[shui5612]

Hello and welcome,


Ive lurked for some time on this site, but first time posting.


I have a 2008 Zenn (for those who dont know, its a Microcar MC2 extended wheelbase) that was converted to all electric here in quebec, with the numbers of plated Zenns dwindling down i come to a hard decision to make really soon...


Last time i checked there are about 11-12 left on the road here in quebec, and on the facebook group there may only be another 60 that remain in existence in the US-Canada market.


The zenn runs off 6 deep cycle-agm 12v DC batteries each 100-105AH rating, meaning about 7kwh of energy packed into a 1000lb go cart/golf cart. Which means the motor, and charging are set up for a 72v system


One of my batteries is finally letting go (second set in its lifetime, none of which i purchased).
Seeing how the pack is pretty worn i cant replace just one battery (or two) and would ultimately need to replace the whole pack.
Here in canada we are talking about 300-350$ a battery, times six, making it an 1800-2200$ expense with taxes... for a car that does ~40km per charge at 40kmh...


And heres where I need your help... I have three options as far as I see it


option A, get a new pack and forget about it for the next 5 years


option B, do a li-ion swap, for which ill need the community's help as to finding the best bang for buck for making a pack, charger and balancer, would probably double the range but i would need a new motor/ecu for any speed increases. buying a 100-105ah 12v battery seems to go for in the thousands for one...


option C, swap it to an infernal combustion engine... which would probably be the cheapest option but require the most work too.


the car doesnt drive in the winter and gets limited miles in the summer, its basically a groccery getter at this point due to its dimishing range...
(has about 2000km on the odometer)


So what do you think i should do? im mechanically verse with all sorts of tools, a decent enough understanding of how EVs work...

 

[brian_]

Personally, I don't see the point in a conversion to an engine, since the only special thing about this vehicle is that it is an EV. If you want a tiny car with an engine, it would make more sense to sell the Zenn and just buy something like an old Japanese kei car.

There might be some performance improvement possible by a battery upgrade without a motor or controller change, if performance is currently limited by the battery (due to current-delivering capability, voltage sag under load, or just an operating voltage lower than the controller's limit).

I am curious, though... I thought these were all low-speed vehicles (LSV, or Neighbourhood Electric Vehicles), and generally not road legal in Canada. Are you somewhere that a LSV is road-legal?

 

[Emyr]

Taking this 100ah agm traction battery as an example, your current battery weighs 6 x 30.4kg = 182.4kg = 402lb. As for volume, the example battery is 306x168x211mm so 6 of them occupy about 65 litres of space, which is 2.3 cubic feet. 26 kg/kwh. 9.3L/kwh.

For comparison, 1st gen Nissan Leaf modules are about 500Wh per module, 68.5Ah at 7.3v nominal (2 x 3.65v), weighing 3.8kg and occupying 3.7L of space. 7.8kg/kwh, 7.4L/kwh.

By volume, you could theoretically fit at most about 8.8kwh for 25% more capacity whilst weighing only 68.64kg, saving 113kg. Wikipedia lists your kerb weight at 1200lb, 544kg, so your acceleration and range could increase by even more, compared with the ZENN's original performance.

The limiting factor will probably be the controller's max rated voltage and whether it can be programmed for a lithium-appropriate low-voltage cutoff (lead batteries peak ~14v, cut at 12v = 85% of peak; Lithium cell peak 4.1v, cut at 3v = 73% of peak). The perfect lithium pack would be 20S for ~84v peak (to match the original), 74v nominal, so 118Ah would give 8732kwh. I'm not familiar enough with OEM EV modules to pick out the ideal option.

 

[brian_]

The Zenn's nominal battery voltage is 72 V, but what are the controller and motor?

According to Wikipedia:

The vehicle originally was built with a DC motor and GE controller, and in 2008 was modified with an AC motor and Curtis controller.

I don't know if this is correct, but what's in this Zenn?

An earlier thread
zenn curtis controller
... said that the Curtis controller was a 1236.

 

[shui5612]

It is very hard to get a kei car here, let alone have it be road legal... Of course I could get an old 90s kei car from someone else but that defeats the purpose to an extent..


if I simply upgrade the batteries to li-ion then the benefits will be range, due to the reduction of weight by give or take 1/2. BUT doing that will mean I will need a new charger , running some new wires for ballast.. etc.. the limiting factor right now is the controller which limits me to 6000rpm, and I do not have the password to unlock it to 8000rpm which half of the US market got, thus upgrading the speed to 35mph or 55kmh.. currently being limited to 40kmh due to a law in the province stating any car that goes above 40-45 needs to have suspension and airbags.


