Targa80’s Electrocooler install final thoughts

[targa80]

Well it has been several weeks since I completed the install of the Classic Retrofit Electrocooler, 175 amp alternator and the Boxer window washer bottle relocation kit. My overall impression is the systems work as advertised and I have no real complaints and I am glad to be able to drive my car without sweating to death. I have spent several days on and off tweaking the system using a laptop and the usb cable. I live in Florida and so does Duc Hunter who created a thread with his thoughts on setting up and testing the system in a hot and humid environment of Florida that is excellent and a must read if you are installing the Electrocooler.

The following are the settings of the system that I have settled on after testing. The settings can be displayed using the list command.




The day I charged the system it was in the low 60’s outside and the center vent temp dropped to 39 degrees right off the bat.




Since that day, I found with warmer weather the center vent temp stalled at 49 degrees when the weather was above 80 degrees. Duc Hunter suggested closing off the top fresh air vent to help lower the center vent temp. On my other cars I always use the recirculate function instead of the fresh air function. Well closing off the top fresh air definitely helped.

The center vent temp dropped to 39 degrees while driving.



The laptop was providing the following data.





I have a VDO volt and amp meters located where the ash tray use to be and the readout while driving showed the following.



While stopped at a light the voltage dropped and the amps went negative. This is expected since the ECU tries to maintain cooling and lowers amperage and operating % based on drop of alternator output voltage.



The laptop readout showed a drop in the voltage and eventually a drop in operating speed % and amperage demand.




The temp at the center vent continued to drop slightly to 38 degrees while I was driving and the outside temp was in the mid 80’s and sunny with humidity in the low 50% range.



If I was at a stop for an extended period of time the operating current and the percentage would eventually drop to zero and the AC power light would go out. The alternator would then recover the operating voltage level and charge the battery and once stable above 12.6 volts the AC would turn back on and continue cooling.

I am sure as the weather gets warmer and more humid I will look to add a thermal blanket over the blower evaporator unit and minimize any leaks of cold air.

The decision to go with the full system with the high output alternator was the right way to go. Adding the boxer window washer kit was a no brainer since you need to remove the 911 washer bottle to install the front condenser.

[reclino]

How much current can the uprated alternator supply at idle? I am very interested in this mod, but it's a big chunk of cash to lay down.
David

[targa80]

Originally Posted by reclino

How much current can the uprated alternator supply at idle? I am very interested in this mod, but it's a big chunk of cash to lay down.
David

The setup for the alternator states 90 amps at idle but you allow for non ac loading and set the total amps for the AC at 75 amps which is five amps less than the 80 amp in-line fuse. The actual idle amperage output will vary by the pulley ratio and the idle engine speed.

I am fully aware that a negative amp draw is from the battery. The issue is how much of a current draw from the battery and for how long. The ECU monitors the voltage and current and based on voltage will decrease current demand by lowering the operating percent of the compressor and eventually lower it to zero. Essentially shutting the compressor off until the alternator brings the battery voltage back over 12.6 volts. At idle the new alternator can handle the normal power requirements. It is a matter of fine tuning the AC ECU to handle the longer idle times by lowering the load demand of the compressor at idle.

Hopefully, someone else will provide input on the individual settings that can be used to improve the stability of the output voltage/current while at idle. My old marchal alternator went negative at idle with only normal operating loads. Put on the lights and the wipers and the alternator lite would glow (not good)

[Jonny H]

Hi Pat, good write up as usual.

As you have discovered, the ECU's internal software is essentially a power management system, its primary aim being to prevent the compressor from 'outrunning' the charging system, which would result in a drained battery. Its secondary role (but arguably more important!) is to deliver cooling in the most energy efficient manner.

The ECU regulates the compressor current by adjusting its speed (slower = less current). This sounds simple enough on the face of it, but it is fairly complex for a number of reasons. The current consumed is not only proportional to the compressor speed, but also to the ambient temperature. In addition, the charging system output is dependent of engine speed. The compressor speed required is also dependent on the cooling demand ( difference between set point and actual cabin temperature ). The cooling demand depends on the temp and humidity.

Another dimension to the challenge is added by the the battery. Battery voltage sags when the current draw is high and the reduced voltage then causes the current to rise. This can become a viscous circle. This is the main reason why ON/OFF electric AC systems with no speed control strategy have not been very successful.

So when I get asked 'How much current does the system use?", the answer is always 'It depends' (although we cap at 75A typically).

The 175A high output alternator typically produces around 75A at idle but this depends on the pulley gearing and idle speed as you say. I generally setup a car so that with the AC on in warm weather, the battery voltage will sit indefinitely at around 12.5 volts. Do this once you have the car cooled after a run. This will prevent full cut off of the AC but will do the slow down at idle.