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[Datsun 1200 encyclopedia]

Electric

From Datsun 1200 Club

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Categories: Engine Swaps | Electric Vehicle

Datsun 1200s are ideal vehicles for electric motor conversion. They are light at 1640 pounds nominal -- a lot lighter than a VW Beetle, yet more roomy. This article focuses on the basics to give you a good overview. For more details, search Google for more information. This article was written circa 2007, and so many details' have changed since then.

Contents

Overview

See actual kit for Suzuki Cultus/Sprint (Chevrolet Geo Metro) here: Canada EV. This is a high-performance kit starting at $8000. Top speed is over 75 mph, range from 25 to 50 miles depending on batteries used and driving conditions.

The easiest fastest way to convert your 1200 is to buy an EV, and then swap all the parts into 1200. See list of cars and parts for sale at EV Trading Post

Basic components needed for conversion:

  • Electric motor and brackets to mount it, and a plate to connect it to a Datsun B210 transmission
  • Electronic motor Controller
  • Safety switches
  • Battery charger -- special kinds are needed
  • Amp meter gauge
  • Heavier springs to handle battery weight

The stock Datsun 1200 4-speed is light duty. The A14/A15 4-speed will better handle the extra torque of an electric motor.

Note: Most of the information here is gleaned from the EVList

How much does it cost?

How much does it cost to convert a 1200 to electric power? It is comparable to what many spending tuning their piston engines. For about $5000 you can go with cylinder head porting, new exhaust, cam, twin carbs, etc. OR you can go electric. The more of the fitting/fabricating work you do, the less it costs.

quote:
That depends on what your desired results are.

(1) If you simply want to make a cheap as possible conversion, and efficiency, range, performance, and handling can all take a backseat, then for a few thousand dollars, you can electrify a 1200 using surplus parts and a small, lower voltage battery pack.

(2) If you want to make an average conversion with acceptable range, good acceleration, good handling, and a nice clean appearance, you’re looking at around $6000-$8000 [US Dollars].

(3) If you want to either build a muscle car type EV, an EV with average acceleration but with farther than average range per charge, or a show car type 1200 that will make people’s jaws drop, you’re looking at around $10,000.


KTA EV Conversion Kit #5 (144V high performance, 85 MPH top speed): ~$6400 without adapters, battery boxes, or upgraded springs. Kits do not includes batteries.

Are high-performance electric vehicles any fun?

quote:
Armature power! As far as getting one's hands dirty, with an electric 1200, gone is the transmission fluid, engine oil, exhaust rust and grime, antifreeze, dirty oil filters, etc....they're all gone. Now, we 'could' talk about zorched connectors, melted cables, blown batteries, and copper snot.....oh well, that's another story

4875.jpg

You can create a reliable, fun electric powered 1200. A conservative design will not need much maintenance, perhaps less than an internal combustion (gasoline-powered) 1200.

Examples

Blue Meanie, a 1972 Datsun 1200 sedan. Pre-converted weight at a light 1587 lbs. Exactly 2340 lbs. conversion weight when running a 156V, 585 lb. battery pack. Single ADC 9 inch DC motor with a Zilla Z1K controller. Battery amps during casual acceleration ~ 150-400 amps. Start in 2nd usually...cruise current at 55 mph on level ground is about 55-60 amps. This is a fun car to test the 'delivered' Ahr capacity of a pack, as it draws nearly exactly 1 amp per mph. When the batteries are in good shape and not 5-6 years old, 25 miles range is possible because a pack of Optimas can supply ~ 25 ahrs at my EV's average current draws. Dream mode on - 200 lbs. of A123 cells (advanced Lithium Ion batteries) would reduce the car's weight down to 1955 lbs. and give it a 50 mile range with killer acceleration, too.

b_meanie.jpg

Lectra 2+2 - Datsun B310. See for sale ad: POST Datsun B310 with only 2200 miles on it
174_5765f1f308f32.jpgPost click for topic

