Battery dropping to low purple on start up

That's not normal, you have a weak battery. Need to charge and balance before it fails

 

Hope it has a warranty.

 

Doesn't sound like it was rebuilt, sounds like someone swapped a module and didn't charge and balance

 

what company did you get it from?

 

Not a good sign for a "new" battery, however pretty much standard fair for an old worn battery. I've got a 2005 model with 300,000 km that's still on the original battery, and mine will do that every time unless I let it warm up for about 45 seconds before driving.

Other than that mine drives perfectly and still gets great fuel economy. So I just let it warm up for a minute before driving in the morning, no more purple one-two bar battery issue.

Before the cats get up to temperature the Prius tries to use the battery more than the engine, so it takes a bit of a beating in the first 60 seconds of driving if you don't let it warm up. Traction batteries in prime condition cope with it ok, old warn ones not quite so well.

 

While it is somewhat sad, those opting for a "rebuilt" battery should ask EXACTLY what the word "rebuilt" means to that supplier.
There is no standard definition.

 

The fix is simply to charge and balance. Nothing really too complicated

 

Modules probably need to be grid charged then load tested to ensure all is well of that battery was recently rebuilt.

 

Well it is what it is, charge and balance and hope for the best. If OP is going to take it apart again, he should test everything and clean the bus bars too

 

By charge and rebalance do you mean something like a Prolong reconditioner? Do those work well?

 

Yes and yes

 

+1!
Prolong Battery Systems. Extending the life of your hybrid. – Hybrid Automotive
Not affiliated, btw. Just a happy customer.

 

Same here, well worth the money whether you have a new HV battery or an old one you're trying to keep going.

 

My 2008 Prius is up to 370,000 miles, and goes down to purple when going up bigger hills, and early in morning. Would this help? How hard is it to do? Thanks

 

I would think it would help. Not sure how much it would get you long term with that many miles. Maybe @jeff652 will be able to give you a better idea. I think it would depend on how bad any particular cell is. If it's just badly out of balance, I'd expect it to help quite a bit if you do the full reconditioning routine.

Edit to answer the other question: It's not very hard at all if you're reasonably handy. You have to take out some panels to access the battery and its fan. There's a little controller box that you have to wire into the cable to that fan. And, of course, you have a couple wires to connect to the battery pack. It'll probably take a couple hours if you haven't done it before.

 

Specifically for this situation, try letting the car sit in READY (with HVAC off) and wait until the ICE shuts off which takes about 50 seconds. It seems like a lot longer, but if you time it you will see that is ~50 secs. This signals moving from stage 1 to Stage 2 of the Prius engine warm up cycle. (Read one about the 5 stages of Prius warm up in my sig.)

Why this may help, is that during stage 1, the Prius almost exclusively tries to use the electric motor to propel the car, so that the ICE can be configured in a very inefficient (fuel economy-wise) but hot running configuration to get the initial engine temperature up quicker. Because it uses the electric motor to propel the car, it draws heavily on the HV battery, and if your HV battery is at the poor end of the scale, it is quite taxing on it. If your HV battery is at the good end of the scale, it has no problem propelling the car, as it is designed to do. YMMV.

hope this helps.

 

Okay, battery getting much worse. It's staying in purple(SOC is 20-35)most of my commute on interstate ( 70 miles). when I get off interstate it comes back up in the blue. Motor really struggles on hills, I am afraid its going to blow. Worse in the morning when its dark. Here are my options

1. I called dealership they quoted me a price of $3700 out the door for new hybird battery.
2. I called around, and a few junk yards have them for $850(2009 114,000)
3. Trade it in for a new 2017 Prius Three (Blizzard Pearl).

 

It appears that you're driving your Prius too hard for it's current age and condition. If the SOC is staying in purple for most of your 70 mile interstate commute then it means that the engine is just not getting enough opportunity to charge the HV battery. All of the power that the engine can muster is being commanded (by you) to go to the wheels, so none goes to the battery.

Even with a brand new HV battery, it can only cover for lack of engine power for a limited amount of time and then you're still going to end up with low SOC if the engine can't provide enough power.

A new HV battery will definitely help, but it might not completely solve your issues if the engine is genuinely sick (low on power).

As a temporary measure can you try warming engine for 45 sec to1 minute before driving as I suggested above. And try driving just a few MPH slower and pushing it less up hills.