48V Electric vehicles

Cupie · Guru

48V Electric vehicles

patrol03 · Senior Member

My Golf cart is 48 volt but won't tow the caravan..

T1 Terry · Guru

Dated the beginning of 2017 and no sign of them actually hitting the market as far as I can tell. The hybrid units hitting the streets now that can tow a caravan are a lot more than 48v, anywhere between 270vdc and 750vdc at the battery end and around that AC at the 3 phase motor end. My Prius has a 270vDC battery and I believe anywhere up to 750vac at the motor end and it can put out 120kW from standing still and that is 2006 technology, the gear coming out now makes that pale into insignificance. The Chevy Bolt has specs of 200 hp @0 rpm 266 ft-lb @0 rpm, that coupled to a small capacity diesel engine would make one hell of a tow vehicle.

T1 Terry

Cupie · Guru

Yep. It is certainly dated, or should I say out of date ... Technology in this area is moving terribly fast these days.

Aus-Kiwi · Guru

Voltages are way high. If or when things go wrong ? They will !! Look out .. I think maybe the way a head is efficient small capacity turbo diesel that can run on bio fuel of say 50% ethanol ? Run at pretty much set rpm and let the elect side do the the motor, transmission much like trains or ships . On a much smaller scale . All light duty . But then theres generators !! Oh hell NO !!

T1 Terry · Guru

Aus-Kiwi wrote:
Voltages are way high. If or when things go wrong ? They will !! Look out .. I think maybe the way a head is efficient small capacity turbo diesel that can run on bio fuel of say 50% ethanol ? Run at pretty much set rpm and let the elect side do the the motor, transmission much like trains or ships . On a much smaller scale . All light duty . But then theres generators !! Oh hell NO !!

:lol: Basically a hybrid drive vehicle without the battery. That would require a much larger power output diesel and much larger generator so it supplies all the current required by the electric motor including the losses.

By adding the battery in between, when full output from the electric motor is required it would be supplied by a combination of the diesel/generator set output with the battery output for the short term full load requirement, then the diesel/genset is used to recharge the battery. There are combinations of which does what and when and that is all controlled by the computer. This is how a Prius works.

If you are sceptical about just how long such a set would last, my Prius has 726,000km on the clock and still going strong and there is a Facebook page with a Prius in the USA showing the equivalent of 100,000km on the clock and still going strong. It did have a head gasket failure a bit after that and the owner sold it so she could replace it with a new Prius. I believe the new owner plans to install another engine and continue clocking up the miles to see just how far the electrics/electronics will go before a serious problems comes up.

T1 Terry

Aus-Kiwi · Guru

Yes MAY cost a little at say ? 7 years ? Keep in mind the running costs over those years has been minimum ! Then if batteries are required ? Its almost all new again . One thing a head gasket doesnt fail on elect motors ! If it needed a new engine ? I would say it was over heated ?? Thing is the trade in price to purchase another one . Most trade them in when the ash trays full !! Lol

T1 Terry · Guru

I think in this case it was probably electrolysis/corrosion between the block and head area eating away support around the water jacket/ head gasket support area. It was a very common problem with alloy heads back when I still had my mechanical workshop. The effected area was welded up, the head serviced and it went back into service for another ever how many yrs/kms. Toyotas were the engines that lasted the longest so they were the most common ones requiring this treatment. If the 4 X 4 Hilux was still doing its job, those in the building trade just got them rebuilt and went again till the body fell off.

T1 Terry

Aus-Kiwi · Guru

Did everyone read the link ? Over the last decade or so, automakers have been replacing traditionally mechanically-driven components with more efficient parts like electric power steering racks, electric brake vacuum pumps and electric water pumps.

On top of that, especially in Europe, automakers have been adding in a ton of new infotainment options, and also driver-assist safety features like adaptive cruise control, lane keep assist, blind spot monitoring, etc. Plus, youve still got heated seats, heated steering wheels and heated windshields. Needless to say, standard 12-volt electrical systems are being stretched thin; so 48-volt systems are stepping in and help accommodate the need for more on-board power.

-- Edited by Aus-Kiwi on Monday 15th of July 2019 03:11:08 PM

T1 Terry · Guru

Aus-Kiwi wrote:
Did everyone read the link ? Over the last decade or so, automakers have been replacing traditionally mechanically-driven components with more efficient parts like electric power steering racks, electric brake vacuum pumps and electric water pumps.
On top of that, especially in Europe, automakers have been adding in a ton of new infotainment options, and also driver-assist safety features like adaptive cruise control, lane keep assist, blind spot monitoring, etc. Plus, youve still got heated seats, heated steering wheels and heated windshields. Needless to say, standard 12-volt electrical systems are being stretched thin; so 48-volt systems are stepping in and help accommodate the need for more on-board power.

-- Edited by Aus-Kiwi on Monday 15th of July 2019 03:11:08 PM

Well, that was the plan back then, now they control the alternator by the ECU and can pulse them on/off at 280 amps or higher while monitoring the alternator temperature. This is just a stop gap measure though, things will change rapidly.

