chromedome

Ok, this is strictly for discussion's sake because no ES300h should be out of the 8-year battery warranty yet, but it's good to know that battery fixes and plugin conversions are available. The battery pack uses NiMH cells and the design is similar to the Prius and GS450h packs. One or two cells might go bad after 8 years - Lexus either replaces the entire pack under warranty or you could get a refurbed pack with replaced cells for much cheaper.

As for plugin hybrid conversions, Enginer sells 4 and 8 kWh lithium ion packs to supplement the existing NiMH one. The extra battery acts like a power pack for an iPhone, by acting as an external charger for the original battery and allowing the car to run on EV mode longer. It also doesn't alter the hybrid ECU parameters so powertrain reliability shouldn't be affected. The company hasn't done an ESh but it has done Priuses and Fusion hybrids.

I'm not going to toss out my spare tire and install another battery pack but it's good to know the option exists. Who knows, 5 or 6 years down the line, these PHEV conversions could become cheaper... I wouldn't mind unplugging every morning and running my commute mainly on electrons

Riles

The Enginer conversion kits have a bad history, unfortunately. They had really big quality issues with their product for many years, to the point where I think they either went bankrupt and/or sold their technology to someone else. Apparently the issue was with the voltage converters- their system uses a 48 volt battery with a converter that steps up the voltage to 201v (the prius used 201v; we have 244v in the 300h), and those things were under such stress that they didn't last. I only know because I was trying to buy a non-working Enginer kit off of PriusChat for my old prius and it was so hard to get replacement parts for it that the sale fell through. I think most people who bought Enginer kits have since had to uninstall them.

There is another, better method used by a company in Colorado which totally replaces the hybrid pack with a big battery that you charge at night but which also functions as your hybrid battery, but I don't know if they offer the product for the Camry/Avalon/ES300h platform since the voltages are different than for the Prius/CT200h platform. It's also $10k+, since it uses a large lithium battery.

I've looked into these quite a bit on the Prius side, and even with perfect implementation, the conversions can be hard to justify. The hybrid batteries are pretty cheap to replace as far as major car repairs go, so even if you are in the worst-case scenario with a dead hybrid battery and you're out of the warranty, it's still going to be hard to choose to pony up 5x the cost for a PHEV conversion.

I totally agree though- if the prices come down, these would be great. Lithium batteries are getting super cheap now with all the EVs on the road. Chevy Volt and Nissan Leaf batteries can be had on ebay for extremely low prices as compared to the batteries of 5 years ago, so it seems like it's only a matter of time until we can interface them with our own systems (either via an Enginer-style converter or through an all-out replacement).

chromedome

Thanks for the info. Quite a few ES300h owners here are also Prius owners whereas this is my first hybrid.

I didn't know Enginer kits had such a bad reputation. Their system seemed like a simple and cheap hack. Replacing the NiMH pack with a larger Li-ion pack is a lot more expensive and requires either hacking the hybrid ECU or piggy backing another controller, but it would be a more efficient install. Here's hoping there's a viable plugin option in a few years' time...