Prius help! Is my battery toast?

hoodie6029 · 05-10-2021 5:01pm #1

My 2006 Prius (285,000km) has been sitting for 4 months since I haven't been using it. I started driving it again in the last week. The 12V battery had been losing it's charge completely after sitting for a few days since last year so I replaced this with the same Yuasa unit that came out of it.

Now I have been getting the red triangle, VSC, yellow brake warning and MIL lights.

I've cleared them by disconnecting the 12V but they come back after a few minutes of driving.

The hybrid battery charges and discharges very quickly now too and the cooling fan, that I don't think I've ever heard running, is running a lot now too.

Do I just need to clean out my cooling fan will I have to replace the battery?

I see if I can get it into the mechanic this week to read the actual codes coming up.

Thanks in advance

[Deleted User] · 05-10-2021 10:00pm

These cars is designed for driving not storing. Only keep one thing on mind if garage offers the replacement battery, the replacement battery can have similar problems thanks for age and long time storing on warehouse. There is even companies who offer re-manufactured units but all cells is old. They mix and match units to get balanced. Still old cells... So think before you buy the battery, is it worth it. May be cheaper is to cut the losses and sell the car as is.

Bigus · 05-10-2021 10:17pm

The battery cooling fan is only coming on because of a battery fault , unfortunately in the traction battery.

I pulled one of these apart a good few years ago and replaced 2 under voltage cells from a scrap battery.

as far as I remember I only used a crappy cheap multimeter to tell me 26 of the individual cells were 28.5 v and 2 were something like 14 or 16 v. So easy physical diagnosis.

swapped 2 cells out and happy days , all done with a 10 mm and 12 mm socket and no other tools and about 3 hrs labour .

pretty scary until you realise, that once you pull the big orange bulky fuse/breaker the battery pack becomes fairly benign.

apparently I got lucky , as other lads on the internet would state that all cells needs to be rebalanced which is a time consuming and technical process.

any way there’s lads in Limerick(DoneDeal) will supply a balanced refurb battery for about 600 euro and swapping out is about 2 hrs, for the complete unit rather than going to the full strip as I did.

hoodie6029 · 06-10-2021 7:20pm

Cheers for the replies, had a look on Prius Chat and it all seems to be pointing towards battery failure. I'll check out those guys in Limerick and stick an update up with how I get on.

hoodie6029 · 11-11-2021 11:13pm

Tried those Hybrid Battery guys on Donedeal a couple of times and they never got back to me.

Found a battery from a scrapped Prius with 90,000 miles in the North and got it for €400.

Installed it myself using Chrisfix's guide and and old Car Mechanics magazine I had and they car is driving perfectly now. The new battery came in its case so it was a relatively quick job.

The fan was very clogged when I took it out so this probably caused the battery to overheat.

There was a lot of white corrosion on the outside of the case. I wonder was this from the overheating? The battery was getting so hot it caused this reaction?

[Deleted User] · 12-11-2021 1:06am

https://www.boards.ie/discussion/comment/118153837#Comment_118153837

Now you can sell the good remainig cells by 400eur, good business! Do not dump all of that, there is many good cells left. Congratulation! Now you figured out how donedeal guys operate. Nothing is new, only old mix and match cells

hoodie6029 · 16-11-2021 10:50am

The success was short lived. I’d done a bit 100km and just as I was getting home the car juddered and lost power. It limped into the driveway and then the same lights came on, VSC, triangle, brake warning and check engine.

Disconnected the 12V battery this morning and reconnected after a few minutes. Left the car idling and after about 10 minutes the lights came back in the dash. The fan was blowing to cool the battery but not loudly.

When I popped the bonnet, the engine sounded like a diesel! I give up…I’ll see if I can get a mechanic to look at it now.

[Deleted User] · 16-11-2021 12:24pm

Who made the initial diagnostics? Swapnostics is the most expensive car repair option (no joke).

hoodie6029 · 25-11-2021 12:19pm

Dr Prius app told me that one module was gone on my original battery. Whole host of other codes on the new battery.

A lot of googling and priuschat searching and it pointed to corroded wiring...somewhere. Pulled the battery ECU out of the 'new' battery and it was fried. 3 or 4 pins heavily corroded or missing.

Swapped the ECU and connector from the original battery to the new one and it's been working fine so far. Fingers crossed it lasts more than 100KM this time!

[Deleted User] · 25-11-2021 12:57pm

Even uber does not ask so much money for 100km

hoodie6029 · 25-11-2021 5:06pm

Don't talk to me...hopefully I never have to update this....

[Deleted User] · 25-11-2021 5:17pm

https://www.boards.ie/discussion/comment/118221927#Comment_118221927

No, it was not joke. We help you if we can. Always challenge, never easy

ozmo · 25-11-2021 5:31pm

Had to replace the 12v battery myself from leaving it sitting too long - Car is not getting much use lately. 120Euros for a battery :(

So this time I also installed a bluetooth 12v battery monitor - it reports back to my phone the voltage on the battery (20 pounds on amazon). Nice.

