Batteries


Surely the batteries are still the most delicate topic of the whole electric road vehicle.

The City-El is equipped with three traction batteries. Traction batteries differ from the starting batteries in normal Internal Combustion vehicles. Both are lead batteries, however the starting battery in the IC vehicle must only supply a quite short high current and then for the remainder of the travel only has "compensatory" activities.

In the electric vehicle the traction battery will discharge during the whole travel, one speaks of discharge cycles. Cycles and their depth determine the life span of the battery.

Standard versions

Yuasa 90Ah C5 batteries

Yuasa BatterieThe standard equipment for City-el are 90Ah batteries of Yuasa type EB90. This battery type has a relatively low internal resistance, and thus good high current characteristics. The nominal capacity is 90Ah C5, i.e. at 5 hours unloading time (5hx1Å=90Ah/C5). With 1 hour unloading time, which is more realistic, the capacity drops to approx. 50Ah (1hx50A=50Ah/C1).

 

 

100Ah C5 batteries / Deka/Hawker/Oldham/Levo

Hawker / Oldham BatterieA 100Ah C5 battery is offered ex factory, with which higher ranges are possible. This battery type still has 70Ah (70AhC1) with one-hour discharge, which is almost 40% more than with the Yuasa. This battery type uses all the available space in the battery rack. Disadvantages of this battery are somewhat higher weight and it cannot accommodate battery heating under the batteries.

 

US Standard Equipment

Apparently neither of these batteries are available in the US. Here's a note from Gary Flo of InEvations:

  • >I notice you're a DEKA dealer now. Do you have access to the big DEKA cells
    >(Group 31?) that City-Com fits as optional equipment?

    DEKA doesn't have a 31 as far as I know. Didn't see it on that page. The
    biggest one is a 27 rated 92AH @ 20 hr, 59AH @ 1HR rate.

    Gary

  • Bill Warf of Pacific Electric Vehicles did a lot of research on batteries for Sacramento Municipal Utilities District, and concluded that Trojan flooded cell batteries were the way to go. We use what is called a Group 31, Deep Cycle, Marine battery, 130 AH C20, the Trojan model is 30XHS, Automotive Post, or the SCS225 for longer life at higher cost. A comparable US Batteries model is their 31TMX. Avoid the widely available Exide/Interstate batteries for demanding EV applications, even if they say "Deep Cycle". - RRY


    Special equipment

    Not offered by the factory, but possible.

    Nickel cadmium batteries

    Saft NC BatterieNickel cadmium batteries have very high amp-hour capacities, very long life span and unfortunately a relatively high price. In the City-el, Juice brand STM130 have been fitted, or different batteries of the Hoppecke brand. The vehicle then has a range of 80km or more. If the battery gets over the guaranteed life span of the manufacturer, it's per kilometer cheaper than lead, unfortunately no one has gotten that far, since one must drive about 160,000 km.

    Closed numerical controls batteries have been developed (Hoppecke FNC recom). Numerical controls batteries are ideal for professionals and many drivers, e.g. courier services. Although numerical control batteries give excellent service, they are astronomically expensive.

    Costs: 10 lead battery records á 1000 DM correspond 1 record numerical control for approx. 10,000 DM

    Nickel hydride batteries

    This battery type is very similar in advantages and price to the numerical control battery type, but is not yet fully developed, i.e. large capacities are not yet available. Advantages are the less poisonous active material and a still higher capacity than numerical controlled Ni-Cad.

    Optima Yellow Tops

    50Ah OptimaHere is an E-mail exchange between Ralf and me on the subject -RRY

    From: Ralf Wagner [SMTP:RalfWagner1@compuserve.com]
    Sent: Thursday, January 14, 1999 2:37 PM
    To: Young, Ryan
    Subject: Batteries
  • New batteries for the city el are available from www.optimabatteries.com . 100Ah- so you need only 3 optima batteries. In the first test we could drive more than 50km.
  • These are the eagerly awaited Optima Group 31's. The stock City-El battery charger will kill an Optima or any other Valve Regulated Starved Electrolyte battery in a few weeks - Bill Warf of Pacific Electric Vehicles proved this. The stock charger equalizes every 10th charge, and will rapidly dry out an Optima.

    Also the Optimas will be about twice as expensive as "Trojan" brand flooded cells of slightly higher C5 capacity, although the Optima amp-hour capacity at C1 discharge is superior.

