Electric Reverse Trike - Eco-Exo R - advice requested
i have seen a reverse trike that you can build in the UK or US at Eco-Exo dot com. The R model is with steering wheel rather than handlebars, which some people prefer. They are based on suzuki burgman components including the original petrol engine power chain. The weight as constructed is 200KG. The desired range and speed for me to use as a city commute is 60mph and 15 miles before an overnight recharge.
I have thought of 3 strategies to reduce weight and electrify the kit and would like your advice on this and any other suggestions:
- use alternative front wheels that are lighter than the stock burgman scooter ones and have smaller section tyres. Use a hub motor (for simplicity) at the rear and a custom designed or adapted burgman swing arm for it.
- same as the first option but using an inboard motor and chain drive to rear wheel.
- 2 hub motors at the front, similar to the original burgman items, with a simple swing arm/wheel and disc at the rear.
Please may I ask you to comment on each option and suggest suitable motors, controllers and battery packs. If your advice is to accept lower performance, please suggest what I can reasonably aim for.
The intention is to build to a budget and save on commuting costs over time. The kit costs about £2K.
The first thing I'd want to know is the nature of your commute. If you have to stop and start a lot, then weight is a big issue, and regenerative braking might be worthwhile. If, OTOH, you don't have to stop much, then the weight can help you coast, and you should focus your efforts and cash on other areas. I assume the Burgman uses a CVT drive? If you can use that with a single high-torque motor, I think you'd find it much more enjoyable than two hub motors, which tend to be rather gutless when you first start to move. OTOH, moving the drive system to the wheels would leave more room (and weight) for batteries...
It sounds like a Burgman is what you *don't* need! Do you already have one, or have access to a damaged one? Because they are highway cruising scooters, and are not popular for city riding because of their weight and relative lack of agility. You need a trike that's big enough to 'take the lane' (aka "Carpe Laneum) but still as light as possible to allow the batteries to handle the load. Dual hub motors may well be the way to go - as long as you don't use two half power (1000 - 2000 watts) hubs. Go with two 3000-4000 watt hubs and a controller that can make them miserly, and also provide strong regen. Some of the other folks here should be able to recommend actual parts. You'll probably also have to settle for about 45mph instead of 60, given your needs.
If you are going to use one hub motor, you might want to consider trying to buy either a 5000 watt unit or the newer 8500 watt unit from ZEV. I have had plenty of bad things to say about my ZEV 5000LA, but I've had both motors in it (the original 5000 watt unit had a badly bent rim from shipping damage, and was replaced even though it still ran fine, with the 8500 watt version) and had zero problems with both. These motors seem to be better designed and more robust than most (the parts are made in China and quality controlled and assembled here in the US), and the 8500 watt unit wouldn't need to be upgraded if you decided you needed to go faster. It also has cooling fins, which might be helpful in city commuting in hot weather. I wouldn't recommend the controller used in the 5000LA, but one of the more expensive versions from the higher end models might be fine. There are two other ZEV owners who post here, and hopefully they can answer that.
Oh, and while you want to use Lithium batteries, Apex batteries has 50AH scooter batteries designed for the Oxygen Lepton on clearance for a *lot* less. You should be able to build a center channel in the trike and use them in the same location as the Lepton. If you go that route I'd also recommend a Zivan three stage charger for them. If you go with a 60 or 72 volt system you should get enough power and range.
Things will be pretty tight in that kit. As far as battery space goes real estate will be a premium. I am curious where you were planning on putting the batteries? I think what you are trying to do is a good idea because it saves you quite a bit of time over a scratchbuilt (ERT) Electric Reverse Trike however there will be compromises here. The good thing is it does not sound like you really need much performance since you are in stop and go the majority of the time.
I am building a scratchbuilt ERT right now as we speak and do plan to offer it as a kit in the future. However mine is much different then what you are looking at here. I use a lightweight backbone chassis platform with rear swingarm for my rolling chassis. This does increase weight however but affords me the ability for a 2 seater side by side and bigger motor more battery and cargo space. The other thing is I can use all the front suspension and steering bits from the donor chassis car which is much beefier and is what you want really. The reason being the vast majority of the time an EV conversion will be heavier than the original due to battery weight. SO you need better braking and suspension up front were the load transfers during breaking! Depending on motor selection you can go with a regenerative braking capable motor/controller combination which I would highly recommend in your situation. Another thing to consider is the payload of the chassis you are converting can it handle the battery load? I would be a little worried with such a small frame to be honest. You want to have a light weight built in an EV however not at the detriment of safety!
