Can 3.3kw charger be upgraded to 6.6kw on Prius Prime or RAV4 Prime?

For other types of batteries (non-automotive), the tapering begins before 80%.

 

Yes, I'd love to replace my 8.8kWh battery with a larger one. Currently though, after a year of use there is no sign of significant degradation so it would be hard to justify currently until we start doing road trips more often again, or the commute to work becomes much longer. Obviously cost would be an issue.

CHAdeMO ver.2 is limited to 400kW/1kV/400Amp direct current according to https://en.wikipedia.org/wiki/CHAdeMO. When CHAdeMO ver.3 is published it might be capable of up to 900kW/1.5kV/600Amp.

Where I live the older public CHAdeMO chargers are typically rated at 50kW. Newer chargers are rated at at least double this, or frequently more. However, the 8.8kWh battery in the 2018 Prius PHEV would be stressed too much if the full power of the public CHAdeMO chargers is used. As a result the car itself protects the battery by limiting the power to 17kW/70Amp, even if the CHAdeMO charger is capable of 100kW or more.

 

The 2018, Gen. 2 Prius PHEV (aka Prime in US) has the larger 8.8kWh battery. On average we get 45km (28 miles) on a full battery, which currently has a capacity on average of 6.0kWh (measured at the wall plug). The reasons I'd like much faster AC charging are outlined in a recent posting above - even though I already have CHAdeMO. Cost and feasibility would determine whether such a modification would go ahead.

AC charging of the 8.8kWh battery has some advantages over CHAdeMO albeit probably a bit slower rate. 3.3kW AC charging is, however, far too slow to compete with CHAdeMO. 6.6kW or even 9.9kW might do the trick. Above I queried whether a second 3.3kW charger could be placed in parallel to the existing 3.3kW unit giving a total of 6.6kW. Originally I'd thought only of an second, identical 3.3kW unit (to minimise possible compatibility issues) but afterwards it occurred to me that perhaps a 6.6kW charger could be added instead (or more?), allowing charging at 9.9kW AC. The existing 3.3kW charger would remain unmodified and continue working under the control of the ECU - the added chargers would be linked as a slave to it, possibly remaining "invisible" to the car itself.

If the added AC charging power is too much above 80% charge then perhaps the extra units need to be shut off completely above 80%. Since CHAdeMO charges at a constant 17kW/70A until 80% then charging at a lower current until 80% (or a bit further) at 6.6kW or 9.9kW shouldn't be a problem.

 

The early Model S had a twin charger option. Easier to do when designed for such.

I don't think making the added charger invisible to the car will work. The standard works on communication between the car and EVSE. If they think there's just a 3.3kW charger, and if either sees more than that amount of electricity being drawn, either will trigger a fault. Making the added charger invisible to the entire system could be possible, but means circumventing safety protocols.

 

If that safety feature is present (which has a certain logic about it) then that would be a problem. I'm not so keen on bypassing safety features in case something were to go wrong. Perhaps a solution might be to make a device to adjust the current limits accordingly. A similar device was mooted elsewhere for reducing the CHAdeMO DC charging rate, refer:

In the case of a greater AC charging, however, we'd want to greatly exceed the maximum current expected by the car, which might also be an issue e.g. compared to a reduction in DC current as in the case quoted above.

Unfortunately a device such as this (plus any certifications etc. which might be required) would increase the complexity and cost of an upgrade to the AC charging system.

 

How much would an 18.1kWh battery (or similar) weigh?

Some have suggested that the 8.8kWh battery in the Gen.2 Prius PHEV/Prime is already heavy. Elsewhere some posts have mentioned weight issues in connection with the number of adults sitting in the rear seats, and possible a factor when Toyota extended the length of the PHEV/Prime vs. the Prius hybrid. So a much heavier battery could be a problem - especially if you are starting with a Gen.1 HPEV/Prime chassis. The Gen.1 body mightn't respond well to much weight, as mentioned here:

Is possible that the 18.1kWh battery will have about twice the energy storage density of the 8.8kWh battery?