POST USPS van with 50 mile range designed by Harbilt Elecric Trucks of milk-float fame. 30 production versions were built by Electric Vehicle Co., of San Francisco. 72 volts.
13671.jpgAlbum click to view

Motors

Motor weight is an easy (although rough) way to judge a motor's abilities. The heavier the motor, the more powerful it is. A popular choice is an 8" diameter DC motor: The small diameter allows for a high RPM range, but it is big enough to move a car. It is recommended to use motors that weigh a minimum of a 100 lbs. That's still lighter than an A12 engine. Smaller motors may need to use forced air to cool it to increase its duty cycle. Even then they are usually prone to shorter brush life than those using motors of larger mass. Remember, think 'use a motor sized for the car'.

For example: ADC 8", 125 lbs or two Prestolite MTC 7.2" (160 lbs total)

You can usually overvoltage a motor, to a point. There are people who run 48V motors at 120V, for example, for short periods of time (or pulsed). Overheating is what is to be avoided.

AC motor or DC motor

Direct Current (DC) motors are simple, relatively inexpensive, and effective. Also since our batteries are DC it is straightforward to use.

Alternating Current motors are more efficient, giving you more power and range. However building a complete system is much more complicated. The big automobile manufacturers used A/C motors on their experimental fleet tests (Ford Ranger pickup, Chevrolet S-10 pickup, GM EV-1), but with the benefit of million-dollar research. The advanced production hybrids (e.g. Prius and Honda Insight) use this too.

DC to AC three phase inverters are hard to find, and expensive when you do. Trying to run a 240 VAC motor means about 325 volts DC. It is recommended that unless you are an expert, do a DC system.

Where Does One Get an Electric Motor for a Car?

quote:
There are four main players that build EV size series-wound type motors that we 'EVers' use....Prestolite, Advanced DC, GE, and NetGain/Warfield. By far the most popular, are the Advanced DC motors. They make them from 6.7 inch, to 8 inch,. to 9 inch, with the 9 inch the most popular of all. The 9 inch can make anywhere from 40 hp to over 300 hp, depending on how much jiuce you want to jam into it. In Rod Wilde's 'Maniac Mazda' RX7 EV, there are two 9 inch ADC motors cranking out in excess of 500 hp....go to to see it pulling a full wheel stand! The GE motors have been around for a long time, and they are really heavy duty. The Prestolote motors are more of the same...very rugged. The electric boat racers actually submerge the Prestolites at the back of the small hydros they race for cooling! I went to Warfield Electric in Chicago to have them custom build the NetGain motors, and I am using two of the high output 8's in my 1200 drag car. I use an ADC 9 inch in my street 1200, 'Blue Meanie'. If you go to the NEDRA page, you'll find a banner for 'Wilde EVolutions' who sell ADC, GE, Prestolite, and other motors, too.

Twin Motors

A lot depends on the rating of the motors. However in general you get this advantage: You can wire them serial or parallel, and 'shift' the wiring as you drive. Another advantage is 'generally' higher rpm ability .

Serial configuration: All the voltage is applied through the motor in series. For example with a 120V battery pack, each motor will get 60V.

Parallel configuration: For example with a 120V battery pack, each motor will get 120V.

Suspension/Weight

The carrying capacity of a Datsun 1200 sedan is 600 lbs. Removing the engine (175 pounds) and fuel tank (50 lbs when full) is about what the driver will weigh. So that leaves 600 lbs for the batteries -- on the stock suspension.

For more battery weight, or to handle extra weight on either end, change the springs. A 1200 can handle 1000 pounds (I've done it) but the rear springs are not adequate.

Putting 3 batteries up front will 'restore' stock front end weight. For a twelve battery pack (144V), put six batteries where back seat goes (?), then add one battery up front and 2 more in the fuel tank location. That might work pretty well.

The stock disc brakes will handle 600 lbs batteries adequately -- they were designed for this maximum vehicle weight. In fact it will stop better (shorter distance) with this maximum load (See the Consumer Information booklet that came with a new Datsun 1200). But if you want to increase braking to match modern car performance, see the Brakes articles.

