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Single 4s Vs two 2s in 8th ebuggy?
06-26-2020, 10:03 PM
#1
Single 4s Vs two 2s in 8th ebuggy?
I'm getting back in the hobby after a few years. All my cars and stuff were in storage along with all my batteries. Most of them seem to have made it out okay. I put them in storage mode before and they actually (surprise) held their voltage pretty well. I safely disposed of any that were puffed at all. That being said 3 years seems like a long time for them to be in storage. They all charge and balance fine. Their IR seems to be fine too. I just dont know. I've decided to buy new ones regardless and keep these as backup.
Here's the question. I run pretty much every class on and off road. 8th buggy, truggy, GT8e. 10th 2wd/4wd buggy, SCT, 2wd ST, TC, USGT, F1. 12th pan and GT12. ( I know some of these use shorty packs and wouldn't want to stack 2x2s shortys as they dont have the capacity for 8th right?)
Would I be better off buying a bunch of 2s batteries and just running them in series to get 4s? Or should I buy 4s packs for 8th and 2s packs for 10th? I like the versatility of having just 2s packs but i'm concerned about the stress on them stacked together when racing. It would be nice to hear from those who run 2x2s in their 8th cars and why you chose that over a single 4s.
Here's the question. I run pretty much every class on and off road. 8th buggy, truggy, GT8e. 10th 2wd/4wd buggy, SCT, 2wd ST, TC, USGT, F1. 12th pan and GT12. ( I know some of these use shorty packs and wouldn't want to stack 2x2s shortys as they dont have the capacity for 8th right?)
Would I be better off buying a bunch of 2s batteries and just running them in series to get 4s? Or should I buy 4s packs for 8th and 2s packs for 10th? I like the versatility of having just 2s packs but i'm concerned about the stress on them stacked together when racing. It would be nice to hear from those who run 2x2s in their 8th cars and why you chose that over a single 4s.
06-27-2020, 03:38 AM
#2
I've run two 2S packs in a series before, and that was because of the truggy platform having a battery tray that allowed staggering of two packs. I also had battery issues when running two packs in a series. A possible cause to my issue lies in the linked article at the end of this post? If I had a choice,I'd run a single 4S pack. A good read here.... LVC Adjustments and Packs in Series
06-27-2020, 06:37 AM
#3
I've run two 2S packs in a series before, and that was because of the truggy platform having a battery tray that allowed staggering of two packs. I also had battery issues when running two packs in a series. A possible cause to my issue lies in the linked article at the end of this post? If I had a choice,I'd run a single 4S pack. A good read here.... LVC Adjustments and Packs in Series
06-27-2020, 07:13 AM
#4
Long before SMC published that article, I had killed a brand new pack that I tried to run in series by pairing with an older pack, I had no concept of IR nor ability to measure IR on the cells at the time, I would still encourage you to monitor the IR of your individual cells even when running a single pack, more info here:
Which charger is the best?
Which charger is the best?
06-27-2020, 08:30 AM
#5
It's pretty common sense, if you use a pair of 2s packs as one 4s pack you have to treat them like a 4s pack. Cells degrade as you use them, so if you have 2 packs of different age hooked up to make a 4s battery then they will have an issue.
As I've seen with other articles from smc, their view is myopic and one sided. Notice how they never mention that the cells in a single 4s pack also have to push through the other cells and imply that it is only something 2 packs combined have to deal with? This is true no matter if the cells are soldered directly to one another, or if they are connected by a wire. Notice how they recommend changing which pack is hooked to ground to help equal out strain on the packs? Notice how they fail to mention that you can't do this with a single 4s pack and that a single 4s pack is likely to fail more quickly because you are locked into cell configuration and can't change which cell is hooked to ground?
As I've seen with other articles from smc, their view is myopic and one sided. Notice how they never mention that the cells in a single 4s pack also have to push through the other cells and imply that it is only something 2 packs combined have to deal with? This is true no matter if the cells are soldered directly to one another, or if they are connected by a wire. Notice how they recommend changing which pack is hooked to ground to help equal out strain on the packs? Notice how they fail to mention that you can't do this with a single 4s pack and that a single 4s pack is likely to fail more quickly because you are locked into cell configuration and can't change which cell is hooked to ground?
