Tightness—Make a visual inspection of your batteries, the battery connections, and the battery compartment. Look at, touch, and pull on things. The battery tops (and anything else in the battery compartment) should be kept clean of dust, dirt, corrosion, and splashed battery acid. Nip any one of these in the bud immediately. An old toothbrush and a box of baking soda work wonders. Use a solution comprising two tablespoons of baking soda added to a small glass of water (one pound per gallon is the ratio), applied to the battery tops and terminals. Never use it in the battery cells—be sure to keep them tightly capped during cleaning. Diligence with baking soda and toothbrush will neutralize any acid and keep the batteries clean. Touch and pull to check that none of your electrical connections have worked loose. Tighten any loose connections immediately. • Measurement—Use a digital voltmeter or hydrometer to give you a readout of the battery state-of-charge. Remember to monitor your batteries in a “rested” condition, and try to shoot for the same rest period in all your measurements, or make a note of any discrepancies.
Today’s Best Battery Solution You already know this book recommends lead-acid batteries as the best solution for today’s EV converters. You also know what type of lead-acid battery to buy and a lot about its characteristics. Your choice is made even easier because there are only a certain number of battery vendors in your immediate geographic area to choose among. Unlike buying motors, controllers, and other parts, you’re not likely to be ordering your batteries by mail. Your choice basically comes down to who offers the best price on the batteries you want, and what capacity, rating, voltage, size, and weight you need. In a slight departure from the previous chapters, we’re going to recommend one manufacturer, then look at several alternative offerings from their line to give you the flavor of the real choices you will encounter. The batteries recommended are from the Trojan Battery Company of Santa Fe Springs, California. As with the motors and controllers, don’t read anything important into their appearance here. They are only one of a large number of battery manufacturers. A list of battery manufacturers appears in Chapter 12, but in this case, which battery distributors are operating in your geographic area is the more important factor. Before getting into the actual batteries, let’s add a few more definitions to your already expanded battery vocabulary: • Power Density (Orgravimetric Power Density)—Also known as speck power, this is the amount of power available from a battery at any time (under optimal conditions), measured in watts per pound of battery weight. It translates directly
195
