AESC LEAF Battery Modules - Making a Charge Controller 2

As soon as I got back from Marseille, I dove into my LEAF / AESC Battery Modules Charge Controller project and started wiring the 2 Tyco Kilovac Contactors to the Dual Relay Programmable Voltmeter already installed 10 days ago ....



Crimping first


I start with a ON OFF ON switch to Charge or Discharge, or OFF




Let's add a fuse, always better, and solder its holder here


and get through the terminal numbers in the back for the relays


soldered fuse holder receives a 2A glass fuse


Everything wired to the Voltmeter now


Discharge / Grid Tie Inverter side Kilovac in place


GTI is active and pushing 250W into our home grid


Lower limit reached, the voltmeter opens its lower relay, which removes power to the Kilovac, which opens the DC line removing power to the Grid Tie Inverter, and the Discharge is stopped


Lower voltmeter LED is lit, indicating we reached the lower limit of the pack voltage


And now I have Automatic Cut Off at low voltage, 3.60V per half module or 21.6V for the pack of 3 modules (= 6 half modules)



After testing this, the next day, I wired the Charger side Kilovac, protection over charge, and stopping at 24.9V for the pack, which is 4.15V per half module



Charger side Tyco Kilovac with 1.5mm2, smaller section solid core wire



Let's start the charge now ...



I just finished this first controlled Charge tonight:



Once we reach the set 24.9V for this 3 module pack (= 6 half modules x 4.15V), the voltmeter opens its upper limit relay, cutting power to the Tyco Kilovac contactor, opening the charge lead and stopping the charge => Simple and Efficient !

Note the upper limit LED on the Voltmeter and the Green right LED on the Charger (a LiFePO4 24V 10A) showing the end of Charge; Now after 10s, the voltage has gone down a bit and will stay there


So now I don't have to stay next to my AESC / LEAF pack, since a Charge and a Discharge will be terminated automatically thanks to this set up :-)

This is why I will not use SSR Solid State Relays instead of Tyco Kilovac contactors

Shopping for components for my DIY ESS Kit #2, I started to look into SSR - Solid State Relays - to maybe replace the expensive Tyco Kilovac contactors, one of the most pricy item in my build, and I need 2 of them for each kit ...

Looking on eBay I found a lot ...

Also I found this interesting video a a SSR maker, explaining how you have to install it:

I discovered that you need to heat sink it because it will use so much power ! In the video it says the SSR is wasting 1W per Amp of current passing through it: this is huge

Unless you want to create heat, I do not see any good reason to use this; The Kilovac EV200AAANA from Tyco uses only 1.7W when the contact is closed, and for whatever amount of current passing through this contact, and it can be a lot !

So I guess I will keep using Kilovac for my build :

It is an investment but a good one for safety - reliable cut off - and efficiency - 1.7W used only -

Dual Motor Electric Vehicle Drivetrain With Powerglide 2 Speed Transmission Walkthrough by EV West

Ex EVtv intern Matt Auber from EV West is showing us the process of coupling two DC Warp 11 Motors and adding a 2-speed PowerGlide Transmission

This is the exact same power plant of their 95' BMW M3 Electric that went up Pikes Peak last year



"Here's a brief 10 minute video that gives a nice overview of the EV West 2 speed Powerglide transmission that runs without a torque converter direct drive to 2 coupled Warp 11 motors. Depending on the voltage and current, these twin motors can put out well over 1000 lb/ft of torque, and 600+ horsepower. We used this motor and transmission combination to power our BMW M3 to the summit of Pikes Peak in 2012 setting an all time record for street legal electric cars. The strength and reliability of this system is key. For more information regarding this bolt in drive train, please visit http://evwest.com for the latest updates."

Another Tyco Kilovac Contactor and an Emergency Cut Off Pushbutton

Yesterday I got this other - brand new this time - Tyco Kilovac Contactor to replace the automotive 24V relay on the charger side of my DIY ESS. Like Jack Rickard says and uses for his heating system, it is overkill but you do not want to leave a ceramic hetaer load on that drains your battery pack to flat, for me, I do not want to chargers not to stop when the battery pack reaches the voltage limit of 3.50V per cell times 8 cells, in my case 28V

I also got, from the same eBay seller here in Paris, a small emergency cut off pushbutton/switch that will cut the 24V to the ESS box and deactivate all contactors, arduino, relays ... and hopefully stop any problem

Just realized after buying it that it is a Tyco Kilovac EV200A1ANA, and not the one I have already for the Grid Tie Inverter side, which is an EV200AAANA; The difference is that this new one I got does not have the Coil Economizer, so I guess it will use more power when the coil is activated - during the charge mode -

The 24V automotive relay, works fine, but get a bit hot, and you never know when it is going to stick/weld inside and not open when necessary, I just do not trust it as much as a good Tyco Kilovac Contactor 

LiFePO4 ESS Update - Daytime Charging OK for a week now

Starting last saturday, I now have been charging and discharging my LiFePO4 ESS for almost a full week

Saturday = Charging all day



Sunday = Discharging all day (with some pauses)

On Monday, I set up a timer to start and stop the charger automatically and leave it all day long while at work 

Starting on a timer at 07:30, the batteries are slowly charging (@ 10A) at home, during the day, until the charge is cut off at 17:40 to simulate the daytime charging it will do with the solar system in the future

Using Karotz as a webcam, I can watch my meters from work while or on my iPhone from anywhere

Arriving home, here is the situation: we are at the very end of the charge, the charger is pushing 1A only into the batteries and voltage showing 29V, the cut off is very near

Lowest capacity cells groups shwoing 3.93V and 3.91V are fine, and probably did not reach 4V

Total energy used to charge on monday = 3.3 kWh

Charger is pushing 1A only into the batteries and voltage showing 29V, the cut off is very near

and charger end of charge cut off has now happened: Ampmeter is reading 0A and voltage is slowly dropping from 29V

Charger LED2 is now green, meaning the charge is over (and it will not start again unless the AC side is cut off for 10 seconds, it is a security feature)

Wattson Pro graph for Monday: Charging 07:30-18:40 & Discharging 18:40-22:30 

The blue line represents the production from the BESPSS and is almost perfectly matching the usage (in red), unless too high (production maximum output is 1000W for now)



Tuesday: Charging 07:30-17:40 & Discharging 17:40-22:30



After that I moved Karotz to see the Ampmeter too

Reaching the end of the charge: Ampmeter showing 5A (half and going down) and voltage 28.6V


Timer cut off => Ampmeter is showing 0A and voltage is dropping

Wednesday: Charging 07:30-17:40 & Discharging 17:40-22:30








Thursday: Charging 07:30-17:40 & Discharging 17:40-auto cut off at 22:45

Overall I am very satisfied with this week of tests:

 - Charger work fine (long periods of charge and automatic cut off at the end of charge) and the batteries are now well balanced (no group of cells is going too high)

- Automated power output from the BESPSS is matching the home usage (as much as possible) and automatic cut off is working fine, protecting the battery bank from going to low in voltage