FAQ
Topic Name: Technical
Batteries
1. What are the dimensions of an Exide Orbital?
2. Miles per charge
Cabling
3. What diameter lugs do common EV devices use?
4. NetGain Controls 3kW charger connections
Charging
5. Why not use individual chargers on each battery?
6. PowerCheq Issues
Controllers
7. Does the Zilla controller do anything to assist in braking?
Motors
8. VW Adapter Plate - Does it retain the clutch?
9. Why choose a WarP motor over an ADC?
10. How does the WarP/ImPulse motor efficiency compare with that of ADC motors?
11. What size motor should I use?
Miscellaneous
12. Hall-Effect Pedal Assembly (HEPA)
13. Can I use multiple contactors to increase their capabilities?
14. Braking
15. Do I need a relay to power my device?
Other EV Links
16. Some other FAQ links
Batteries
1. What are the dimensions of an Exide Orbital?
Question:
What are the dimensions of an Exide Orbital?
Answer:
The actual dimensions are a bit deceiving. The following information should paint a pretty clear picture of the actual dimensions of an Exide Orbital, as well as a comparision between other similar batteries (information courtesy of George Tylinski).

_____________________________________________
BCI group size limits from table linked below: 10-1/4 L x 6-13/16 W x 7-7/8 H

http://www.rtpnet.org/~teaa/bcigroup.html

BCI group size limits are shown in transparent blue in images below.

Optima Yellow Top, model D34

http://www.optimabatteries.com/products/deep_Cycle/index.asp

Exide Select Orbital Extreme Cycle Duty, model 34XCD

http://www.exide.com/products/automotive/exide_select_orbital_XCD.html

Overall dimensions:

L x W x H, weight


Manufacturer specs


Measured, sample of one

BCI group 34


10.25 x 6.81 x 7.88, no spec


Optima D34 (YT)


10.00 x 6.80 x 7.80, 42.9 lb. min


9.97 x 6.79 x 7.85, 43.0 lb.

Exide Orbital 34XCD


10.17 x 7.00 x 8.12, 41.0 lb.


10.18 x 7.17 x 8.08, 39.5 lb.

The CAD models shown below followed the measured dimensions rather than spec sheets.

Dimensions were measured with a variety of squares, triangles, scales (.01? divisions) and dial calipers.

Weights were measured on a bathroom scale calibrated at 40 lbs with cheap iron weightlifting plates?

YT D34 prototype, Orbital Select Extreme Cycle Duty 34XCD, Optima YT D34/78.



Bottom view of Orbital XCD and Optima YT



Exide has walled-over the side lobes of the 6-pack on the long sides, whereas Optima has essentially covered them on the short sides only. It would be difficult to apply heaters effectively to the vertical sides of the Orbital compared to the YT.

At the bottoms of the batterie, neither is conducive to easy attachment of simple heaters, the Orbital being particularly difficult.

Optima YT D34 (Prototype) CAD model.

The slots in the short sides for removable handles were not modeled.



Exide Orbital 34XCD CAD model.



The YT fits within BCI group 34 limits. The long dimension (out of the page) is 10?, ¼? smaller than the limit. The height of the top of the lid main surface was 6.74?.

The Optima D34/78 model (no CAD model) has side terminals and would exceed the limits in that area, but by less than the Orbital XCD. The side terminals add .25? to the width (including the supplied caps) and add.28? raised areas to the lid.



The Orbital exceeds the limits in two areas: the height of the terminals and in the side terminals.

Side terminals are shown with the included plastic caps installed (tapered). The 34XCD is not available without side terminals. The height of the top of the lid main surface was 7.29?.

The ?non-extreme, non-select? Orbital Marine Deep Cycle (ORB34DC) is available in the group 34 size without side terminals. 10-1/8 L x 7 W x 8 H:

http://www.exide.com/products/marine_rv/orbital_deep_cycle.html



Orbital (dark gray) overlaid on YT. Note difference in height of lid structure (.55?), and terminal locations. Both YT and Orbital positive terminals are on the left in this image. The highlighted green area is the outline of the Orbitals? built-in handles (shown folded down).


