Problem Lipos

[MuntyScruntfundle]

I'm sure there are many topics on Lipos and chargers, but I'm having problems with a couple of relatively new batteries I can't understand and I can't find solutions for.

 

I have several batteries, and a couple of chargers.  Some batteries charge fine on any charger, some batteries won't change on any.  So the chargers are ok, but I consistently get CONNECTION ERROR.

I have a small tester from ebay which is a great bit of kit, you plug it into the discharge lead and it reads all the cells quickly, plus I have a good multimeter here.  If I test the problem batteries I get a good reading from all cells and the main charge lead.  One battery is very low, but I still get good consistent readings and all the batteries charged perfectly last time round, a few days ago.

 

I seem to have a building collection of batteries that don't want to charge now, I've even tried the trick of charging through the discharge connection and I can't get a single cell on a couple of these batteries to charge, and this trick worked perfectly ok the other day.

 

I've read somewhere a guy saying he had this problem while using Deans connectors, swapped to bullet/banana connections and hasn't had a problem since, but my head cannot accept that as the answer, surely the connector type or size can only have any effect when discharging.  And I have 2 identical batteries here, both bought at the same time, one is perfectly ok and the other isn't.

 

So, what's going on with these batteries?  There is no connection problem, all connections are good and test ok.  

 

Just to fill out the information a little, I have a couple of 1:10 trucks that I run on 2S, a couple of 1:8 which run on 3S and a crazy DBXL which I run on 2x 3S or 4S.  

The 3S and 4S batteries are being problematic, all 2S are perfectly ok.

Is it possible I'm damaging the batteries somehow?  I have a reasonable size garden and a small track setup, but no truck is ever flat out for any amount of time so I'm not asking for huge power draw.

 

I'm a bit confused with this, and I can't afford to keep replacing the damn things, they're papping expensive.

 

Just out of interest, what do you folks fine the most reliable?

I have some TrackPower, I have a problem with one of their 3S and 4S.

I have some Ace Gens, I have one 3S and one 4S that's packed up.

I have 2 Zippys, 3S which I bought for a Yeti XL, neither of those charge.

In all these cases they test fine.

 

Ideas please!!

 

Many thanks.

[Tug]

Fake Deans can be a real problem, seen that several times. 

 

I run 5.5mm bullets, they're fault free and no Y-leads needed for running multiple packs. 

[littlemonsta]

Have you tried charging as Nimh for about a minute ?

Then charge it as lipo again ?

Works for me.

Sent from my Lenovo P1a42 using Tapatalk

[dazp1976]

5 batteries playing up?

What are you discharging down to in use?

Is it intermittent problems? Could be dry/breaking solder joints under the shrink sheath on the connector that don't like being moved.

 

If you can solder go with the 5.5mm bullet change over. Only issue I've ever had with deans copies is the joint breaking off.

[RegisteredUser]

What voltage are you running them down to?

[MuntyScruntfundle]

I have found the smoking gun.

 

For some reason, and it must be my fault, I had two ESCs set with voltage protection disabled, so they were taking batteries well below 3.3, and I don't always take the batteries out for charing immediately.  That practice has changed!  As have the settings on the ESCs.  So, I shouldn't be breaking any more.

 

My charger won't put anything through a battery that's less than 3.3v, I've read up about charging as Nimh to get them to 3.5, then charging normally again.  What I couldn't find is the lowest safe values to do this with.  I have a couple that are reading in the 2.Xv range, I have a couple in the 1s and a couple that don't read anything on the tester I have and only 0.x trace on the volt meter, so they've really suffered.  Actually, I think they're  new and have never been used which is even more annoying!

 

Now, I know these things get more dangerous the lower the values get, so where would people draw the line?

 

Thanks for all your responses, I do appreciate them.

 

It's odd about the deans, I really can't see how how they could be a problem, even with different grade copper, or gold coating.  I guess you could have dry joint issues, but then you'd expect usage issues as well.  Anyway, It's not my problem.  Yet!

 

[Tug]

Trust me, fake Deans are awful! 

 

Minimum voltage on Lipo is 2.8, at 2.7 the chemical reaction takes place that permanently harms the cells. 3.4 is the lowest safe cut-off because this allows for imbalances between cells to not allow the lowest cell to drop below the aforementioned 2.7. 

 

A lot of people set theirs to 3.5 to 3.7, this leaves their cells quite close storage voltage. 

 

I favour 3.4.

[Fly In My Soup]

+1 on that tug.

 

People bash deans all day long, the fake ones are indeed crap and will melt their casing at the first whiff of heat.

 

Real deans are OK IMO, I've used them on loads of stuff, I'm currently using them on 6s setup and all is good

 

On 19/04/2018 at 11:56, MuntyScruntfundle said:

have a couple that are reading in the 2.Xv range, I have a couple in the 1s and a couple that don't read anything on the tester

 

Most cheap chargers I've used won't charge if voltage in a cell dips below 2.5/2.7v

 

But you can use the charger to recover the bad cells in most instances, by charging each cell individually through the lipo's balance tap