Batteries

For an electric powered Datsun 1200, in keeping with the the 1200's character of 'Inexpensive, and built to stay that way', you might consider either regular car batteries, or advanced lead acid batteries.

ult-9040-218_w_s.jpg Optima Yellow Top

Real world usage has proven that a dozen Optima Group 34 deep cycle batteries (50 ah rated) can handle 20 miles quite easily in a Datsun 1200 at medium speeds The pack would have a drop dead range of around 15 miles at high speeds (to be avoided at all costs for battery health).

Battery Amperage

The more amps you pull out of your batteries, the less overall lifespan they will have. For example, in a 128 volt car on flat road, it may draw 80-100 (battery) amps at 55 mph and 120-160 (battery amps) at 65 mph. But when climbing hills, it may pull 200-240 amps for 1-2 minutes at the longest.

(360 Amps * 144 Volts = 52kW = 69HP, about what the stock A12 engine peaks at, although the electric motor will have a much different torque curve. This suggests you could pull your 94 mph power-limited top-speed using this configuration).

Amps Needed for Acceleration

For average acceleration, count on 145 lb-ft torque at the flywheel (because electric motor torque drops as it revs up).

Taking off, say with stock 12" tires (21" diameter/10.5" radius) and stock 3.90 gear ratio.

0.5 g (average acceleration)
0.7 g (brisk acceleration)

If the tire radius was 12" if would be one foot, the foot in pound-feet. But with stock 10.5" radius we get a 10.5/12 = 0.875 factor.

In a 1200 with batteries weighing (with driver) 2140 pounds, to get a 0.5 g launch, you need 2140 * 0.5 / 0.875 at the axles (1223 lb-ft). Now the 3.9 final gear is a multiplier, so 1223/3.9 = 314 lb-ft at the driveshaft. Since the F4W60 transmission second gear is 2.17, it requires 314 / 2.17 = 145 lb-foot of torque at the flywheel.

If the engine takes 360 amps at 144 volt:

With Transmission: 145 lb-ft at motor, 290(?) amps
W/o  Transmission: 314 lb-ft at motor, 630(?) amps

Either one is do-able with a Zilla 1K controller. But with the transmission it is much easier on the long-term battery life..

Battery Rule

Lee Hart suggested this for a rule of thumb for a long life for flooded or gel lead-acid batteries:

  1. Keep the *average* current below the 20-hour amphour capacity.
    For example:
    • 220 amps for a 6v 220 amphour golf cart battery
    • 175 amps for an 8v 175 amphour golf cart battery
    • 100 amps for a 12v 100ah deep-cycle battery
  2. Keep the *peak* current times the seconds you draw it below 5 times the battery's 20-hour amphour capacity.
    For example:
    • for a 6v 220ah golf cart battery:
      • 220 amps for 5 seconds
      • 440 amps for 2.5 seconds
      • 880 amps for 1.25 seconds
    • for an 8v 175ah golf cart battery:
      • 175 amps for 5 seconds
      • 350 amps for 2.5 seconds
      • 700 amps for 1.25 seconds
    • for a 12v 100ah golf cart battery:
      • 100 amps for 5 seconds
      • 200 amps for 2.5 seconds
      • 400 amps for 1.25 seconds

If you exceed these rates, you are accepting a shorter battery life as a consequence. How much shorter depends on how much you exceed these limits.

For AGMs, you can push these limits harder. Depending on the type, anywhere from 2 to 5 times harder. In part this is because of their lower internal resistance. But it is also because their basic life expectancy is perhaps half as much, so you can do more 'damage' from high currents before it becomes the dominant factor in their life.

What kind of batteries

Lead acid car batteries are recommended for the typical Datsun 1200 conversion.

