IEEE Consultants' Network of Long Island

THE RUSH TO ELECTRIC-ONLY VEHICLES----Carl Schwab

It does appear that the time is right for a mass shift to EVs, Electric Only Vehicles, particularly as a “second car” and in some cases even the “only car”. This writer has pointed out that it makes much more sense to compare CPM, cost per mile rather than MPG, miles per gallon. For sure as gasoline/diesel approaches and exceeds $4/gallon, which computes to $.20/mile when your mileage is about 20 mpg. Even for hybrids that produce 40 mpg, the CPM is still $.10/per mile.

Once off Long Island electrical power ranges from $.04 to $.14 per KWh. A good number of E-only cars are becoming available now that provide a 100 mile range per charge with a charge of 23-25 KWh. Now the CPM is (25 x .14)/100=$.035 in this case---SUBSTANTIALLY less expensive.

AN ASIDE---Ford in promoting their FOCUS Electric only, uses the term MPGe, meaning miles per gallon equivalent. They are promoting the FOCUS EV as 100 MPGe. This is true if cost for KWh =$0.14 and the gasoline is priced at $3.50/gallon.

Flashlight Batteries and Bulbs - John Dunn, Consultant, Ambertec, P.E., P.C.

It's a small thing perhaps that so many flashlights become unreliable with use, but it's been a pet peeve of mine for quite some time.

Many flashlights depend on the tip of the bulb to make contact with the positive end of the upper flashlight cell as sketched below on the left. This works okay for a while, but eventually, the metal of the bulb's tip deforms by flattening out while the positive tip of the flashlight cell also deforms by becoming concave as sketched below on the right.

Then the flashlight doesn't stay lit as I hold it. I have to shake a little it to get light or I have to twist the light bezel back and forth a little bit.

CELL BALANCING BASICS:-- Carl Schwab

The question of cell balancing really comes to the surface when we are considering multi-cellular battery packs and when we are considering chemistries based on Lithium. The reason for the interest in Lithium is its high specific energy density i.e. for a given weight it stores the highest Joule level or watt-hrs/kilogram. The drawback with Lithium is its sensitivity to over-charging or over-discharging. Either condition causes permanent loss of capability for the cell. The writers experience is with the hobby industry and interest in electric powered vehicles.

SOME BACKGROUND: For the electric vehicle industry a few different chemistries have been used. Specifically lightweight lead-acid, nickel-iron, nickel cadmium and nickel-metal hydride. All these chemistries can withstand moderate over-charging and even over-discharging to the point of cell voltage reversal. Experience by Toyota (and others) has shown by keeping the SOC, State Of Charge, within a 20% to 80% range the batteries will yield long life and support peak loads such as by acceleration and fast recharges by dynamic braking. The negative point about these chemistries is weight-----compared to Lithium they are nearly 2 to 1 heavier.