A few years ago, some crazy businessman asked us: ‘What electric drivetrain would you put in my restored oldtimer HY bus? It’s for selling honest streetfood!’ He kept coming back and was serious after all. So we started our calculations. This is our challenge:
- the bus should do 100km range in every situation (frost, wind, rain, whatever) at 70-80km/hr max.
- the wagon will be driving in The Netherlands, flat country, no regen. breaking necessary
- the weight of a full street food wagon including the conversion will be 2200kg, as a consequence a standard keyway shaft will not be strong enough for this application
- there will be more HY conversions coming from this customer, continuity is an important factor
- the HY drivers are probably not technicians, the bus has to be very reliable
- the budget for the conversion has to be realistic: not low budget but not carte blanche either
Batteries and BMS
For a 2200kg car to do 100km on one charge even in bad weather, we would need 35kWh of batteries. We suggested 60 cells of Calb CA180ah (adding up to about 190V together) with an Orion BMS here. The Calbs have a minimum loss of capacity in winter and the Orion BMS is the only DIY system that supports DC fast charging (Chademo). For the future this could be an interesting option.
AC or DC
Then there is the choice between AC and DC, which is often made emotional instead of rational. AC seems more sophisticated, because most systems support regenerative breaking and have a better temperature control. It is appealing to modernize an oldtimer into the 21st century with an AC drivetrain. But it tends to be more expensive so we had to be rational. We compared a few possible setups:
1. Siemens AC motor – Azure Dynamics Controller
A Siemens AC motor in combination with an Azure controller would do the job just fine. The Siemens motor has a tooth splined shaft as a standard, which is the preferred driving shaft coupler, given the weight of this van. Both the motor and the controller have great automotive quality, we’re a fan. Aftersales is a big problem though, because there are only a few sets left from the bankruptcy. Doing a series of the HY bus would be a problem. Getting into the Azure controller and programming it to the right settings is a real pain, so not a pro in this discussion. This combination is now for sale at around €6.500, including Rebbl’s EMC certification which is necessary in Europe.
2. Emrax 268 AC PM motor – Unitek Bamocar D3 controller
An Emrax motor with a Unitek Bamocar controller would be an awesome solution. The Unitek controller is already EMC certified, the question is whether this will be accepted in combination with the Emrax motor. The Emrax motor is very promising because of it’s power and very small size (20kg), but according to the website ‘first customers are part of a fieldtest’. That might not be a problem for a DIY conversionist and we can’t wait to start experimenting with it, but for an entrepreneur selling streetfood on a daily basis this is might be a bit to early. The Emrax does not have a tooth splined shaft, so this has to be engineered as a special option. The heavy van really needs a sturdy coupler. The combination will cost at least €10.000, which is about 80% more than the solution we finally choose for.
3. Double HPEV AC motor – 2 Curtis controllers
The HPEV AC Motor and Curtis controller do great in smaller cars with a small to medium range. For the streetfood wagon there is the possibility of a twin HPEV setup in combination with two Curtis controllers, to give it enough power and enough voltage intake. Both are thoroughly tested and reliable. Also aftersales is great on these products, as is programming and finetuning settings. Drawback is the budget, our customer would need a minimum of €12.000 for this. Another drawback is the shaft, which is not tooth splined. This has to be engineered as a special option. This set is available including Rebbl’s EMC certification for the Curtis 144V/500A controller in a HPEV 51 or 75 set up.
4. Kostov Alpha DC motor – EVNetics Soliton1 controller
The Kostov Alpha 11” aircooled DC motor and the Soliton1 from EVNetics is a combination that can do the job on the DC side. The Soliton1 has an wide battery voltage inputrange of 9-340V DC and can deliver 1000A to the motor. Experience and aftersales on both products is good, and programming the controller is easy. Because the Kostov Alpha is well cooled it has a continuous power rating of 50kW, which is the best weight/power ration. This DC motor also has the necessary tooth splined shaft as a standard option available. This set is an investment of €5.750 including the Rebbl’s necessary EMC package.
We came to the conclusion that the quality/price ratio of the DC set would be highest for our customer, and so was our advice. We configured a kit that will serve as a model for future HY conversions from the same client, and other clients living in flat countries like The Netherlands. This includes the tooth splined shaft and coupler. But if you have the same plans in the mountains of Switzerland for example, your optimal kit will be quite different.