Enginer PHEV DC/DC Overheating issues

Not a bad idea. I thought of removing the charger to outside the car onto my Carport pole as I only charge at home and just supply a 48Vdc heavy gauge cable Anderson plug to the car.

The idea of installing the converter into the wheelwell is good except that the metal chassi of the car is not aluminum. Aluminum (aluminium for the Aussies) is more thermal efficient than steel. Correct me if I am wrong but the converter case is made out of aluminum to maximize cooling and so are all heat sinks. I would install a huge heatsink to the underside of the car that physically joins to the DC converter with silicon paste which may require oxy weld cutting the car body.

 

After my charger burned out in June, I have removed the charger to the upper part of the kit to avoid charge heat accumulation. With 2 cooling fans to blow in, 2 another fans above the converter and put 4 aluminum cooling plates on both sides of converter I can feel the converter cooling is faster. Some pics

 

Hi EPA,

I am not registered with Enginer anymore so I cannot see your pictures. Maybe Mr Fang will start a MD-TECH user forum. Can you please attach your pics to a reply. Thanks.

 

Hi John
I'm sorry to hear that and cannot understand why? Maybe you can pm or mail to me.
As the weather was getting warmer. My charger was burnt out at the end of May despite rear door opened, deck off, lid off, indoor ventilation on. During the repaired period, I read the good modification thread < Added Cooling from Cabin >http://www.enginer.us/forum/index.php?topic=954.60

Besides adding AC air to the charger oulet area (fig 1). I removed the charger and dilatedly cut the porous steel case (It's a heavy work to me) and put 2 12V CPU cooling fans (fig2), I put another 2 12V fans on converter & some cooling plates on both sides of it. (f-3). The 4 fans were power by a wind-power 12V battery (18AH) (f-4). As the fig-4 during my charging, the hot air of charger was directed outside the car and I set the KAW off 30 min every 1 hr charge. If continous charge is going I will put another high RPM 120V fan to cool the charger and blow out the heat. The rear door opened and the lock was put on a heavy wire to keep the door-open light off. My indoor garage ventilation was on to prevent the charger overheat. During my driving (kit discharge phase), the deck off and 4 fans on. I can feel the converter cooling is faster. Maybe In the future I will put some frozen ice packs on the back of the 2 blow-in fans.
Thanks

 

Thanks for the pics EPA. It is winter at the moment in Australia. I will probably move the charger outside the box and install a heatsink on the converter to get ready for summer.

I may also install a second converter and have each one share the load so they can alternate a cooling off cycle. Obviously the second converter would have to be installed outside the box.

 

I've been reading this thread with great interest. Let me say that I've never owned a Prius (however have been looking) and the idea of putting in an Enginer solution in a Prius has actually made me have a serious look at owning one. So, if I make any incorrect statements, please feel free to correct me.:behindsofa::sorry: I'm just trying to help the community before moving in.

One of things that has always puzzled me was the poor levels of venting in the Enginer box (from the pictures and postings I have seen) given the heat output of the DC/DC converter as well as the placement of the box under the trunk with the carpet and other cargo. :tsk::tsk:

This situation reminds me of how people overclocked their CPUs resulting a great amount of heat being generated inside a computer chassis with no way out. The extra heat cause reliability issues for those computers that didn't lower the ambient temperature in the chassis.

I think epa5epa has the right idea but I don't think it hasn't got to it's full conclusion.

How I see it -

Summary of Problem: Heat build up is causing reliability issues with all components of the Enginer system. Heat is trapped in two spots - the Enginer chassis and the Prius' spare tire compartment.

Solution: Reduce ambient air temperature both in the chassis and the compartment by moving air more effectively.

Current situation: Small fans are used to move relatively low volumes of air within the chassis. The hot air is pushed out of the chassis into ducting and out. Nothing is done for the air trapped in the compartment.

Proposed Changes to the Enginer chassis:

1. Remove/reduce restrictions to airflow into and out of chassis. Currently, small fans are used to draw air in and push air out from the charger to the DC/DC converter. These fans are trying to draw air through metal finger guards stamped into the the existing chassis. From the looks of the guards, approx 50% of the area of the fan is blocked by the metal guards. This reduction in area will cause the air flow to drop by at least 50% (probably more due to turbulence).

Cut the metal figure guards out and leave the air to flow freely through the fan. If you are worried about safety, install wire finger guards (cost about $1 a guard). The wire guards block a lot less area and are rounded to reduce air turbulence. I believe the fans in the DC/DC converter does this.

