Elcon Charger End voltage and other mods

Below are the calculations using the PDF for reducing the Elcon charger voltage endpoint.

R1 - 482300 ohms
R2 - 8680 ohms

Trim Range (Decreasing it only):​

Note I only tried this quickly on my unit, it seemed to work, but tread carefully.
In this case you want to make R1 a bit smaller so you will add a large parallel resistor
between Pin 2 and DC+ (see the following photo).​

1) Measure the upper resistor R1 (between pin DC+ and pin 2). R1 - 482300 ohms​

2)
RatioMax = Vmax/ Vorig = 252v / 256v = 0.984375
RatioMin = Vmin / Vorig = 256v - (256v x 0.10) = 230.4v / 256v = 0.9​

Vmin = 10% reduction of original voltage Vorig​

3) Parallel Resistor total for R1 (in this case)​

RPmax = RatioMax X R1 = 0.984375 x 482300 ohms = 474764.06 ohms
RPMin = RatioMin X R1 = 0.9 x 482300 ohms = 434070 ohms​

4) ​

RAddmax = 1 / ( 1 / RPmax - 1 / R1) = 1 / (1 / 474764.06 - 1 / 482300) = 30384900 ohms
RAddmin = 1 / ( 1 / RPmin - 1 / R1) = 1 / (1 / 434070 - 1 / 482300) = 4340700 ohms​

I think I got that right!!! It should end up a resistor about 10 times R1 for a 10%​

reduction.

Raddmin / R1 = 4340700 / 482300 = 8.6 (not exactly 10 times)

 

Using values from FWD's Elcon charger.

R1 - 600000 ohms
R2 - 8500 ohms

Trim Range (Decreasing it only):​

Note I only tried this quickly on my unit, it seemed to work, but tread carefully.
In this case you want to make R1 a bit smaller so you will add a large parallel resistor
between Pin 2 and DC+ (see the following photo).​

1) Measure the upper resistor R1 (between pin DC+ and pin 2). R1 - 600000 ohms​

2)
RatioMax = Vmax/ Vorig = 292v / 292v = 1.0
RatioMin = Vmin / Vorig = 292v - (292v x 0.10) = 262.8v / 292v = 0.9​

Vmin = 10% reduction of original voltage Vorig​

3) Parallel Resistor total for R1 (in this case)​

RPmax = RatioMax X R1 = 1.0 x 600000 ohms = 600000 ohms
RPMin = RatioMin X R1 = 0.9 x 600000 ohms = 540000 ohms​

4) ​

RAddmax = 1 / ( 1 / RPmax - 1 / R1) = 1 / (1 / 600000 - 1 / 600000) = infinity (open circuit) ohms
RAddmin = 1 / ( 1 / RPmin - 1 / R1) = 1 / (1 / 540000 - 1 / 600000) = 5400000ohms​

I think I got that right!!! It should end up a resistor about 10 times R1 for a 10%​

reduction.

Raddmin / R1 = 5400000 / 600000 = 9 (not exactly 10 times)

 

For FWD's Elcon charger mod I would go with using a 6Mohm trim pot if they exist. But I would not adjust it to any lower than 1 Mohm. So say a 5 Mohm trim pot in series with a 1Mohm resistor.

The V+ to solder the resistor to in the photo is a vertical inductor for the output. The inductor is covered with heatshrink tubing.

I did not see any photos where Ian connected a resistor in series with a trimpot connected to the V+. So I have to assume that Ian has never done this mod to decrease the endpoint voltage in practice. He did the calculations to decrease the endpoint voltage but that is all.

 

I might try it on the weekend using a 33Mohm resistor across V+ and pin 2.

 

I have just made up a graph showing the different values of Radd over a range of end-point voltages for my Elcon Charger which has a existing Endpoint voltage of 256 volts.

 

I bit the bullet and did the modification. I put in a 10Mohm resistor which according to my calculations should give me an end-point voltage of about 244.5 volts according to the PDF. I measured 244v on my DMM during CV mode as the current slowly decreased from 6.2 amps down to 0.9amps and then the charger stopped charging. Voltage too low as none of the red LEDs lit up on my miniBMS.

I then increased from 10Mohm to 14.4Mohm by adding two 2M2 resistors in series. This gave me an end-voltage of 248.1 according to my DMM. All the LEDs lit up on my miniBMS for a while before charger stopped.

I also checked that the current pot still worked and it did. It was not affected by the modification.

The resistor calculations for Radd were almost spot on.

Everything went according to plan.

I did my solder connection of pin 2 on the other side of the small PCB. I used a wire with 240v grade insulation and used heathrink tubing over the wire and resistors to keep all well insulated. I soldered one end of a resistor to the PCB copper tracking pad at V+ before the fuse so it does not get 240V+ if the fuse blows. What I thought was a glass fuse looked like a small HRC fuse after cutting a slit in it's heatshink insulation to take a peek.

