I have an older rx 2007 400h with lowish 140k miles, but the battery is obviously on a decline and possibly on its way out. It drives fine, but I can hear the engine kicking in more regularly to charge. I just check the battery status w/ Dr Prius, and the internal resistance seems high at 30-32 milliohms across the board, though the voltages are reasonably similar within a volt or so ~20v. So I'm considering what to do next, with a list of possible steps/options: 1. Closer monitoring w/ Dr.Prius, to see if there's any particularly bad cell unit. A thread here said I should be looking for cells that discharge/charge quicker than the others while driving around. I also have Toyota's techstream set up for it, but haven't dug much into that so don't know if there's any further diagnostic possible w/ the more complex factory software. 2. Try the Dr Prius app battery test add-on for 10 bucks. No idea if that provides much value other than tell me the battery is old. The test cycle of mashing the gas and brake looked a bit wonky to be honest. 3. Get a Prolong battery reconditioner, possibly split the cost w/ a friend who has a prius. No idea if it's worth the install & effort with an old battery. Prolong says I can share the charger but not the discharger which is specific to each model of battery. If there are any other seattle/pnw hybrid owners interested in sharing that'd be great. 4. Sell/trade the car? Far as I can tell there's no great battery replacement option. Green bean has $2500+ "rebuild" with long warranty, but not sure how good those rebuilds are given all batteries for this prev gen are old. New battery is at least 4k + install. On the used market this condition 400h seems to fetch maybe 7k. Any advice is much appreciated.
Welcome to Prius chat. Note that the size of the battery is larger than the Prius, so the charger will also be larger. If looking to share with other owners, you'll need to find other RX or Highlander Hybrid owners, as their batteries are the same size. If you get the Prolong equipment, you can maintain the battery and if a module fails, you have the correct equipment to rebuild the battery and make the repair last longer.
I would suggest (assuming the rest of the car is in good shape) just drive the ccar until the battery gives up the ghost and then spring for a new one. 4K is not a bad price for a new battery, if you had a Tahoe with a blown tranny and the same mileage you would be looking a 5k for a rebuild. If you have the money and don't want the bother, sell the car and buy a new one. remember life is too short.
Another member here DenverGuy in his thread in the lexus forum is trying to reconfigure a new gen SUV battery (from salvage) into the old shell. RX400H - Pitfalls of buying a used battery? | PriusChat The older battery is in a 12+6+12 physical layout and new one is 10+10+10 so it's likely similar electrical format. This seems the way to go if it works out since there will be plenty of supply at low cost. I think next step for me is to use the dr prius app while driving to monitor the cells and research what the techstream SW can tell me (I only set that up before to program a key).
I did some additional testing, driving around with Dr. Prius app running. The cells all seem reasonably well matched with voltage <.2V diff, and resistance within 1mOhm, but depending on driving condition (after startup, driving around town or hwy after a while) the resistance of all the cells seem to fluctuate uniformly between 25 up to 32 mOhm resistance, which makes determining life based on that tricky. Also found an interesting product online from "OKACC" (can't post link but if you google it's on their site under /products/fast-delivery-3-years-warranty-ni-mh-6500mah-288v-hybrid-car-battery-replacement-for-toyota-highlander-2006-2009-hybrid-battery.html. Basically battery innards/cells made from large cylindrical cells instead of the flat/prismatic. I emailed them and shipping/tax was ~$500 to the west coast, ie. $2.5k, vs. the $4k + tax for OEM from lexus.
The only cylindrical cells I would trust come from @2k1Toaster . While the other capacities are cited as 6500mAh, I wouldn't be too sure of that. I don't believe he makes a pack as large as what a RX requires, I've tagged him for his input. Good luck and keep us posted .
The cooling venting of the pack is designed for the prismatic cells. The cylindrical ones may not get proper cooling.
