Am I overcharging and damaging my batteries?

[MarkJohnston]

Hello

I have two 54.6 volt 10 amp batteries. I have two chargers saying the same voltage 54.6 volt 1.5 amp from tangs power.

Here's the deal, I plug into charge and it charges the batteries up to 55.1 volts !!! I unplugged it and it balance out to 54.6 volts. I'm not sure if it is getting charged so high is shortening the battery life and if so, how dramatic is the shortening?

I used a multi meter to prove the charger and it says 56.9 volts!!! So I really don't trust this Chinese crap. But you can't beat $10 per charger! The picture shows the voltage fresh off the charger

 

[neptronix]

What's the nominal voltage of your battery?

A 48v battery is 13S. 13 x 4.2v = 54.6v fully charged and balanced.
A "51v" battery is 14S. 14 x 4.2v = 58.8v fully charged and balanced.

Now if you have lifepo4 or some other less common chemistry, then the math is going to be very different.

 

[ZeroEm]

You want longer life then stop charging them to 100%. turn it off around 53V and let them set and it should drop a bit. 13's X 4.05 = 52.65 is a good spot. Another thing charging is faster just to 80% and you will spend more time riding than charging. Want it much lower for storage.

 

[docw009]

If your voltmeter is accurate, yes, 55.1V is too high, but it's more likely the voltmeter is off.

A 13S battery has 13 cell groups in series. Max charge on a cell is 4.2V. So 13 x 4.2 = 54.6V, The battery BMS should isolate the battery when any cell gets to 4.2V, so in theory, it cannot charge over 54.6V.

 

[E-HP]

I have two chargers saying the same voltage 54.6 volt 1.5 amp from tangs power.

Here's the deal, I plug into charge and it charges the batteries up to 55.1 volts !!! I unplugged it and it balance out to 54.6 volts.

I used a multi meter to prove the charger and it says 56.9 volts!!! So I really don't trust this Chinese crap. But you can't beat $10 per charger!

When you say 54.6V from the tangs, does that mean you measured the charger output voltage using the same meter that you measured your battery with?

You can definitely beat $10 per charger, if it were $10 per working charger, especially if they ruin hundreds of dollars of cells.

 

[Chalo]

The chargers likely have a trim pot inside, and you could lower the voltage instead of worrying about it.

 

[MarkJohnston]

The batteries are 13S3p

The nominal voltage is 46.8 v

Yes I thought about the fact my volt meter could be off. I tested it against a fresh TRIPLE A AND I BOUGHT A NEW MULTI METER. no it WORKS FINE!

I've heard about trim pots. But when I google images to know what I'm looking for...Nothing. by all means of you can somehow tell me or show me what im looking for. Am I looking for a potentiometer of some sort?

Heres the dealio. If I charge these AND TAKE THEM OFF THE CHARGER RIGHT AFTER THEY FINISH CHARGING, the voltage drops to 54.6 v. However IF I FORGET TO TAKE THEM OF THE CHARGER they charge ALL THE WAY UP TO 55 VOLT!!!!! this is also happening with my more expensive $50 charger.so the price I don't think is the problem. Something to so with he BMS letting it get overcharged

Is it normal for the output voltage of a charger to be HIGHER Than the voltage of the battery? because even the $50 charger when tested at the output port shows 54.9 volts!

 

[Chalo]

I've heard about trim pots. But when I google images to know what I'm looking for...Nothing. by all means of you can somehow tell me or show me what im looking for. Am I looking for a potentiometer of some sort?

Yes. The cheap chargers I have opened up have trim pots that look like this:



They don't adjust the output much-- only a volt or two. But they should be able to get you out of the danger zone.

 

[E-HP]

Is it normal for the output voltage of a charger to be HIGHER Than the voltage of the battery? because even the $50 charger when tested at the output port shows 54.9 volts!

The battery voltage will never exceed the output voltage of the charger. The charger should output the maximum voltage of the battery pack, when fully charged to 4.2V/cell, or 54.6V for 13S. Your $50 charger needs adjusting, or you need a better meter, take your pick.

 

[MarkJohnston]

Well, I think the cheap tangs do work! But you have to be really careful and pull them straight off the charger when they're done. I think it purposefully overcharges then to 55 volts because the cells all balance down to 54.6 , the correct voltage. If you forget about them, it WILL CHARGE THEM to 55 volts! it's happened a few times so I've probably severely killed some cycle lives.

