Stiggosaurus

iTrader: (4)

Two electronics-related questions, but unrelated to each other:

LiPo Overcharge?
Picked up a pair of Powerhobby 4S 8000mAH LiPo batteries while I wait for my SMC batteries to come in. One of the packs has been used once, maybe twice. When charging it last night, I realized this morning the time cutoff kicked in on my Venom Pro Duo charger. The battery is showing a total voltage of right around 17v, with cells showing a high of 4.285v and a low of 4.263v. Not entirely sure why this didn't stop charging as it should have, but should I be concerned about this battery being overcharged? It doesn't appear swollen, but it is in a hard case so it would have to be quite swollen for it to be obvious. I absolutely do not want to take chances when it comes to safety with any battery, but I'm unclear if this is significant enough to be concerned.

Hobbywing XR8 ESC
When cleaning my buggy this week, I noticed the ESC has this white substance between the two capacitors. I don't recall seeing it before, but I'm honestly not sure I've looked this closely before. Is this normal?

Roelof

Dit you check the voltages with a good voltmeter or a multimeter? Many so called LiPo checkers are not that precise.
If the voltmeter shows the same then yes, it should not be that high but still in a safe range for the lipo.
I have heard stories where after charging the voltage does rise a little bit further, but again, with a good volt/multi meter you can rely better on the measured values afer charging but also during charging.

Is the white stuff hard or flexible? In the world of electronics it is quite normal that larger capacitors are glued to withstand vibrations. most of the time it is done with a kit (flexible) or with an epoxy (hard stuff)

Stiggosaurus

iTrader: (4)

Unfortunately I've already started very slowly discharging the battery, so I can't check with a voltmeter at this point. For future reference, how would I do that? Negative probe on the black wire and then positive probe on each red wire (of which I'm assuming there are four--don't have it right in front of me)? I did check with two different devices and they definitely did vary, but not by that much. The Venom Pro Duo reported the figures in my original post. My Hobbywing programmer though read the voltages just a tiny bit lower. Just glad to hear it is still within a safe range.

As for the white stuff, it seems pretty hard. It's difficult to tell though, as I can just barely poke it with my smallest hex driver. It gives maybe just the tiniest bit, but I'm not sure I'd call it flexible.

Roelof

You can measure on the balance plug You can keep one end on the negative and measure all pins and calculate the differences or measure te cells directly by 2 pins next to each other.




If the white stuff is hard then high chance it is an epoxy to glue the capacitors

Skynet5

White stuff is good mate.

It is basically a non-corrosive silicone sealant. Keeps caps upright and protects from vibration.

I have the xr8 pro (3 caps) and actually added a bit more as there was non between 2 of them.

It'll have the slightest bit of flex.

frewster

iTrader: (1)

I would invest in a better charger after that happening. I am very happy with my Hota D6 Pro. Hobbymate and Turnigy also sell a rebranded version.

Stiggosaurus

iTrader: (4)

This is good stuff, thanks!

Fantastic, exactly what I was hoping to hear. Thanks for the confirmation!

Yeah no kidding, it's definitely got me reconsidering the Venom. Had one when I first got back into the hobby back in 2017 and it did great by me then for over a year. But this has definitely got me thinking about alternatives, so thanks for the recommendations.

Roelof

I also have a Venom Dual port charger but I have the 2x 100w Medion model, with the build in speakers.

To be honest I have one port that charges a 2S battery to 8.44v while the display says 8.40, not a big deal and handy for racing but not with races where the charged voltage is measured before the race/heat.

GerryH

iTrader: (26)

While I'm not 100% sure this is the cause of your battery charging issue. Many of the 4 button chargers, don't have any safety features to prevent one or more cells going over the target voltage. Basically what's happening is most likely your battery has cells that are not close to the same voltage. As the higher voltage cell(s) reach 4.2v, the charger starts putting a discharge on that cell(s). But because of the wimpy discharge circuit in the charger, it can't keep up with the total current it's pumping into the battery as a whole. As a result those cells get over charged.

I took an old battery I was about to dispose of and purposely created a voltage difference of .1v between the cells. Then charged it at 1C. I stopped the charger when the higher voltage cell reached 4.3v.

If your battery when you start to charge is has cell voltage differences of .1v or more, you're probably over discharging it.

Minor voltage differences and a cell going a couple centivolts over target then pulled back down to target are fine.