Gen 2 ... Dr Prius says two blocks bad

Sorry chaps... you must get lots of these

69 year old ag engineer

135,000 mile old Prius

full range of lights on - triangle, brakes etc - they have been like that for six months

- then two weeks ago the car mpg fell from rock solid 61mpg -(English gallons) to 50 mpg

I bought a dongle and ran Dr Prius... It said that blocks 2 and 3 are bad

so I bought four second hand battery units for £22 each

took the car apart and replaced blocks two and three with the four ebay battery elements

same symptoms

and here is the film

when under way the pack voltage drops from 220 or so to 160 or so

blade voltage also falls to around 6 - but only for short periods - the IC engine never turns off

what - what next?

also it says that the 12 volt battery has no voltage although avometer says it has 12 volts in it

 

Thank you B,

I do have some corrosion on the bus bars and spent some time last night looking for ways to clean them up...........



I have checked the voltages on the removed battery units and they seem okay - the voltages on all the units seemed okay - although I did not load test them

I shall remove the battery again and have a good clean up of all the connections on both sides of the units

planning to use vinegar and fine sand paper - is that okay

the car is an ex uber from London so I assume that it has had lenty of moisture in the back - there was some sign of corrosion around under the seat

I shall re-approach the problem with renewed optimism



Dylan

 

with joy in my heart and spent the morning diligently cleaning the bus bars and contacts on both sides of the battery until they shone like burnished gold

the good news is that the skid light warning has now gone out

the long term battery longevity test said that the battery registers 59 per cent - which is better than yesterday when it said it was 46 er cent.

however, Dr Prius is still throwing weird stuff from blocks 2 and 3 -

I have lots of codes from the battery test

the lovely woman said that my battery needs attention

and offers me several codes - enunciated at the end of the film

P0A0D

P3000

P0a84

P0aFA

resistance is fine

loadtesting bottom voltage block 3

should I scrap the car and a Ford Focus

 

I have just spent the past two or three weeks attempting and failing to solve a battery problem on my 135,000 mile old Gen 2 Prius. I bought it four years ago for about £3,500 when it had 95,000 miles on the clock. The annual service has been about £300... plus a 12 volt battery... brakes and steering... tyres etc. Not too bad. The local garage said that they would look after the mechanics but anything electrical is down to me.

It has been turning in a rock solid 62mpg (UK gallons). About 18 months ago the red triangle appeared - then followed by the two brake warning lights - but the car drove as well as ever.

I did the paper clip trick and disconnecting the battery to clear the lights but they soon came back. Then about three weeks ago the mpg went down to 50mg, the engine was on all the time and the little arrows on the energy monitor kept flashing green and orange - clearly the battery was no longer pulling its weight. The battery level was close to the green - but still blue.

So I bought a wireless scanner and downloaded Dr Prius

That told me that there were two dodgy blocks - blocks 2 and 3. So I bought four ebay battery packs at £22 each - took out the battery - installed the replacement blocks - checked the voltages of each battery and they all seemed fine - as were the voltges on the four cells I had removed. An ominous sign.

There were signs - bits of sharpie across bolts and battery blocks that suggested that I was not the first person to delve into the battery. It had caused problems in the past... before the 95,000 miles

I was surprised at the amount of corrosion on the bus bars - I cleaned them up a bit - but thought it best to leave them well alone

I redid the 150 odd bolts and nuts to replace the battery - turned on the car

same problem.

I started a thread on here

Gen 2 ... Dr Prius says two blocks bad | PriusChat

there are a couple of films of Dr Prius. You can seen that it was throwing a lot of faults at me.

I removed the battery again - and as per instruction on web I polished all the bus bars and put them back. I used vinegar and sandpaper. This was a first for me attempting to repair anything with vinegar. It felt a bit silly.

Re-intalled the battery - same problem

Dr Prius was also reporting faults on every module - and weirdly double reporting more faults on modules 2 and 3.

Then following a suggestion from Bryan I took out the battery cleaned up the BMS cables and saw that there was some corrosion on the 14 pin socket to the BMS.

(I trained as an ag engineer 45 years ago and have owned a string of diesel cars over the years. I have done some serious engine repairs on tractors and small vans, I build ebikes so I am not a numpty but this was my first experience with Hyrbrid batteries - this has not been a good experience as I was losing at every turn.