I looked for trim pots but these tangs are the cheap kind with no serviceable parts. They have no screws on them. My $50 charger DOES HAVE A trim pot though.

 

[E-HP]

Well, I think the cheap tangs do work! But you have to be really careful and pull them straight off the charger when they're done. I think it purposefully overcharges then to 55 volts because the cells all balance down to 54.6 , the correct voltage. If you forget about them, it WILL CHARGE THEM to 55 volts! it's happened a few times so I've probably severely killed some cycle lives.

I looked for trim pots but these tangs are the cheap kind with no serviceable parts. They have no screws on them. My $50 charger DOES HAVE A trim pot though.

I have no idea what "tangs" are, but I think at this point, Dogman Dan should be posting a picture of his burned out garage as reminder of what you have up until now been able to avoid, out of pure luck.

The typical behavior of most chargers is to charge at constant current for the first stage, until the battery reaches closer to full charge, then switching to constant voltage to finish the charge. Neither involves an output voltage higher than the maximum voltage for the particular battery, assuming the chargers a set up for the battery chemistry you are using. Cycles are the least of your worries.

 

[neptronix]

I would guess some damage is done to this battery already which could affect safety in the future.. i would recommend keeping it outside or in a place where a big fire would make a small impact.

 

[MarkJohnston]

Alright, damn... I didn't realize this was so serious. One charger was more expensive and advertised that it was one of those smart chargers. But it still doesn't know when it's overcharging.

I was thinking about charging in the oven. I live alone.

I've actually used these tangs power chargers a lot with a mechanical timer to make sure it stops charging at a lower voltage

Here's the link for chargers

Tangspower

https://a.aliexpress.com/_mKmvq0B

More expensive one I got

https://a.aliexpress.com/_mtEsr2P

 

[MarkJohnston]

Hi,

I read this article. So all the cells would be getting charged to 4.3 volts. It doesn't say anything about exploding, just that it would severely reduce cycle lives. Eventually the BMS would shut off the off. These batteries do have a BMS.

https://www.powerstream.com/lithium-ion-charge-voltage.htm

I've already charged with the cheap tangs power charger at least 200 times. As I said Ive Kept it on mechanical timer to cut off and charge after a certain time, so the voltage falls to 53.9 or so. That's where I like it. 80% is just too f'n low.

Maybe the BMS is protecting it from getting damaged, really complicated stuff all this. I didn't sign up for this. a lot of time and money seems like it is getting thrown at this.

I think for the time being I should use the timers and also charge on top of a lithium fire blanket in my room or outside. If I'm charging inside I always have a gallon of water ready to go plus a bucket outside. That's going to have to do for now. Eventually when I get my own apartment I can charge in side the oven.

 

[ZeroEm]

No one did

say anything about exploding

The odds are you will never see a fire. If you do you will not forget it. Good luck with the gallon of water.

 

[MarkJohnston]

What do you guys think?

https://bridgehill.com/fire-blankets/

 

[docw009]

When Lunacycle first started out in 2015, I bought a 13S 48V Dolphin with charger. Eighteen months later, I discovered it was a 14S 52V pack with a 52V charger, Luna's error. Meanwhile, I had been mixing the 48V and 52V chargers on my 48V batteries. The Luna battery had no markings. The charger said "48V", but in finer print said 58.8V.

What saved the bacon was a good BMS. When I used the wrong charger, the BMS shut off when any of the 13 cells on the 48V pack hit 4.2 volts, so there was no overcharge regardless of charger. By the way, you think 80% is too low? WHen I had the 14S on the 48V charger, it was more like 75%. I sure wondered why I had inconsistent performance.

Anyway I think this should be the case for the OP's tang chargers too. I wonder about that 55.1.

 

[neptronix]

What do you guys think?

https://bridgehill.com/fire-blankets/

That's not a bad idea at all. I've never heard of that before!