The days of non hybrid powered vehicles are limited because meeting the emission requirements without cheating will become near impossible while still using small fuel efficient motors, the loss of performance is noticable even now when they have to remove the cheats. The next round of emissions cuts is already set in stone, partly because the governing bodies thought they had forced the manufacturers to clean up so more pressure would mean even cleaner emissions.

This is the reason all the manufacturers are going down the electric vehicle path, many have added a hybrid version already and the option of not having a hybrid if you want to buy a new vehicle will just about nil in a few yrs time.

Once all the vehicles have hybrid batteries and motor/gensets the battery problem will go away. The 12v battery will return tolight duty (bad pun I know) and running accessories like the entertainment system. Everything else is high voltage motors that draw very little current. The Prius has had electric driven air conditioning compressor, brake vacuum pump, power steering pump and coolant pumps since the late '90's, all the Aust plated vehicles have these systems and the later Prius models even have an electric water pump so no fanbelt at all. The motor/genset is the starter motor and alternator and the 12v battery is kept topped up via a DC to DC converter.

A lot of mum and dad investors did their dough investing in companies that had set themselves up to cash in on the 48v vehicle revolution that never happened. In the automotive trade we had people like Bosch and the like giving seminars on what was coming and that was back in the late '90's as well, so they did their dough as well.

My guess is the electric vehicle revolutions happened much faster than many had expected once lithium batteries became a reality and Elon Musk introduced the first Tesla roadster, everyone suddenly had to play catch up and reliance on the internal combustion engine to meet all the future requirements was put into question. Once the emissions scandals hit, the nails were driven into the coffin for the fossil fuelled vehicle industry and the 48v system went with it.

The plan was to do away with cam shafts and valve springs and have the inlet and exhaust valves electrically driven and computer controlled the same way as single rail injection is now days. That way the valve timing could be constantly varied depending on load and cycles could be dropped out if not required or by holding the inlet valve open after bottom dead centre some of the air in the combustion chamber would be pushed back out reducing the effective swept volume or engine cubic capacity as we know it.

The possibilities were huge, adaptive to different fuels, catalyst ignition rather than coils and spark plugs, homogenous ignition like the model small engines use, the list goes on, but all out the window now.

My guess it will be turbine driven gensets and all wheel drive for heavy vehicles and straight electric/battery for everything else by 2030 if not before. Add the autonomous drive vehicle revolution into the mix and we won't recognise any comparison between the vehicles in 2030 compared to the vehicles released in 2010. It will be much like the change from horse drawn vehicle to internal combustion powered horseless carriages, that change occurred in roughly a 5 yr period. Can you imagine what the streets would be like these days if we still depended on horses? Can you imagine what the RV life style would like?

T1 Terry

Aus-Kiwi · Guru

Yes that was my theory with small Diesel engine . Say the best RPM for gen set and engine is 2200 rpm . Then build a real strong efficient engine at that rpm with bags of TORQUE ! Not having to have power through its rev range as the electrical motors and computer sort the best option . Heavy load on engine would just require more boost and a little more fuel .

T1 Terry · Guru

That is why I'm thinking they will go for multi fuel capable turbines, they are more than 70% fuel efficient yet small and light weight compared to the power they can develop. I'm thinking along the lines of the turbo prop type turbine engines used in small planes, the massive gear reduction allows the turbine to spin at crazy speeds yet the output shaft is a much slower rpm, between 2,200rpm and 3,300rpm I think, yet very high torque because the turbine takes a lot to slow it back down, sort of like a flywheel.

T1 Terry

Aus-Kiwi · Guru

Talking to engineer on cruise ship . They use turbines also . Hell fast rpm but very quiet, not too fussy on fuel type either . From memory and stand to be corrected . The turbines on helicopters is around 80,000 rpm !! Think ships or where high torque is involved ? They have multi stage turbines or fans as gear reduction . So many variables .,

T1 Terry · Guru

The only reason they would need to computer control the injection for the turbine to use different fuels would be for emissions. Ships don't suffer the same emission rules that road users suffer

Aircraft have to use certified Jet A fuel because of the extremely low temperatures the fuel experiences and pulling over on the nearest cloud isn't an option if things go bad and a bit of power is lost. So sort of half way between aircraft turbines and ship turbines is where the future genset turbines will sit, very fuel efficient, relatively quiet compared to a big cube diesel on full noise, but not as quiet as the electric motors doing the actual driving.

Certainly a whole different world, a B triple, 28 wheel sets each with a 20kW electric motor driving it putting 600kW on the ground from standing still to full speed, yet able to slow the vehicle at the same rate without a brake squeal or smell of burning brake linings and zero brake fad. It would be a matter of keeping out of the B triples way as he left the lights, climbed a hill or pulled out to pass. No more needing a km to wind up enough speed, indicator on and go, gone. It's bad enough watching them pull off into the distance now, there just wouldn't be a hope of getting a slip stream tow from one of these new trucks

T1 Terry