2001 prius battery problem and pictures

A couple weeks ago, my 2001 prius would drive normally for about 10 miles then decide to go into limp mode, turtle light triangle brake light, check engine light.

I also noticed that the MFD shows the battery as full, then all of a sudden it would drop to the last "bar" then recharge, that would happen about 5 times then the warning lights come up.

This prius was a salvage car restored, roughly 40-50k miles later this starting happening. the vehicle was not covered under any warranty so the battery seal TSB was not performed on this car.

I have worked on the HV battery before, with my charger, so I understand the dangers associated with high DC voltage.

Today I removed the HV battery from the vehicle and examined the copper plates which were severely corroded.

Here is the imageshack gallery:
ImageShack Gallery

[imglink]http://img6.imageshack.us/img6/613/img8102m.jpg[/imglink]
[imglink]http://img6.imageshack.us/img6/3261/img8103o.jpg[/imglink]

this is the area with worst corossion, i recorded the lowest voltage accross on this module, 7.2 volts vs the rest which were 7.8 volts.

[imglink]http://img99.imageshack.us/img99/4018/img8104.jpg[/imglink]


heres some questions, would any experts here suggest removing copper plates, cleaning them with a solution and wipe around the positive and negative terminals, then applying a sealant ?

also can i use muriatic acid to clean the oxidation off the copper?

 

i checked all the batteries with a volt meter, i got the copper plates off and the orange things surrounding it, the terminals itself look really clean.

I measured 7.8 volts on all the individual modules except for one, which read 6.5 volts. This set that read this low voltage had some real good corrosion.

Luckily i finished rebuilding the accord hybrid in time, so I have that and the 05 prius to drive.

I was planning on repainting the 2001 prius and this ruined my plans


also I was wondering since each module is 7.8 volts wouldn't that make the total voltage 296? which is considerably too high i think.

My guess is the compression was giving the battery ECU a false capacity reading and making the hybrid system charge the battery continuously

 

ok i made a typo, the one that measured 6.5 is located where there was no visible corossion, Im thinking that maybe the corossion could cause varying voltages between the modules.


i also checked each module to the battery case, one of the modules, specifically the one that had major corrosion read 2.4 volts to the battery case, the rest of them read 0 volts.


the bus bars are removed and i cleaned them and have them sealed until im ready to reinstall, tommorow im probably going to buy some 3m contact adhesive similar to what toyota used for the TSB.


im not sure whether or not to keep going with this battery or to purchase a salvage battery

 

more pictures to clear up some confusion

the module that reads voltage to the case
[IMGLINK]http://img7.imageshack.us/img7/6638/img8116m.jpg[/IMGLINK]

corossion underneath the module
[IMGLINK]http://img526.imageshack.us/img526/1006/img8112.jpg[/IMGLINK]

how i read the voltages red is the positive probe and black is neg
[IMGLINK]http://img196.imageshack.us/img196/2994/img8117.jpg[/IMGLINK]

heres a link to the gallery
ImageShack Gallery

from the battery computer the modules 1-30 were fine, i think it was 31 or 32 which read 6.5 volts, this module had no visible corossion.

im suprised that the module which is reading voltage to ground is still good reading 7.8 volts, maybe it is the KOH leaking and its virtually invisible to my eyes, i got my hands on some dielectric cleaner and 3M electrical compound, but im thinking of taking apart the battery case and removing some of the modules with massive corossion on the bottom, i somewhat want to do this right so i wont have problems in the future.


to take apart the battery case i would remove the restraining bar on the top of the whole thing and the modules should pop out? also looking at the bottom of the case, i see 10 MM bolts which seem to hold each module in place.

im not sure where to go from here, im thinking of charging the module with 6.5 volts and doing a load test to see whats going on.

would a 04-09 prius module work on the 01 prius battery? is it physically the same size? i understand its the same voltage, but does it have the same power? i find that the 04-09 prius used HV battery are considerably cheaper than a 01-03.

 

how hard is it to dissassemble the pack, for example to remove one module?

from what i can see the vent hoses just pop off and there are clamps for the restraining rod, and then the thermistors.

so once those are removed should a module pop out once i unbolt the 10 mm screw underneath?

also, would that 6.5 v module cause a DTC?

and lastly, to clean the goop can i use 90+ % ethyl alcohol?

 

ill take out the module that is leaking to ground today, i cleaned out the visible areas of the module and its still leaking, so today ill lift up the module and take a look underneath.

 

ok bob wilson remember how you said the electrolyte is damn near invisible? well it sure is because i wiped down the terminals with alcohol and dielectric cleaner,and the battery that read voltage to ground still read 2.5.

I decided to seal around the terminals with the stuff toyota uses, ( similar stuff just not the same color ) 3m electrical compound, so I proceeded to seal around the terminals. 2 hours later after it dried somewhat i checked for voltage across each module to the battery case 0 Volts, not even 0.01 volts, i was suprised, so this electrolyte is sure invisible.

the rust under module 3-4 was due to electrolyte leakage, the module itself is in good condition. The 6.5 volt module handled a charge to 7.8 and is holding it, upon a load test it still stayed at 7.8 volts, my guess is the corrosion lead to varying charges of a few modules.


Here are pictures of the final product, tommorow ill reinstall the bus bars and give it a try. wish me luck

i know the goop looks like a fluid grease type of thing, but its harder than the plastic on the battery.





I need to find pictures of the battery from 6 years ago, I believe i posted them somewhere. it would show the change in the corrosion over the years.

 

module 3 and 4 had a leak probably there for years, and those two modules had the most corodded bus bars.

the stuff i put on is VERY hard now, you cannot even scratch it off, maybe a tiny bit more will leak but it sure beats reading 2.5 v to the battery case.