2. Miles per charge
Question:
What kind of range can I expect from my battery pack? How many miles per charge?
Answer:
Performance depends on battery pack voltage and amp-hour rating. In this example I will use a 120V system and 150 amp-hour lead-acid batteries. Since power equals volts*amps, the maximum theoretical power output of the system is

120*150 = 18000 Watt-hours

Lead-acid batteries have this interesting effect called Peukert's Effect". Basically, it states that the faster a lead-acid battery is discharged, the less you'll be able to get out of it. Battery manufacturers list the amp-hour capacity of batteries when discharged over a long period. A 20 hour rating is common. So if you discharge the 150AH battery over 20 hours, you can get 150AH out of it. If, on the other hand, you discharge it in just one hour, you will get some amount less than 150AH out. We'll save the calculations of Peukert's Effect for another conversation, and just reduce the capacity by 25% as a rough value:

18000*.75 = 13500 Watt-hours

Unfortunately, we still have to hack away at this number to arrive at the total amount we have available. We can't take out 100% of this capacity consistently, and get a lot of cycles out of the batteries. 80% is about as much as you can take out, and still get a decent number of cycles on the batteries before they give up the ghost. If you take it to less depth of discharge (DOD), then you'll get more cycles on them. Let's use 80%:

13500*.80 = 10800 Watt-hours

Each vehicle has a different overall power efficiency due to mechanical efficiencies among other things. Typical values are 250-350 Watt-hours per mile. For this example, let's use 300 W-h/mile.*

10800/300 = 36 miles

Keep in mind this number is based on new batteries which can take a full charge and deliver the same. Older, used batteries cannot deliver a full charge and so their performance will differ over the life of the battery. Also, temperature will have an effect. Colder lead-acid batteries will not hold as much charge.

If you are looking for a quick estimate using all of the above numbers, use this formula:

((Pack Voltage*Amp-hour rating) * .75 * .8) / 300 = miles.

However, be cautious when designing your conversion. You don't want to plan the above-mentioned system if you *require* going 36 miles every day, year-round. The batteries will age, some days will be colder, and some batteries in the pack will begin to retire earlier than others. It's always good to plan in some extra capacity.

*Watt-Hours/mile varies with each vehicle. Here is a good link to some typical values of this variable for various vehicles and how to get a good estimate of the WH/M for your specific vehicle.
CLICK HERE

Cabling
3. What diameter lugs do common EV devices use?
Question:
What diameter lugs do common EV devices use?
Answer:
Here are the diameters of lugs that are used on several of the devices that we sell:

* Albright contactors: 3/8"
* Zilla: 5/16" with 1/4" bolts
* ImPulse 9: 3/8"
* WarP 9: 3/8"
* WarP 11: 5/16"
* TransWarP 11: 5/16"
* Ferraz/Shawmut Fuses: 3/8"


4. NetGain Controls 3kW charger connections
Question:
What size anderson connector comes on the NetGain charger??


Answer:
SB-50 Gray (EVS Part No. 600-SB50-G)

For reference, the other end is a standard 3 prong power plug that is commonly used to power a desktop computer.

