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Can a hybrid be converted to be plug in hybrid?

  • 03-07-2022 5:03pm
    Moderators, Science, Health & Environment Moderators Posts: 19,423 Mod ✭✭✭✭

    I hear talk of converting diesel to electric which sounds impossible to me (at least from a cost pov).

    But could a hybrid (non PHEV) be made plug-in?

    If so, likely cost?


  • Registered Users Posts: 1,552 ✭✭✭Thumper Long

    You would need a new larger battery and the associated on board charging hardware and software additions / adjustments can’t see it being economically viable for any car never mind trying to find the expertise to carry out such works or trying to get the car passes for road worthiness etc

  • Registered Users Posts: 10,977 ✭✭✭✭the_amazing_raisin

    Bizarrely enough, this is actually harder than going from full fossil to full electric

    Fundamentally, hybrids and plugin hybrids operate in different ways

    A hybrid has a small electric motor and a small battery. Generally the electric and petrol motor drive the same axle through a planetary gearbox. The idea is that the petrol engine stays as close to it's ideal rpm as possible and the electric motor handles any extra power output needed. The battery is only big enough to handle a small distance driving the car slowly

    A plugin hybrid often has the petrol engine driving the front axle and the electric motor driving the rear axle. The electric motor and battery are much bigger and capable of driving the car independently for a reasonable distance (typically 30-50km). Because the battery can be recharged the car can in theory be driven as an EV

    To go from hybrid to plugin hybrid, you'd need to find space for around 10kWh of batteries plus put an electric motor and gearbox on the rear axle.

    I guess you could keep the regular hybrid bit, but often the battery is kept under the rear seats, which is also where the battery for the big motor lives

    You'd also need to figure out some way to tell the car when to use each of the electric or petrol engines, so dig out your software manuals 😁

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Registered Users Posts: 10,977 ✭✭✭✭the_amazing_raisin

    I guess to give you a very simple example, you could attach an external battery charger to the battery in a regular hybrid and this in effect makes it a phev, sort of

    Could be done for a few hundred if you're handy with tools

    How useful it would be is up for debate. It'll allow you to creep along in traffic for around 20 mins without consuming any petrol

    If that's what you commute looks like then I'd counter that you'd be better served buying a bike 😉

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Moderators, Science, Health & Environment Moderators Posts: 19,423 Mod ✭✭✭✭Sam Russell

    Thanks for those explanations.

    I assumed that there was just extra charging hardware in the plug in.

    Interesting to consider that the hybrid gets the petrol engine to work in its most efficient rpm - did not realise that that was the way it works. So that must be why taxis are using the Prius.

    How far can a Prius go on a fully charged battery? How big is the Prius battery?

    I was thinking (not me personally) of adding the charging stuff and a larger battery to get 50 km of electric rage. If that cannot be done, at least achieve better fuel consumption figures by charging the battery.

    If either is worthwhile, then that is an good opportunity for an entrepreneur.

  • Registered Users Posts: 1,085 ✭✭✭sh81722

    The hybrids usually have a battery in range of 0.5->1.5 kWh with quite a low power output. Think of extra couple of hp max from the battery when in EV mode as opposed to few tens of hp on the PHEVs. The prius utilises a Ni-MH battery and I'm too lazy to check how high discharge rate the battery pack has. If you expanded the battery to 5-10 kWh and added a charger for it the built-in electric motor might be able to operate on higher power output if the programming of the EV system can be changed. The motors typically are quite beefy just that battery pack seriously limits what they can draw.

    Above is for real hybrids, not the light hybrids which often use the alternator via belt to provide some very limited assistance.

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  • Moderators, Science, Health & Environment Moderators Posts: 19,423 Mod ✭✭✭✭Sam Russell

    I suppose if someone were to try to convert a hybrid to a PHEV, they would need to select to most suitable candidate vehicle to do it with.

    Doing it commercially, it could only be done model by model - a bit like boosting the performance of an ICE vehicle.

    I am sure we will see some attempts at it. I think converting a diesel car to an electric car is just too close to the cost of the EV version to be profitable.

    Manufacturers could offer conversion kits but why would they? It would be more profitable to just put wheels on the kits and sell as cars.

  • Registered Users Posts: 10,977 ✭✭✭✭the_amazing_raisin

    Manufacturers won't offer kits, and unless you're going to going very in depth on the DIY side then the conversion kits are going to be expensive. So it only really makes sense for converting a car which is very valuable in the first place (think Ferrari Daytona with a wrecked engine, there's been a couple of conversion projects of those over the years)

    The reason it's easier to convert an ICE to EV is because it's a conversion, not a modification

    You're ripping out the existing engine, fuel tank and possibly the gearbox. This gives you plenty of space for an electric motor and batteries

    Also because you still only have one motor in the car, you don't need to do any messing around trying to optimise the performance of a petrol and electric motors

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Registered Users Posts: 10,977 ✭✭✭✭the_amazing_raisin

    Was speaking to a taxi driver about this recently. He said the Prius will go about 20 mins in stop start traffic without using the petrol engine

    I don't know what that would translate to in range but you're probably talking less than a kilometre at walking pace

    The issue with the electric motor in the Prius is that it only really has enough power to move the car at slow speeds. Otherwise it's dependent on the petrol engine

    So if you made the battery bigger and put in an external charger, all you're really getting is a very large mobility scooter

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Registered Users Posts: 10,977 ✭✭✭✭the_amazing_raisin

    Here's a counter proposal which is potentially much easier, convert a PHEV to full EV

    You'd basically just be removing the existing petrol engine and adding batteries in its place

    Charging wouldn't be ideal, most PHEVs top out at 3kW with no DC charging

    So you'd probably want to add a CCS socket and the charge controller from another EV

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Moderators, Science, Health & Environment Moderators Posts: 19,423 Mod ✭✭✭✭Sam Russell

    Maybe PHEV to EV would make sense. Some drivers never charge their PHEV, just fill up and drive. Carting a heavy battery for no benefit. Getting rid of the engine and gearbox are replacing with batteries and a decent charging interface could be attractive if it was not too costly.

    Do they have a full ICE or is it underpowered?

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  • Registered Users Posts: 1,909 ✭✭✭kanuseeme

    Stick a Honda genset on a clapped out leaf or fluence, make a battery bank on wheels some what usable.