I spent a lot of time on forums and watched lots of really annoying videos on youtube - emntioning no names but some of them are way too fond of their own voices.

I cleaned up the connections re-assembled the battery and suddenly it started to run really hot - 178 f. Red lights all over Dr Prius.

I was worried that the car was going to catch fire so I removed the battery quickly and set it on the drive - it stayed hot for about an hour. There was some swelling of the cells. Then it cooled down and the cells went back to their proper shape.

I put the battery back in and fired up the car. Same faults again - as expected. But no overheating. I have since driven it for an hour and no repeat of the overheating.

Dr Prius threw up so many fault codes it made my head spin. Some I could not find on the web.... or said could be the fan, could be the BMS , could be the Control unit module.... it also said that I had problems in every cell. Details on the other thread. Dr Prius just kept telling me that my battery needed attention - duh!

I found one local repair man who said he would have a look at it - but warned me that it would be expensive. He was basically telling me that he could fix it - but it would probably not be worth it and he needed to keep the car for two weeks!

The local Toyota dealer wanted to replace the battery with a new one and replace the BMS and the control unit. The bill would be more than the car would ever be worth.

There are some second hand batteries on ebay at about £500 a pop - the nearest is a three hour drive away in Nottingham - the bloke wants cash... it would have a one year gauarantee but he wanted to add £200 for fitting it and there might be more costs on top.

but I still do not know if that would solve the problem. I have never heard the cooling fan go on - It was clean - no clogging .The fan runs when connected to 12 volts but I have no real way of testing the sensors it as the battery does not seem to get hot enough to fire it up - is it the temperature sensors, is it the main computer? I still do not know and am no closer to finding out how to find out.

I was now five days into this - and still no solution. The car still runs - but the battery is still not helping. The battery temperature is about the same as the interior of the car - peaking at 20c. No red warnings on Dr Prius. Not a peep from the fan but it would only be blowing cabin air through the battery anyway.

We only run one car so it needs to be fairly reliable.

On the bright side I am now getting really good at fitting and removing the battery and upholstery - three fittings so far.

However, I still do not know what the problem is and am worried about throwing good money after bad.

The car has been really comfortable and fairly reliable. Certainly quite economical.

For me the big downside is that the corrosion inside the battery is alarming. I do live near to the coast in the wet UK and the car is kept outside. I have had a slight leak on the back quarter gutter - which I sealed up and the 12 volt battery box often fills with water. All common Prius faults I now see from the web. These are pretty bad faults for a car in a wet climate.

As an aside I am a sailor and was thinking of converting my small yacht to electric but the thought of a BMS with its tiny wires and many, many connections in a marine environment is not encouraging. I fear that I will stick with the 25 year old smelly diesel inboard for a bit longer.

Dr Prius and fault codes seem all very well and initially make you feel rather powerful...but less than specific about what is going wrong. Some of the fault codes are weirdly vague when I look them up on the web.

There is a Gen 3 Prius for sale at £4,000 some 50 miles away - it has 100,000 miles on it but I do not really trust the batteries or the ability of Dr Prius to identify much of any value or of Toyota to produce a waterproof Prius.


As a scrapper the old Prius is worth about £400. It still runs without the help of the battery ... but I do not know how much longer it will do so.

I will not sell the car yet - but we will be buying an 80,000 mile old Diesel VW Polo for £2,500 - they are slower, noisier, less comfortable, more economical and it is easy to find a local garage who are willing to repair it.

I will not yet scap the Gen 2 Prius and would still like to get it going properly as the mechanics seem fine - the battery and associated computers are the problem

But I will not be buying another Prius even if I get this one going as I am not sure that they are all that good in a damp environment and the battery on this one has obviously gone wonky twice in 135,000 miles.

I am open to suggestions - a neighbour who was a tank mechanic said he would help me have another go at it so I am still oen to suggestions or shared experiences.

Please don't flame me as I am rather foolishly using my real name on here.

 

there was a tiny amount of corrosion on three pins to the BMU down in the same corner as shown in the osts linked above

I cleaned those up - re-instaled and then the battery started overheating

I removed it again and it stayed hot for about an hour and then cooled down

I re-installed it all ran the car and it was back to the first state - bttery not performing but not overheating either

I see that a second hand BMU is around £65

there are lots on sale on ebay

that maybe worth a punt

Dylan

 

the ebay seller says that they are for gen 2 and gen 3 Prius

is it the same unit in both cars?