HUGE VOLTAGE SAG LGHG2 HELP!!

[Yungyakz]

I recently Purchased 45 lg hg2 cells from LiitoKala Official Flagship Store on aliexpress and they had very good reviews and when they came they where charged to 3.4-3.7v and i built at 15s 3p battery powering my ebike which draws 30a max. After soldering the battery together with 2mm solid core copper wire the battery charged up to 63v and i stuck it on the bike to find the voltage sagged 10-13v from 63v and stayed there. The battery should be able to handle 60a continous and 90a peak so why is it sagging so much. Are they fake cells? They get hot but not hot enough to burn you. I have another 30 cells from aliexpress but from liitokala Official Store which seem to be real because micah from ebikeschool.com suggested them. I was planning to take my ebike up to 60a constant.

 

[john61ct]

Didn't you thoroughly load-test the cells before building the pack?

I would think should be done as soon as possible after receiving the shipment, mimicking the conditions they'd see once put into production.

 

[wturber]

The spec sheet does give a maximum discharge of 20A per cell continuous. But it doesn't say how the battery will perform under such loads. The most I'd infer from such a rating in the absence of other info is that such a discharge rate will be safe and shouldn't harm the cell in a major way. Note that the standard discharge is 600ma and that rating is what is used to determine cell capacity. Higher rates of discharge will result in lower effective capacity.

I'm running LG MF1 (I think) cells and they have a max discharge of 10A and a standard discharge of (I think) 450ma. But I'm running them 16P (8 x 2P packs) and I get about 1V of sage under a 26-28A load.

https://cdn.shopify.com/s/files/1/0674/3651/files/lg-hg2-spec-sheet.pdf

FWIW, the tests here suggest that you should expect maybe 6-8 volts drop on a 15s pack at a 10A per cell draw.
http://www.batteries18650.com/2016/05/lg-hg2-review-18650-battery-test.html

 

[pwd]

Did you observe the 30A max current draw with a watt meter?

 

[Hayds13]

Here are some discharge curves for LG HG2. http://www.batteries18650.com/2016/05/lg-hg2-review-18650-battery-test.html

 

[Tommm]

Graph says 0.3v drop compared to 0.2A at 10A.
15s*0.3v=4.5v drop across the pack.



11v sag at 10A each is laughably bad guys, come on. That is Pana PF/Samsung 35E level, which are the weaker end of 10A/8A rated cells. It should sag no more than ~6v in cold and ~5v in warm weather.


Either you forgot to parallel some cells, damaged them during assembly or they are fake.

 

[Tolkano]

They're fake and you should use a spot welder anyway

 

[wturber]

Yep. A quick google search shows lots of reports of fake cells from LiitoKala Official Flagship Store. What did you pay for your cells and what is the standard price from known reputable sources?

[youtube]1GcDK0bLLyA[/youtube]

[youtube]6hYlhmtKEuY[/youtube]

 

[Yungyakz]

On of my controllers where faulty the controller the shunt was overheating and eventually exploaded. I now some what know why it was sagging so much also i was using yellow brick connectors for motor connections but recently switched to 5mm bullets. I doubled up the series connections with 8awg. the battery saggs alot less now from fully charged 63-56 and slowly goes back up. these cells are fake after inspecting them and removing heat shrink. I have not yet tested capacity and planning on doing so once my balance chargere arrives. they have hundreds of reviews saying there real but they arent.

 

[Yungyakz]

Yep. A quick google search shows lots of reports of fake cells from LiitoKala Official Flagship Store. What did you pay for your cells and what is the standard price from known reputable sources?

[youtube]1GcDK0bLLyA[/youtube]

[youtube]6hYlhmtKEuY[/youtube]

i paid £1.64 per cell buying total of 45 coming up to £75 for the pack.

 

[john61ct]

they have hundreds of reviews saying there real but they arent.

So now you realize those reviews are not worth the paper they aren't written on.

As fake as the cells

 

[wturber]

i paid £1.64 per cell buying total of 45 coming up to £75 for the pack.

So, from IMR battery that would cost about £230. When prices are lower by such large amounts, you should be suspicious. Sure, sometimes there are excellent deals. But you have to look carefully and make sure that the reason for the good deal makes some kinda sense. Usually such big differences in prices - especially with 18650 cells that are easy to re-wrap - means fraud. Keep in mind that there are people on ebay selling 9900mah cells?!?!?!

 

[Yungyakz]

i paid £1.64 per cell buying total of 45 coming up to £75 for the pack.

So, from IMR battery that would cost about £230. When prices are lower by such large amounts, you should be suspicious. Sure, sometimes there are excellent deals. But you have to look carefully and make sure that the reason for the good deal makes some kinda sense. Usually such big differences in prices - especially with 18650 cells that are easy to re-wrap - means fraud. Keep in mind that there are people on ebay selling 9900mah cells?!?!?!

micah from ebikeschool.com reccomended them so I thought they must be genuine and few other people have bought them. I think some other cells are fake and some real and like there 26650 5ah cells. Some People have tested theese cells and they come up to 3ah but can only do 5 or 10a max which isnt too bad considering price. Im going to use these on lower amp builds 25-35a max and buy some lipos. Im thinking of buying a bunch of 5ah 20c lipo cells for 15s 2p delivering 400a constant but lipos are reccomended to be used at half there c rating so total for 200a more than enough for my bikes which will draw 20-110a and have less voltage sag than 18650.

 

[john61ct]

micah from ebikeschool.com reccomended them

The model you thought you were getting?

Or the actual deal / vendor?

The latter is just as important as the former

 

[wturber]

micah from ebikeschool.com reccomended them ...

Then I'd tell micah about your experience and maybe he'll stop doing that.

 

[Yungyakz]

micah from ebikeschool.com reccomended them

The model you thought you were getting?

Or the actual deal / vendor?

The latter is just as important as the former

On one of his youtube videos in the description he linked the cells where I got them from. So he linked the deal/vendor.

 

[john61ct]

So yes let him know that deal / vendor is now a rip-off, maybe he can prevent others from being misled