Need battery help

[Lukedavis]

I have a question. Can I run a 2s and a 4s in series to make 6s or will it hurt my batteries?

 

[DavidB1126]

I'm not sure. To run 6s, usually 2 3s in a series or one 6s.

But I'm wondering how you can fit that much battery in a standard rusty 4x4 battery tray?

 

[Greywolf74]

It will ruin your 2S in the first run or two. Ask me how I know

Everything got to be the same. Cell count, mAh, brand, etc etc.

 

[Lukedavis]

It will ruin your 2S in the first run or two. Ask me how I know

Everything got to be the same. Cell count, mAh, brand, etc etc.

Okay! Thank you lol. I looked it up on google and it said it was okay but I decided to come to the battery expert

 

[Greywolf74]

Okay! Thank you lol. I looked it up on google and it said it was okay but I decided to come to the battery expert

I ruined two 2S lipos running them in series with a 4S a long time ago when I first got in to lipos. The first one I thought was a fluke but after the second one I realized it was not. DOH! ( 8(|)

 

[Lukedavis]

I ruined two 2S lipos running them in series with a 4S a long time ago when I first got in to lipos. The first one I thought was a fluke but after the second one I realized it was not. DOH! ( 8(|)

How do people run 5s then?
Not trying to argue just generally curious lol

I'm not sure. To run 6s, usually 2 3s in a series or one 6s.

But I'm wondering how you can fit that much battery in a standard rusty 4x4 battery tray?

I have the expansion pack

 

[Greywolf74]

How do people run 5s then?

I have not ever personally seen or read about anyone running 5S by running two packs in series. If someone is doing it, I'd bet big money that they are ruining the smaller of the two batteries.

Not trying to argue just generally curious lol

I don't just generally assume someone is trying to be argumentative. I just become that way when I have to explain something over and over that I know to be true to someone, and then they just wants to tell me I'm wrong without proving that I'm wrong. If I am wrong, I'm grown enough to admit when I'm wrong when faced with facts. Those type of people are usually trolls, but I argue with them because I don't want people who come across that thread/information later and then they don't know which info is true and which info is not true. I actually hate spending my time arguing on here, but I hate misinformation more.

 

[Lukedavis]

Like nomis and griz?

 

[tntpoof]

I have run 1 cell with 3 cells b4 no issue.. you can run how ever many cell in series or parallel as long as C rate and mah rate are the same

 

[Grizz03]

I have run 1 cell with 3 cells b4 no issue.. you can run how ever many cell in series or parallel as long as C rate and mah rate are the same

I agree.

I've run 5s in my Summit without issue. Both batteries were made from the same cells. Meaning that the individual cells in each battery are the same just packaged as a different voltage size.

 

[bill_delong]

I am not a fan of running packs in series for all reasons explained here:
https://www.smc-racing.net/index.php?route=product/category&path=166

Long story short, you CAN mix 2S with 4S, BUT.... as Greywolf explained they must be matched cells and brand new and can never be used for any other application other than a dedicated 6S setup.

Do yourself a favor and buy a single 6S pack, it will save you money and frustration in the long run.

 

[Greywolf74]

I am not a fan of running packs in series for all reasons explained here:
https://www.smc-racing.net/index.php?route=product/category&path=166

Long story short, you CAN mix 2S with 4S, BUT.... as Greywolf explained they must be matched cells and brand new and can never be used for any other application other than a dedicated 6S setup.

Do yourself a favor and buy a single 6S pack, it will save you money and frustration in the long run.

The two times I did it, it destroyed my 2S pack within a couple of runs. Have you ever actually done this yourself? I'm just curious.

I found this on the web:
"Using a 2S LiPo pack and a 4S LiPo pack together in series is technically inadvisable, primarily due to voltage mismatch and the resulting imbalance in discharge cycles. The 2S pack, with a nominal voltage of 7.4V, and the 4S pack, with 14.8V, when connected in series, will not discharge uniformly. This discrepancy leads to one pack reaching its low voltage limits faster than the other, risking over-discharge of individual cells. Over time, this imbalance can cause premature wear, reduce overall performance and efficiency, and significantly increase the risk of battery failure or hazardous situations due to the sensitive nature of LiPo chemistry."

HERES another article from BatteryGuy.com
"During discharge the weaker battery will run flat first. As batteries discharge, their voltage drops. When this voltage drops in a device below a certain point, the auto cut-off may engage, switching off the item or causing it to refuse to operate. Its one reason why the ignition lights in a car might turn on, but the starter motor wants nothing to do with you.

These built in cut-off points are there because batteries have a shorter life if they are run completely flat each time. In fact, if you look closely at some manufacturers who claim their battery will last for thousands of cycles, they clearly state something along the lines of “when discharged to 80% State of Charge”.

