A possible design

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Taffy
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A possible design

Post by Taffy » Wed, 28 Jan 2009, 05:14

What are peoples thoughts on this set up.
Aims: 80km range, neck snapping acceleration, top speed 110kph.
Not spend $10K on 160AH Lithium batteries now... at $1.5-2K a month budget into the build that is too much. So SLA are the only option.

Make: Individually constructed vehicle (ICV)
Model: Lotus 7 replica (Low Cost)
Seating capacity: 2
Front brakes: Disk TE Cortina
Rear brakes: Drum TE Cortina
Kerb weight of IC: 680kg
Kerb Weight of rolling chassis: ~ 300kg
Coefficient of drag: 0.7
Frontal area: Not sure, small. But looks like a brick to on coming air!


Motor: Advanced DC FB1-4001
Batteries: 12 x 12V 100AH AGM Sealed lead acids
Controller: Curtis 1231C
DC-DC Converter: DC converter to 13.5V
Auxiliary power: 12V Seal lead acid charged by DC-DC converter
Pot (Speed controller): 2 x Curtis throttle pot (Safety feature)
Charging: WOODS EV charger, via 10Amp 240V AC power outlet
Safety devices:
HV: Inline fuse, circuit breaker, contactor (connected to ignition)
LV: Inline fuse, safety interlock switch, ignition switch
Separate and isolated low and high voltage circuits.


Questions:
1) Thoughts on a 203-06-401 (8") vs the FB1-4001 (9") in such a light weight car? Overkill, considering aim is sports car performance up to a point.

2) Trying to strike a balance between kg vs AH in SLA.
12V 100aH is ~30kg (144V pack is around $3360)
12V 100aH is ~32kg (144V pack is around $3600)
12V 120aH is ~38kg (144V pack is around $4000)
(Knowing lithiums kill for kg to ah but $$$)

3) Are there any other options for 120/144V controllers other then the curtis 1231C now that zilla's are no longer producing (for now).

There are more but that will do for now, mostly based around the safety features.

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Post by evric » Wed, 28 Jan 2009, 05:19

Kelly Controllers have a new range of controllers. These model numbers end with a "B" - with higher, hopefully true, power ratings... Ric
Prius Plug-in Conversion: http://www.evplus.com.au ...Holden Barina EV: http://www.evric.kestar.com.au

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Post by Taffy » Wed, 28 Jan 2009, 05:26

Thanks, i see a Kelly KDH14651B which has my attention.
Continuous: 260A
Boost 1min: 600A
144V/regen/programmable.

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Post by zeva » Wed, 28 Jan 2009, 06:05

Firstly, nice choice of donor. I've always thought a Lotus 7 replica would make a great EV. Your list of components looks pretty good, a few comments:

Batteries: 12 x 12V 100AH AGM Sealed lead acids.
Should get the range you want, but weight is substantial of course - a third of a tonne or so? Unfortunately it's always a balancing act between range and performance.

Controller: Curtis 1231C
A well-proven option but overpriced, underfeatured and not commonly associated with neck-snapping acceleration!

Pot (Speed controller): 2 x Curtis throttle pot (Safety feature)
A cheaper alternative, you can use the potbox's microswitch hooked up to the controller's KSI (power) pin for redundant safety. (i.e if the pot fails you can still stop the vehicle by taking your foot off the pedal)

1) Thoughts on a 203-06-401 (8") vs the FB1-4001 (9") in such a light weight car? Overkill, considering aim is sports car performance up to a point.
Overkill? No such thing.. Image Go for the 9", it's worth it.

2) Trying to strike a balance between kg vs AH in SLA.
12V 100aH is ~30kg (144V pack is around $3360)
12V 100aH is ~32kg (144V pack is around $3600)
12V 120aH is ~38kg (144V pack is around $4000)
(Knowing lithiums kill for kg to ah but $$$)

Going by the numbers, these all have relatively high energy density for lead acids - which is good for range but often means they're not designed for high power. Just something to watch (e.g check rated CCA or Peukerts).

