Would a Bi-mode (Battery-Diesel) Multiple Unit have been possible in the 1960s?

[BlueLeanie]

Petrol Electric railcars were first introduced around 1903, the Ballater Battery Unit was built around 1958.

The BEMU did have a few problems, with reports of small battery fires. But technically, would BR or the UK have had the ability to build a hybrid unit back in the 1960s? Mostly off-the-shelf components. The Class 101 body, the 150bhp Leyland engine, an alternator/dynamo/generator of the era with the Chloride batteries as used on the BEMU, and two 100kW sets of traction gear in a two car unit.

I'm thinking it would probably go like a rocket (in comparison to a classic two car DMU with a total of 300 bhp) and considerably smoother than a DMU with mechanical transmission.

 

[AndrewE]

Maybe not the '60s, but https://www.batteriesinternational.com/2015/03/14/james-sudworth/ is a good read if you are interested in the details and history of the chemistry:

During the next 15 years, based at the British Rail Technical Centre in London Road, Derby, Sudworth was responsible for directing a team of 20 to 40 scientists and technicians in the development and production of beta alumina, cells and batteries.

So what were the initial and practical challenges for sodium-sulfur battery-electric trains to replace diesel trains?
“When we looked at what the characteristics of a battery needed to power a locomotive would be, it was clear that it would have to store several megawatt hours of energy,” he says. “And it had to be recharged in a couple of hours. Even for the sodium sulfur battery, that was a huge challenge.”

The BR team came up with the idea of a hybrid locomotive, with a diesel engine running at constant speed and maximum efficiency and the battery taking care of the peak power requirements. They built several batteries but never got to the point of installing them in locomotives (although over 20 years later, General Electric did build a hybrid locomotive using a different type of sodium battery as described below).

and

Abruptly, in 1981, the project at BR was closed down before Sudworth and crew could test their battery on trains. BR had been in a cooperative government supported programme with Chloride Silent Power (CSPL) and AEA Harwell. CSPL decided to tie up with General Electric, which was also developing the battery. This resulted in the breakdown of the cooperative agreement and ended BR’s rationale for continuing development of the battery.

Sudworth says: “I suggested to Hamish Duncan and another of my colleagues, Roger Tilley that we should go for a management buy-out and to continue developing the battery for other organisations. We went public and as a result were approached by companies interested in funding the development. We were also approached by Ron Dell who was in charge of Harwell’s battery programme.

and lots more history. Quite interesting.

 

[Zomboid]

I'm not sure what problem a battery - diesel would have solved, other than fumes in stations like New Street. Ultimately you're just burning diesel to get your power.

I've been told that the SR Mark 1 EMUs had a button that the driver could use if they got gapped that would put the carriage batteries into the traction circuit and allow the train to move a few metres and hopefully pick up some con rail, so that kind of thing with more storage might have been possible.

 

[mike57]

I think the issue would be that the batteries were much heavier back then, and you pretty much had a choice of Lead Acid or Nickel Iron. Interestingly the Drumm battery (Nickel-Zinc), used by CIE in the 1930s had promise but was never developed further.

Given 1960s technology the weight of the battery and extra equipment would pretty much negate the boost in performance that you would get from using the battery to assist the diesel. Traction motors were series wound DC machines, and larger traction motors would also add weight, until power elctronics developed in the late 60s/early 70s everything was contactors and restistors to limit currents.

You also had the SR motor luggage vans, and although there are reports of these operating over considerable distances on battery power it seems that the general consensus is that once the batteries had been in use for a while they were pretty much limited to low speed operation over short distances, which is what they were intended for anyway. The issue was battery deterioration over time.

I have often wondered if the DEMUs could have been built as Bi mode deisel/electric, and I think the answer is yes, as the class 73 pretty much acheived this. The problem would have been where to house the extra equipment, which would mean a further reduction in the passenger space in the power car, and bearing in mind at this time I suspect there was little benefit seen from operating on 3rd rail where it was possible.

Again on the SR the 'booster' locomotives used energy stored in a flywheel to avoid gapping, but it wasn't sufficent to provide anything beyond short moves to get back on the 3rd rail.

DB in Germany operated pure battery emus from the 1950s, and these operated for around 40 years, but were restricted to mainly level routes. They were also considerably heavier than their diesel equivalents.

So to come back to the OP question, yes it would have been possible, but given the constraints of the technology in the timeframe, 1960s, it wouldn't have been practical, and wouldn't have happened because there would have been no benefits.

