We are converting a Bradley GT2 to 96V electric. We will be using 8 Trojan T1275 batteries. We ordered a kit from the good folks at Wilderness E.V.
The 72-144V motor was ordered with dual shafts in the hopes of adapting a 12V clutch assembly belt driven to an alternator. The signal from the brake light would engage the clutch which would spin the alternator, creating drag on the electric motor to aid in slowing the vehicle.
I’ve asked some EV enthusists about this and they seem to think that it should work. My question are:
Can I use a regular 12V high output alternator or a 24V?(I don’t think a 96
V alternator is available)
Has anyone here tried this before with any success?
Should I give up the idea?
We are hoping to get at least 30-40 miles on a charge and hit speeds of 60 -70 mph.
Any and all input is appreciated.
I think what you really want is a DC motor/generator. You can usually find 2 or 3 on E-bay for around $50 it will add 2-3 HP of breaking resistance and dump 100-130 V DC into your charge controller. It seems to me to be more weight and space efficient to have regen built in to the traction motor, but I understand what it can be like to work under a budget.
Yes, that is one example of the type of generators I was thinking of. You will still need a charge controller between it and the batteries though. It would be unlikely to overcharge the pack in your use, but theoretically if you live on a big hill start down the driveway with a full charge and hit the breaks the juice could overcharge your pack and cause damage to the batteries.
sorry i’m a SuperNoob on this EV stuff, but basically, regenerative breaking is a generator, (or AC motor???), wired in a reverse manner that makes electricity to put back into the batteries - all activated by a clutch which is activated by a break signal?
Either it’s very simple - or I’m missing something.
Here’s another shot in the dark - is a dual-shaft motor a motor that has a shaft coming out of both ends of the motor? one used to drive your vehicle, and the other to possibly use for a regen breaking system or alternator?
again sorry for all the silly questions and not knowing a thing…
The Curtis 1231C is a great controller. Very well made and does reverse if your motor is reversible but it is not a regenerative breaking controller. Most DC controllers are not. Resellers of speed controllers almost always include the word “REGEN” in the description if it does regenerative charging. The SEV-SIM 80 is a DC controller with Regen.
However Nomagas was asking about attaching a separate charging generator. If he already has a speed controller (any brand) I am recommending adding a separate charge controller that monitors the charge of the battery pack and limits charging if they are full. Something like this http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200332575_200332575
It would be cool to put in the dash so you would be able to monitor the condition of the batteries too.
Patzke;
You are right on both counts. Regen is usually done with AC motors, just one of AC’s advantages. And dual shaft is an output shaft on both ends of the motor.
another thing to consider, is that there aren’t a ton of motors and controllers for sepex above 72V that I’ve seen, that are readily available to the community. If you want regen on a small NEV or motorcycle, sepex is great because cost is lower than AC. As soon as you get above 100, 120 or so, AC seems to be the choice for regen.
This is my first post on this forum, so ‘Hi everyone’.
All these ideas make for healthy debate and discussion.
I have read somewhere recently that Hybrid (which is mainly targeting fuel savings remember) uses regen to collect lost energy in decelleration and to put it back at the acceleration phase, leaving the ICE to run more efficiently. However this works best on heavier vehicles (Yukon?!!) as the losses are greater and hybrids (and by default, regen) is pretty pointless on light vehicles and probably that means motorcycles.
The concept of adding power by combination of batteries AND ICE is a good one because it provides the peak demand (both electric and ICE combined) or either of the other two on their own, so three possibilities.
Each to his own as the saying goes but I think personally that regen is a bit over-rated except for really significant stop-start driving that most of us don’t do.
Actually a lot of people do the start-stop driving at 5 o’clock where I live and places where I have lived. This is where everyone works in a general area and there is mainly only one road to take to leave the area.
The city I’m in (Raleigh-Durham) there are a lot of stop and go situations and as time goes on, more and more cities will be like this.
