Greensaver batteries on order

I have ordered some sample Greensaver batteries. A 20AH, a 27Ah and a 12 volt charger.

I have also ordered 4 x 1 ohm 200w resistors for building a battery analyser. I am workon on the Bascom AVR code at the moment to check their capacity at different loads. The Peukert fact er of 1.09 for the 20Ah unit seems a little too good to be true but if it tests out after many cycles then they are great value for a bit over USD20.

Speedo

I have been browsing the workshop manual for a 93 Hilux / Tacoma and checked the vehicle and it has an electronic speedo. This is brilliant because I wont have to retrofit one.

The speedo just requires a 4 pulse per revolution input from the shaft.

There is a pulse output from the Danfoss VFD that is programmable. I will also be able to adjust the VFD output to compensate for the change in differential ratio.

This setup will require that I use closed loop control to have an accurate speedo.

Vehicle Purchased!

I have finally purchased a vehicle for the conversion.

It is a '92 Extra Cab Toyota Hilux ute (Tacoma Pickup for our American viewers). Model is a RN90R.

The good:

The right price for Sydney. These vehicles are about $2000 more expensive in Sydney. I payed $4k for it. The body is straight apart for a ding on one guard.

The interior is in good condition apart from the drivers seat that will need replacing.

The Bad:

It looks like it is from Mad Max as it has been painted black and has very dark tinted windows

The tray has no sides

The black respray is peeling off in places.

It has done 330,000km so I can not really sell the motor

To Do:

Replace drivers seat and various trim pieces inside.

Remove interior for cleaning. (I did this on the weekend. I just need to wash the carpet.

Investigate re-paining the body white or touching up bad paint job.

I took it to the local tip to put on the scales. The kerb weight (no driver or fuel) is 1250kg. A little more than I expected as it has an aluminium tray back rather than a well side. The GVM is 2050 allowing 800kg of load.

The rear axle has 41% of the weight. I will mount the motor as far forward as practical in order to maintain the balance.

I would still prefer to remove the gearbox. There is a 5.29 ratio differential available (existing is 4.1) from an early Hiace. This would give a final drive ratio a little high than third which may be acceptable. The top speed would be about 80km/h which is adequate for me.

Battery Balancer

I have been thinking about how best to balance my chain of batteries, all 50 of them.

As there are 50 units the price could be quite significant.

Ideally a microprocessor based system would be implemented with isolated sensors on each battery however at this time it is cost and time prohibitive.

There are 2 alternatives I have seen the first would place 15V Zener Diode in series with a light bulb or suitable resistor across the battery. When a battery exceeds 15 volts, the Zener and lamp would bypass current proportional to the over voltage. This would be the simplest to implement.

Another alternative is a more aggressive voltage clamp described here.

The clamp voltage will have to be above the maximum charge voltage from the chargers and the regenerative braking.

Under regen this is 15 volts. Under charge this is about 15 volts but will need to be measured on the charger.

Obviously this solution will only work under charge but should be sufficient for now.
I will test it on my self balancing scooter first.

Greensaver Silicon batteries

I have just been reading about these batteries.

http://www.greensaver.cn/

They seem to cope better than Lead Acid on high discharge. Here are the specs of the 2 models I am interested in.

27 Ah



20 Ah

Updated - The gearbox will stay / Go.

I now have a better VFD and have a 5.125 ratio diff so I will no longer need the gearbox!

[I made a design decision that the gearbox will stay in the build unless I can get a more powerful motor controller. ]

I don't think the one I have will provide sufficient power for a standing start.

Gas less MIG: I am thinking of buying a Gas less MIG welder to do my own welding. I will have to be sure this is allowed by the engineering inspector.

Aerodynamics and LRR tyres

Here ares some nice pages regarding ute aerodynamics and Low Rolling Resistance tyres from Greenseal and SJEAA.

Better Vacuum Pump

After spotting a post on the AEVA forum I bought a different style vacuum pump. This seems to be a rotary vane type. It may be able to be connected to the brake light switch via a relay which will simplify the build a bit. It sis lighter and seems quieter.

Update

I haven't posted for a few weeks. I took my family on holidays to rainy Queensland for 2 weeks and I haven't done much more EV purchasing.

I do have the contactors ordered from ZEVA and I have ordered a different brake vacuum pump from eBay.

The next critical step in the project is to buy a vehicle. Most people buy the vehicle first, then design around it. I am do it the other way around. Mostly because of my technology choices. (AC). I have been checking tradingpost.com.au and drive.com.au every Thursday for a 2 week drive, 89-95 Extra Cab, Toyota Hilux.

I have also bought some 12 volt kettles to use the elements and a pump for a water heater. Construction photos to follow.

In the last week I have enquired about ZEBRA batteries from MES-DEA. They said they 'usually' only supply to OEMs so I asked for pricing anyway. These are fantastic batteries. I only hope that they will allow me to purchase one.

If you are reading this and you are in Australia, I strongly recommend you check out www.aeva.asn.au/forums This is a great source of information on conversions.

Speed controller arrived today from WA

My Danfoss VLT6042 arrived today.

It is in an IP54 case so it is splash proof. This is the best considering it will be under the bonnet. The penalty is that it weighs an extra 20Kg above the IP20 model.

I removed the fan unit from the top as it will be cooled from the heatsink on the back.

All going well it will be just short enough to fit between the front guards of the yet to be purchased Extra Cab Hilux. With the fan removed it is 820mm. The guard width is 900mm.

I ran it up on 230V and it can be programed from the keypad. I am having trouble getting the RS485 computer connection working. I will have to buy a different RS485 converter I think.