3) Are there any other options for 120/144V controllers other then the curtis 1231C now that zilla's are no longer producing (for now).
A warning about the Kellys - discussion on EVDL indicates that even the KDHB series are still pretty "generous" with their claimed current ratings. You'd almost certainly get better performance with a 1231 than the KDH14651B. Also, Kelly now admit that regen does not work with a series DC motor, and only suggest regen models for permanent magnet DC motors.

Right now my vote would be for a Logisystems controller. Maybe the 1000A one if you seek performance!
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Post by tassie_tiger » Wed, 28 Jan 2009, 06:12

zeva wrote:
Right now my vote would be for a Logisystems controller. Maybe the 1000A one if you seek performance!



Just be careful with that one too, seems they blow up a bit if you check the threads over at diyelectriccar.

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Post by lachlanmac » Wed, 28 Jan 2009, 06:14

Just some thoughts cos I love the idea of a lotus electric. And remember I am new to this. 90ah Lithiums should give you more usable capacity than 100ah LA unless you are quoting the C1 rating. My 45 thunderskys cost about $7300 and weigh 135kg. The charger for them was about $1000 I thought woods chargers were a lot more than that so you save a bit there. I also have been told that sla batteries cant deliver the short burst high current an EV needs especially yours.

Keep looking I want to see it pass me.

Lachlan

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Post by zeva » Wed, 28 Jan 2009, 06:25

tassie_tiger wrote: Just be careful with that one too, seems they blow up a bit if you check the threads over at diyelectriccar.

Yeah this has come up on EVDL as well.. On the up side it sounds like their after-sale service is very good, but that wouldn't stop it being very annoying if your own blew up during use. It's a real pity that there are still no particularly good options for DC motor controllers *. (Plenty of good AC controllers on the market but they all cost a small fortune.)

FWIW my latest controller prototype seems to be working well, though I wouldn't feel comfortable building one for others yet!

* Edit: since CafeElectric ceased Zilla production, anyway!
Last edited by zeva on Tue, 27 Jan 2009, 19:27, edited 1 time in total.
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Post by acmotor » Wed, 28 Jan 2009, 07:08

How much does the Lotus replica cost ?
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Post by antiscab » Wed, 28 Jan 2009, 08:17

motor sizing is more dependant on how much continuous power you require, rather than vehicle weight.
since you have a vehicle with fairly poor aerodynamics, id say go for the 9".

if you want 80km range on 7.5kwh (ish) (100wh/km), you may need to drive slow.
unfortunately, you dont know real world energy usage until after you build it.

thats not to say it shouldnt be done, just you may not get 80km on lead acid.

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Post by Markoid01 » Wed, 28 Jan 2009, 17:16

Hi Guys,
Here is a link to an Electric Clubman!

http://autospeed.com/cms/A_109549/article.html

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Post by Taffy » Wed, 28 Jan 2009, 18:54

acmotor wrote: How much does the Lotus replica cost ?


There are a number options
#1 Buy a kit car
#2 Build your own chassis

#1: Kit is normally around 12-20K
#2: LoCost (as there known) is:
Donor: $200 (Ford Cortina TE)
Shocks/springs: $300 (That was getting lucky a couple of times but normally $1145 new)
Chassis: $300 steel
Bodywork: ~$1000 (Not really started this yet)
Finishing & misc: ~$3000
Budgeted rolling chassis: $5K
Rolling chassis Total: $3.5-8,000 (Dependent on finish, skills etc)
ICE Total: $15,000 - 30,000 normally

Couple of books to read:
How to build a sports car for less then 250 (pounds) (Champion)
How to build a sports on a budget (Gibbs)


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Post by Taffy » Wed, 28 Jan 2009, 19:08

Batteries:
Should get the range you want, but weight is substantial of course - a third of a tonne or so? Unfortunately it's always a balancing act between range and performance.
Yes, it will weight nearly 1/2 of the cars total mass sadly... Longer term i would like lithiums but right now its a little too $$$.

Curtis 1231C
A well-proven option but overpriced, underfeatured and not commonly associated with neck-snapping acceleration!
I had found this issue with the 1221 we used in the RMIT racer, will explore some of the options put up.