My car previously belonged to the city and was the first road legal LSV in montreal, while generally speaking yes LSVs are very limited in Canada, in fact in Quebec you can no longer even register a new LSV, only use it "offroad" or in big environmental/wildlife conservational trails. HOWEVER, all previous owners and cars that were registered prior to a certain date have the right to use their LSV on public roads. Which like I stated earlier, means about 10 of us in the entire province.


To convert this car to use 18650 cells would mean about getting 800-1000 of them, a charger and cases etc... which just in batteries alone is about 3 grand so far..


So on one hand I am conflicted as to keeping this car alive and its "heritage" , on the other I would like to get something that can be used on a "daily" basis, meaning more range and speed and on the other... something that will be pretty cool and use-able...


hopefully this turns into a nice build


EDIT:
yes ive been looking into getting a wrecked cars battery pack i.e. a leaf or a ford escape hybrid which is an option on getting some more range and reduce weight/size...
only real issue is having to repackage them to get the voltage I need and a charger/way to ballast the cells...


2008 Zenns and up have the AC motor with the Curtis, you are correct.

 

[brian_]

It is very hard to get a kei car here, let alone have it be road legal... Of course I could get an old 90s kei car from someone else but that defeats the purpose to an extent..

I was thinking of a 15-year-old or older Japanese Domestic Market import; there are companies which do nothing but bring these into Canada. Due to their age, they don't seem to be a problem to license.

 

[brian_]

if I simply upgrade the batteries to li-ion then the benefits will be range, due to the reduction of weight by give or take 1/2. BUT doing that will mean I will need a new charger , running some new wires for ballast.. etc..

To convert this car to use 18650 cells would mean about getting 800-1000 of them, a charger and cases etc... which just in batteries alone is about 3 grand so far..

Personally, I wouldn't even momentarily consider hand-building a pack from hundreds of 18650 cells.

yes ive been looking into getting a wrecked cars battery pack i.e. a leaf or a ford escape hybrid which is an option on getting some more range and reduce weight/size...
only real issue is having to repackage them to get the voltage I need and a charger/way to ballast the cells...

That's what I assume would be the rational approach for a lithium conversion. All production EV batteries are built of multiple modules, so the reconfiguration consists of choosing the right number of modules, likely all in series. But yes, then there is a bunch of wiring and housing work, and a suitable charger is needed.


Do you have a photo or description of the original battery compartment? We have an idea of the total volume (since it contains six typical lead-acid batteries, perhaps GC2 size), but not the shape. It would help in suggesting which production EV modules might fit.

 

[brian_]

2008 Zenns and up have the AC motor with the Curtis, you are correct.

the limiting factor right now is the controller which limits me to 6000rpm, and I do not have the password to unlock it to 8000rpm which half of the US market got, thus upgrading the speed to 35mph or 55kmh.. currently being limited to 40kmh due to a law in the province stating any car that goes above 40-45 needs to have suspension and airbags.

Despite Zenn's claim that they were going to build a high-speed version, these were designed as low-speed vehicles. It doesn't make sense to me to change nearly every part of the car to make it into something that it was never intended to be.

My car previously belonged to the city and was the first road legal LSV in montreal, while generally speaking yes LSVs are very limited in Canada, in fact in Quebec you can no longer even register a new LSV, only use it "offroad" or in big environmental/wildlife conservational trails. HOWEVER, all previous owners and cars that were registered prior to a certain date have the right to use their LSV on public roads. Which like I stated earlier, means about 10 of us in the entire province.

So on one hand I am conflicted as to keeping this car alive and its "heritage" , on the other I would like to get something that can be used on a "daily" basis, meaning more range and speed and on the other... something that will be pretty cool and use-able...

If higher speed is required, my guess is that the Zenn is not the right starting point. It could be sold to someone who actually wants a low-speed vehicle (NEV). Some people use golf cars, UTVs, and even the occasional GEM in places such as RV parks... where they belong.

 

[Yabert]

To convert this car to use 18650 cells would mean about getting 800-1000 of them, a charger and cases etc... which just in batteries alone is about 3 grand so far..

Today, used batteries coming from crash electric cars is the way to go.
Here is an example of supplier: https://evbatterycenter.com/HAC4/in...ashop&view=category&layout=listing&Itemid=605
You can also contact me, I have some Chevy Volt battery left. A 70 lbs battery will increase your perforance and range and can cost you less than 1K$..

 

[shui5612]

So as far as being cars go.. yes there are brands that bring them over here but it wouldn't be able to be registered in Quebec to be road legal..

As far as the speed concern goes... I'm not "too" concerned due to these same chassis and components drive around at 110kmh in Europe on gas-diesel engines..

For the compartment size in the back it's basically 30inches wide by 14 inches long by 11 inches deep.
I won't mind if I have a pack that sticks out higher than that. It is exposed to the elements so I could close off the bottom and invade into the cabin Abit.