Charging
5. Why not use individual chargers on each battery?
Question:
I've read a number of comments regarding reliability with various chargers. There is also the question of balancing a battery pack, etc. In lieu of a BMS (Battery Management System), does it make sense to use a number of small chargers (i.e., one per battery) instead of a large pack charger?
Answer:
Individually charging each battery really offers each battery the best charge possible, assuming you have a smart charger on each battery. So why is this scheme not more commonly used? There are a number of critical factors. First, and probably foremost, is ultimately cost vs. charging times. Most people want at least a moderately fast charge on their EV. Placing a fast charger (i.e. in the range of 10A or more) on each battery would be really expensive! The other key issue is reliability. Failure rates on cheap components is generally high enough that the probability of having one of the chargers fail in the first year or so is pretty high. If a charger fails, and you don't know about it, you run the risk of driving off with all the batteries full ... except that one with the failed charger! If it isn't already clear, let me elaborate. Let's say your drive the day before pulled the batteries down to 40% state of charge (SOC). Let's say the charger that failed quit after putting in 10%. So the next morning, all the batteries are at 100% SOC except the one that's now at about 50%. You head out on your normal commute, that will again pull the batteries to 40% SOC. You make it to work just fine, since this only takes out 30% (the ill-fated battery is now sitting at it's maximum allowed discharge of 80% discharged, 20% full). At about two thirds of the way back home, the battery is now sitting at 0%. You continue to drive, possibly noticing the vehicle not performing very well (you've now got a huge resistor in the pack!). Cell reversal is imminent, with damage almost certain.

If you find a way, either manually or automatically, to monitor each charger, and you can live with slow charge times, then individual chargers (as long as they are "smart"), is a pretty good way to go.

6. PowerCheq Issues
Question:
What potential issues should I be aware of before purchasing or installing a powercheq module (or any battery equalizer)?
Answer:
Before answering this question, it is important to understand just how various equalizers that are available work.

There are two basic types of equalizers. Active and shunt.

An example of an active equalizer is the Powercheq. A single module is connected to two adjacent batteries in the string. It actively monitors the two batteries' voltage and attempts to keep them identical. Practical limitations with the device keep it from achieving identical voltages. The product's specifications state that it will equalize until the batteries get within .075 volts (75mV) of each other. This type of equalization is desirable, as it is always working - during charging and discharging. However, the practical limitations listed for the Powercheq keep it from being completely useful in some battery pack arrangements. More on that in a bit.

Shunt equalizers (or shunt "regulators", which is probably a more suitable name), in contrast, only regulate during the charging cycle. A module is placed on each battery. When the voltage rises above a preset value, the module will shunt some of the current through the regulator instead of through the battery. This keeps the battery from reaching a potentially damaging voltage (as long as the regulator can "keep up" with the battery charger). Some shunt regulators can communicate back to the charger to indicate if it is not able to keep up.

Here are some issues that arise when using an equalizer such as the PowerCheq:

1. Long battery strings: The modules have a limit to how close adjacent batteries need to be, in terms of voltages. The PowerCheqs specify 75mV. If you cascade that allowance down a long string of batteries, you can end up with a large variation from one end of the pack to the other. The PowerCheqs will think everything is perfectly alright!

2. Long separations between packs: the separations between batteries needs to be fairly consistent. Every wire/cable has some resistance to it. Thanks to Ohms Law, we know that if current is flowing and there is resistance, there will be a voltage potential. If two batteries have a long span in between them, the voltage drop in the wire/cable when a large current flow is present, will make the PowerCheq think that the two batteries are far from equal to each other. There's some nasty inductance effects too, and when combined with the voltage drop, these factors can actually damage the PowerCheq.

3. "High" current output chargers: the PowerCheq module can equalize 2 amps of current. If your charger is cranking away at a much higher level, and a battery in the string has a relatively higher internal resistance, the PowerCheq module will not be able to keep up. There is not provision for the modules to talk back to the charger to tell it that they can't keep up.

So what can be done to protect the batteries? Is there a specific product that will do the job? Currently, there is no comprehensive, cost-effective solution for lead-acid batteries. The closest option are the Manzanita Micro Rudman regulators. They have the ability to talk back to the charger to let it know if any battery is going over-voltage. The charger is supposed to respond intelligently to this feedback. Our past experience with this setup didn't yield perfect results. But, it did protect the batteries.

With non-sealed batteries, it is much less critical to protect against overcharging. Non-sealed batteries will vent, but the electrolyte can be replenished through a regular maintenance program. Sealed batteries, on the other hand, must not be allowed to overcharge (and consequently vent). We anticipate additional solutions for sealed batteries such as AGM's will be available in the near future.

