Do you want an electric A2?

Peter

Member
Back on topic: I wanted an electric A2 and now I've got one!

My initial idea was to convert an A2 (with a budget of around 10k). In June I found an A2 in Belgium with a broken timing belt (so the AUA/BBY engine was total loss) for € 350 and took it home on a trailer. I removed the engine, fuel tank and exhaust and in parallel started to discuss the approval process with the RDW (Dutch registration authority). Soon it became clear that I wouldn't be able to get the converted car registered unless either:
- I would use components that are used in cars that are registered already (so get a damaged Nissan Leaf or similar)
- I would have to submit the car to an extensive (and expensive) homogation process without any guarantee of success.

End of August a converted A2-EV was offered for sale on the German "kleinanzeigen" website - the car had problems in the battery pack and possibly in the controller-engine areas so no test drive... Then again, it was only € 6k and again I rented a trailer and took the car to the Netherlands. This car was converted by LE Mobile (Swen Streubel) together with Bosch Leipzig back in 2011. These guys have done several conversions but LE Mobile doesn't seem to exist anymore. The Belgian A2 was completely stripped and sold in parts (delivering over € 1k ;-)

The A2e has done appr. 65k kms with its BBY engine and 40k kms electrically, mainly while being used for 5.5 years by the Stadtwerke (city authorities) Leipzig. Because the car was registered in Germany, the registration in NL was no problem: this week the RDW has issued the Dutch registration. The German registration mentions specifically what engine (Azure AC24LS) and controller (Azure DMOC445) are used in the car, as well as the reinforced rear springs. The Dutch registration however only mentions "fuel: electricity" so if need be, I can change whatever I want without having to have the car inspected again (larger capacity battery pack, more powerful motor/controller, ...).

The car runs off 86 LiFePO4 cells (3.2 Volts, 60 Ah) in series, which results in about 300 Volts, 17 kWh capacity and 200 kg weight. LE Mobile specifies a range of 120 kms and a top speed of 75 mph. All subsystems are in place: an electrical heater (4 kW), electrical airco pump, a small vacuum pump to support the brake booster, a 900 W DC/DC convertor and a CANbus simulator controlling the rev counter to display power in/out the battery (regenerative braking is supported). The clutch has been removed but the gearbox is still there.
The 12V battery was moved to the engine compartment. The HV battery pack is in two boxes: behind the rear axle (62 cells) and under the rear seats (24 cells) and no luggage space is lost.

The first phase of my project is getting the battery pack healthy again: last year 11 of the 86 cells have been replaced, but after that the car has hardly been used and consequently the battery pack was not charged. The BMS reported only 14 active cells (voltage over 2.5 V) and the built-in charger could not do its job: a LiFePO4 cell that is charged presents a resistance to the charger, so the empty cells in the pack never get charged.

I took the whole battery pack out and started charging all the individual cells. This is quite a job: charging 86 cells with 3..4 chargers took 2 weeks. The process of charging and daily measuring voltage per cell suggests another 10..15 cells do not hold charge properly and need replacement.

In the coming 2 weeks I will be "gross balancing" the battery pack (ensuring all cells are fairly close in voltage) before the battery can be installed in the car again. Hopefully the built-in charger can then take over the final balancing and I can start looking at the engine/controller.

So only partly a DIY conversion but I expect to have my A2e running by the end of the year and for less than €10k.

To be continued!
 
Last edited:

damadgeruk

Admin Team
@Peter congratulations, looking forward to seeing some photos when you get a chance. Any idea what weight the car is? Good luck getting it back up and running. I found a broken Tesla model S recently though that's a conversion that's way beyond my skill set and time constraints.
 

A2Steve

A2OC Donor
Thanks for sharing with us Peter. Out of curiosity, how much are the replacement battery cells going to cost?

I’m hoping it’s only a matter of time before mainstream companies start offering cost effective complete conversions.
 

Peter

Member
Thanks! The car was registered in Germany at 1180 kg (ready for driving) - in NL that boils down to 1080 kg (empty).
The Winston LiFePO4 cells (60 Ah) are about € 85 each.

The outside of the car is nothing special obviously, but inside there is the battery pack (top of the picture is the box under the back seats)

IMAG0835.jpg


and a special rev counter...

IMG_1566747086_16264.jpg


and behind the fuel flap is the connector for the two charging cables that came with the car (one for house socket, one for public charging station).

P5100263.JPG
 

Un4tural

Member
That looks awesome - love the rev counter.

Did it have official power figures? You mentioned gearbox is still there - how does that work or is that new gearbox for electric motor?