2. Upgrade fans. Not all fans of the same size move the same amount of air. Often a manufacturer will make low, mid, and high volume fans of the same size. The higher the volume, the more airflow. Go to the fan manufacturer's website and find out the existing airflow (usually measured in CFM) and look for a high flow replacement. Sometimes high flow fans can move twice the amount of air as mid speed ones. This might be a good solution for the fans inside of the DC/DC Converter and the charger.

Note: high flow usually means a higher current draw... but you might be able to find another fan from another manufacturer which won't draw as much power.

3. Upgrade size of fans. The larger the fan, the more air it will move in each rotation. Use the largest size of fan that can fit in the chassis. You will need to cut the metal of the chassis to install a larger fan. From looking at pictures and reading user accounts, this might not be an option available to some people as different chassis have a slightly different design - some have two small fans and others may have one big one as well as the placement of the DC/DC Converter may force you to slide it over so that the fans can fit. An added bonus of larger fans, they will use less power and make less noise for the amount air moved. The same idea applies in point 2 (above) as here - different grade fans available.

If I remember correctly, the chassis is approx 7" deep which should easily allow for a 120mm or even an 140mm fan or two. How much airflow are we talking about? Example - A 80mm fan (common size) at 1,700 RPM moves approx 32 CFM while an 140mm fan at 1500 RPM moves approx 90 CFM.

4. Direct airflow so that it travels one way in a logical/natural direction. Hot air rises and cold air sinks... draw air from below and exhaust air out through the top. Don't let the air circulate inside the chassis - it will just get warmer and warmer and warmer.

5. Add additional 12V fans to cool the chassis while charging. An internal 12V power supply can be added to power these fans while the charger is plugged in. An adventurous solution may be to replace all of the chassis fans with 12V fans (of the same or higher CFM - see points 2 and 3) and add a small 12V battery and charger so that all fans can run while charging and when the system is supplying power to the traction battery.



NOTE: Don't worry about too much about adding extra heatsinking capabilities to the DC/DC converter. Concentrate on reducing the ambient air temperature - the lower the ambient air temperature, the more effective the heatsinks will be.


Proposed changes to the spare tire compartment: Since I don't have a Prius, just a few general observations...

Keeping with the idea of point 4 above, if all of the warm air is exhausted through one side of the Enginer's chassis, concentrate removal efforts on that side while supplying cool air on the other side. Could be as simple as installing a metal grill with a fan or two connect to it to push the hot air out on the warm side and and pull the cooler air in on the other side. There has also been various ducting options - out the Traction battery duct or ducting AC cooled air in - presented and can be used in conjunction.


How do you know if you have improved the situation? Install temperature probes and stick them to various areas to see if each change made a difference. The areas I would start with would be the DC/DC Converter, the Lithium batteries, and the spare tire compartment.

 

I have observed that the Enginer 5KW DC Converter has not had a major redesign since it was introduced (jusr revisions). If the DC Converter was ever redesigned I would include the temperature of the heat sink case and that of the airflow and have them sent to the BMS16D along with the other instrumentation values so they can be logged. One then should be able to see if the DC Converter is tripping out on the thermal overload protection that is built into it. The converter has two devices attached to the metal case which appear to be self-resetting thermal cut-outs.

 

We are pilot testing a new open architecture design for kit component mounting. It puts the battery pack, charger and BMS in the spare tire well and leave only the converter and the spare tire in the compartment. There would be more air circulation for the converter as well as for the charger. The kit is running much cooler this way. Attached are some pictures.

 

Great ! The new setting has much better space arrangement. Really looking forward to a good test results.

 

My solution for converter heat management has been to add 4 new 12VDC fans and remove the 48VDC fan that is already on the left side of my Gen 2 kit. The kit has Mott cells and a BMS16C for management. I tried to do this with minimum expense. My supplies for inside the Enginer box consist of 4 fans (12V at 250ma), 4 Zener diodes (12V at 5 watts), a 20 ohm resistor, a ½ amp fuse, and a terminal strip. The 4 fans which are 60 mm in size are used as follows. I replace the 48VDC fan (a 60 mm fan) on the left side of the Enginer box which is an exhaust fan with one 12VDC fan. I put a 12VDC fan on the circuit breaker opening on the right hand side of the box as an intake fan. It is about 30% blocked by the metal of the box and does not get full air flow. The mounting requires drilling two holes in the steel, but it was soft enough to allow for this modification. Drilling was done in place so I put cloth covers over everything on the inside of the box to catch the shavings. The other two 12VDC fans are placed vertically on the bottom of the box, under the BMS location. They are placed to blow air into and around the converter box. These two fans are attached vertically to the bottom using cable ties through the holes on the bottom of the Gen2 box.