Up front you have two batteries and in front of them is the deltaQ charger, the Curtis controller and the DC to AC converter..

Behind and lower the batteries is the motor from which the halfshafts connect to both sides of the motor...

I'd be very interested in doing a swap to maybe a pack off a Leaf or Prius maybe?

Just wondering if I have a pack that is say 288-300v at x amps, is there something you guys use to reduce the voltage (like a regulator) to say 72v etc? Would make finding a pack easier with nothing to fiddle with besides connections and the charger...

 

[brian_]

So as far as being cars go.. yes there are brands that bring them over here but it wouldn't be able to be registered in Quebec to be road legal..

They're legal federally. I didn't realize that Quebec has some rule which bans them; they're legal in other provinces.

As far as the speed concern goes... I'm not "too" concerned due to these same chassis and components drive around at 110kmh in Europe on gas-diesel engines..

So they're only low-speed here. Not safe at high speed from a collision protection viewpoint, but roadworthy.

 

[brian_]

For the compartment size in the back it's basically 30inches wide by 14 inches long by 11 inches deep.
I won't mind if I have a pack that sticks out higher than that. It is exposed to the elements so I could close off the bottom and invade into the cabin Abit.

Up front you have two batteries and in front of them is the deltaQ charger, the Curtis controller and the DC to AC converter..

I'm not sure that it is worthwhile to use the front battery space, and deal with the wiring and packaging complications, since a reasonable set of production EV modules which fit in the main battery space will have significantly more capacity than the entire original lead-acid battery set.

Behind and lower the batteries is the motor from which the halfshafts connect to both sides of the motor...

Presumably this is actually from both sides of a differential, which is driven by the motor through a set of reduction gears... likely in the same Comex transaxle as used in the Microcar MC1/MC2, but without the CVT.

I'd be very interested in doing a swap to maybe a pack off a Leaf or Prius maybe?

Just wondering if I have a pack that is say 288-300v at x amps, is there something you guys use to reduce the voltage (like a regulator) to say 72v etc? Would make finding a pack easier with nothing to fiddle with besides connections and the charger...

It's expensive to convert the voltage down from the battery pack to the controller input; instead, the normal solution is to use a lower-voltage pack by configuring an appropriate combination of the modules of a production pack.

Current production EVs typically run around 360 V (nominal), and so you could use only less than one quarter of the pack. These packs are much bigger and heavier than the Zenn could accommodate, so you couldn't use the whole pack, anyway; you would use only a few modules. The Nissan Leaf and Tesla Model S/X are the popular choices (mostly because they are the most common EVs), but there are others.

• a stack of three Tesla Model S/X modules (with a supporting rack, and protective housing) should fit in the main battery space, and if connected in series would have a combined capacity of about 16 kWh at about 70 volts
• a stack of 20 Nissan Leaf modules (pre-2018), connected in parallel pairs then those pairs in series, would fit in the main battery space and have a combined capacity of 10 to 12 kWh (depending on generation) at about 75 volts

An alternative would be battery modules from a plug-in hybrid. These packs run similar voltages to battery-only EVs, but they're smaller (typically about 15 kWh, rather than 30 kWh to 100 kWh). The Chevrolet Volt is probably the most popular in this category by far; there are now some others, but they are recent and so salvage battery packs will be less common.

• the space is awkward for Volt modules because two won't fit side-by-side running across the car, but a single row across the 30-inch width of the main box plus another row in the front box might work (if the front box is wide enough); about half a pack would be needed for enough capacity but would need to be in two smaller sets in parallel to hit a suitable overall voltage

Non-plug-in hybrids tend to run somewhat lower voltage (200 to 300 volts), but have very little capacity; you would need multiple complete packs, and would still need to disassemble and reconfigure packs for lower operating voltage.

 

[shui5612]

They're legal federally. I didn't realize that Quebec has some rule which bans them; they're legal in other provinces.
So they're only low-speed here. Not safe at high speed from a collision protection viewpoint, but roadworthy.

Most provinces require an inspection if a vehicle comes from outside of the province or has not been plated for over 12 months, which would mean the kei car would have to be inspected, which it most likely wouldn't pass because then there would be a LOT more on the roads here then there are today.. im sure there is a work around but quebec is so strict we cant even register right hand drive vehicles anymore unless they were imported and registered before a certain date...


As far as roadworthiness goes.. they drive them around in Europe but here... would be kinda sketchy with all of the f150s and other massive cars roaring down the highway ay 120kmh+.. not to mention having no airbags which motorocycles don't have either..


id have no problem taking the car on a 70kmh or 90kmh road but going down a freeway is a slightly different story... maybe in a rural area...