 

the new 18.1 in the new Lexus is lighter, smaller, and more powerful than the 18.1 in the rav4 prime. Not sure if you know but.. I have a good 1,000lbs of extra weight on my Prius and ill tell ya... the extra weight won't make a difference. If anything, particularly my rear cargo box, makes this thing grip!!! I'm undefeated downhill on a road called Rim of the World Highway... i challenge all!

 

Yes, interesting. If (... when ...) I replace the battery then I'd want to know:

1. Is the new battery compatible e.g. is it "plug-and-play" (or a trivial mod)?
2. Are the volume and weight OK?
3. How many more kWh/km/miles? and how many $?

Do you have any estimates for any these points for a 2018 Prius PHV?

 

Hmmm, so we would need a "dumb" power supply. A Commando/Caravan socket can supply up to 32Amp, which at 240V provides 7.7kW. These are easy to install at home (depending on whether the supply, cabling, fittings, etc can handle this, of course). There are a large number of these power supplies around most countries although Plugshare doesn't show them in US. Presumably the US will have something equivalent in caravan, campervan, and RV camping sites. The are connected to the car the same way as the home AC supply, for example using the Zencar Model C at https://www.zencar.net/ev-charging-level-2/#.

Commando sockets (32A) and Caravan sockets (16A) for both 110V and 240V are suitable for indoor and outdoor use and are described by IEC60309 e.g. refer https://en.wikipedia.org/wiki/IEC_60309. An image of one such socket like the ones I've often used at campervan/caravan sites can be seen at https://en.wikipedia.org/wiki/File:CEE_16A_230V_Wandsteckdose_Pinning.png (in this case for 16A).

 

6.6kw worth to get if you have a lvl2 at home. Otherwise regular 120V still needs about 12 hours for a 18kwh battery size as it will be on 3.3kw.

My Lexus NX450h+ takes 12 hours to charge vs lvl2 2.5-3hrs (same as RAV4 Prime). I thought I didn't need a lvl2 on day 1 and I was wrong and ended up installing a lvl2 charger

 

The equivalent connectors in North and Central America appear to be NEMA connectors rated at 120V or 230V. (Plugshare shows these "dumb" power supplies available if location is set to USA.) NEMA connectors in campsites, caravan parks, and RV parks have similar power ratings to commando and caravan connectors elsewhere in the world i.e. NEMA 14-50 at max. 7.5kW/250V/30A and NEMA TT-30 at max. 3.6kW/120V/30A (sometimes NEMA L5 max. 12.5kW/250V/50A) compared to the common "blue" Commando at max. 8kW/250V/32A and "blue" caravan at max. 4kW/250V/16A (and the occasional "red" commando for 3-phase supply max. approx. 40kW). The available max. supply voltages are a bit below these ratings. For comparison, the NEMA 5-20 "wall" socket delivers max. 2.5kW/125V/20A. (Info from https://en.wikipedia.org/wiki/NEMA_connector.)

All these "dumb" connectors are all cheap to install at home (often DIY) and are commonly available globally. To connect to an EV they require only a connector similar in design to the common 110V or 230V connectors charging at 6A or 8A i.e. approx. 1kW to 2kW, and are generally low cost. They are already available to buy and can deliver 7.7kW (or more, depending on the power supply available). Since they are much cheaper and easier to install that J1772 and Type 2 connectors (and DC chargers) they are likely to remain more plentiful and per kWh will cost less (or be free) in public places and homes. They are already widely installed in commercial and industrial sites globally, as well as in countless caravan, campervan, and RV parks.

These "dumb" connectors could enable owners to upgrade the charging rate from 3.3kW (to 7.7kW, for example), by adding a second AC charger in parallel to the current 3.3kW charger, or is there something I've missed? Such a second charger might be controlled as a slave to the 3.3kW charger but be "invisible" to it. A 7.7kW charger could potentially charge a Prius PHV (aka Prime) to 100% in under an hour.

