Replacing bad cell #65

The ECE Lotus has 4 battery packs with in total 100 cells. Based on the fiber optical cable which runs from the VMS thru all 4 packs I guessed that cell #65 would be in pack #3. Pack #1 has 24 cells and is behind the driver seat. Pack #2 is above the gearbox and Pack #3 is next to it, both have 24 cells. Pack #4 is behind the passengers seat an has 28 cells

Lifting battery pack #3

Lifting battery pack #3

Pack #3 removed

Pack #3 removed, Pack #2 above the gearbox and Pack#4 slightly vissible

After Pack #3 was removed it was placed up-side down and opened up.

Battery pack (Up side down) showing wires to LOM modules

Battery pack (Up side down) showing wires to LOM modules

The top cell of the lower 8 cells was defect.

Disassemble battery pack

Removing the bad cell from the pack

The replacements cell was at it’s nominal voltage of 3.7V it need precharging to match the other cells at 4.10V. The picture shows two cells in serie.


Precharging the replacement cel

After charging the pack was assembled and bench tested. Each set of two cells is monitored by LOMs (Lithium Optical Monitoring system by AC Propulsion). Each LOM is connected to the next cell with a fiber cable.

Bench test of new assembled pack of 8 cells.

Bench test of new assembled pack of 8 cells.

Lom module

LOM module

LOM module

LOM Utility test software screendump.

New cel 65 in pack

New cel 65 in pack

After some testing the 8 cells where placed back in Pack #3 and the car was put together. I’m getting better at it 🙂

The VMS showing nice voltage levels (first line). The second line shows the temp of the cells. Pack #3 is a few degrees warmer since 8 of the cells where in doors for a day or two.

VMS display after replacement of defect cell #65

Defect cell in battery pack

One of the 100 cells, cell #65 is dying. This is noticeable under hard acceleration and the top speed has dropped to 141 Km/h.

VMS display defect cell

VMS display showing cell #65 dropping in voltage

It will be quite an operation to get to the defect cell. First te body needs to be removed and than I need to open the black box.

battery pack, rear clam removed

Battery pack, rear clam removed.

Opcom OP-Com V1.45 interface

After working on the Lotus Elise the airbag light stayed on. A thread on told me that the airbags in the Elise are the same as the ones used in the Opel Speedster/Vauxhall VX220 and that the diagnose interface also works on the Elise. So I purchased a Opcom interface (OP-Com V1.45) on dealextreme for €20,- . It did the job. Cleared the fault codes and noticed that it is possible to disable the airbags and seatbelt tensioners. This might be handy if you want to carry a child in passenger seat or visit the track.

Op-Com interface

Op-Com interface

Lotus airbag opcom

Lotus airbag opcom

Airbag measurement blocks

Airbag measurement blocks

Parking heater with Webasto remote in the Lotus Elise ECE part II

In one of my previous posts I installed a Webasto HTM T100 remote to control the MES-DEA RM4 heater. The remote works perfect, it shows the actual temparture in the car and has a great range.

Webasto-remote-show-tenpUnfortunately the MES-DEA heater isn’t connected to the PEU and in the situation that the PEU isn’t charging the battery, the heater drains the battery which affects the range. To prevent the heater to “drain” the battery the PEU charge mode needs to be enabled.

By feeding 12v into pin 8 of connector J1 (see Interface Document for the AC-150 Gen 2 Electric Propulsion System) the APS (auxiliary power supply) turns on and when connected to the grid it will start charging.


Webasto HTM T100 inbouw in Lotus Elise ECE

Wiring schematic Webasto HTM T100

DIY EV charging cable

Since the Lotus Elise ECE is built in 2008, before the charging standards (IEC 62196 and IEC 60309) where released. The car is equipped with a standard CEE 32A 5-pin connector for charging. It can charge with 32A on 1 phase at 230V AC. The charge current can be adjusted manually.

Charge port CEE 32A 400V 3P+N+E

Charge port CEE 32A 400V 3P+N+E

To be able to charge at a public charging station in The Netherlands you need a type 2 connector. Due to the limitation of a maximum of 16A per phase (mode 1), the Lotus can only charge on a public charging station with 16A max.

Type 2 connector

Type 2 / VDE-AR-E 2623-2-2

Building the cable, Mennekes type 2 (see picture above) and CEE (32A 3+N+E female)
I bought a secondhand Ratio charging cable for only € 75,- . I removed the white j1772 connector and added a 220 ohm resistor. I started with a 220 ohm risitor because I wanted to charge with 32A. It didn’t work the charging station gave an error. Finally a 680 ohm resistor between Earth and PP (Proximity) gave the best result.

Ratio cable

Ratio cable EVP32-3 2P+E 16A/250 AC Mode 3, type 2 to 1

Wiring diagram

Wiring diagram Mennekes type 2 to CEE 32A

The above schematic shows all 3 phases. The Lotus only uses L3.

Rpp values with corresponding maximum charging currents
1k5 Ohm  13A or 16A
680 Ohm  20A
220 Ohm  32A
100 Ohm  63A

New rims and tires for the Lotus

I decided to keep the winter tires on the OEM rims and buy new rims and tires for the summer. After reading a lot on I went for the Team Dynamics Pro 1.2 rims and A048 tires from Yokohama. My first experience is that there is a lot of grip and the steering is somewhat heavier. Also noticeable is the rolling resistance which is higher and resulting in a 5% less range.

Front: Team Dynamics pro 1.2 part number 5M2-67030BL
Pro Race 1.2 Black Matt 898  RFBlk 7.0×16 e30 4×100-56.7

Rear: Team Dynamics pro 1.2 part number 5M2-77536BL
Pro Race 1.2 Black Matt 898 1.2 RFBlk 7.5×17 e36 4×100-56.7

Team Dynamics pro 1.2

Black Matt Team Dynamics pro 1.2


Front: 195/50 VR16 84W Yokohama A048 LTS
Rear: 225/45 WR17 TL90W Yokohama A048 LTS

lotus Yokohama A048 LTS

lotus Yokohama A048 LTS

new rims and tires side view

new rims and tires side view

Parking heater with Webasto remote in the Lotus Elise ECE

Before I owned the Lotue Elise ECE, I drove a Landrover Defender, it was fitted with a parking heater which is very nice in winter. Especially when it’s freezing and you want to pre heat your car interior. Pre heating your EV while it’s loading won’t affect your EV’s range. My EV has no parking heater, so I wondered if I could use the already installed MES-DEA RM4 as parking heater. Due my experience with the Webasto parking heaters I knew that de remote option, which is sold separately, could be used as standalone remote. I used the Webasto Telestart HTM100 because it is able to display the actual temperature in the car on the remote.
In my EV the MES-DEA heater is controlled by an on/off switch on the dash. It’s only working when the ignition is switched on. since I don´t want to leave the key in the ignition over night, in needed an other solution. I connected the control wire from the MES-DEA directly to +12 volt to see if the heater would fire up, it did. I installed a relay which is controlled by the Webasto remote, when it’s active it disables the original switch and connects the control wire from the MES-DEA to +12 volt.  To get the heat in to the car the interior fan needs to be switched on, I used a relay to connect the interior fan directly to +12 volt.

25-10-2015 Update: see part II