Engine overworking with little Turtle Sign on the left

does this diode thing work on the 2001 prius

 

yes,

will work on all nw11 models and should also with the NW20 with the correct pin-outs(not shown) as the temp sensor is exactly the same(encapsulated PT100).

Hannah is coming around and we'll install and see if its just overall battery capacity or likely a dead cell.
Could be either,but given he does really short trips in the car around 5-7km,here's hoping all that continuous charging hasn't nuked a cell.
You need to use 2x signal diodes in parallel as the circuit caries around 20-30ma from memory and most signal diodes aren't good for that continuously.
The .2v across the diode is the important factor in diode selection.

regards
Graham

 

I didn't know NiMH even had a significant memory effect....

-Chap

 

It doesn't. The NiCd cells do. The literature suggests it may be associated with dendrite formation, another NiCd characteristic.

Bob Wilson

 

Yes,it was invigorating to see the improvement in Hannah's vehicle's performance.
Lets hope it continues to improve.Certainly a lot peppier now anyway.

Anyone doing this mod to regain battery capacity must creep in their car at low speed for as long as possible to draw the battery DOWN initially then take their foot off the accelerator when the petrol motor kicks in and try creeping again and so on.Ignore the turtle.Slowly the gap between the turtle coming on and the motor charging should decrease,until the motor charges the battery before the turtle arrives.
Once sorted you will note the turbo like pep when accelerating compared to sluggish vehicle you owned prior.This should slowly improve until it gets as good as it can be.
My NW11 with 285k on it can creep between 1-1.5km on the flat at around 50km once up to that speed with a steady foot on the pedal,without the motor kicking in.

Hannah plans to produce a description with explanation in his words of the mod as i left him a little confused with my posting.

I will however explain my observation of the turtles operation.

The turtle or motor/ battery alarm is initiated under two conditions in the NW10 and NW11.
It is not unusual for it to throw up all other manner of unrelated alarm codes either.
Firstly if any cell bank falls below a minimum voltage and secondly if any bank of cells falls around 1.2v below the highest reading bank-thus indicating one cell in a bank is POSSIBLY dead /dying.
Cells continually charged but rarely discharged can build a high internal resistance and a way of relieving this situation is to run them flat and then charge them up again.Known as "the memory effect" and well documented with Ni-Cad batteries.
In layman's terms its asking a unfit continually overfed man to run a mile against a lean fit man used to the run.
This high battery internal resistance creates heat on a charge and discharge cycle just like a fat man sweats and that is why your battery warms up and its fan motor starts.
Motor revving fast cycling occurs when the low voltage bank triggers a charge and charging stops when the highest voltage bank reaches the upper limit.This can heat up a battery rather fast.

If the battery gets too hot thru this continual cycling the battery will be disengaged from the charging circuit,it is not just temperature but also the actual rate of temperature rise that will trigger this.
That is when you pull over and turn off the motor and turn it on again,which resets the parameters,you often can continue normally as if nothing has happened.

One important thing i did garner from ' ECOMOTIVE' was that if you ever change a cell with a second hand one,you do not need to worry about balancing the HV battery as a consequence of the 12v battery is charged from the HV battery and it would appear to me that involves automatic selection of the highest voltage HVBank to charge the 12v battery.So any rebalancing is automatically done on 12v battery charging and can be hastened by running the air conditioning and 12v battery draw.

The use of an OBD2 connector and an obsolete version of" techstream" from China for $9.95US incl courier mail has helped considerably with these battery observations.However this did not work on Hannah's model NW10.

I believe if you understand your battery operation then you understand your Prius.

Toyota didn't build these vehicles to be embarrassed or humiliated and Hari Kari is not the desired end of employment option in Japan for senior management.So us early Prius owners have got a ROLLS ROYCE designed vehicle for a chicken feed cost.Mine continues to do 110km/working day,saving me $80/week in gas at at least 880km/44ltrs a tank full doing most of it at 100km/hr.(speed limit)
Still I'm talking to the converted here.

regards
Graham

 

Were NHW10 batteries not only D-form instead of prismatic, but also NiCd instead of NiMH?

-Chap

 

what does this do exactly? make the car think the engine is warmed up? so when you start it cold it runs for about a minute then shuts off?

 

Hi Graham,

First I want to thank you for the details about New Zealand resources. However, I wanted to add some details about the diodes:

A typical silicon diode has a 0.7 V forward drop. What this means is if the voltage is higher than 0.7 V, the diode conducts and nearly regardless of the current, the diode will sit at 0.7 V. Now polarity is important because reverse biased, the diode will not conduct.


The ideal configuration is to alternate the signal diodes so if one does not conduct, the other will. In effect, it clamps the voltage a 0.7 V in the engine thermostat temperature-voltage curve:

Source: http://techno-fandom.org/~hobbit/cars/ect/ (and others)

Because of the parallel installation, the signal diodes will shift the indicated engine temperature up but stop working as it reaches higher operating values. The problem are those of us who live where the temperature reaches freezing. If the engine is too cold, the diode hack can lead to the engine stumbling and dying.

Now if I were doing a strictly analog version of my microprocessor based hack, I would design a long RC time constant base circuit (i.e., big cap, high resistor) that feeds a signal transistor base through a signal diode. The long time-constant would be in the order of 60-120 seconds to enable "closed loop" mixture control from the O{2} sensor operation before enabling the transistor so the engine coolant can reach a stable operating temperature. But I kinda like my microcontroller hack.

My hack measures the temperature and if too low, leaves the bias out until the engine coolant reaches 30C. But it also monitors the engine cool-down when in freezing winds. So instead of letting the engine start upon reaching the lower 60C, it lets the engine cool even further but not below 30C.

The diode solution works great in moderate, non-freezing weather. But in colder weather, it makes sense to have a driver accessible switch to disable it if it is too cold.

Bob Wilson

 

how low would you say the temp should go before one would install that switch. here in pa, last year i saw 10 f overnight

 

If you ever have ice, frost, or snow in the morning, install the switch. If you drive somewhere that it gets cold enough for ice, frost, or snow in the morning, install the switch. In short, install the switch regardless as you are going to use it.

Bob Wilson

 

haha, lol sounds like a good idea to me. this weather is screwy up here anyways. its was 95 and humid last week for 2 days now i see my breath in the mornings out here. crazy

 

Forgive me if I missed this but the item you describe says its fr a VW? But you say it works for a gen 1 prius, please explain.

Also do you or anyone else know if this unit is comparable to the "AutoEnginuity OBDII Windows Scan Tool" here is a link to one on ebay Electronics, Cars, Fashion, Collectibles, Coupons and More Online Shopping | eBay I am interested in purchaseing one of these I just want to purchase the correct one.
Thanks for the help