As a comparison to DC charging, CHAdeMO charges a Gen.2 Prius PHV to 80% at 17kW in 16min (equivalent to AC 17kW/230V/70A), while a 7.7kW would charge the same amount i.e. to 80%, in about 37min - little more than double the time. (Our Prius PHV does have CHAdeMO charging.) However, CHAdeMO is far more expensive to install and maintain, and only charges a Prius PHV to 80%. (The Prius Prime is the same as the Prius PHV but doesn't come with CHAdeMO.)

 

If the car's software is for a slower charger, the computer could limit the current draw to the rate of what it expects. Even if two chargers are actually being used.

It could like upgrading the intake and exhaust to increase engine power output. If the software isn't adjusted, the ECU will just make adjustments so the output matches stock, despite the better airflow.

 

I imagine the additional charger would be "invisible" to the car so the sensors would only see and adjust for the existing charger and current. In theory this would be achieved by connecting the input terminal of the additional charger to the power inlet and outlet terminal directly to the battery terminals. The existing software should (... in theory ...) be unaware of an additional charger. in reality it might be more complex, of course.

It would be also necessary to have an automated switch disconnecting the additional charger whenever the existing charger has reduced or zero current flow. This should stop overcharging the battery and for human safety. This switch should also prevent excessive currents when the battery is almost full.

 

there is only one way to find out!

 

Yes. Could I/we encourage you to include this project in your tinkering with batteries and charging systems? It might be easier to install than CHAdeMO into your Prime, as discussed in:

As previously mentioned, advantages could include charging to 100% (not just 80% as for CHAdeMO), much easier and cheaper to install connectors at home, and much cheaper to provide wide-spread, public infrastructure.

 

The thing is... I still need to get my hands on an ECU from your spec vehicle.

 

Upgrade from 3.3kW to 6.6kW (or more?)
Addition of a further charger in parallel to the in-built charger shouldn't need ECU details (as envisioned above). The second charger should be "invisible" to the car although controlled as a slave to the in-built charger.

Installation of CHAdeMO to a Prius Prime
I imagine a solution can be found via PM for the ECU details/info/etc once you get that far. Have you got prices, parts, etc for installation of CHAdeMO to your Prius Prime yet? Bear in mind that I've a Gen 2 2018 Prius PHV, which is closely related to the Gen 4 Prius hybrid - do you have a Gen 4 Prius rather than an earlier (or later) model?

Personally, I think upgrading the 3.3kW AC charger is more worthwhile, but perhaps you would like both an upgraded AC charger and CHAdeMO for DC charging?

 

PS: There are some useful thoughts about safety and DIY wiring of EV charging systems elsewhere on PriusChat, for example:

Of course this particular example is much different to our current discussion on upgrading the 3.3kW charger but does illustrate the importance of safety.

 

I keep finding places that say they can get what I need then I'm told they cant, the ECU is needed as I feel like it holds the keys to a lot of what I need to know ECU wise between the two models. I have a 2015 PHEV and a 2017 PHEV. Have the Japan spec ECU for the 2015 Gen1 PHEV and now need the Gen2 PHEV ECU. Things like the control of the car when using EV mode over 75mph is what I need to see in the Gen2 ECU so I can modify whats in the Gen1 ECU so it can as well. I just haven't wanted to take out the ECU in the Gen2 until I get my hands on the Japan spec and even then, I'll get a US spec ECU from the dismantlers and use it to make changes never really "touching" the OE Ecu in the car per say.

 

Your 2017 PHV should be pretty similar to my 2018 PHV, and so the specs could well be similar.

Is it possible to download a copy of what you need? I've met a guy with a pretty good OBD2 system, which looks at and can adjust all sorts of things. Do you know if it is possible to download any relevant digital files? If so then I'll ask him if he can do this. (Presumably it's more than just a few settings which need adjusting so writing a few numbers or codes into a PM/post isn't feasible?) Would Toyota have issues with this, do you think?