We travel 365 days a year in a RV (Class A Motorhome) and tow a Honda Civic for local transportation. I’d like to get an EV to tow instead. I want to use the regenerative braking on the EV to slow down the motorhome each time we stop. So my first question will be, does anyone tow an EV and do this?
Second question, can you give me references to detail information about regen braking systems. I have a good grasp of the general principle and need to learn more about specific systems.
My criteria for an EV are:
Must have 80+ miles range on level land, 60+ miles with moderate hills
Should cost less than $12k total
Must carry 2 people and have room for a grocery shopping trip
I have experience with AGM batteries in a solar power installation and plan to use Concorde AGMs for the EV.
first of all, good idea. second of all, what car are you planning on using? I am having trouble thinking that AGm batteries will give you an 80 mile range. I guess if you get a car that can handle a large amount of batteries, like a small pickup, you might. So i am guessing that you already know you are going to be using an AC system, which leads me to my next point. You will have a hard time keeping the budget under $12,000 with the specs that you want.
I don’t have a specific vehicle in mind, but leaning towards a compact pickup truck. I have a 1996 Honda Civic 4 door, and I see two problems with it. First, it’s a little heavy to start with. Second, I don’t think it would be easy or cheap to modify the suspension to carry the extra weight.
I know the budget is somewhat optimistic. The Concorde AGM’s will at least double the cost of batteries vs. Trojans, but I like them for safety, no maintenance, and their charge and discharge characteristics. With exception of the batteries, I’ll consider used components for just about everyting else. Hopefully a few key second-hand purchases will keep the costs down.
Having the regen braking really appeals to me because there’s SO much energy available when we tow. Of course it would extend the range of the EV too, and help us achieve the distance goals.
Is there a general formula to aproximate range in miles per KW with a given vehicle weight?
It would be interesting to hear from someone who has an EV similar to what we’re thinking of. I saw a pickup advertised for sale that claims 100 mile range, but looking at its equipment it seems to be little different from others claiming 50 miles.
I would say a small pickup would make a great tow vehicle. It can easily handle the quantity of batteries you are looking at, as well as have suspension that can be upgraded with ease. Keep in mind, AC componants are usually difficult to come by “used”. As far as calculating the KW per mile, it is more commonly called WH/M. Here is a blurb i posted previously in this forum. Hopefully it can help you to determine this.
You can calculate your approximate range by finding a car with similar weight, size, motor etc from the list below, it will have a WH/Mile rating. To use this number, you first need to decide how many miles you want your EV to go. So theoretically I will have a car that should get 350 WH/M, I multiply this number by the milage I want (100 miles) so I get 35,000 WH. Now you must divide this number by your system voltage. A little not about voltage, make the voltage as high as your system will allow. I want a voltage of 348 V so I take 35,000 and divide it by 348V to get my AH rating wich is about 100.5 AH. So I need a pack that has 348V and 100 AH. Li-Ion comes in 3.2v cells so I need 109 cells to get me to 348.8V. Although there is no 100 AH cell, there are 60AH cells that I can use twice the cells for to get me a total of 120AH. (a little extra range never hurt)
Ford Ranger (Production) 400 WH/Miles, AC, 4,750 lbs, 312V
Toyota Rav4 (production) 250 WH/Miles, DC, 3,500 lbs, 288V
Small truck (4wd) 366 WH/Miles, DC 9", 4,060, 192V
Small truck (eff. 2wd) 300 WH/Miles, AC, 4,880, 312V
Medium Sedan 345 WH/Miles, DC 9", 3,650, 228V
Micro car 133 WH/Miles, DC, 1,750, 120V
Small Car 250 WH/Miles, DC 8", 3,280, 114V
Aerodynamic Small car 180 WH/Miles, DC 9", 2,725, 240V
Small SUV 200 WH/Miles, AC, 1,650, 600V
Try http://www.electroauto.com/
That organization has loads of D-I-Y EV conversion information, and sell complete kits for a variety of ICE vehicles. Good luck.
I don’t have a specific vehicle in mind, but leaning towards a compact pickup truck. I have a 1996 Honda Civic 4 door, and I see two problems with it. First, it’s a little heavy to start with. Second, I don’t think it would be easy or cheap to modify the suspension to carry the extra weight.
I know the budget is somewhat optimistic. The Concorde AGM’s will at least double the cost of batteries vs. Trojans, but I like them for safety, no maintenance, and their charge and discharge characteristics. With exception of the batteries, I’ll consider used components for just about everyting else. Hopefully a few key second-hand purchases will keep the costs down.
Having the regen braking really appeals to me because there’s SO much energy available when we tow. Of course it would extend the range of the EV too, and help us achieve the distance goals.
Is there a general formula to aproximate range in miles per KW with a given vehicle weight?
It would be interesting to hear from someone who has an EV similar to what we’re thinking of. I saw a pickup advertised for sale that claims 100 mile range, but looking at its equipment it seems to be little different from others claiming 50 miles.
There is more involved than just running them. you have to dump the power somewhere. On a typical EV they aren’t used until you have driven about 10 miles so you don’t over charge the batteries. You would need to monitor the charge in your battery pack. On my car I would need to split the pack into 2 72 volt packs with a contactor activated by a switch switching on and off the regenerative system. with 400 amp diodes in line, there is a resistor involved also made with threaded rod and Stainless Steel nuts and Washers for a heat sink dump for loads greater than 400 amps. I am not saying that it is not a good idea but there is more to consider than just doing this without thinking it thru. The book that is available is for DC motors
Regenerative Braking with DC Series Motors A Practical Guide by G. L. Jackson
I bought my copy from http://www.ev-america.com/:cool:
what you want is almost a hybrid.
with a solid tow and a spare or separate evs accelerator in the cab of the towing vehicle you can touch the evs accelerator at 1/2 speed and it will slow down the larger vehicle and charge the batteries.
on steep hills the same can be used for the ev to help the towing vehicle to climb with pressing foot on both accelerators, Electric and gas, to use up some of the excess generated power.