Would be super curious to see some under the hood pictures too! 120km/h seems a bit slow though but around city would be plenty i bet for daily commute etc.
 

Weetank2

Member
Good find

120km range 75 miles approx
75mph top speed
Battery pack alone 6k euro new for 17kwh, with some resale value for static storage?

Could you split a tesla pack between three cars for similar cost and 50% to 100% increase in range?
 

Peter

Member
The gearbox is the standard GRZ installed by Audi in 2004 - switching gears without a clutch requires the "rev counter" / power-meter to be at 0.
The motor spec is 22 kW continuous and 37 kW peak (I don't know whether the peak's width is 10 seconds or 5 minutes).

If I have to replace many cells, i would certainly use the old cells for my solar panels. A Tesla pack would absolutely increase the range due to its higher energy density. But you'd probably have to build an airconditioned box to use all that power. I believe Tesla use Li-Ion, which will burn / explode if mistreated, whereas LiFePO4 won't. And splitting a battery pack in three leaves two owners without BMS...
A Tesla pack delivers 24V so I would need at least 10 of those to get my 300V motor running. So in practice I would need another motor, which also means another controller, another BMS, ... I'll think about that when my motor runs smoothly and range becomes an issue.

Here's the picture you've been waiting for...
DSC_1292.JPG

From left to right (in the picture that is):
1. electric airco pump
2. 230V 3kW mains charger
3. airco controller
4. motor controller with air cooling fans on top
5. DC/DC-convertor from 300V to 13.8V (replacing the generator)
6. motor
7. gearbox without clutch
8. electric heater 4 kW - the car has heated seats, so most of the time the heater should not be needed
9. vacuum-reservoir for brake booster, the pump is behind / below the heater and not visible in the picture
10. 12V battery for lights, wipers, power steering, ...

The "secret" storage below the passenger's feet contains the main fuses (160 Amps in both + and - line) and contactors; there is another 160 Amps fuse between the two battery boxes in the back. Due to the relatively high pack voltage, the current is rather low: 280 Volts and 150 Amps is already 42 kW, well above the motor's peak power of 37 kW.
The room below the driver's feet has the CAN-simulator, BMS-unit as well as the comfort module (I have three (!) remote control keys). The jack and tool set is in a bag in the luggage space.
The BMS reports total pack voltage, charging / discharging current and pack temperature on the (non-Audi) radio display. It can also show each indivdual cell's voltage.
 
Last edited:

DJ 190

A2OC Donor
I subscribe to "Autocar" and it's into electric propulsion in a big way. Most new models are electric or hybrid. A recent article featured Firms that are converting cars to electric, classics included. Defective Teslas are highly sort-after for parts! (I think that those firms were mainly in the U.S.A.) I think that if I could end up with an electric Audi A2 for ~ £10K, then I'd do that immediately! I'm retired and most of my driving is short distance. I'd rarely exceed 120 miles. If a greater distance was required, then there's my Partners A2 or my Mercedes SLK. I'm sure that I will eventually own an electric car, anyway.
Of interest to myself, what is likely to be your total expenditure on your fascinating project, Peter? Do you have an idea of the likely range on a full charge? What about the possibility to charge more rapidly with a superior charger?

David
 

Peter

Member
Total expenditure is not yet clear, but I keep track in a spreadsheet and will report on that at a later stage. For the time being, I spent € 6k on the car and € 1K on 4+7 cells from 2 Czech companies.

If you need to take the battery pack apart, like I had to, and charge the cells individually, you will need lots of time and one or (preferably) more dedicated chargers for LiFePO4 cells (constant current first, then constant voltage of 3.65 Volts and stop charging when current drops below 0,01C).

I first bought a 5A charger but that failed after 1 cell (and took forever to charge a single 60Ah cell); I also purchased a 10A charger off eBay, which took a month to be delivered but it works. But the best are 3 (with number 4 ordered and now on its way from the Czech Republic) 20A chargers from my two cell suppliers. The chargers' cost was about € 400 in total and it allows me to charge 4 (next week 5) cells simultaneously.

Typically I measure all 86 cells' voltages each morning and input the numers in a spreadsheet. My spreadsheet tells me which cells are the weakest and are to be charged next.
 

