EVTV and Water Cooling the Soliton1

I’ve been watching EVTV for years now, I don’t always agree with what Jack says but it’s still somewhat entertaining and usually informative even if you only learn what not to do from Jack’s experience.  Love him or hate him, Jack is doing great things for the EV community and his show EVTV is one of very few current information pipelines.  His shows tend to be long and boring to the non-EV type person however those of us who have done, are doing, or plan to do a conversion can relate to his stories, experiences and mishaps.  Jack had been playing with the A123 pouches for a very long time but never ended up with anything in a car, I had expected him to beat me to the finish and show everyone what the cells can do.  He’s busy doing other things and I’ve got my car on the road and I drive it every day so I thought I’d share my experience and build with his viewers.  My video is crappy and shakey, I should have narrated over or at least spoken during latter part of the drive, but I’ve had good feedback about simply sharing.

I’m confident that many more people find out about me from his show than would find out about his show from my blog, but if you haven’t already watched the August 17th episode of EVTV I would say grab a coffee and a comfy seat and enjoy the show.



The Soliton1 is an amazing controller, it’s powerful, feature rich and simply works.  I live up in Canada so our average summer temperatures here in Calgary are between 20-30C  (68-86F)with the odd day a bit warmer but seldom above 35C (95F).  Due to this fairly moderate temperature I thought I would get away with air cooling on the Soliton1, well it turns out that ambient temperature plays a part but doesn’t mean the Soliton1 will stay cool on it’s own.  I believe that this would apply to any conversion in almost any location.  The Evnetics staff as started to clarify that it’s true virtually every Soliton1 install requires water cooling, and a cooler controller will have a much longer life span.


There are a bunch of companies that have put together “water cooling” kits, some based on computer water cooling parts, and others using more industrial or automotive grade components.  There is a pretty big cost variance between the two, with the computer style starting in the $250-300 range and the automotive style in the $700-1000 range.  I wanted something slightly better than the basic computer stuff but less than the automotive style.  This meant putting together a better computer style cooling kit.


I had a few main goals:  Cost, Functionality, Silence, Appearance.

Starting with cost, I wanted a system that worked better than the low end kits, but every extra dollar was worthwhile in the system.

Functionality, It must outperform air cooling with only the pump running (no fans) and must be able to automatically turn on the fans for increased cooling when required.

Silence, I wanted a system that would work better than simple air cooling in virtual silence.

Appearance, It can’t look out of place and must contribute to the appearance in install of the system.

The system is optimized for high flow fan use, but still provide effective cooling with zero air flow.  I chose a fairly large reservoir to increase the thermal mass of coolant so that it takes longer to raise the temperature of the coolant.  I chose an inexpensive triple 120mm fan cooled radiator, this radiator is optimized for efficient high airflow cooling and I used three 120mm x 38mm fans.  These fans will run well between 24-48v with 200cfm (each) of airflow at 48v.  I’ll start with a 24v system and easily have the capability to run 24v, 29v, 35v, 39v or 48v.  The amount and effectiveness of cooling required will determine the final fan voltage.  The Soliton1 has a number of programmable outputs depending on the features you want to implement, control or monitor.  I’m currently using one output to drive the tachometer in the dash, I’m using another output to represent battery current by driving the stock oil pressure gauge and the final output is driving the stock temperature gauge to represent controller temperature.  Instead of “seeing” the controller temperature I am going to configure that output to turn on the radiator fans, this is controlled by the Soliton1 and corresponds to the temperature in which the Soliton1 would automatically turn on it’s own fans.

I have not yet reconfigured the Soliton1 to control the fans, I’m still watching the temperature of the controller on my stock dash gauge, the immediate trend is that temperature changes are much slower, and peak temperatures are much lower, I will use the logger program to collect some data about the Soliton1 and compare it to some earlier air cooled logs.

I was not able to find a single source for all of the required pieces to put together this system but I was able to narrow it down to two.  There is an online Canadian store called Dazmode.com that has a nice selection of computer water cooling components, fittings and tubing that let me put together most of the system.  The fittings required to connect to the Soliton1 came from an Ebay store along with a roll of thread sealing tape.  Service from Dazmode was very good, there was one small error in my order, I received all 3/8″ tubing and no 1/2″ tubing but this was quickly rectified through the RMA process on their site, the 1/2″ tubing is in transit right now.  You will see in the pictures the clear tubing was improvised and less than ideal but let me test the system while I wait for the proper black 1/2″ tubing to arrive.

The pump is mounted level with the bottom of the reservoir so that it is always primed simply with the force of gravity on the coolant in the tube.  I used the variable speed version of the common Laing D5 pump, I like the amount of flow on setting “3” but this could be tweaked to optimize cooling with some trial and error.

I used a combination of 3/8″ ID and 1/2″ ID tubing to connect to the various components, this was simply based on the best way to connect to each piece and not for any type of flow optimization or pressure.  The type of fittings required depend somewhat on the location where these items are mounted and where the tubing is to be routed but I will make a list of the components that I used and where I bought them to make it easier for others to put together a kit that meets their specific needs.

I mounted the reservoir in a way that gave me three fitting holes in the top which allowed me to use one for the input from the radiator which completes the cooling loop, the outlet is on the bottom so that gravity does a good portion of the work in keeping the pump primed.  The other two top holes make for easy implementation of a fill hole and vent hole.  I don’t want the system to pressurize as heat is built up I simply want it to raise the level of fluid in the reservoir but remain at normal air pressure.  The vent was easy to make out of the included clear plastic “LED” holder that is already drilled 90% of the way through, I just finished of the hole with a small drill bit which will let the pressure equalize.  The other fitting is a metal plug that makes a good plug for a fill port.  I used a small funnel and filled the system while letting the pump run, it quite quickly moved the fluid through the complete system and removed all of the trapped air bubbles.  I was going to make a video of the system in action but once I had the system filled up and all the bubbles removed you can’t even tell the system is on.  The input to the reservoir from the radiator goes through a 2″ long tube that is below the water level in the reservoir so there are no bubbles or even moving water visible and the system doesn’t make any noise so it didn’t make for good video.

I will be using the same technique for the heating system and have already ordered a similar but smaller reservoir to be using in the heating loop that will allow the same style fill hole, and vent hole to keep the system from pressurizing.



2 Replies to “EVTV and Water Cooling the Soliton1”

  1. Robin,

    I’m also going back and forth on whether to water cool my Soliton 1 on the 86 944 Turbo. Sounds like you are saying it’s almost a must? Thoughts on using the stock coolant reservoir, and stock turbo water pump?


    1. Simple answer is yes, I would recommend water cooling. The stock reservoir should work just fine, it is a bit ugly though (best use of that odd space though) I’m not familiar with the turbo water pump but if it’s electric and separate from the engine it sounds like it would work.

Leave a Reply

Your email address will not be published.