Thanks for all the help, im actively looking for some Nissan leaf modules which seem to be the easiest route to go or look up some teslas but its hard to find anything here yet...


As far as cooling goes, will I need to think up of some way to circulate water in the tesla packs? is this something to even consider or will I not even be close to heating those up?


Lastly, for the charger, any clue as to where to start looking to get something reasonable?


thanks again.

 

[brian_]

... im actively looking for some Nissan leaf modules which seem to be the easiest route to go or look up some teslas but its hard to find anything here yet...


As far as cooling goes, will I need to think up of some way to circulate water in the tesla packs? is this something to even consider or will I not even be close to heating those up?

Yes, I think that the Tesla modules should have coolant circulation, as much to even out temperatures among the cells as for overall cooling or heating of the modules. The Leaf modules do not have active thermal management (although you can add a heater - the Leaf has one optionally), so in that way they are easier to work with.

 

[shui5612]

I have my fingers crossed for my search.. looking for a bargain on either tesla modules, leaf cells, or even chevy volt modules.. so far those three are the ones that would require the least amount of work and fit in the space pretty well.. also giving me more kwh while reducing my weight over stock...


add a solar panel at the top and I can drive forever! lol just kidding. but a panel would probably give me 100-200w/h in sunlight.. so.. 1 mile an hour or so..


having looked it up I also think I have a Curtis 1236 controller (password locked)
something along the lines of a an AC12 550A(??) motor..
which makes some sense due to it being 72v, the main fuse is rated for 600A.. which means about 37hp max, and 86lb-ft (im sure its toned down in the controller settings). with something like a KY06 gearbox..


don't know what I have as the dc to ac converter...
and a Delta-Q quick charger which I fixed..


So.. looking to start this project next spring and see where it goes...


hopefully I don't get a bug and end up wanting a 100mph EV speed-kart

 

[brian_]

having looked it up I also think I have a Curtis 1236 controller (password locked)
something along the lines of a an AC12 550A(??) motor..

There have been lots of variations of the Curtis 1236, with different voltage limits and current capacities. Is there a more specific model number marked on the controller? It would be helpful to know what voltage options you have for the battery.

don't know what I have as the dc to ac converter...

Do you mean DC-to-DC converter (for 72 V battery to 12 V conversion)?

 

[shui5612]

Here's where I may be confused...
Being an AC motor, and my batteries supplying DC current, is there not something that switches it to alternating current?

As far as the controller goes.. I'll try to find some info online but unfortunately it's tight up behind the bumper so I can't see what the controller model is.. I'll try to look at it tomorrow and see If I can find anything..

 

[MattsAwesomeStuff]

Here's where I may be confused...
Being an AC motor, and my batteries supplying DC current, is there not something that switches it to alternating current?

While in common parlance it changes one thing into another thing, and thus, is a "converter", most people describe that component and function as an "inverter". Especially as, a DC-to-DC (which is also an inverter) is called a "converter".

I suppose "conversion" seems definite and fixed. As a DC-DC is. While an "inverter" describes the process but leaves the result open ended, as a speed controller would be.

 

[Yabert]

For the compartment size in the back it's basically 30inches wide by 14 inches long by 11 inches deep.

Perfect dimensions to receive a 6 kWh battery build from Chevy Volt modules. That represent around double the capacity of your current pack because a 7 kWh lead acid battery discharge in less than an hour have only around 3.5 kWh available.
Similar pack had been test at 675A of disharge in my Smart few years ago: https://www.diyelectriccar.com/forums/showthread.php/power-capability-chevy-volt-battery-109698.html

70 lbs and dimensions of 30x12x10''.
Only possible reprogramation of your controller could be challenging.

 

[brian_]

Up front you have two batteries and in front of them is the deltaQ charger, the Curtis controller and the DC to AC converter..

having looked it up I also think I have a Curtis 1236 controller (password locked)
...
don't know what I have as the dc to ac converter...

Do you mean DC-to-DC converter (for 72 V battery to 12 V conversion)?

Here's where I may be confused...
Being an AC motor, and my batteries supplying DC current, is there not something that switches it to alternating current?

You were listing two separate devices: the Curtis 1236 controller and a "DC to AC converter". While something does make DC into AC - an inverter - that's done by the Curtis 1236.

In other words, the Curtis 1236 controller is the inverter - it inverts DC to AC at a controlled frequency and voltage.

If you have another box, separate from the Curtis, and connected to the battery, it is probably to convert 72 V DC power from the battery to 12 V DC for everything that runs on 12 volts (headlights, radio, whatever). Some careful checking across input and output terminals with a voltmeter (set to a range handling more than 72 volts) should confirm what the box does.