Battery Hot When Charging

I was charging an eGo battery last night (from my Tornado Tank kit) via the USB to PC connection and when I went to move it, discovered that it was really hot. This is not normal.

I've charged the eGo batteries many a time before, and they may get a little warm - a little warmer than room temperature - but this was definately 40-50C range.

Is it a sign that the battery is about to give up the ghost? I took it straight off and, checking to see that it still works, have used it since but should I give it the ol' heave ho?

 

got a volt meter? worth checking it over to make sure it is still behaving like a battery.

 

No, they shouldn't get hot all, charging or in use. Send it back for warranty replacement or bin it.
Out of interest, exactly where was it getting hot?

 

The battery was hot all over - very strange. I'm using it now, so in use it seems fine - just when it was being charged. Although, I'm thinking that it has been given its last charge by me. Don't want something like that setting something alight next to the PC. Last thing I need!

It's a 650mah eGo battery - I'll go the warranty route, TW have lucked out with what they sent me. Nearly all of the Tornado kit they have credited back due to failure.

I'll also do a quick experiment with the volt-meter and come back with the results...

 

Hot all over sounds like it is overcharging, could lead to cell venting if left unchecked. I'd be looking at your charger.

 

I have had warm batterys on charge, kept using them and the same charger.
They seem to do it near the end of the charge cycle, once thats over they will cool off pretty quick. So unless yot grab it in a 10 minute period you won't notice it.
45/50 degrees is not real hot in the battery scheme of things.

Easiest test for battery failure .. does it still vape for a 6 or 8 hour period.

 

The only battery that ever got more than a little warm on me was a 12 month old Riva - previous to that it had been gradually losing run time. I pulled it down and found the cell had vented, most of the circuit board had been "eaten" by acid.
Definitely the battery on that occasion, but on yours I'm not as sure.

 

Thanks for your thoughts and feedback. I'll run some tests and post an update.

"Venting", eh? Doesn't sound good... *looks at charger suspiciously*

 

put a volt meter across the charger make sure it is around 4.2 volts, might read 4.3 or something with no load. which would be ok. ideal test would be putting a voltmeter in series with the batt while it charges and making sure it cuts off at 4.2 volts.

if you'd done some readings of the batt you might have found out if it had just been over volted or something a bit more sinister, if you keep on using it i would be particularly careful once the performance starts to drop off as from around 20-30% of the capacity down to 0% generates a lot of heat vs volts.

if you dont have a volt meter then your options are pretty limited.

 

Well, the battery reads a solid 3.7V, the charger reads 6.1V.

6.1V is well above the 4.2V that you mention azzaj!

Isn't that strange - it's plugged into the PCs USB port... I thought that only generated 5V, must be wrong, eh?

Time to get a new charger - fortunately I have a pass-through 650mah that I can use in the meantime.

 

the PC supply is high, thats the internal 5v rail of the PC. under no load you ain't gonna see 4.2v.
Their is no smarts in the eGo chargers, internally they are analog beasties, with a bunch of comparators and what I assume is a band gap reference. so they closely monitor the cell voltage, a higher voltage is likely to be charging quicker especially at the end point of 4.2V.
Instead of the supply being 0.8V above the cell it is 1.9V, so its possible your charger is charging at up to twice its designed rate, its the PC not the charger tho, plug pack that mofo.

 

you can get into the bios on most non name brand pcs and get a read out of the various voltages, might be worth it. if its a dell or similar then I'm pretty sure the molex (hard drive connectors) have +12 and -5 so that wouldn't be any good to you as im sure the usb is driven from the +5v rail. so youd probably have to get the reading off the main motherboard connector which would involve a lot of farting about.

if you have steady hands im pretty sure the pins at either end of the connector are +5 and gnd but the connector shell is also ground so you dont want to be shorting the shell and the +5volt pin out. maybe easier to do it on the board but then we're getting out of the realm of what most people feel comfortable with.

got a power pack you can check the chargers voltage out on?

i just buzzed my charger and found 4.15 volts which tells me im not getting full capacity in my charges

 

I might post some pics to show what I'm doing. +6V seems weird, and it could be I'm just gumby with the multimeter. I haven't had trouble with other gear - such as my headset and thumbdrives.

I checked with the USB mains adaptor (ie plugged into the wall, no PC) and the charger read 6.1V from there too! Something's screwy.

 

its gotta be the charger then.

got another one (or can procure?) to compare?

 

Bart may come to my rescue. Thanks for the tips all.

 

dude .. some pretty crappy advice there
Hard drive runs off +5 and +12, the same +5 rail as the USB.

As I mentioned before, you can get no useful info off of 'buzzing' the charger without a battery being connected. You could charge a 4.2V battery off of 10 billions volts so long as there is some form of current limiting and monitoring of the end voltage, guess what an ego charger does .. exactly that.

please don't try and measure a PC voltage off of a USB socket, thats PC death right there.

 

It's been a while since i ran a pc fan at 7 volts off a molex, apologies for any crappy advice due to a failing memory

It depends on the charger and the chemistry of the battery, from my experience of lipos with my r/c stuff i've never seen a charger go hotter than 4.2 volts, most actually ramp up with the battery voltage. Simple chargers such as with my micro planes have a fixed 4.2 volts and pulse the battery til there is no differential. I would not recommend charging a lipo battery off a billion volts no matter how short the pulse and how low the current was as they like to be charged at 1c and if you overvolt it i would assume you'd need to under current it. My answer was also based on what i saw on my kgo charger.

buzzing a usb socket has been done before successfully, i did mention how to not fry the pc if attempting it.

I guess i show my age when i call headphones 'cans' and measuring 'buzzing' but meh

but anyway i bow down to superior knowledge on point 1

 

lol, sorry .. had a nic headache and a generally shitty day.
I owe you apologies, I just buzzed my (standard ego) charger as I should have done in the first place, 4.22V unloaded running off a ipad charger plug pack.

I made a silly assumption that his charger was fine .. in fact it may well not be fine at all.

 

No worries dude, we all have shitty days from time to time.