For more information/details/answers about batteries, see Curtis Battery Book

Lead acid -- your typical car batteries

The problem with lead acid batteries is to make them last, you should not ever drain them completely. If that happens, recharge them right away. A pack of lead acid batteries handled properly should last three years in a typical street car. However if they are drained below 50% they won't last that long. If drained only to 25% they can last up to 12 years. Count on 4 years for most uses.

What is your primary goal? Low cost? Long range? High performance? Pick one! :-) Everything involves trade-offs -- you can maximize one without minimizing the others.

Low Cost

For lowest cost, go with flooded lead-acid golf cart batteries. They are the least expensive initially, and have the longest cycle life. This will force a lower total pack voltage, as only 6v and 8v are available. This means lower top speed and acceleration, but good range.

Or, if you move up to 12V batteries, this moves you to a higher voltage pack with the same number of batteries (many controllers can only handle a maximum number of batteries).

Longest Range

For longest range, you need to crowd in the most weight of batteries you can safely carry. Traditional flooded car batteries, gel batteries (Optimas, etc), or AGMs are all about the same; just go for the most total weight that fits. You can pick the type based on your secondary criteria:

  • Longer life: 12V floodeds or gels
  • Better performance: 12V AGMs

High Performance

For high performance (e.g. fast acceleration, hill-climbing, or high speeds), or if you will be discharging the pack in well under an hour, you'll need to use AGM batteries. Expect higher prices and shorter life, especially if you have no battery management system and an inexpensive charger.

Car Batteries

  • Inexpensive
  • Limited power output

Flooded batteries will typically provide more range than others at moderate currents (slow acceleration). At the moment, the most economical EV (in terms of operating cost per mile) will be one which uses flooded golf car batteries. Its acceleration will be modest.

Advanced Lead Acid - Hawker Genesis, Optima, etc

  • Twice the power of same-size regular car batteries
  • More expensive, but last longer
  • Hi amperage output
  • Super fast charging

AGM

  • Absorbed Glass Matt (AGM) battery design yields deliver best lifetime if recharged before the battery drops below the 50 percent discharge rate. If these AGM batteries are discharged to a rate of 100 percent the cycle life will be only 300 plus cycles.

If you are consistently discharging your battery in a half hour or less, meaning consistently high currents from frequent heavy acceleration, then as a general rule AGM batteries will last longer than flooded batteries. This is because most flooded batteries are not designed for such high current.

They will also often provide more range at these high currents because of their low Puekert exponent.

AGMs cost between 4 and 7 times as much per mile compared to flooded golf cart batteries.

Deep Cycle/Marine

  • Heavier construction, higher power output (can pull more amps out of these)

6V/8V Golf Cart

  • least expensive initially
  • longest cycle life
  • total voltage is limited

Heavy Equipment (D21, etc.)

Ni-CAD

  • expensive
  • memory loss effect

NiMH

  • Self-discharge rate not as good as lead acid: 50% capacity gone in one month or so.

Lithium Ion

Lithium Ion is the battery type used in new cell phones, digital cameras and laptop computers

* High performance, expensive price
* No memory effect
* Very low self-discharge rate

Tesla Motors, Reva and Kewet are all releasing new lithium ion battery electric cars in 2007.

One reason they are so light is because Lithium, although a metal, is the third-lightest element after Hydrogen and Helium.

Lithium Ion with nanotechnology leads

The latest and best?

  • A magnitude better
  • Extremely expensive ($15,000 for typical street conversion)

Hydrogen Fuel Cell

The future of electric power?

Troubleshooting

High self-discharge rate

  • Check each cell voltage. If 1 or 2 cells in the pack are bad it drags down the others

Where do the Batteries Go?

There are several places in a 1200 to fit batteries. You could even put a few in different places -- they do not need to be together.

  • Rear seat area should fit 8-12 standard batteries
  • The area where the sedan gas tank fits (behind the rear seat, in the trunk area), you could fit maybe 6 standard batteries there. A slide out tray will make it accessible
  • under the hood (bonnet) you can fit 6 batteries above the motor
  • 1200 sedan spare tire area (see 1200s of John Wayland

How Can Automotive Batteries Provide This Much Power?

