Does it hurt anything to Drive with Bad HV Battery

You are beyond 150,000 miles?

 

Oh. Sorry about that.

My guess is you'll be better served by finding an HV battery in salvage. This topic has come up several times before. If you are quite fortunate, you may find someone on PriusChat who is willing to help you replace the battery.

 

Luscious Garage - Gen 1 Battery Failure.

Explains the symptoms, likely future problems, and cost of remedies.

 

Driving with a bad module will probably hasten the demise of further modules (more charge/discharge cycles and higher charge/discharge currents).

I hear from this site that the 2001-2003 used batteries are getting expensive (demand). I also hear some have been making a new battery by using modules from the 2004-present model. It takes two batteries to get enough modules ($400 each), and there will be physical implications as well as interfacing issues re sensors.

The trade option may be your best bet. Many Toyota dealers have lots of new Prius in stock that they would like to move.

 

Contact Bob Wilson

PriusChat Forums - View Profile: bwilson4web

as he has been experimenting on charging and module replacement in classic Prii.

JeffD

 

Good, fast, cheap:: pick two of three.

1. Battery replacement is good and fast.
2. Swapping the traction battery by getting a salvage, is cheap and fast. You don't know how good that battery really is!
3. Good and cheap means learning a lot more about NHW11 batteries than you every possibly wanted to know:

Prius Battery Photos

If this is your primary car and there is no backup, look at #1 as giving you a potentially 50 MPG (or whatever you are currently getting) for $4-4,500 (depending upon negotiating skills.)

Swapping the traction battery can work but a used Prius NHW11 traction battery is somewhat iffy. Toyota changed the modules with the NHW20 and the new ones are much, much better. Regardless, you will need a smart NiMH charger such as a $150 RC, computer controlled one. You'll also need a couple of weeks depending upon your technical approach.

Refurbishing the individual modules remains a very experimental technique that I have put aside for a while. The problem is the terminals in the NHW11 battery look to be weak and there is no easy way to 'toughen them up.' Normal internal pressures can lead to electrolyte leaks, which eat up the bus bar and eventually fail the battery. There is one highly experimental approach I've been thinking about but it is scary ... (ask me in "Prius Technical Stuff".)

So life isn't easy and you need to make choices. If your transaxle oil looks good (you've been changing it, right?), a 50 MPG car for less than $5,000 looks like a steal to me. If you still don't like it in August when gas prices peak, sell it and get some of your money back.

The swap of a slavage traction battery or get two, NHW20 batteries and charger to balance the cells would cut the price nearly in half but double or triple the down time. Sweat equity, it can be done and be half-way interesting.

GOOD LUCK!
Bob Wilson

 

When you guys speak of bad "modules" you mean bad cells, I assume. There's just the one battery "module" in the Prius, yes?

 

A module is one of the grey things, 6 cells, 7.2 nominal volts.
A "block" is two modules, which is the granularity with which
the battery ECU monitors things along the string. That's still
enough to tell if a small portion of the string has gone bad.
One big hazard after a cell goes bad somewhere in a block is that
it's going to get reverse-charged fairly often, since it can no
longer "push back" against all its neighbors with regard to handling
charge and discharge current; that only makes things worse and
you wind up with a region of high internal resistance in the
middle of the string somewhere, basically making the whole pack
unable to supply or accept enough current. Even if all the other
cells around it are still good. But hopefully when a cell reaches
that point the other cells are close to the same end-of-life
point so it makes sense to change out the whole pack.
.
Some people *have* changed out one ailing module and had acceptable
results that tides them over for a while, especially if it's
relatively early in the car's life. I don't know the long-term
success of such fixes.
.
It's starting to sound like trying to refurb NHW11 modules isn't
so worthwhile, but the concept of building a pack from NHW20
modules is pretty cool. They're slightly shorter so they should
fit in the NHW11 case. Question: are they exactly the same length,
as implied by Bob's photos? Would they require extensive mods to
the case to make sure they stay in place, and don't swell, or are
the original end-plates and battery box fittings sufficient?
.
_H*

 

I think the module dimensions came up here and following in the same thread (somehow I think I also found dimensional specs somewhere with the same finding that the terminal-to-terminal (longest) dimension is about 10mm greater for the newer modules (though their height may, as I suspect you meant, be less).

Of course the extra 10mm terminal-to-terminal would make me very cautious about putting the steel cover back over the bank. When I realized there are black plastic insulating covers to snap over the bus bars before the lid goes on, my concern about that abated some, and Bob Wilson did not seem to be concerned about it. I suppose you'd probably feel any interference between the plastic insulators and the lid while putting it on, and without blowing anything up. As long as there's ample clearance that shouldn't be a problem.

I think the only other significant mechanical difference is that the old modules have a threaded insert in the bottom foot at each end, to be secured to the carrier plate by two machine screws per module. I think the new modules have the threaded insert for only one foot, and the carrier is stamped with lips to stick the threadless-foot-end of each module under, securing with one machine screw at the other end. I haven't seen one, but it must alternate lips and screw holes as the modules alternate direction.

The old-style carrier plate won't have the necessary lips. But I can't imagine that once all the modules are secured by one foot screw each, mated to each other by their interlocking dimple/wart patterns, and clamped between the end plates, they'd be likely to go very far vertically. I haven't experimented.

-Chap