EM3EV charger switch voltage?

I just received a 50v 14s li-ion battery and charger from em3ev. There were no instructions in the box or on the website that I could find. Can anyone explain the charging voltages for each position II O I ?

THANKS

joshseitz said:

I just received a 50v 14s li-ion battery and charger from em3ev. There were no instructions in the box or on the website that I could find. Can anyone explain the charging voltages for each position II O I ?

THANKS

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For general use, you're going to want to use the middle position. This will charge the battery to about 90 percent of its total capacity. The 'II' position charges the battery to its full capacity, but you should only really use this if you're going to ride it right after it charges. Even so, you're introducing stress and shortening the life of the battery. The 'I' position is 50 percent, and you should charge to this if you'll be storing the bike for a while. You'll also want to recharge to this level at least once a month for as long as the bike is not in use.

Thanks spisska!

joshseitz said:

Thanks spisska!

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Ditto

If you look on the charger it should be written on it like mine was, I couldnt see Paul not having that on his chargers.

One trick that might help. I bought the cheap 3 buck, two wire, digital voltmeters. I put the same plug on it as the charger, and put it to measure the voltage between the charger and the battery.

This way, not only can I tell which setting it's on by the chargers output voltage, I can tell if I have a full charge at the end. Good to know before you set out, YES it really did charge fully.

Chargers really should have a volts display on them!!! Its a 3 buck item, retail and shipped! So don't tell me it costs too much to do.

Hi Guys,

I also purchased a kit from em3ev (Bafang 48V 750W BBS02 Kit with Battery). I used the position O to charge the battery overnight. After 14 hours I got three battery bars on the display, but the battery lasted for 3-4 minutes ride and gone flat… Is there anything I did not do properly – I just plugged the black/red connectors from the battery to the black/red connectors from the charger.

I noticed that there is a fan in the charger and I did not hear the it worked at all…

Thanks

Unfortunately you will need to provide us with more information before we can help you out. How many volts was the battery after charging? How many volts was the battery after the ride? You will need a multimeter to measure the # of volts.

-Tim

Thanks! I will not be able to provide the data on the volts after charging - I assume the volts are gone already.

I have the multimeter and will try to use it when I get home... sorry, this is completely new topic for me (e-bike, watts meter, multimeter, etc.). At least I have the equipment...

Anyway, tln suggested that the battery can have a switch that turns off the current from the BMS... I will need to check this as well.

I checked the bike again and it shows three battery bars just after turning on, but they disappear after a short ride... I checked the battery and there is no switch to turn on / off the current from the charger. The battery was pre-charged and worked for me for 30 miles. It means for me that the charger did not work at all.

I have this charger. How to find out it is working? What are the replacements on the US market and where to get them (in case it is broken)?



I will measure the volts in the evening when I get home.

Thank you for your help!

I believe the highest setting is good to use occasionally to top balance the whole pack. The BMS balances at 4.18v per cell. For the 14s 50v pack that's 58.52v or the highest setting. The BMS will still protect the cells at the lower settings but its good to get them all completely balanced every once in a while with the high setting. If the BMS is never allowed to do its balancing job they could continue to drift and reduce your capacity. Then when you do want to charge them to 100% sometime it will take longer since balancing is slow and can require the charger to cycle a lot.

Bono, sounds like your charger is not working. Check it with a voltmeter while its charging to see if the voltage increases. I have one of these that was killed by hooking it up backwards and it still says 58v when its not plugged into the pack. This makes it appear functional but it drops to pack voltage when its plugged in meaning its not actually charging.

As far as a replacement in the US market, I have not seen one with a switch. Any lithium charger with the correct output voltage will work. All of the metal case chargers I have seen are voltage output adjustable from the inside so if you get one that is close you can adjust.

If you just got it you could contact em3 and see if they will replace it. Its a pretty nice charger since it has that switch. I miss mine. The switch was enabling me to charge different packs safely with just one charger as well as the balancing feature I mentioned.

if you open that charger up we can try to diagnose what dies when you reversed it. you can measure the charger voltage on the output but it does not push current?

you can use a wattmeter in the negative charger lead to measure the charging current. if the charger is charging you will see the current on the meter and if it goes to a balancing charge you will see the reduced current then too.

that is really the only way to diagnose charging problems.

Hi Guys,

So I have this multimeter



I turned the voltmeter to DC mA (not sure if this is correct). Both battery and charger show 0.06 in this position... Of course, it does not say anything to me, so please could you let me know what does it mean / or if I should do another measurement?

do not use the amps scales or the ohmeter until you know how to use the voltmeter. if you apply the amp or ohm scale to an active electric circuit it will burn up the meter.

OK, thanks for warning. So which position to use with battery and charger?

thanks!

A couple more questions:

1. Is it best to let the pack cool completely after use before re-charging? After a 1+ hour ride at mostly full-throttle, it was fairly warm.

2. Paul ships his packs with a 3-pair anderson dongle (see below) with bullet connectors on the other end. Any idea of the purpose of the additional sets of connectors? Adding accessories or an additional controller for 2WD or something? All three pairs show the same voltage, including the green pair. Or for very high-current applications? As I recall, standard Anderson connectors are good for 45A. My 14S6P Samsung 29E pack should really only be able to deliver 30-35A, I believe. And my bafang BBS02 has only recorded a peak of 26A thus far, according to my watt meter.

