HV Battery failing?

Two things I would check. One, has your HV Battery Fan been cleaned? It is possible that your fan is clogged, the battery is overheating and therefore you are experiencing a reduction in power... Also, have you removed the cap from your inverter reservoir and checked for turbulence? This indicates proper flow from the inverter pump. I would check these first.

 

Hi skip. It definitely sounds like your battery has lost some of it's capacity. My 2005 Prius also seems to have lost some capacity, though fortunately I don't have any mountains that I need to maintain 110 km/h over. Luckily I don't get that problem as the mountain passes I often traverse are steep and windy with about an 80 km/hr limit.

As for the clicking, are you certain it's not the thermostatic fan that only runs when the radiator temperature is high enough? If you stop does it keep running for a while, or is the clicking only happening precisely when the engine is also revving?

As for "clicking of a dead battery", as far as I know no batteries ever make a clicking sound of themselves, but a low battery can cause a relay to drop in and out and make a click. The clicking sound you sometimes get in a conventional car, when you try to start on a flat battery, is the starter motor solenoid dropping in and out. The solenoid energizes and comes in, but as soon as it does so it causes starter motor current to flow which collapses the instantaneous battery voltage causing the solenoid to drop out - and the cycle repeats.

 

Ok that's weird, it definitely seems like an engine related noise then. Perhaps the somewhat weak battery is making it worse by causing the engine to work hard, but it's actually an engine related problem. Are you sure it's not pre-ignition (pinging/detonation)?

 

Put the car in "inspection mode" and that will allow you to rev the engine at will and the engine will not shut off.
See "Prius Inspection Mode" on youtube. Have someone rev it so you can listen to it.

The battery fan can be serviced. Pull the sticker off the back bearing hole and use 20 weight oil oil that hole. That will oil the back bearing.
Lowes sells a small tube of Electric Motor oil in a little spout bottle. Its basically 20 weight but in a convenient tiny spout.

Your motor at its age is probably got some top end noise. Chain, valves etc. Its using oil now so have to watch it closely. Its probably low on oil right now lol.

By the way if the Hybrid Battery was failing under load it would throw a DTC. If you are really concerned about the battery take it to the dealer or any other place that has Toyota/Lexus Techstream software and the HV battery an be thoroughly interrogated for balance and health. See youtube techstream for more info. Dealer for instance charges $125 for diagnostic fee and you can get a print out of the battery page. Please post that here.

Btw, going up hills with load and speed and the Hybrid Battery in low or not fully charged is the hardest thing to do to a Prius. MG2 will pull max load on the Inverter and things start to heat up fast. The Inverter coolant and trans fluid will spike super hot and its the most dangerous as MG2 motor winding will get really hot. Thats how the electric motor fails. Its the usual way for a Prius transmission to fail. MG2 will not be able to supply enough motive force to satisfy your gas pedal position forcing the engine to race to supply motive force. Its super duty right there. Many a Prius has ended up on the side of the road waiting for a tow truck while trying to go up steep mountains with a load in the cabin, ac ,lights, cd on, and at speed and not having good fluids on board. And not realizing you can't just floor the car up hill when the battery is low. Your basically killing the car.

Next time you go up a mountain and the engine has been racing pull over and see how hot the Inverter is.
See if you smell anything burning.

Your one owner. How many times have you replaced the trans fluid and Invert Coolant.?

 

Okay. So you've got the first step done. Now, check for turbulence in the inverter coolant tank and please report back!

 

Ok glad to help. Your doing something right to with all those miles on the car. Its a great little workhorse.
I like the battery module numbers. Not to bad. Looks like the delta (difference in module voltage the true sign of a bad module) is not to bad.
Noise may just be the top end is getting old. Keep the old at the full mark she needs all the lubrication she can get when your in the mountain mode with low batt and the engine is maxed out and screaming.

Good Luck!