Anyway, so SepEx motors are generally unreliable after 72 volts? This seems to be the concensus.
[QUOTE=polygonfla;3382]The Curtis 1231C is a great controller. Very well made and does reverse if your motor is reversible but it is not a regenerative breaking controller. Most DC controllers are not. Resellers of speed controllers almost always include the word “REGEN” in the description if it does regenerative charging. The SEV-SIM 80 is a DC controller with Regen.
However Nomagas was asking about attaching a separate charging generator. If he already has a speed controller (any brand) I am recommending adding a separate charge controller that monitors the charge of the battery pack and limits charging if they are full. Something like this http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200332575_200332575
It would be cool to put in the dash so you would be able to monitor the condition of the batteries too.
Patzke;
You are right on both counts. Regen is usually done with AC motors, just one of AC’s advantages. And dual shaft is an output shaft on both ends of the motor.[/QUOTE]
I’m confused as to the “12 volt 30 amp” that this controller will take. If you’ve got 72V on the battery bank, can it be hooked up directly to this apparatus? How efficent or worthwhile would this be? Is it even worth the effort?
You wouldnt have to put any kind of clutch on it. It dosen’t take much power to turn an alternator with no load on it. I would just use a relay to put load on the alternator. You would have to figure out how to turn it on and off. The alternator needs to be turning when its charging. I would probably just put a switch on the shifter so I would be able to charge or free wheel.
I’m sorry, by using the first charge controller I saw online I may have muddied the waters here. My intention was only to show an example of a DC charge controller. For Nomasgas’s purposes he would need to look at what is available from the solar and wind energy suppliers. I am sure he would be able to find the right controller there. But only if he already has a speed controller that does not do regen, and is unwilling to replace it with one that does. A traction motor with regen and matching speed controller is always going to be more efficient than a mechanical linkage. My impression was that he wanted to make the best use of items he already has.
Regen works the same for all EVs. A light EV with regen puts less energy back into the batteries but also pulls less out to get back up to speed. Regen usually adds 10-15% to range depending on how the vehicle is driven, even on electric bicycles.
Try this link, he has a schematic using an alternator with clutch, like you were talking about.
Go to wiring diagrams section
Hope this helps some
Rick
If so, is it done with a dual shaft motor + generator?[/QUOTE]
It is usually done with a SEP-EX motor and controller. You can buy controller with REGEN built in. Any other way other than AC motor and controller will be a headache. Even with REGEN you will only get about 30% power back unless you live on a large grade. You will save power stopped in traffic anyway since you dont idle your electric drive motor.
Nomasgas,
I like your regenerative breaking idea and think I would like to try a similar scheme on my conversion after I get it going. I would however make two significant changes:
1), I would not try to recharge my main battery bank with the braking energy, As discussed in one of the responses to your blog, it becomes a technical nightmare to step the voltage up to match your battery pack and run it back through another controller. I think the winding- down motor energy could be used to power an ordinary 12 volt alternator that would be used to recharge the auxiliary battery. It remains to be seen if that alone would provide enough power to eliminate the need for a DC-DC converter.
2). In order to maximize the energy recovery, I would have the clutch engage, not by the brake light switch, but by whether or not the car was in a power or coast mode, as sensed by a signal from the controler. This would reduce the car’s coasting performance, but probably not to a detremental extent. A simper way might be to use a position switch located under the gas pedal. The switch would be adjusted so that even a slight pressure on the pedal would disengage the clutch and the simple act of letting off the gas all the way would engage the regen feature. Proper adjustment and foot control would still allow for coasting.
My idea was to hook a small 8 to 9 hp gas motor on the end of the dual shaft and have a 80-90 mpg plug in hybrid.
did this in 1974 and when on down hills used the electrics to brake the ev and the petrol motor to boost the power on the up hills.
after a 100 mile trip i have plenty of electric power left to cruise the city on electrics form the power i would have lost braking on down hills