The electrical connection uses the 48VDC that powers the original, removed fan. The 4 fans are placed in series with a 12VDC Zener diode across each one as protection. The 20 ohm resistor is placed in series to drop about 5 volts of the 53 volts from the converter that was used to power the 48VDC cooling fan that was removed. This may be overkill but I didn’t want to take chances. The final item is the ½ amp fuse in series with all these components for protection. All connections are made on the terminal strip. I used the European type strip as it looks less likely to get an inadvertent short than other types, plus you can put several connections on each terminal without attaching a lug.

How does it perform? Well I’ve had two converter failures in a year. I think both failures were heat related, but am not certain. These failures and subsequent down time for the system, caused me to look for a simple and cheap solution for getting more air flow inside the Enginer box. The newest converter was installed in May. So far, the new cooling fans have been installed since early June with no apparent problems. There has been no fan burnout, converter failures or blown fuses during the summer. The voltage dropping resistor gets warm but not hot. Granted, summer in New England is not as hot as most of the rest of the country, things look good so far. Our maximum daily highs are only in the mid-90s. It will take more time to see if this is a good solution and I’ll put up some more posts if there are any problems.

 

I got some inspiration from cold bags from supermarket and cooling mod from computer. Yesterday, I changed the 2 12cm 12V fans ( on the top of converter, tilted toward the left ) to more powerful 2500RPM 99CFM ones and stuck multiple CPU cooling plated on the left top of converter. I added one of the previous 12cm 12V fan on the top of the 2 6cm intake fans to draw more AC cooling air. I put a DIY 22x15x6cm cooling box containing 0 degC coolant (only downside with heatsink, the other 5 walls with insulation ) on the left lid, just above the left converter area. After 1hr to and back driving, The usually most hot area of the lid is much improved.

 

Hi EPA,

Are you still driving with the Enginer box lid open?

How hot is it in Taiwan where you are during the day?

My new MD-TECH DC Convereter barely gets warm after a 40 minute drive to work, but it is winter here in Australia.The daily temperature barely reaches 20 degrees celcius during the day.

I have found that the output end of the DC converter is much hotter than the input end of the DC Converter just by using my hand. I figure that the heat is being transferred from the input side via fans to the output side. Unfortunately it is the output side that all the intricate control electronics is located and is subject to most of the heat.

 

Hi friend,
For safety, The lid is closed and locked by my glasses screwdriver (easy pull rods) during my driving. The temp is around 26~34 C this week , the weather bureau reports around 27~36 C next week here.
All my cooling plates are located over the left half of the converter scince I also have found the output end of the converter and the left corner of the Enginer box lid are the most hot area.
I'm realy worry about the overheat of my converter in this summer. It would be a big problem to send it for warranty.

 

As the enginer box lid is cold but the left side of converter is still hot after 30min city drive, I put a 75mm height powerful CPU cooler with silicone gel on the outlet of converter and stuck a 1x120x150mm heat conductive pad on the inner side of box lid. It just fits the height of converter to lid when it is closed. It would further cool down the converter by my DIY cooling box.

 

Hi EPA,

I decided to log some temperature measurements of my DC Converter to see just how hot it is getting during my thirty minute drive to work. I bought a couple of temperature sensors that log via a USB connection to my laptop. See pics. The outside air temperature was 19 degrees celcius.

I found that the output end reached 35 degree celcius and the input end reached 32 degrees celcius.

 

Hi EPA,

Have you considered using a liquid cooled CPU cooler?

 

Hi John,

Good experiment and finding !

I have found the side wall (near the porous outlet, current limitor) of the charger case is more hotter than the upper wall. The converter has the same phenomenon. So I put multiple heatsinks on both side walls of conveter & 2 12 cm high RPM fans tilted toward them. My fans are always on during my drive. I think it will be higher temp and less steep temp curve if you probe the side case wall especiall the flat area. The dramatic temperature increase when PHEV switch off and on may be due to initial current surge and ventilation difference (48V fans on and off, then on as reaching temp threshold).

The mid day temp is around 36~38 deg C here. Before my cooling mod when I switched off the system due to high SOC of toyota HV battery for 5 min or so, the 48V fans turned on immediately affer I switched on. After my further cooling mod, I will closely observe the condition in the next few days.
Thanks

 

I had considered it, but it needs to cut or drill the steel case made me stop.

 

I have just installed my new 5KW Enginer DC Converter and have done some temp logging and came up with the same results as the MD-TECH DC Converter.

 

However when the DC Converter was running at an output current of aprox 2 amps, the input end of the converter heated up considerably meanwhile the temp at the output end stayed at about a cool 26 degrees celcius.