The batteries used for drag racing should be a battery that can withstand fast discharging. The Exide Orbital 'Blue Top' (XCD model) can put out 2000 amps without destroying the battery. Also helpful is a battery which can take a fast charge.
540 lb-ft of torque? Are you sure?

The torque is estimated, but it's based on some pretty sound information from Warfield. I've always tried to be accurate with both the horsepower and torque levels of this car, but absent actual dyno tests, it's hard to determine just how much twist these motors are putting out at the very high current levels they're hit with at the track ... The controller in White Zombie outputs 1400 amps into each motor while in the series mode, and 1400 amps into each motor is about 270 ft. lbs. each, for a combined 540 ft. lbs ... Minus a transmission to multiply off-the-line torque, White Zombie still easily out-pulls most V8 powered and tweaked muscle cars with 400-500 ft' lbs. of torque that 'do' have a torque multiplying transmission. These machines are only about 300-500 lbs. heavier than the now 2500+ lb. Zombie, so the amount of vehicle weight to get going is fairly similar. It's possible that White Zombie's twin electric motors are actually making even more torque than my estimate.

What Kind of Clutch is Needed?

Well, if you run a transmission, and if it uses a clutch (neither are necessary in an electric car...

It had a solid copper three point disc and a pressure plate, and even though it was activated hydraulicly, it would give your calf muscles a real workout. Even in a built-up turbo motor that could come up with say, 400 lbs. of torque, that torque doesn't happen instantly, and instead, it has a ramp up. Electric motors don't care about rpm...they jam out FULL torque at...get this, zero rpm! Additionally, that torque stays flat as a ruler until the motor controller comes out of current limit, which in the case of my drag race 1200, is around 5500 rpm. The clutches that only hold up for a short while under the extreme stress of electric motor torque, work very well for gas engines without slipping. When we electric drag racers first

contacted clutch experts, they gave us their toughest, baddest clutches to try out....they all failed.

Clutches...Tearing up car?

Big Clutch

quote:
In the world of high performance electric cars, clutches that can handle the instantaneous BIG torque that electric motors crank out, is difficult. Before I went to direct drive (threw out the flywheel, clutch, and tranny), I went crazy looking for a clutch to handle the 500 ft. lbs. of torque my 11 inch modified Kostov motor produced. I found a Russian fellow who custom built a setup that he claimed 'Eeet Vill Not Schilp!!!' This was truly, a monster clutch, and for a while, I could stop on it in top gear from a dead stop (motor at zero rpm) and fog the tires. But, after a while, clutch slip came into the picture. Now that I'm direct drive and am using a Ford 9 inch rear end, all is well and nothing has broken for a while.

Regeneration

Can you engineer the system to put power back into the batteries when coasting? Yes, on the Prius hybrid it seems that about 15% of the fuel efficiency comes from braking of the vehicle. This is fed back into the batteries by having the axles drive a generator. Some GM 'hybrids' like the Chevrolet Pickup and Saturn hybrid simply have a large belt-driven generator/motor (like a 1950's car starter/generator) bolted to the regular gasoling engine, and achieve about 10% fuel economy improvement.

However it is not a trivial undertaking to make this work in a conversion and few converted vehicles use any form of regeneration.

Traction?


Wheel spin isn't something one 'tries' to do with an electric, it just happens...trust me. In drag racing, when the lights say 'go' and you tromp down hard, even with wrinkle wall drag slicks, wheel spin is a constant problem with electrics.

reference: Clutches...Tearing up car?

Controllers

In the past vehicles used simple contactor switches. You pushed it with your foot to go ahead, then let off to slow down. Many forklifts operated this way. Push, let up, push again. A more sophisticated way is to use multiple contactors at different voltage levels. This could give you slowest, slower, slow, med, fast, faster and fastest (for example). If you have a dozen 12V batteries, you could apply 24V, 48V, 72V, 96V or 120V to the motor to get different 'speeds'.