Bono,

For measuring the voltage you want the DC V setting. You will be checking the output of the charger by putting the probe ends on the red and black plugs. Be careful not to let the two probes touch each other while they are also touching the connectors. This will measure the output voltage of the charger. This will be close to the voltage where the charger will stop at when charging and should be about the same as your pack voltage when full.

Next plug it in to the battery the way you would normally charge. If you have some kind of display like a cycle analyst or a dashboard of some kind you can watch to see if the voltage increases while you charge. This wouldn't require the meter. If you cant be plugged into the charger and the controller at the same time you will have to sneak the meter probes into the Anderson connector housings so you can measure while charging. Again make sure the probes don't contact each other while touching the connectors. Bottom line is the pack should have more voltage at the end of a charge than it did in the beginning.

Joshseitz,
I don't think the temp is a problem unless you were using it well outside of the recommended discharge current. If it was sitting on the back dash of a car in the sun all day and was really hot I would let it cool but I wouldn't think temps from normal riding would be a problem.

Paul shipped mine with enough extra parts to add a pre-charge connector to my controller since lots of controllers don't have them but his packs do. Also included some bullets with my pack. I figured it was just good customer service to ship necessary parts to adapt to common connectors.

Dnmun,
I talked to you about that broken charger in another thread. I have been meaning to work on it but haven't found the time so I didn't want to bump my thread and then leave it hanging. It does have a no load voltage of 58-59v which was my end voltage. I used a remote shunt and my Cycle analyst to verify that it wasn't pushing any current. The other time I tried it the voltage was erratic and the fan switched on and off a few times. There is also an audible clicking noise that sounds like a quiet buzzer when it is powered. If I figure out whats wrong with it I will update in this thread because it might be the same component that is bad in bono's unit.

I too have the same charger and 14S battery from EM3EV, the first time i charged the battery it was fine but on the second charge the charger didn't work, no leds, no sign of voltage ore anything, dead.
Paul is sending a replacement.
I opened it up the other day to see if anything looked wrong inside and there are several bits that are blackened, one disc thing near the mains connection is actually blown apart. The black things on the heat sink (power transistors?) are also very blackened.
On my battery that set of red/black/green connectors connects to the BBS02, the charge lead is the single red/black on its own.

@shorty: the black disc next to the input AC is called an Inrush Current Limiter ICL. it is a negative coefficient thermistor that is used to slow the initial current inrush as the charger is powered up. it heats up rapidly with the current flowing through it and as it does then the resistance drops dramatically. but they stay hot all the time when the charger is on which allows the current to flow to power the charger and some will eventually just burn up and explode like that.

this is the most common failure among these switch mode power supply SMPS chargers and you can buy a replacement ICL and solder it in place of the one that blew up. you are too far off but in the US i sell replacements for $1.50 including the stamp on the envelope i ship it in.

they are rated 6.3A and 5 ohms, Epcos brand, from mouser. if you buy them off ebay, make sure you get one that is 15mm diameter or a little larger to ensure it can handle the heat.

if you post up a picture of the transistors we can examine it.

OK, I used the DC V setting. The battery shows 46.3V and the charger shows 47.3V in alll setting (I, O, II). What it would suggest? I do not know a lot about this stuff, but would this not mean that the charger should charge the battery to at least 47.3V? But it did not, it was 14 hours on and did not charge the battery...

The fact that it outputs the same voltage in every setting is a strong sign that the charger is not working. In 14 hours it should have definitely increased in voltage. You should contact EM3 about getting a replacement. If they send you a replacement without needing that one back you could attempt to fix it or maybe sell it for a few bucks to someone on here that wants to fix it.

dnmun,
Your mention of an ICL got me thinking. My 72v charger has an on off switch. When I connect my battery with the switch off it sparks and burns my contacts so I have been connecting it with a precharge dongle. Do you think the switch being off when I connect it is making it spark because the circuit with the ICL might not be active with the switch in the off position? I have always heard that plugging the ac main in first keeps it from sparking but the instructions might be talking about the AC side sparking. Never tried connecting with the switch on.

the switch on your charger turns off the front end switching transistors. you leave that switch OFF when you plug into the AC outlet to prevent the huge current surge through the entire charger on power up.

after the charger has been energized by plugging into the AC, then turn ON the switch and the back end will be charged up to final voltage on the output.

now when you plug the battery into the charger there will not be a spark from the battery discharging into the output caps on the charger. we can still try to diagnose your other charger too.

bono may just have a blown fuse. can you measure the battery voltage on the charging plug of the battery? if you cannot measure a voltage there then the fuse in the battery to the charging plug may be blown open.

That make sense. Its basically using my 72v pack to energize the output side. I would imagine those caps are hungry. This explains why my non switch chargers don't spark and why I don't notice the spark when disconnecting. I will try to get into the EM3 charger soon.
Thanks for the info.

yep, the caps look like a dead short to the battery. i have burned up a few charging connectors too. and i should know better.

It shows 46.3V...

dnmun said:

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bono may just have a blown fuse. can you measure the battery voltage on the charging plug of the battery? if you cannot measure a voltage there then the fuse in the battery to the charging plug may be blown open.

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