It is much more critical with Lithium cells to ensure that no cell goes over-voltage. A Lithium BMS that's worth buying will have the ability to protect the cells by various combinations of shunting and/or feedback to the charger.

Controllers
7. Does the Zilla controller do anything to assist in braking?
Question:
Does the Zilla controller do anything to assist in braking?
Answer:
The Zilla doesn't do anything to stop the vehicle (i.e. it doesn't have regenerative braking capabilities). You have to rely on your brakes to stop the vehicle.

Motors
8. VW Adapter Plate - Does it retain the clutch?
Question:
If I use the VW Adapter Plate/Coupler Kit will it eliminate the clutch or will it remain functional?

Answer:
All the adapters sold by EV Source retain the use of the original clutch. The bell housing mounts to the motor face and the taper lock bushing and hub grip the shaft. The flywheel from your transmission then attaches to the steel hub using the original flywheel bolts. The clutch disk assembly then attaches to the flywheel and is controlled by the clutch fork or rod.

Then all that is left is to bolt the bell housing to the transmission to complete the assembly.

9. Why choose a WarP motor over an ADC?
Question:
Why choose a WarP motor over an ADC?
Answer:
While ADC motors are good, WarP motors are great! Here are some reasons why:

* High quality commutator - "silver over copper"
* Better than class H insulation
* Motors advanced by default (can also be shipped without advancing)
* High-quality brushes - not quick-seat type equating to longer life and better contact
* Brushes 90% pre-seated from factory
* WarP 13 is unsurpassed in power - produces over 2700 ft-lb of torque at the rear wheels
* WarPs prices are very competitive with ADC prices
* Continual product improvement
* Usually lower overall shipping charges for WarP motors
* Most motors compatible with ADC mounting


10. How does the WarP/ImPulse motor efficiency compare with that of ADC motors?
Question:
How does the WarP/ImPulse motor efficiency compare with that of ADC motors?
Answer:
The advanced timing of the WarP Motors (which allows higher voltages and currents to be used without arcing) results in the motors being "slightly" less efficient at slow speeds and low power levels and "slightly" greater at high speeds and higher power levels. The WarP Motors will spin more RPM's per volt and produce greater ft. lbs of torque and HP. It seems many of the graphs with ADC motors are done at 75 volts, whereas NetGain uses 72 volts - some people don't catch that, and it makes a difference!

To understand the motor efficiencies, you really need to look at the dyno spreadsheet data. The WarP 11 actually hits 91% efficiency - which is about the highest efficiency claimed for a series wound motor. Larger brushes, fan design & composition, wire diameters (depends upon source for that batch of motors...) larger laminations (9.25" diameter versus 9.0") used in the WarP Motors, and larger bearings will cause a slight variation in efficiency. The bottom line is that the efficiencies of the ADC 9 and WarP 9 are so close that from the engineers' viewpoint they usually say "they're the same". The same holds true for the old WarP 8 and the ADC 8. The ImPulse 9 should be looked at as an "improved" 8" motor.

A comparison graph of the ADC 9 to the WarP 9 has not been produced, but the following is a graph of the ADC 8, WarP 8, and ImPulse 9 - all plotted at the same voltage (with the NetGain motors extrapolated to 75 volts to match the ADC). What people need is the greatest ft.lbs. at the highest RPM and lowest Amp draw - the ImPulse 9 is a clear winner (plus it has ~30% greater brush area and other beefy components from the WarP 9).

If a customer is referring to the extrapolated graphs found on some dealers web pages he should be aware that they are probably inaccurate. ADC has recently informed NetGain that they no longer NOT advance time any of their 8" or 9" motors! (though it has been widely accepted and known that they were advanced 8-10 degrees in the past ) The degrees of advancement from where ADC advanced their motors is quite a bit different from the way NetGain does it. We were recently notified that although the ADC motors still had advanced holes the last time they came in for repair - the holes had been filled with plugs so as to make it difficult to change the advance. If this is still the case and the Dealers/Distributors are aware of it, they could still be claiming that ADC offers advanced timing - though as mentioned previously - the degrees are NOT the same as what NetGain does.