But nowadays, the pulse-width-modulated electronic 'Controller' is the way to go. It give you control over the car similar to a regular accelerator pedal.

  • Zilla 1K, popular for typical conversion
  • Zilla 2K, high performance and racing
  • Curtiss, the big name in electric power commercial vehicles

Maintenance

In addition to the regular body & chassis maintenance common to any Datsun 1200, these are important to an electric:

  • Tire pressure, critically to using less power
  • DC motor brushes
  • Battery pack maintenance.
    • Measure voltage of each cell. Voltage at each battery. Voltage of the pack.
    • Keep a trickle charger on if not driving the car regularly.
    • Monitor heat of the batteries.

Keeping the batteries at the right temperature is important. Lead acid likes about 120F degrees. With any kind of battery, if they get too hot they don't charge correctly. Using a fan on the battery box may be needed. For winter, keeping a heat pad on the batteries may be necessary.

Gauges

Of course the standard Datsun 1200 speedometer will be handy for measuring road speed. The other 'necessary' gauge is the motor Amp meter.

Generally you want to measure power at the Motor, and also at the Battery Pack. Ideally some monitoring of each individual battery and supply is nice. This can however be done by circuitry so having a gauge for the driver is nice but not necessary.

A single E-meter can monitor many modes of indications of the battery pack, from AH, Wthr, battery ampere, battery volts, temperature, time remaining, etc, and can download the status that is stored to a PC. Alternatively it is useful to have dedicated standalone gauges for certain things.

  • The motor amp meter (ammeter) is the most important gauge, you do not want to exceed the rating of the motor, or pull more amps out of batteries than they can handle.
  • Motor RPM, so you know when to shift gears. Alternatively you can watch the motor amps and shift when the motor start taking reduced amps
  • Battery amps: This amp meter so you stay at or below the amp rating of the battery or you may melt the battery post
  • Volt meter, which tells you how low you can go with the battery voltage
  • Invertor. If you have an invertor to supply AC power, put gauges on it too.
  • DC-DC convertor. If you have a convertor to go from Pack voltage down to 12V to drive accessories, put some gauges there too.

A vacuum gauge is not needed on a 1200, since there are no vacuum powered systems on a 1200 (other than emission controls)

Water temperature gage for the water cooling unit for the controller (it used).

Motor thermo switch indicator

Charger input and output meters.

Time clocks:

  • Vehicle running time
  • Motor running time

Vacuum Pump

Some cars need vacuum pump and vacuum canister to work the heating and A/C system, (ancient) wipers, or power brakes. The 1200 has no such accessories needed vacuum. Keep it simple.

Heater

You can use a ceramic heater element in the original 1200 heater box. Or just plug in an el cheapo acccesory car heater as from J.C. Whitney.

Tires

For maximum range, use Low Rolling Resistance (LRR) tires. For best performance, use your regular sport tires as with any 1200. Your choice. In general, narrow tires will have less resistance and thus use less electricity. Avoid sticky compound peformance tires unless roadholding performance *is* your goal. Skinny and hard tires, while reducing ride comfort will likely result in even better efficiency.

In a nutshell, you can use any tires you want.

Alignment for maximum range can be 0 toe-in, and zero camber. But for cornering performance you may want negative camber.

Aerodynamics

The Datsun 1200 sedan or coupe has a Coefficient of Friction (Cx) typical of most 1970s cars: around 0.42. The best cars today are under 0.30. Compare to the Tesla Roadster which doesn't look aerodynamic but has a drag of coefficient of 0.30. However, the Datsun 1200 is small -- which is even more efficient than a larger, more aerodynamic car.

Main Contactor

This is an off switch for the battery pack, and is a safety feature. This is necessary because sooner or later the controller will fail, and you don't want a runaway vehicle when it does! With the contactor you can manually cut the power.

Invertors

DC to AC power invertor can be used to run AC appliances like TVs, air conditioning, heaters, air compressors, etc. However this topic is not unique to Datsun 1200 -- and not needed for a DC motor system -- so please search the web if you'd like more information.