Dont know if the battery I got was a dud - but the 12V battery goes from full charge(12.55+v) to red (12.03v flat) in about 8 or 9 days doing nothing just sitting in driveway.

hoodie6029 · 25-11-2021 5:42pm

https://www.boards.ie/discussion/comment/118221983#Comment_118221983

I knew you were joking. Stupid internet, can't pick up my tone 😁 Should've put a smilie on that that last post

https://www.boards.ie/discussion/comment/118222053#Comment_118222053

I had to replace the 12V recently to. A Yuasa was the only one the motor factors said was suitable for it since the hybrid is a stop/start system in some ways, cheaper batteries aren't sutiable.

[Deleted User] · 25-11-2021 7:37pm

Yuasa is very good battery. Only remember to disconnect it, if you do not planning to drive over 100km.

hoodie6029 · 25-11-2021 10:12pm

https://www.boards.ie/discussion/comment/118222690#Comment_118222690

😂😂

blackbox · 26-11-2021 9:17am

I got the VSC warning in the middle of changing the brake fluid on my RX400h. Thought I had fried something with the spurious programming unit.

Turned out I was only getting 8 volts from the 12v battery.

Car had been starting OK but these normally put very little demand on the 12v battery which probably had been poor for a while.

New 12v battery and all problems solved.

ozmo · 26-11-2021 3:55pm

https://www.boards.ie/discussion/comment/118222109#Comment_118222109

This is just from my observations:

I would say any 12V should be fine - The only thing that's really important is the battery has an Air Vent and its connected - so any fumes/gas from battery leave the car - not stay in the cabin with you.

From what I can see now Im monitoring the voltages - the 12V battery is used only for powering the car before the car ignition is switched on.

so...for powering..

the door locks
booting the computer system

once the center display is on - its computer is booted - and all power comes from the traction battery - even when prius ignition is not in Drive (ie. powered on without foot on brake).

At this point the 12v battery is just trickle charged.

Now if the car is in Park - the petrol engine will kick in occasionally to assist charging the 12v battery.

corks finest · 03-01-2022 5:26pm

https://www.boards.ie/discussion/2058211811/prius-help-is-my-battery-toast

12 v last 5 years approximately ( same with my Honda Insight hybrid)quoted e88 via micks garage for mine

[Deleted User] · 03-01-2022 6:23pm

4 months is very long time for no usage. Lets say the car electrical system is perfect and standby current is 0.015A, it suck about 43Ah by 4 months. It is so easy to disconnect the negative terminal, no problems. The worst what can happens by dying battery, it corrupt 1, 2, some, all EEPROM memory. Not sure how many EEPROM that car have, at least tens of units. Flash memory is not so sensitive but low voltage can corrupt that too.

ozmo · 04-01-2022 2:41am

10 days of non-use and my prius has gone from fully charged to fully discharged :( is that normal because its a pain to keep charged- battery is very inaccessible in boot of car.

all stock no mods.. battery is brand new.

[Deleted User] · 04-01-2022 8:08am

https://www.boards.ie/discussion/comment/118414193#Comment_118414193

You must have a serious parasitic draw. Easy test, set multimeter to mV range and measure the across the fuses. The circuits where is no load you get 0.0mV and where is current draw you get 0.x mV. Check what that fuse feeds and focus to that fuse circuit. If it is not important circuit, you can live without some accessories.

CJhaughey · 04-01-2022 3:55pm

If your battery is hard to get to you can set up a lead system so that you can plug in a small smart charger to keep the 12v battery topped up.

Motorcyclists commonly use these for keeping bike batteries alive over winter.

They are not expensive and can save you the price of a battery very quickly.

https://www.louis.ie/artikel/set-procharger-1-000-incl-procharger-comfort-indicator/10059600?list=9787cea9be17323e3a052196caf8ffe9&filter_article_number=10059600

[Deleted User] · 04-01-2022 4:54pm

Why not to fix the prius parasitic draw? Ignoring the problem can lead to fire because that parasitic draw is massive.

Is it really easier to mess with 1A charger / maintainer than disconnect the battery for full winter? Disconnect the motorcycle battery, charge full and it survive the winter. Sure depends by battery condition. It is really worst idea to cook the battery over the winter.

hoodie6029 · 21-05-2022 2:59pm

https://www.boards.ie/discussion/comment/118220126#Comment_118220126

Small update on this. Done a few thousand KM with no problems. Even sold my old battery. Got €150 for it from a garage. No ECU knocked the price down unfortunately. https://www.ryansautomotive.ie/ just up the road from me work on hybrids and EV.

corks finest · 23-05-2022 10:10am

Trickle charge

Prius help! Is my battery toast?

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