RAB

Technical Specialist 1.2 TDI
Not wishing to put a dampener on this but the problem with LiFePO4 cells is that if the cell voltage drops below 2.5V (the cell is essentially flat), severe damage can occur, at least according to Wikipedia:

https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery (Advantages and Disadvantages)

so you may have a few more cells to replace, Peter. As the vehicle was used for commercial service, it is likely that it was mainly, perhaps solely, fast charged. This is normally done to 80% only as the last step to 100% takes too long. If a vehicle is only fast charged to 80%, it may lead to differences in cell voltage. Slow charging to 100% would or should eliminate this. My E-Up! manual warns against consecutive fast charges. Our E-Up! is never fast charged and still displays its original range.

Fast charging can also cause thermal damage to the battery. The VW ID will avoid this by water cooling of the battery.

RAB
 

Peter

Member
You're totally right RAB, there may well be more cells weak or even useless. Many cells were below 2.5 Volts when I started charging them. So far I have only tested cells on their capability to hold charge without any load but under load, the situation is likely to be worse.

The good news however is, the car cannot be charged fast. I do have a cable to connect to a public charging station (with Mennekes type 2 plug), but there is only one 3 kW (230 Volts / 16 Amps) charger in the car. Assume the battery is discharged to 20%; charging to 80% then takes 4 hours at least. Charging while having a coffee break or even lunch break will restore only little range.

I have seen specs from Swen Streubel (LE Mobile) were 3 chargers are used, using a 3-phase 400V outlet. All three chargers would be active until a certain voltage is achieved, then only 2 until a slightly higher voltage is reached and finally only 1 charger takes care of the final phase charging and top-balancing. A full charge is specified to take 2.5 hours and cell balancing still has to start.
Balancing certainly suffers from (fast) charging immediately followed by discharging.

For this car overnight charging is the only practical way and gives the BMS plenty of time to restore cell balance.
The BMS is there to eliminate differences in cell voltage and it can only do its job given sufficient time to measure all cells' voltages while charging, switch off the charger when one cell reaches full charge, discharge that cell a bit and start charging the whole pack again.
 

RAB

Technical Specialist 1.2 TDI
Presumably the users, not being owners, didn't charge the batteries after they had finished using the car, in order to keep them in good condition. With an EV, the number one priority should be to look after the battery, if you own it. Even with (overnight) AC charging, I always charge at the lowest possible rate (there are 5, 10, 13 and 16A options for the E-Up!). A timed charge will end at the time you set, so you have to be careful not to set the charging rate too low, otherwise charging will start when electricity is at the higher rate (the Economy 7 rate locally is between 22.30-00.30 and 02.30-07.30).

I hope that you don't have to replace too many more cells.

RAB
 

RAB

Technical Specialist 1.2 TDI
Hi Peter,

Optimate have a range of LiFePO4 chargers that might accelerate the process of sorting out your cells:


Optimate LFP about a 1/3 down the page. You would have to connect 4 or 5 cells in series but it would immediately tell you if one (or more) of the cells is (are) duff., according to the blurb anyway!


RAB
 

Peter

Member
Thanks RAB, very useful info! I wish I'd found these guys earlier. Unfortunately, the charger that will do 4s and 5s is sold out... My cells are grouped in blocks of 4 and 5 cells, so this charger would be useful.

Today I will start connecting blocks in parallel (which requires W-shaped connecting wires as the blocks a assembled for series connection) so they will "self-balance".

IMAG1383.jpg


Now I can charge them as a block to a predefined level (say 3,320 Volts appr. 90% full).
 

Peter

Member
A saw that one too, but it doesn't do 5S (I have 6 blocks 5S and 14 blocks 4S to be charged). More importantly, Optimate do not mention BMS functions like cell protection and balancing.

These 4S battery packs are used to replace traditional lead acid batteries. They typically have a BMS built-in, so balancing the cells is taken care of inside the battery. I fear these chargers only protect the pack as a whole, not the individual cells.

My BMS is in the car, so when charging (groups of) cells outside the car the BMS is me, myself and I.

To be useful in my case, a 4S or 5S charger would need BMS functionality and 2 or 3 extra wires to connect to the intermediate cells for external balancing...
 

RAB

Technical Specialist 1.2 TDI
I wasn't thinking of Optimate as much as a charger, more as an early eliminator of duff cells, as both models feature a short circuited/dead cell check which terminates charging. You would then have to determine which cell(s) of the four/five were dud by other means. The 4S/5S charger does mention BMS in the description but as you say, that will be for an internal BMS.

RAB
 

sunsurfer

Member
This article from Pistonheads suggests Swindon powertrains are creating a 'crate' electric motor of 80kw suitable for small manufacturers and enthusiasts.


If this motor is suitable it makes our search for an electric conversion kit-of-parts, easier.
Of course we still need to work out batteries and all the controls.
No price mentioned for the engine.
 
Top