My plan is to use a mains mechanical timer to switch on power to Elcon charger to do top balancing every hour during the night. Cycling the top balancing during the night allows the miniBMS resistors and PCB to cool down until the the next top balance cycle.

I will post photos on Monday when I have access to a computer at work to download them. Only have IPad on weekend.

 

Only used the calculations supplied by the PDF. You can see how I scratched away some of the varnish on the PCB layer pad edge to expose the copper for the V+ solder connection to a resistor so the remainder of the fuse solder joint remains unaffected which requires a fine tipped soldering iron. See photos of my mod below:

 

Your HVC ( high voltage cut-out) is very low 3.54v. You can take it as high as 3.8v. Better to be safe I guess. Best to lower Elcon charger maximum voltage or it could overcharge your cell/s if your BMS fails. I lowered my charger maximum voltage from 256v to 248v. You can decrease your maximum voltage by doing a modification. I did the modification and it works great.
My miniBMS will not allow charger to reset after a HVC using a timer on the AC side. It will only allow charger to reset using a timer if the battery pack goes through the compete charge cycle without being stopped by a HVC. If my charger gets a HVC I can only reset the miniBMS by cycling the Prius ignition.

 

Back to Elcon 1500 end-point modification. I used my DMM to measure R1 to be 504.1kohm and R2 to be 10.02kohm. Assuming that the control voltage is 5.0v the ratio gives me a end-point voltage of 256v which does match my charger maximum voltage (also called the end-point voltage) of 256v.

Since my HVC of my miniBMS is set to 3.65v I want my end voltage to be 3.5v x 72cells = 252v. So I need to lower my end voltage from 256v to 252v.

 

The miniBMS can be bought with a HVC of either 3.65v or 3.80v, you specify which one you want when you purchase it. Most BMS units have a HVC of 3.8v. My charger was set for a maximum voltage based on using a BMS with a HVC of 3.8v. There is a big difference between 3.65v and 3.80v i.e. 0.15 x 70cells = 10.5v. Enough so that my Elcon charger will not go into CV mode due to getting a HVC first from my miniBMS which has a HVC of 3.65v. So a cell will reach 3.65v and BMS will do a HVC and terminate charging before the charger can reach 3.65v to go into CV mode

 

Despite this they will set the maximum voltage to your own unique setup - 14 days at least. These max voltage of 258v or 320v are probably setup already so no time is needed to change setup.

See photos below: Max voltage 255.5v for 70 cells at 3.65v/cell but this requires a BMS with a HVC of 3.8v for the charger to go into CV mode. A miniBMS with a HVC of 3.65 will not allow charger to go into CV mode. Need to plan well when selecting your maximum voltage. The HVC of my miniBMS is 3.6v.

I have asked Michael Cheung whether I can change the max voltage to 3.5v/cell x 70 = 245v, after a couple of days I am still waiting for an email answer.

 

I got this response from Dimitri on the other forum DYIElectriccar

http://www.diyelectriccar.com/forums/showthread.php?p=282815&posted=1#post282815

 

I found a lot of websites which have a Elcon PFC manual but lacked a lot of info. Anyhow I have found a 10Kohm pot to use as a current controller. Charging is disabled when enable is disconnected.
I could also use a time delay relay N/C contact to bridge out pins 1 and 3 to do a full current charge (6.2 amps - 100% - 5v to 12v) for a preset time then trickle charge (0.75 amps - 12.1% - 2.36v ) until HVC events occurs or just top balance. A time delay relay could be a backup should the BMS HVC event faulter. But you need to estimate lithium pack SoC accurately to set timer time delay value.

 

Do you have any more details? Is it standard or does it have to specifically setup for this?
The control plug has extra wires, maybe this is what they are for.

Found some info on changing the charging curve setting:

Choice of Charging Curve(curve 1~10)
1.The LED will flash red several times when AC is first connected, then the LED will flash green once. The number of red flashes denotes the present curve. E.g. If the red flashes three times, it means the present curve is curve 3.
2.To choose another curve, please cut off the power supply first, then unpeel the label, pressing the button while connecting the power. If you want to choose curve 3, release the button after the 3rd LED Flash. Now the selected curve (e.g. curve 3) will be recorded in memory. If you want the charger to work with the selected curve (e.g. curve 3), cut off the power and reconnect it.


Below is a description of pin functions:

Pin Number

1 ENAB\ Connected to pin 3 = enable charging; Open = disable charging Must be programmed with Alg 500~599 1 mA load
2 GND Common
3 V+ +11 V when plugged in 50 mA max load; do not short circuit!
4 RED Red LED anode Cathode to common
5 GRN Green LED anode Cathode to common
6 RX Serial in For factory set-up
7 TX Serial out

 

My Elcon charger will arrive on Monday. I just received a tracking number 5 days after it was posted. It will take only 38 days from paying to receiving!!

 

Yesterday I just moved some posts from the other thread Using a BMSplus with lithium, these posts are more applicable to this thread.