Pot (Speed controller)
A cheaper alternative, you can use the potbox's microswitch hooked up to the controller's KSI (power) pin for redundant safety. (i.e if the pot fails you can still stop the vehicle by taking your foot off the pedal)
I will look into this, did not know about this feature. Since i would like to use it in a hill climb or two some kind of robust system is a must.

Motor:
Overkill? No such thing.. Image Go for the 9", it's worth it.
9" it is. First thing to buy so i can finish the chassis off with gearbox mounting and getting the drive shaft shortened.

Going by the numbers, these all have relatively high energy density for lead acids - which is good for range but often means they're not designed for high power. Just something to watch (e.g check rated CCA or Peukerts).
Hmm i knew it was too good to be true! Does anyone have any ball park figures which i can use when i go talk to some suppliers?

Curtis Vs Kelly
Nuts...

Right now my vote would be for a Logisystems controller. Maybe the 1000A one if you seek performance![/QUOTE]
More research... For now though i need to get back to work! At least i can stagger purchasing so i have time to look around.

Will draw up a better budget idea later this week and play with how things fit.

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Post by acmotor » Wed, 28 Jan 2009, 20:06

Just observing Taffy,
you are going from a lighweight racing car with reasonably good specific energy batteries (SAE) to a lead sled.

This post is not meant to be derogatory, just checking your expectations.
It would be the batteries that will 'hold you back'.

IMHO I would think of a lot shorter range with high discharge rate lead acid, even as little as 20km, if budget steers you toward lead.
That way you can build and experience some performance. Then if you are pleased with the result then upmarket batteries will provide the desired range in the future.

There are plenty of lead conversions that have reasonable straight line performance or range (not both) but cornering (and heaven forbib - hill climbs) are just not in their vocabulary.
Even the tesla shows its weight in corners !

Just my two bits worth, and not trying to put you off.
The choice of vehicle is great !

Question.... wouldn't a 9" in the lotus be quite suitable for direct drive ? The weight saved could be used on batteries.

Edit: 9' was a bit big changed to 9"
Last edited by acmotor on Wed, 28 Jan 2009, 11:19, edited 1 time in total.
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Post by Taffy » Wed, 28 Jan 2009, 21:38

IMHO I would think of a lot shorter range with high discharge rate lead acid, even as little as 20km, if budget steers you toward lead.
That way you can build and experience some performance. Then if you are pleased with the result then upmarket batteries will provide the desired range in the future.

I believe you may be right, Possible go for a 72V pack with high rate of discharge? Thoughts?
Then i can eithter put a 2nd 72V in series or parrallel depending on where it it is lacking after some testing.
Or maybe i should make 2. Image
1 ICE with Super, Tubro, NOS for going stupidly fast.
2 Electric for cruising 100km.
(Joking. No way i am making 2, never finish!)

There are plenty of lead conversions that have reasonable straight line performance or range (not both) but cornering (and heaven forbib - hill climbs) are just not in their vocabulary.
I am under no illusions in what 1/3 ton of batteries will do to trying turn this thing. The hill climbs are just for fun, not aiming to win! I understand perfectly what your saying sadly. Image

Question.... wouldn't a 9' in the lotus be quite suitable for direct drive ? The weight saved could be used on batteries.
I thought that it would, but i did not find a suitable example to copy there set up that didnt use there gearbox. Not using it would make the set up easier as i can locate the motor in the transmission tunnel.
Do you know of any performance (similar set ups) which dont use gearbox's?

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Post by acmotor » Wed, 28 Jan 2009, 22:14

I should say that I have plenty of time for the Goombi style conversion. But it is all about your expectation in the Lotus !

If you use a gearbox then you will most likely need to go for higher voltage (for more revs on the motor).

I can't make personal experience comment on the 9" in direct drive other than to say that if you have the amps available in battery and controller then the gearbox is less important. If for instance the controller had only 500 or even 1000A limit then it will limit the takeoff. In most motor sport, it is the pull at speed that you need to target anyway. Picture the tesla.