I might think about welding on to the side my battery packs so that I can keep them low and the resulting center of gravity low as well. This is very important in a reverse trike build you want the center of gravity low and forward. SO to me looking at this kit as it stands currently the only room for batteries are directly behind the seat where ICE engine and CVT tranny is located. This wold not be a good place for extra batteries as they would need to be stacked high up most likely which would alter your center of gravity (cg). I would think about a single motor/controller set up (PMAC) Brushless AC would be my choice. The ME0913 or ME1115 and Sevcon Gen4 series 4 or 6 would do the job quite nicely. The motor weighs 35lbs and controller is 5.9lbs. They produce 12kw cont and 30kw peak at 5000rpm! Zero motors uses this combination and can be viewed here at this link = http://www.zeromotorcycles.com/powertrains/powertrains-sales-sheets.pdf
The other option is to go with a Hub motor as others have suggested. The drawback to this is always increased unsprung weight which is a bad thing. The advantage is you gain real estate which in this case does not really help you as the best location for batteries is forward! So hence is why I would build my own battery racks and weld them on the side of the vehicle. However this opens up the space behind the seat for cargo not much cargo but you could fit your backpack or one small grocery bag which would be nice!
The other consideration is the open compartment style. My ERT will be fully enclosed as this will allow me to drive in all weather conditions. I would consider designing an lightweight composite body shell for your ride to increase aerodynamic efficiency as well as provide protection from the elements. London weather can get pretty wet so you will be lying in puddles much of your time as well as getting splashed from other road goers not my idea of fun for sustained periods of time.
So you have much to think about here and to consider the good thing is you are committed to electric and to me this is the number 1 goal and something we should all strive for in our vehicle strategy especially if we drive less than 50 miles a day. If so there really is no reason we should not have an EV capable ride.
Good luck with your project,
Until someone comes up with a "rubber-airbag" battery, putting the batteries around the outside of a vehicle isn't a great idea. You want to protect the occupants first, but the batteries a close second. Between the relatively high voltage and the at least mildly toxic batteries in use, the batteries need to be able to survive front, side and rear impacts.
I would have to agree with you putting the batteries on the side would not be my first choice either as you are correct they need to be able to survive impact but in something that small I don't see much of anything surviving an impact let alone the batteries!
Hey Johnny J,
Those trikes look very similar to the ones you can purhcase in China! The way the suspension design is laid out really reminds me of them. I was looking into the KAXA models for my conversion which adopt this suspension design. I decided against it in the end for my ERT-1 Project as I thought I would be better off adopting a light weight backbone chassis for my foundation. Plus I had a little more freedom working with a backbone chassis than with a tubular design. However its a nice looking trike and you can and should absolutely convert it into electric :-) With the right component selection that would be a blast to rip up the boulevard! If you drive less than 60mi a day total I would highly consider it in fact I would just do it with that little of driving its just a no brainer.
Thanks for sharing your idea good luck with it,
Yeah, those are from China :-)
Recieved them only a few days ago and the construction looks solid. I've only driven a few 100 yards so far but they seem ok.
Not too heavy either around 250kg, so maybe around 210-220kg without the ICE-stuff.
I have converted 2 cars before so this shouldn't be too hard.
Haven't decided which motors to use yet, I have an 8kW 100V hubmotor laying around, might try that one first (might be too weak).
Man I thought those guys looked familiar well its good to see somebody outside China took the plunge and got some. I thought and still do that these would be a great conversion option for people wanting a quick DIY project. Everything is there engineered up and built. Not knowing the payload of the chassis I would go with Lithium hybrids in this guy to keep weight to a minimum. I would also go with a PMAC brushless motor design again to keep weight and maintenance down. A 96V-144V system would give this thing pretty good performance ability. The last thing I would do is toss the plastic and design a fully enclosed body so I could enjoy it year round and in any elements. If you went a dual motor configuration which is what I am currently doing in my ERT project you could also get away with only having a single gear thus eliminating the tranny all together. Just make sure your rear sprocket reduction is around 4 or 5 to 1 and you would be good to go. Your performance with the dual motor configuration would be crazy :-) Going without the tranny would also help keep weight lower and give you the ability to increase the battery pack size for better range or performance or both if desired. Either way with this platform you have quite a few options at your disposal. I am curious what was the final costs on these guys? I think if my memory serves me they had me priced at around $4,000 to my door although it could have been a little more but it was under 5k I am pretty sure. Of course I am on the West Coast though so shipping to the east may be more not sure.
Anyways I hope you go for it I would love to see how one of these performs with an all Electric drive system.