 

[docw009]

I bought some cinder blocks, $1.39 each. I keep my shrink wrapped packs inside the internal cavity. They will also hold my downtube packs if I stack the blocks. I think they will contain a fire from a smaller pack. I have steel ammo boxes too, but have seen the youtube videos. They're not that good,

 

[MarkJohnston]

When Lunacycle first started out in 2015, I bought a 13S 48V Dolphin with charger. Eighteen months later, I discovered it was a 14S 52V pack with a 52V charger, Luna's error. Meanwhile, I had been mixing the 48V and 52V chargers on my 48V batteries. The Luna battery had no markings. The charger said "48V", but in finer print said 58.8V.

What saved the bacon was a good BMS. When I used the wrong charger, the BMS shut off when any of the 13 cells on the 48V pack hit 4.2 volts, so there was no overcharge regardless of charger. By the way, you think 80% is too low? WHen I had the 14S on the 48V charger, it was more like 75%. I sure wondered why I had inconsistent performance.

Anyway I think this should be the case for the OP's tang chargers too. I wonder about that 55.1.

I read your post but these crappy Chinese chargers are charging at 55 volts. That's only half a volt over the chemistry of the battery. I guess you're right the BMS must be good in these batteries because I've CHARGED over 200 times with it and don't have any problems YET (knock on wood)

I also use a mechanical timer and guesstimate when to shut off so they don't OVER CHARGE. I know it takes 5.5 hours from 20% to 90%. You really get Serious KICK AND SPEED with a fully charged battery WOT. I know it's bad for THE LONG LIFE , but seriously a battery is meant to get kicked and beaten around.

But yeah I also read about the Beijing fire which claimed 4 lives. Apparently they were mixing cheap after market chargers at a bike shop there.im no bike shop but still.also wouldnt you expect the Chinese to get this shit right for once? I mean EBIKES are Uber popular over there so wouldnt ECONOMIES OF SCALE come into play? F u c k. That was my thinking. I guess we'll never have the Chinese get stuff right.

Yeah you guys are right need to f'n careful though. My step dad went into a dive boat in Santa Barbara California ONE WEEK BEFORE it exploded with a lithium fire. GUARDIAN ANGEL, BUT VERY CLOSE. This was all over the national news a year ago

Yeah these tangs power are probably garbage. I've bought stuff from them before like cables. Everything is fLIMsy and cheap. What I really need is the grin satiator and in a perfect world id have money to go buy EVERYTHING

 

[E-HP]

Alright, damn... I didn't realize this was so serious. One charger was more expensive and advertised that it was one of those smart chargers. But it still doesn't know when it's overcharging.

I was thinking about charging in the oven. I live alone.

I've actually used these tangs power chargers a lot with a mechanical timer to make sure it stops charging at a lower voltage

Here's the link for chargers

Tangspower

https://a.aliexpress.com/_mKmvq0B

More expensive one I got

https://a.aliexpress.com/_mtEsr2P

LOL, now I see what you're talking about when you say "Tang(s)" . The company name the stamp on a generic Chinese charger. I have one of those, but never use it. Mine is stamped "Fuyuang". So I guess it's a Fu charger.

 

[ZeroEm]

We will just call it Fu's.

 

[MarkJohnston]

Hi guys,

I did more research

"You can discharge a cell under 3.3V but it will provide less current and you can charge it even up to 4.3+V and it will have higher capacity, but both practices will lower its lifetime.

So in emergency cases, overcharge them to 4.3V and you'll have some extra capacity to work with and if you want to have a very long time for a cell, let it charge only up to 4V but that will only provide ~80% of the stated capacity."





"The minimum voltage for charging a standard Li-Ion is 4.201V. But considering impedances of the charger and cell, most chargers have 4.25 or even 4.3V when running blank (not connected to a cell" !

Maybe THE CHARGERS CHANGE their current when plugged in? How to test a charger??


"If you can't find a datasheet for the exact model of battery that you're using, you should err on the side of caution and charge it very slowly. Lithium-ion batteries are prone to catching fire or exploding if abused."

The tangs didn't have a data sheet. My other one did have a data sheet. $40 vs $12 I suppose.

 

[MarkJohnston]

Link for research

https://electronics.stackexchange.com/questions/92000/what-is-the-minimum-required-voltage-for-charging-a-3-7-v-li-ion-battery

 

[MarkJohnston]

Hold on the tangs max out at 1 amp. That's a pretty slow charge. Maybe they don't need to charge at constant current or whatever. I'm no scientist though.