Certainly the key to the Lotus would be in keeping the weight down so the 9" 's torque would be suitable direct drive ?

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Post by fuzzy-hair-man » Wed, 28 Jan 2009, 22:26

Taffy wrote: Question.... wouldn't a 9' in the lotus be quite suitable for direct drive ? The weight saved could be used on batteries.
I thought that it would, but i did not find a suitable example to copy there set up that didnt use there gearbox. Not using it would make the set up easier as i can locate the motor in the transmission tunnel.
Do you know of any performance (similar set ups) which dont use gearbox's?
Does this count? It's AC but it is direct drive...

AC direct drive Electric 7

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Post by Taffy » Wed, 28 Jan 2009, 23:39

It does count, though a little more advanced then what i was looking at. I had seen this build before, very impressive.

There another in the UK which is close to what i am looking at i believe, http://www.e2v.co.uk/html/gallery.html, though there are no details provided. I will shoot them an email and see what that set up was and performance.

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Post by Johny » Wed, 28 Jan 2009, 23:58

Wow. The UK one uses two motors with chain drive - no diff. Looks like the motors have reduction gearboxes on them and VERY small cogs for the motor end.

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Post by acmotor » Thu, 29 Jan 2009, 00:44

At least it wasn't me who suggested AC ! Image

BTW, flick Rod Dilkes an email, he is trialling a Chinese AC system.
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Post by antiscab » Thu, 29 Jan 2009, 08:39

the only problem i see with going with a gearbox, is the reduction in max power you can get out of the series DC motor (assuming the controller can dish out the amps).

even at 1000A, that 9" will give 315Nm
at 2000A, itll be more like 630Nm.

as far as voltage goes, dont skimp on voltage (use smaller batteries if you have to).
voltage = performance

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Post by Taffy » Thu, 29 Jan 2009, 14:41

Got a reply RE to the EV2Go

Taffy
Here's a quick basic spec for the Kit-E-Cat.
It was based on the Cat-E-1 kit from Tiger racing.
The drive was a Advanced DC FB1 9" motor fitted in the transmission tunnel and coupled directly to the differential, a Ford 3.9:1 from a Sierra.
The car was originally fitted with Trojan batteries (115Ah) and a Zapi 800A 120 Volt controller that had re-gen capability.
The charger was a Zivan NG3 and it originally had a Zivan DC-DC converter.
The car had an all up weight of 750kg, the target weight as this was the weight of a standard vehicle with a Ford pinto engine.
The performance was stunning and t5he drive very smooth. Some work was required to the throttle response as those not used to driving the car has problems with the rapid response so it was damped with a ramp!
The car was later upgrade to Hawker Genisis batteries, 13 for 156 Volts but the batteries despite their spec gave disappointing performance and proved to be a power bottleneck.
A 156 Volt 1200 A DCP controller was bought along with 156V charger and dc-dc but they were never fitted as the battery pack was not up to sourcing the current.
I then ran out of money for the project!
What was needed was Optima blue tops as I know these will source the current.
2 banks of 13 would have put the mass up but would have given over 200Hp with a 0-60 under 4 seconds.
Sadly the cost of the Optimas is prohibitive at this time so the project has been mothballed.
I am currently working for Think as a drive train engineer and am now working on high power AC drive systems, watch this space!
Regards

Dave Bock

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Post by acmotor » Fri, 30 Jan 2009, 23:31

Yep. Image
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Post by carnut1100 » Tue, 24 Feb 2009, 23:46

sounds great!
I helped someone build a Locost chassis once...he couldn't weld...great fun little projects and ripe for EV conversion!

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Post by Taffy » Wed, 25 Feb 2009, 15:51

Good to see someone else has seen one of these on this forum! I am currently trying to solve a small problem with a suspension mount being in front of my steering column. Think i might have to change the mount point to being further out, not too major as i am yet to make the A arms.

Been reading the thread about direct drive and keeping the sliding spline in the system, did not think about this!

Not got alot of time this week but hopefully will finish the steering mount, transmission tunnel and suspension mounts this week. (being hopefull here).

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