Actually, there are a number of retrofits, both TBI and port injection for 'popular' engines, i.e. don't count on one for your Studebaker, but easy enough to get for anything GM, most Ford, most Chrysler and even AMC. Price point starts at $1K and goes up. Most are marketed as "performance" EFI kits; GM ECU and matching throttle body from the mid 90's are a popular starting point. Fitment isn't too hard, involving O2 sensor install and a MAF sensor, as well as distributor-based crank position sensor. Compared to carbs, drivability is great.

BTW, there is a sizable community on ToyotaNation that waxes nostalgic over 70's and 80's vintage Coronas, Carinas, and Celicas. They're showing some real creativity in fitment of later systems into earlier cars.

 

Interesting! Thanks for the info. However, I question the financial logic of spending upwards of $1,000 on these old vehicles, many of which are not worth that much to begin with. Restored classics, are a different story, and most restorers would prefer to keep things "original".

I don't think anyone would argue that our TCHs are MUCH more complicated than the 60's US vehicles. The cost to update to Lithium would most likely be prohibitive. With that assumption, (yes I know) I modify my prediction to say: there will not be any easy/cost effective way to upgrade a current TCH to Lithium batteries. I certainly won't be even remotely considering it, as I will most likely replace the TCH with another Hybrid in about a year, when my '07 becomes 3 years old and will have about 60,000 miles.

I might be wrong...it certainly wouldn't be the first time, just ask my wife.

 

Restomods are a surprisingly popular sub-genre in the old car hobby. There was an article in Car and Driver last year about a company selling restomodded Challengers/Baracudas, complete with modern Hemi, modern brakes, decent seats, etc. At a 100K pricepoint.

As to modern cars being more comples - it's largely a different sort of complex. Sorting out drivability issues of an old carburated crock can be far more daunting than resolving a drivability issue on an OBD-2 car; it'll tell you where it hurts (mostly, and a scan gauge is a critical component). Hacking the ECU is a bit harder, but even that has a suprisingly large support community. Not saying the TCH is has or is likely to get such aftermarket support (cars are too new, and most TCH owners would just as soon keep it original), but if there is money to be made in a set of mods, someone will develop the components and software needed to do them.

 

Jbollt:

I am afraid that you are laboring under a couple of pieces of bad information here. Admittedly the fields are a bit obscure, so I will endeavor to help you.

1) There are more than a few "retrofit" kits to convert carbuerated systems to fuel injection. This is a non trivial conversion involving the installation of sensors, computers, and other fittings. The conversion is not considered worth the expense for anyone but the high-performance market. The last figure I heard was they started around a grand and went up from there.

2) The conversion from NiMH batteries to Li Ion would be only the change of a few parameters in the firmware / software of the charging system of the vehicle, to compensate for slight differences: a few tenths of a volt difference in the batteries, and a slight modification in the charging current parameters. These changes are minor, and in all likelihood, easliy done by "flashing" a new program into one of the ECU's.

In the first case, you are inadvertently using an 'apples to oranges' comparison: There is no real, compelling need to make an involved conversion; while in the second, there would be sizeable benefits from making a minor 'adjustment'. There would be ample economic motivation to provide the conversion, even if Toyota doesn't.

I'm sorry if I get a bit long-winded or pedantic, but I tend to just 'dump everything' when I get started on a subject that I have some familiarity with

 

Not sure I agree. First, NiMH cells are 1.2V and use a current-based charge method. Full charge is determined by dV/dt under constant current going to zero. Li cells are 3.7 volts (varies slightly by specific Li technology) and use a voltage based charge method. Full charge is determined by current going to zero (trickle) under constant voltage, but with a maximum current limit during early charge.

Second, NiMH cells will pretty much auto-balance everytime a full charge is reached on a pack. Cells need to be very far out of balance before there is a risk of overcharge on some cells. On the other hand, series Li cells need to be individually voltage monitored during charge to insure they stay in balance as an out-of-balance condition will easily lead to cell damage before full charge is reached.

