EMC-400 charger setup+Mods

[crossbreak]

Hi,

i'd like to use my old 10s lipo EMC-400 charger from bmsbattery with my new 12s lipo now, since I sold my old battery.

There are two values i'd like to setup: HVC and current. I found both values and it works ok,
Old HVC: 42V
New HVC: 50V
Old charge current: 8amps
New charge current: 7amps


there is a third trim-pot I dont know what it's good for :? (see picture below)

Any ideas?

other problem: I tuned the trim-pot, which I dont know what it's made for, the yellow iron core gets quite warm during charge now :? is this normal?

I read the EMC-1000 thread http://endless-sphere.com/forums/viewtopic.php?f=14&t=41733 but it seems like this one is different.

BTW I use the SmartBMS for LVC/overcurrent/short-ciut-protection/balancing, which I had to setup, so it accepts the 7amps charge current (normally it only takes 5amps, this value can be changed via I2C porgramming), the single IRFB4410 charger Fet should be OK with 7amps I hope.

 

[dnmun]

the one with the question mark determines the current during the final balancing CV part of the charge. you should not adjust that one.

you can expect the choke to get hot as well as the transformer.

there is no HVC on a charger. also that is not a lipo charger. it does not have the latching output daughterboard to turn it off at final voltage.

the EMC chargers never have that even though the solder pads are there for it. only the kingpan chargers have it and people have to remove it to make the charger into a lifepo4 charger like what you have.

 

[crossbreak]

Thanks for your quick reply!
Sadly i did already turn the ?-trim-pot a bit any method to find the right adjustment again?

Thx for the info about iron core, it gets as warm as the tranformer so it should be fine

I dont get what you mean with final balance, since this charger does not balance the cells.

After reaching 50V, the EMC-400 should just continue to output 50V.

If one cells has more than 4.2V, the smart BMS will simply shut down the charge FET. In normal condition, this should never happen, since i do not charge the pack that long. After the 4.2V cell was balanced down to, say 4.1V, the smartBMS should continue charging, by switch on the charge FET (i'm not sure about this behaviour).

I use this charger for year on 10s lipo, it has always worked for me :? Maybe i treated my pack wrong all those years? I thought I just have to keep it balanced and not overcharge it? Do you have some educational link/key word here? Thx a lot for your help!

 

[crossbreak]

I will test my setup and keep an eye on the current and the charge voltages. Hope i can come up with some results tomorrow.

 

[dnmun]

it will work fine and stop on your 50V.

you can turn the charging current up to 10A if you wanna.

it won't do that much continuous but it will handle it for the time it takes to charge up, imo.

 

[dr_lulz]

hmmm from my experience the 3rd poti adjusts the current at which the fan switches off?

 

[crossbreak]

thx for your info, i'll try that! sadly I left my measurement equipment in my other home, so it will have to wait a few days.

it works fine with 7amps, 10amps isn't that much more... I wanna use it with a 44.4V/25ah battery, so charging will take a while That's why I wanna mod the fan, it's horribly load...thought about a fan controller like this one: http://forums.saltwaterfish.com/t/374356/diy-fan-temperature-control-how-to

This one isn't that sophisticated, hope i'll find a better one using google.. any suggestions here?

seems like the transformer is the one that gets most warm, so i should hook up the NTC there?

 

[dnmun]

if you don't like the fan noise, and who does, why not look into putting the charger into a cabinet so the sounds are baffled.

use a cardboard tube over the end of the charger where the fan hole is and run that tube away from you.

or buy another fan and use it?

that trimpot (along with another resistor) is across the input to one of the op amps in the 358 so the op amp turns on when the voltage is above a certain level and turns off when the voltage drops below a certain level. by adjusting the resistance that the charging current goes through then the current at which the voltage across the op amp inputs causes it to turn on or off is changed. when it goes into the CV mode then the fan is turned off too.

 

[DanGT86]

I have an emc-400 related issue I hope one of you charger experts could solve. I bought a used emc-400 that was set for 21s lipo. I figured I could turn the voltage pot down to 82-84v for 20s lipo. Turns out it will not adjust any lower than 87.5 volts. Is there an easy way to get below the minimum adjustment of the pot or are there other components in the charger that determine the minimum output voltage? Could I just put in a trimpot with a different range to cheat it down a few volts?

 

[motosen]

My charger was taking only 50w power from socket when charging so I adjusted the voltage to 73,8V and then connected the charger to battery and started to increase current. When it was taking 280W from the socket something clicked and charging stopped. Fuse is ok. Where to begin to search the fault?

 

[DanGT86]

Have you removed the daughter board or cut the transistor on the daughter board of this charger or is it unmodified. There is a daughter board that makes them shut off and stay off when they reach the specified voltage to go into CV mode. Most of us remove this board or snip the transistor on that board so the charger will cycle back on if it turns off. That modification allows them to be used for balancing with a bms. The reason I bring that up is that I had a charger that made a click and then quit working like yours. I hadn't modified the daughter board yet and wanted to do that anyway. When I snipped one of the legs of the transistor on that board it started working again just fine. The board I didn't want was the problem all along.

Also, you may want to measure the output side when making adjustments to current and voltage. The charger will taper the current off to just 200-300mv when its in CV mode at the top voltage(your 73.8 set point) .200 x 73v= 14.6 watts. If it was in CV mode at only a few hundred mv when you kept cranking it up to get 280 watts then the output setting would be way too high when not in CV mode. I would try to turn the current pot back down and see if you can get it to come back on. Again, measure at the output side while adjusting because the input side doesn't take into account what mode its in. Also when something trips in these chargers you commonly have to cut the main power and plug in again to reset it.

 

[motosen]

Thanks for your help. The board is unmodified, I’m still figuring where the daughter board is. I have no amp meter at the moment for measuring the output current. When I connected the battery the drain from socket was about 50W. Then I started to increase it. Shouldn’t it handle at least 360W drain from socket since 4A*72V/0,8η=360W(non-CV mode)? I have no idea what is the efficiency of the charger but I assume It’s a lot lower than 80%.

 

[dnmun]

you should buy a DVM to use and also it helps if you have a wattmeter to charge the battery through to measure current.

there is no reason the charger should make a click sound. it has no relay if it is like the charger in the picture above. we have no picture of your charger.

 

[motosen]

It’s like in the picture above, no relay. DVM=digital volt meter?

 

[Owl]

Hey guys,

I have a problem with my charger EMC-400. I bought it from bms battery few years ago.
Inside of the case are a capacitor broken. You can see it at the picture in the red circle. I want to repair it, but I don't know what kind of element must to this place. On the board are RTH written.
I charge nearly 4 years a 16s LiFepo4 Pack with it.

I hope anyone have the same charger and can help me. Maybe you can take a picture of the element.

Thank you