Automatic Transmission

Can you use an automatic transmission? Sure, there are two approaches:

  • some EVs use automatic transmissions and just use the stock torque converter normally or locked the torque converter solid and in both cases the motor would stop when the throttle is released and then when it is depressed again there is a slight lag before the vehicle moves as pressure builds back up.
  • Keep the motor idling to maintain transmission line pressure while stopped. But with most controllers you'll hear noise while this is occuring.

An automatic will reduce your range:

  • Because of the fluid coupling, it takes more power to run
  • Automatics weigh more than manuals

Another idea is to fit a modern auto-shifting manual that most car manufacturers offer since the year 2000. Or a CVT transmission which are now becoming commonplace.

Main Fuse

For example, you might use one 400 or 600 Amp fuse in the battery lead. It will carry 1000 amps for several seconds without blowing. But if there is a real problem, it will blow soon enough to protect the other parts.

In practice, use the fuse recommended by the controller vendor.

Audio

  • CD players should work fine
  • AM may get interference from the DC motors or controllers(when in use), but usually is OK
  • FM will be OK if proper steps are taken:
    • Keeping the high current wiring and potential noise sources

(controller, contactors, DC/DC, etc) out of the passenger compartment and away from the radio

    • Keep your high current cable bundled together in pairs
    • Radio and 12V system and wiring separated from high-voltage wiring

Charger

This is the most critical piece of equipment for making your expensive string of batteries last. Overcharging causes damage to batteries.

Having a timer on the charger can be a lifesaver. If all else fails or the person monitoring the charger gets distracted, at least the charging time is limited.

It is a matter of setting up whatever charger you have to produce the right charging algorithm. Even a really crude, simple, stupid charger can do a good job if carefully set up and monitored. Conversely, a very expensive sophisticated charger can still screw up and fry the batteries if programmed wrong.

Here's the bottom line: You need to know how many amphours you took out of the batteries. Put back that amount, plus about 5% more. batteries will be full charged, with just a bit more overcharging for equalization and balancing.

Now, how do you find this point?

1. Amphour counting: Put back 105% of what was taken out.

2. Voltage level detect: Charge until voltage rises to about 2.45v/cell. (Assumes the charger's current drops off as it approaches full charge.)

3. DV/DT: Charge until voltage stops rising. (Assumes the charger regulates current at the end of a charge cycle.)

4. Current level detect: Charge until current falls below about 2% of the battery's amphour capacity. (Assumes the charger limits voltage at the end of a charge cycle).

5. DI/DT: Charge until the current stops falling. (Assumes the charger regulates voltage at the end of a charge).

6. Time-based: Charge for a fixed length of time. (Assumes the charging current automatically tapers off when the battery nears full).

7. Temperature-based: Stop charging when battery temperature starts to rise.

Automatic chargers generally use one or more of these methods. But you can also do it manually, or set up a simple system to accomplish the same result.

Terminology

Amps: Current flow. To get horsepower, you also need to know the voltage. Power = A x V.

  • Example: 100 amps at 120 volts = 12000 watts (12kw, 16 hp)
  • Example: 50 amps at 240 volts = 12000 watts
  • Example: 1,000 amps 12 volts = 12000 watts

As you can see, if you have more volts, it takes less amps to do the same work (power). With lower amps, smaller battery cables can be used. This is why EVs don't use a 12V motor voltage, but usually somewhere between 48-440 volts by stringing 12V batteries together in series.

  • The average ampere draw for a EV is about 75 battery amperes.

Ampere Hours (Ahr): The ampere-hour rating of a battery is the measure on how many amperes it can draw in a specific amount of time. The standard rating which is chosen by battery companies is how long it takes to discharge a battery to 0%.