    Bill Warf had special charger boards for this type of battery (VRLA/AGM), and he offered me one before he left, but I spent what little money I could spare on tires instead. Peter Senkowsky probably has them, as he bought a lot of spares from Bill. As of February 9, 1999, the Optima Group 31 batteries were not yet in full production or available from dealers- RRY


    More (lead) batteries

    More batteries are more capacity and thus more range, and more weight.

    With vehicles with serial number before 3006 one should install the new springs before one installs additional batteries. (The springs are marginal in even late model vehicles; Peter Senkowsky has special springs for accommodating macho battery packs - they're arched differently, and have a small helper leaf - RRY)

    With all additional battery installations, a safe attachment of the battery is important! The battery otherwise in an accident can cause much damage by flinging itself at the driver! Additionally the battery should be attached to the gas venting system.

    A good point to make such a change is when the original batteries are exhausted. The extended battery pack, with 42 or 48 V, can then " age " together.

    42 V

    A relatively simple method is in-series add an additional 6 V battery with the same capacity. That is, from the positive terminal of the left battery a new line leads to the negative terminal of a new 6 V battery placed in the "trunk". At the positive terminal of the new battery the vehicle positive lead is attached. All components of the vehicle can accommodate this slight modification. A small modification of the battery charger and the capacity meter is necessary.

    Research with the battery manufacturers showed that it is cheaper to procure a 12V battery and saw it in half to make a suitable 6 V battery. This is not quite the finest craftsmanship, but it is economical. A further advantage is that one can take the same as the inserted battery type and thus the same ampere-hour capacity has. (I have tried to find a 6V deep cycle battery with the right capacity without success, it looks like chopping a Trojan in half is the only way to go. If you do this carefully, you'll end up with a 6V battery, and a 4V battery for the next battery pack change. Do this on a dry battery of course! For terminals, you have 3 choices: you can drill a hole in the lead cell interconnect bar and connect your cables with a bolt, Belleville washer and nut similar to an L-terminal; you can have your battery distributor solder an automotive post onto the interconnect bar; or you can screw an adapter post from Exide into the interconnect bar- RRY.) The maximum charging voltage should not be increased over 60 V, since the protection diodes in the vehicle overload with approx. 61 V. (See the Workshop Manual for information on adjusting the charging voltage - RRY.)

    48 V or higher.

    48Volt VersionThe change to 48 V is more complex, the controller and battery charger must be exchanged. The auxiliary electric's and capacity gauge cannot be operated with this voltage, but must be supplied with 36 V. The road performance improves a lot. The motor does not have to be exchanged, it is operating over its rated voltage, but it has never had therefore a defect. A 48V City-el with 100Ah batteries can achieve ranges of 70-120km, as per my own vehicle. A typical average value consumed is thereby 1Ah/km starting from battery with normal driving fashion. I registered this version with the German Department of Motor Vehicles. One must bridge the 50km/h resistance at the engine, since the vehicle drives otherwise clearly over 50 km/h. (And the German DmV won't register this class of vehicle if it goes faster then 50 km/h, and they know City-El's - RRY)

    Battery Aging.

    In the case of lead batteries the amp/hour capacity and thus the range become ever less. The best life span is achieved by batteries much to be used. Many City-El drivers achieve 7000 - to over 10.000 km battery life. With rarely used vehicles there were already run-outs of battery after 2000 km of driving.

    If lead batteries are idle for a while, we say " the battery sleeps ", i.e. it does not have from the outset again your full capacity. The battery needs only a few cycles " to wake up ". To quite new batteries the same applies.

    In order to bring back weak batteries, I recommend the following procedure. Take yourselves one Sunday, and drive in the morning a small round, to approx. for the half of the capacity. Charge the vehicle up to the 100% of the capacity display again and drive it afterwards again down - this time somewhat further. Charge it again, and the whole play repeat. If one holds out consecutively this several times, the battery will somewhat warm up. They will possibly notice less charge, as indicated on the capacity meter, is used on a given route. The following night, charge the battery again to 100%.

    Who has an appropriate battery charger can the battery also longer time with small current charge, until all cells are again on same acid concentration - cook it on a small flame. The individual charging methods are so dependent upon battery type that I can give no overall solution here.

    Tip


    letzte Änderung 12.09.99