EV Conversion FAQ

andrew's picture

Q: I want to do a conversion! Where can I find all the details?

A: The best two conversion books are:

"Convert It" by Mike Brown

"Build Your Own Electric Vehicle" by Bob Brant


Q: I want to convert x vehicle. Has anyone else done this specific conversion?

A: Check http://www.evalbum.com


Q: How long will it take to do a conversion?

A: It depends on the type of conversion, your skills, and the resources you have available. Generally, at least 200 hours.


Q: How much will it cost?

A: It depends on the scope of the project, and your performance goals. It also depends on what resources you have (including recycled parts from other EV enthusiasts or EV projects). It definitely pays to be resourceful, but it is also justifiable to spend money on good components when one is spending a lot of time with the conversion.


Q: I really don't want to use lead-acid batteries for my conversion. Can't anything compete for a decent price?

A: In general lead-acid batteries are still the best. Due to rising lead prices these are becoming more expensive while other technologies like LFP (lithium-iron phosphate) become cheaper. A good comparison can not be made yet.


Q: Should I use flooded or sealed AGM (absorbed glass matt) deep-cycle lead-acid batteries?

A: Personally, I've had to experience these down sides to flooded lead acids:
● They smell
● They leak acid and corrode the battery box, in addition to leaving stains where they are rinsed off
● It is difficult to avoid acid contact with clothing completely during maintenance. Acid eats clothing.
● They require adding water
● They can potentially spray acid at any time

AGMs have none of these disadvantages. They also have numerous advantages. It is a matter of debate and this answer is far from complete, but I would always suggest seriously considering AGMs even at the higher cost.


Q: About how many batteries are needed?

A: About 30% of vehicle weight.


Q: About how much range will I get using lead-acid batteries and 30% vehicle weight?

A: If it is a car, 30-40 miles. If it is a motorcycle, 10-20 miles.


Q: Why did person x say they get 90 miles range?

A: People tend to exaggerate. Also driving slow and accelerating slow will give significantly more range.


Q: I don't really want to do a conversion. Should I buy one instead?

A: There are no guarantees when buying a conversion. Some are very poor, while others are decent. Stuff will fail and you will need to know how to work on it either way.


Q: Should I buy a factory production EV?

A: If it still has support, than these are the best full size EVs available. Unfortunately, once support is gone, than many of the components may be difficult to find and install.


Q: Will the existing batteries likely work in the conversion I buy?

A: Probably not. Most people sell conversions when the batteries are bad. Even expensive NiMH batteries used in some production electric vehicles will deteriorate.


Q: How good are the components available off the shelf for DC BEV conversions?

A: It depends on the component, and also how much you are stressing it. Some components that were available in the past have all failed. Also, controllers can and do "blow up", especially if you run them at their maximum rated voltage. Some components are very reliable, such as ADC motors. A great resource is people who've actually used the components (check the EV album for contacts). Also I've found that the BEV conversion suppliers in the USA in general sell quality parts.


Q: What brands of batteries are best?

A: Trojan appear to be a very reliable flooded batteries. B&B are good budget sealed AGM batteries. Hawker Odyssey are very tough sealed AGM batteries. Exide Orbital XCD are the performance sealed battery of choice.


Q: Can I use the auxiliary 12v battery to power the 12v system?

A: Yes, but this is generally not a good idea because the auxiliary system was designed to operate on 13.8v, and the auxiliary battery will will sag to 12-12.5v. You will probably want a dc-dc converter using main battery pack as the energy source.


Q: Can I build my own controller?

A: Sure you can but it is not as easy as it looks. It is best to buy one if you do not want to spend considerable time.


Q: Can I use a 12v vehicle starter contactor for the main contactor of the high voltage system?

A: No because it is not meant for switching higher-than about 12v, and it is not meant to operate continuously.


Q: Why is it important to be safe around batteries?

A: Because if you short circuit them on accident then the point of contact will arc sending flying metal plasma. Flooded batteries can also spray acid, and both sealed and flooded batteries can vent explosive gas. It is best to wear both safety glasses and gloves, keep baking soda handy, and insulate your tools with electrical tape.

[this is in progress]

[Updated Feb. 20, 2008. Please add any Q/A additions below and I will link them in here]

before comments


reikiman's picture

HybridCars.com has also has decent overview for beginners: Electric Car Conversion: Top 7 Issues to Consider

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