HV battery thoughts for a newbie please

Firstly it's been amazing having this wealth of knowledge available over the years, so thanks to all you regular contributors who provide all us lurkers with so much free advice.

I got alot of good info from reading about uart's experiences here: My HV battery replacement experience - Australia. | PriusChat

I'd like to get people's thoughts on whether I have a dying HV battery on my hands. If so that's fine, we knew when we bought the old girl that we'd need to put money aside in a battery replacement fund for when the time came. Just want to make sure I'm not putting the cart before the horse. Don't want to go running to a dealer for a new battery pack if it's not necessary. And I'd rather shell out an extra $1500AUD to get the OEM battery pack than try buggering around with a refurbishment, and yes I know it's really easy to fit it yourself but I'm prone to stuffing up anything vaguely mechanical, so I will begrudgingly pay the dealership labour rates just to not worry about it.

The background:

• 2008 Gen 2 Prius
• 330,000 km (or 205,000mi), still on original HV battery.
• 2nd owner, we bought her in 2018. Original owner was a mechanic who took good care of her. Sadly we haven't been as careful. She does get serviced every 6 months and our mechanic consistently says she's in great mechanical order for her age, but he's no expert on hybrids. Neither am I.
• Australian climate, no garage or carport so the poor thing cops full sun in summer. We crack the windows and put on an external windscreen shade when we can, but it's still seen some serious heat over the years.
• Daily city commuter until 2020, since then it's been mostly used for shorter trips, would sometimes be a few days in a row of not being used. However for the past 3 months we've been living in the country and doing mostly very short drives on bumpy potholed roads to the neighbours, and the occasional long highway drive to the city.
• We love her. She's safe, roomy, comfortable, cheap to run. She might look like hell but we'll happily replace the HV battery if we need to, not going to find a more reliable car for the $3000 AUD it would cost. Here she is now (if you think the side panel damage is bad, wait until you see the roof and spoiler, it's a clearcoat massacre. Alternatively, ignore it like we do and just admire her for the trusty family car she is):

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The problem:

• For about the past 8 or 9 months the SOC/battery levels have been gradually getting more temperamental (discharging and charging faster). This has been much more noticeable in the last 3 or 4 months. Often I'll start the car and it'll be on purple bars, and then within a minute or two of driving it will be up to green bars. A year ago it was on blue 90% of the time, now it's probably split equally across purple, blue and green.
• It feels like the combustion engine is working harder than it used to. I see it coming on way more often now on the MFD than it did a year ago.
• Fuel efficiency (MPG) has not changed though. The average has always hovered around 5.3-5.4L/100km (43.5MPG) for more than a year, and that hasn't changed. Also watching the yellow bars on the MFD, it doesn't look to behave differently to a year ago.
• Might be unrelated, but a week ago while doing a tight turn on a highway off-ramp, the red triangle of death light came on for a split second and then disappeared. I searched PriusChat and the consensus seemed to be that it was probably low on oil. Dipstick seemed to show it was very low (my bad for rarely checking it) so I topped it up. Hasn't come back on since. It sounds like it might be consuming more oil if the combustion engine is working harder to make up for a dying HV battery?

The big question:

• We could keep driving it as-is, until the great red triangle of death comes up and throws a code, and then we know for sure it's time to replace the battery pack. If we do this, are we damaging the combustion engine by continuing to drive it now? And if we know we'll have to replace the battery pack in the next 6-12 months anyway, should we just bite the bullet and do it now?

Just want to know if there's any reason we shouldn't go and get the battery pack replaced (ie if this sounds like a typical 12v battery problem instead).

Thanks all.

 

Thanks bisco & nancy for the responses! That's the reassurance I was hoping for.
Cheers

 

Ah beaut, loving all the responses. Thanks heaps sam spade 2, mr_guy_mann and Frank1956.

Sam- Good points. I've now started checking the oil levels every few days and taking a photo to track the rate of consumption. You're right, she is old, but aside from the recent oil consumption issue she's never had any other problems (since we've had her anyway). She has a solid service history too.

Mr Guy- Yep it's our only car, agree that we should figure this out now before a real problem starts.

Frank- I'm inclined to agree with you. She's been really cheap to run, no mechanical issues to date. We're not looking to upgrade to another car (the plan is once our kids are at school-age we could ditch car ownership altogether. We'd get an electric cargo bike and subscribe to a carshare service- much cheaper than rego, servicing etc). So it suits our timeline pretty well to just keep this one running for a few more years.

We actually got her serviced yesterday (prompted by our toddler ripping the rear view mirror off the windshield, but she was due for one anyway), mechanic said she looks all good, just needs a new drive belt and apparently the exhaust needs replacing.