In our example, we are powering an 18 volt device, which may have a cut off at 16 volts. Our smaller 6 volt battery as it drains might drop to 5 volts, but the 12 volt battery (which is actually in this example 12.6 volts) still has enough charge. Meaning the total voltage being supplied is 17.6 volts (5 volts + 12.6 volts).

The 6 volt battery should be disconnected by now, but the circuit is being kept alive by the larger 12 volt unit as the smaller battery continues to drain, moving far below its design capabilities.

This is not an immediate disaster for disposable batteries, but for rechargeable batteries you will dramatically shorten the life of the battery as well as its ability to recharge."

These line up with what the SMC article about running packs in series says also.

That being said, I suppose you could make it work if you run a separate LVA on the smaller of the two packs, but then you won't get anywhere near the full capacity out of the packs because the 2S pack will run flat before the larger pack.

Like nomis and griz?

I wasn't referring to anyone specifically.

 

[bill_delong]

No, I have not ran 2S+4S in series personally, but long before the SMC article was published, I had damaged many 2S packs by mix matching new/old and also running packs intermittently on 2S only in other cars. I would swear off series altogether, the biggest issue I learned was that capacity would drain inconsistently and I never had an issue with 5 min quals, it was the longer 10 min mains that would cause LVC issues and I learned the hard way that I had to increase my LVC because one of the packs was always draining faster than the other.

I guarantee if you ran a 2S-8Ah pack with a 4S-5Ah pack in series that the 4S pack would drain first, but everything about running packs in series is just a bad idea.

The majority of race grade brands have switched over to saddle pack designs and many pros will claim they never have issues, but I have many friends who have confirmed that temps are mismatched after a long main and they experience degraded longevity.

If you're racing and have the belief that saddle packs are going to make you more competitive, then it may be worth the added expense, but I don't see any reason why a basher would ever need to run saddle unless they prefer to burn a hole in their pocket faster

 

[Greywolf74]

No, I have not ran 2S+4S in series personally, but long before the SMC article was published, I had damaged many 2S packs by mix matching new/old and also running packs intermittently on 2S only in other cars. I would swear off series altogether, the biggest issue I learned was that capacity would drain inconsistently and I never had an issue with 5 min quals, it was the longer 10 min mains that would cause LVC issues and I learned the hard way that I had to increase my LVC because one of the packs was always draining faster than the other.

I guarantee if you ran a 2S-8Ah pack with a 4S-5Ah pack in series that the 4S pack would drain first, but everything about running packs in series is just a bad idea.

The majority of race grade brands have switched over to saddle pack designs and many pros will claim they never have issues, but I have many friends who have confirmed that temps are mismatched after a long main and they experience degraded longevity.

If you're racing and have the belief that saddle packs are going to make you more competitive, then it may be worth the added expense, but I don't see any reason why a basher would ever need to run saddle unless they prefer to burn a hole in their pocket faster

I gotchya. For some reason, I thought you were endorsing the idea of running mismatched cell counts at first.

 

[Lukedavis]

Alright guys, I’m gonna take one for the team and try it. That’s how people run 5s which is cool. Actually, my esc has a 5s lipo setting in it too which is cool. I’ve made sure they have the same mAh, C rating, and are around the same age. It’s a 4s and a 2s

 

[bill_delong]

Can I run a 2s and a 4s in series to make 6s or will it hurt my batteries?

...they must be matched cells and brand new and can never be used for any other application other than a dedicated 6S setup...

...I’ve made sure they ...are around the same age...

FAIR WARNING... they must be brand new and matched cells, otherwise you need separate LVA's placed on the balance port of each battery if you don't want to risk damaging one of the packs that are not matched:
https://www.amazon.com/Aoicrie-Battery-Checker-Detector-Indicator/dp/B08YY5ZL93

 

[Lukedavis]

FAIR WARNING... they must be brand new and matched cells, otherwise you need separate LVA's placed on the balance port of each battery if you don't want to risk damaging one of the packs that are not matched:
https://www.amazon.com/Aoicrie-Battery-Checker-Detector-Indicator/dp/B08YY5ZL93

View attachment 177647

I just ran it for around 30 minutes and the 2s got down to 3.57 and 3.56. The 4s was at the same levels.
I’ll be careful though

 

[Lukedavis]

Both at basically the same volts per cell

@Greywolf74 we should start another page in the lipo spread sheet and experiment and document what I have done so far with running a 4s and 2s in series.

 

[bill_delong]

Good info there, I find it interesting that the cells on the 4S pack were ever so slightly lower voltage, curious if that pack was the older one of the 2 packs?

What would be really nice to see the IR readings on all cells, that would confirm they are all matched cells

 

[Lukedavis]

Good info there, I find it interesting that the cells on the 4S pack were ever so slightly lower voltage, curious if that pack was the older one of the 2 packs?

What would be really nice to see the IR readings on all cells, that would confirm they are all matched cells

Yeah my charger doesn't check IR Readings which sucks. The 2s is older by far.