11. What size motor should I use?
Question:
What size motor should I use?
Answer:
A TransWarp 9 motor should be used with vehicles that are about 2200lbs or lighter, and a TransWarP 11 about 3000lbs or lighter. Any heavier, and you should consider adding another motor in series with the TransWarP motor for direct drive (i.e. no transmission). In that case, two 9" motors, for example a WarP 9 coupled to the tailshaft of a TransWarP 9 motor.

Miscellaneous
12. Hall-Effect Pedal Assembly (HEPA)
Question:
What advantages does a Hall-Effect Pedal Assembly (HEPA) have over a potbox?
Answer:
The traditional method of speed control input has been a potbox (potentiometer). While this works okay, its performance tends to degrade over time since there are moving, contacting parts inside the potentiometer. It's often a pain to mount the potbox right where the throttle resides in the engine compartment.

The HEPA uses magnetic sensors (Hall-Effect sensors) which have no contacting parts. This equates to a long-life, non performance-degrading throttle unit.

While for some, the pedal might just not fit, most vehicles can be made to accomodate the HEPA with a custom mounting bracket.

13. Can I use multiple contactors to increase their capabilities?
Question:
Can I use multiple contactors to increase their capabilities?
Answer:
You can parallel contactors, however, they don't necessarily share the current evenly. That means one could take too much current, and eventually weld.

To do this properly, each contactor should be fused with a carefully chosen fuse that will protect the contactor! I have probed Kilovac before for the data that would allow for making this sort of decision, but they haven't provided it. Fuse spec sheets show how long a fuse will take a certain current. The information needed about the contactor is the time vs. temperature curves that show how long the contactor can take a certain current before the temperature rises to a level that could weld the contactors. The fuse should be such that it blows before this temperature is reached.

I prefer the SW-200 style contactors, as you can inspect the contacts. They are only rated for 96V though, so to stay within specs, you need to put units in series to get to whatever voltages you're operating at. You can then parallel series groups of contactors to get the current ratings you're after. Enough in series to accomplish the voltage requirements you have, and enough sets in parallel to keep you in a safe range on the current-carrying capabilities.

14. Braking
Question:
Will the brakes on my EV stop my vehicle at top speeds?
Answer:
For your brakes to work most effectively you will want to use a vacuum assisted brake kit. This will allow your existing power brakes on your car to operate like they would with a combustion engine.

15. Do I need a relay to power my device?
Question:
I am in need of a cut off/on switch for my brake pump. I have read a few that say they also require a 'relay' because of the difference in amps. The two draw - switch may require less amps, say 4 and the pump will require 8.
Answer:
This is the idea of "amplification". Think of it like a dumptruck moving a load of dirt. There's no way a human could haul around a ton of dirt, but humans can drive the truck (which is capable of hauling huge loads). Similarly, the switch that will turn on your pump (likely something like your ignition switch) might be only capable of moving a couple of amps of electrical current load. But if all the switch does is command something else to move the load (e.g. a relay), then that's do-able.

For example, the adjustable vacuum switch, part number 131-PMF-4200-X30. If your vacuum pump is on the order of 5-8 amps, then this switch (actually a relay of sorts) can handle the load. But if you're using a pump that will draw more than that, you better use another relay. The Bosch Micro Relay on this page: http://evsource.com/tls_relays.php, would do the trick for smaller pumps. For larger pumps, the 75A Tyco on the same page.

Other EV Links
16. Some other FAQ links
Question:
Where can I get more info on EV conversions?
Answer:
1. becketts.ws - Advantages of EV's
2. So You Want to Build an Electric Car - More specific converting questions
3. Miscellaneous Links

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