Most consumer 2 and 3-cell Li packs come standard with cell balance monitors built in which act as circuit breakers should the cells get out of balance. The more cells in series, the more complex cell monitoring becomes. The 80 or so Li cells in series needed for our HSD packs would be a challenge for balance monitoring since a simple circuit breaker function would not be adequate. What is needed is 80 independent charging circuits, each biased by the voltage of the preceding cell. (Note that parallel cell packs are an analogous challenge for Ni technology that are no problem for Li cells.)

You could put all this added hardware in the Li conversion pack and minimize the firmware changes needed in the hybrid computer, but you will be mostly replacing the charging system with the battery, and the firmware changes will not be simple.

-- Alan

 

The following is only from a layman's perspective...

If the Li cells require more dedicated circuitry, would it not make sense then if building a retrofit pack to have the retrofit pack pretend to be a NiMH pack at the point of the TCH plug and just do all of the other fancy charging stuff internally? ie, accept power (from ICE or regen) and when less/no power is required give the TCH ECU a signal that the battery is full to cut off the power being sent to the battery pack (send a pseudo SOC to the ECU).

 

The HSD controller regulates the current flows between the two motor/generators and the battery by controlling voltage as a function of braking demand, engine efficiency optimization, and, lastly, battery SOC. I believe this suggestion reverses the priorities, which would impair the overall efficiency of the HSD system.

With NiMh cells, control over charge is by voltage: when the controller set voltage is higher than the SOC voltage, the battery charges, and conversely, when the control voltage is lower than the battery SOC voltage, current is extracted from the batteries. The motor/generators work the same way. For any given speed of the MG, there is a "desired" or "open circuit" voltage. If the controller sets a higher voltage, the motor will "suck" current and try to speed up, but if the controlller sets a lower voltage, the generator will push out current and try to slow down (brake).

The beauty of this system is that the HSD controller is mostly a voltage regulator, which in turn determine which way current flows between MG1 and MG2 and the battery. However, Li cells need current regulation, with nearly constant-voltage control. To put the current regulation inside the battery pack so that it acts like the original NiMH pack would be another point of efficiency loss as well.

-- Alan

 

Thanks guys for all the techno info. You guys obviosuly and admittedly know alot more than I do about the workings of NiMh and Lithium batteries, and how that relates to our TCHs. I just had a feeling that it would much more involved than a "modular" change.

This is from a guy that once converted a 1968 Olds 442 from an automatic trans to a 4 speed manual. It was possible, and we did it. But we kept coming up with more and more "oh yeah! what about xxxxx?" items. I have no idea anymore what that cost me, but I seem to remember after it was all done, that it was close to the value of the vehicle at the time. (1972ish)

Now, if I still owned that car today!!!...Naw..It was carburated, had drum brakes, yada yada yada.

 

I'd like to point out that the TCH's NiMH control ECU monitors the voltage and temperature at numerous internal points along the string of 34 series-connected NiMH modules, each of which contains 6 series-connected NiMH cells. It also monitors the dc current flow in/out of the battery, as well as other parameters. There's absolutely no way that a LiIon drop-in replacement for the NiMH battery would be compatible with the existing controller, which has been optimized specifically for NiMH cells.

Stan

 

I heard that each NiMH pack has a monitor like you mention that scans the cell packs. If any show below normal low voltage, the monitor then activates a proper trouble code to the cars main ECU. I think each cell pack has it's own led indicating which on is weak.

SPL, your correct, any battery monitor would have to be designed for the LiIon battery pack. If that monitor was included on the pack itself with similar voltages then it might swap out with the NiMI pack. The problem would be that MG1 and MG2 are rated to handle just so much amperage. They may have to be built for the higher amps. This would be for full throttle acceleration from the LiIon batteries and in turn to properly generate more amps to charge the higher amp lithium pack.