  • Example: a battery that can be discharge at 5 amperes at 20 hours, this is a 5 Amps x 20 hrs = 100 AH battery.
  • As you increase the ampere draw of the battery, the ampere-hour rating of the battery decreases. If you increase the the ampere load of the battery to about 20 amperes, it may only deliver 20 amps for 4 hours, which is an actual capacity of 80 ampere-hours.
  • The average ampere draw for a EV is about 75 battery amperes.

Reserve Minute Rating: How many minutes you can withdraw a certain amount of amperes. For example, a battery with a 100 AH rating with a listed Reserved Minutes of 180 minutes for a 25 amp draw would be about:

180 min / 60 = 3 hrs
3hr x 25 amps = 75 amp-hrs
  • Example: The reserved minutes listed for a 100 Ah battery is about 60 minutes at 75 amps (typical EV draw) which is about one third the time at the rated 25 reserved minutes.
  • Example: Trojan T-145 battery is rated at 260 AH @ 20 hr rate with 145 Reserve Minutes at 75 amps. The actual ampere-hour would be:
    145 mins / 60 = 2.41 hrs
    2.41 hrs x 75 amps = 181.25 AH

DOD: Depth Of Discharge. At 100% DOD the battery is dead flat. It is best not to discharge a Lead-Acid battery below 50% DOD, so you can consider the maximum ampere-hour draw out the battery would be half the calculation. For a long life, charge at about 25 DOD% (3/4 full).

SOC: State Of Charge. At 0% SOC the battery is dead flat. At 100% SOC it is fully charged.

Parts List

To make a Blue Meanie-style high-performance Datsun 1200 (Top Speed: 100mph, range 25 miles, see specs at plasmaboy racing site:

  • A Datsun 1200: $500-$2000 will get you a nice condition car.
  • Upgraded 60-series transmission from a B210 or B310 ($75 at a wrecking yard)
  • Heavier springs to handle battery weight: $50 from wrecking yard. B210 coil springs can be cut down and fitted. An extra leaf can be added at the rear. Do the opposite of what the Lowering article discusses.
  • 9' motor: Advanced DC FB1-4001A Series Motor. 28 HP cont., 72-144 VDC, $1500 new
  • Motor-to-Transmission adapter plate: $1000 custom-made includes motor hub
    • Or, make yourself for less than $250 or so. You need a precision taper hub
  • Motor mounting plate: $138, bolt to existing crossmember
  • Twelve 50ah batteries for 144-volt operation: $600
  • Good Battery charger: ???
    Best battery charger: Manzanita Micros PFC20 $1650. See http://www.manzanitamicro.com/chargers3.htm
  • Curtis Controller, 1231C-8601 Motor Controller. 96-144 VDC, 500 Amps $1500 new
    Or Zilla 1K high-performance motor controller: $2000 new. This will allow more options, and room for increasing performance later.
  • Throttle switch: CURTIS-PMC PMC #PB-6 (with microswitch), $75
  • Contactors: KILOVAC #EV200-4A up to 320V $80
  • Main battery (12V) disconnect switch: POLLAK #44030...SP Battery Disconnect Switch $30
  • Sensors:
  • Switches:
  • Cables and connectors
    • 12' 2-gauge wire (peak 800 amps): $36
    • Cable lugs: 30 lugs (24 for batteries, 4 for controller, two for motor): $75
  • Custom battery boxes: ?
  • charging safety interlock: MAGNECRAFT #W389ACX-9 $16
  • Intertia safety switch (disconnects battery in accident): FIRST INERTIA SWITCH #FCS1 $55
  • Fuse/circuit breaker: ???
  • Battery gauge: CURTIS INSTRUMENTS #900RB-144-BN, 144V $225
    Or, programmable E-meter: about $300 for 144V operation
    Or, best, E-Vision:

Optional car interior Heater

  • ceramic heater element (can be fitted to original heater core box): $80
  • switch for high voltage: P&B/KTA #DPDT-12 $25

Also See

  • CHW Electric 1200 Car & Driver magazine Oct 1973 - 'Athol's Answer to the Energy Crisis' (CHW electric-powered 1200)
    3715.jpg

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