 

[Helvellyn]

What battery technology did BR use in the 97/7s, converted from redundant Class 501 driving motor coaches? As I recall they were used in the Moorgate and Merseyrail tunnels to haul engineering trains.

 

[eldomtom2]

I'm not sure what problem a battery - diesel would have solved, other than fumes in stations like New Street. Ultimately you're just burning diesel to get your power.

With batteries you can charge them from dynamic brakes instead of having to dissipate the energy produced as heat, thus reducing diesel consumption.

 

[AndrewE]

With batteries you can charge them from dynamic brakes instead of having to dissipate the energy produced as heat, thus reducing diesel consumption.

and brake pad/disc wear - and the material and labour costs of replacements. It's why rheostatic / regenerative braking pays for itself regardless of whether you can harvest the power.

 

[BlueLeanie]

For benefits, wouldn't a diesel engine operate more efficiently, and deliver a smoother passenger experience, if running longer at optimum output (recharging the batteries) and powering a generator rather than clunking up the gears in a mechanical gearbox?

For performance, what would the acceleration of a unit with a 1960s 110kW (150bhp) engine + 100kW (30kWh) battery driving two 100kW engines be like compared to two 150bhp engines driving a mechanical gearbox?

 

[supervc-10]

I'm not sure what problem a battery - diesel would have solved, other than fumes in stations like New Street. Ultimately you're just burning diesel to get your power.

It would basically be like Nissan's e-Power hybrids, many years before. Reduced fuel consumption being the key benefit.

Whether such thing could be made to work with '60s technology, is a different matter. Of course the duty cycle of a battery in a hybrid car is very different to that of a train, with much more constant-speed running and fewer stop/start cycles on the rails. I'm still not sure that '60s battery tech could have handled much in the way of regenerative braking though- older battery tech charged very slowly, and would likely have been a limiting factor in how much energy could be recuperated.

 

[mike57]

For benefits, wouldn't a diesel engine operate more efficiently, and deliver a smoother passenger experience, if running longer at optimum output (recharging the batteries) and powering a generator rather than clunking up the gears in a mechanical gearbox?

For performance, what would the acceleration of a unit with a 1960s 110kW (150bhp) engine + 100kW (30kWh) battery driving two 100kW engines be like compared to two 150bhp engines driving a mechanical gearbox?

I think the first issue would be a 1960s battery. A 30kwh battery supplying 100kw is fully discharged in 20 mins, and with lead acid being the only readily available technology in this time frame battery life would be poor under this sort of discharge cycle. Also remember power electronics didn't become readily available until around 1970.

Ultimately you still only have one 110kw engine so battery recharging is going to run the engine flat out. You still only have 110kw per hour available.

You then have the extra weight. As I said earlier it could be done, but you probably wouldn't want to do it given the technology in the time frame which is probably why it wasn't done

 

[etr221]

You also had the SR motor luggage vans, and although there are reports of these operating over considerable distances on battery power it seems that the general consensus is that once the batteries had been in use for a while they were pretty much limited to low speed operation over short distances, which is what they were intended for anyway. The issue was battery deterioration over time.

The first generation BR 50Hz ac from c1960 had batteries for shunting around depots - I don't know to what extent this was used, or how long it lasted.

DB in Germany operated pure battery emus from the 1950s, and these operated for around 40 years, but were restricted to mainly level routes. They were also considerably heavier than their diesel equivalents.

These were successors to a series of battery railcars built between c1907 and c1928, by/for KPEV (Prussia) and DR which lasted (after modernisation c1950) into the early 1960s.

So to come back to the OP question, yes it would have been possible, but given the constraints of the technology in the timeframe, 1960s, it wouldn't have been practical, and wouldn't have happened because there would have been no benefits.

Something I wonder is whether BR - in particular the Southern Region - ever considered a bi-mode (battery/third rail) mu in the modernisation plan era (so c1960), that could charge and take traction power from the third rail where present, and then use battery power where it wasn't. As Merseyrail are now doing/trying 60 years later...

LT had battery locos working on such a basis from quite early days.

The Americans had some tri- and bi- mode locos (using conventional electrification, diesel and battery power in various combinations) c1930, for the special requirements of working in downtown New York, where steam locos were banned.

 

[HSTEd]

Conceptually such a unit could have been built, but it probably would have been a significant expenditure to put it through trials, when the Deeside line trial had not resulted in a later order.

You'd presumably select the battery voltage to allow direct charging from the third rail, but you'd likely need current limiting hardware to avoid massive gassing.