06-27-2020, 08:56 AM
#6
I am not a pro and don't make any claims to be an expert ( I also have no affiliation with SMC) but I do have about 10 years of experience using LiPo's and I admit to wasting a couple of those years in failed attempts to run packs in series and have personally discovered on my own (before SMC published their article) that running packs in series would tend to shorten the life of my packs and also created premature LVC issues, where running a single 4S pack of the same capacity would allow my buggy to last a full 10 min main without worry of hitting LVC.... I was running 2S-5Ah packs in series when having LVC issues with fairly new packs, but never had a LVC issue when running a 4S-4.5Ah pack in my personal experience on the track.
06-27-2020, 11:30 AM
#7
You are missing the point that they have made perfectly clear, the external wiring in series is what increases the resistance across the entire second pack, so if you run a single pack, then there is no added resistance to the circuit:
This statement is 100% false with no basis or scientific evidence to prove this claim. I challenge you to link to a reputable source which proves that running packs in series will increase longevity.
I am not a pro and don't make any claims to be an expert ( I also have no affiliation with SMC) but I do have about 10 years of experience using LiPo's and I admit to wasting a couple of those years in failed attempts to run packs in series and have personally discovered on my own (before SMC published their article) that running packs in series would tend to shorten the life of my packs and also created premature LVC issues, where running a single 4S pack of the same capacity would allow my buggy to last a full 10 min main without worry of hitting LVC.... I was running 2S-5Ah packs in series when having LVC issues with fairly new packs, but never had a LVC issue when running a 4S-4.5Ah pack in my personal experience on the track.
This statement is 100% false with no basis or scientific evidence to prove this claim. I challenge you to link to a reputable source which proves that running packs in series will increase longevity.
I am not a pro and don't make any claims to be an expert ( I also have no affiliation with SMC) but I do have about 10 years of experience using LiPo's and I admit to wasting a couple of those years in failed attempts to run packs in series and have personally discovered on my own (before SMC published their article) that running packs in series would tend to shorten the life of my packs and also created premature LVC issues, where running a single 4S pack of the same capacity would allow my buggy to last a full 10 min main without worry of hitting LVC.... I was running 2S-5Ah packs in series when having LVC issues with fairly new packs, but never had a LVC issue when running a 4S-4.5Ah pack in my personal experience on the track.
SMC even agrees:
You can't take a single pack and rearrange the cells which means your cell on the positive lead will almost always fail first.
You have a considerable amount of data, look through which cells have failed on you or have lost capacity. Let me know if you notice a trend.
06-27-2020, 02:06 PM
#8
Tech Regular
iTrader: (2)
Some good knowledge coming up here. I hope it stays civil, we can all always try to learn more!
Oh!! For the record, I've found that in 1/10 mod wheeler, my shorty packs have lasted longer than saddles. Have still had some really good packs and performance from both, but losing a "half" of a saddle and having to replace not 1 but 2 packs because I didn't know better and paired up a different set from leftovers.
Oh!! For the record, I've found that in 1/10 mod wheeler, my shorty packs have lasted longer than saddles. Have still had some really good packs and performance from both, but losing a "half" of a saddle and having to replace not 1 but 2 packs because I didn't know better and paired up a different set from leftovers.
06-27-2020, 04:29 PM
#9
On the other hand, there is the concern that with more wiring and connections you have more things to go wrong/possibly screw up. All it takes is one bad connection to write off one or both 2s batteries. How many threads do we see here about people plugging in a battery backwards? For some the simplicity of a single pack is without a doubt the way to go.
06-27-2020, 08:05 PM
#10
Long before SMC published that article, I had killed a brand new pack that I tried to run in series by pairing with an older pack, I had no concept of IR nor ability to measure IR on the cells at the time, I would still encourage you to monitor the IR of your individual cells even when running a single pack, more info here:
Which charger is the best?
Which charger is the best?
On the other hand, there is the concern that with more wiring and connections you have more things to go wrong/possibly screw up. All it takes is one bad connection to write off one or both 2s batteries. How many threads do we see here about people plugging in a battery backwards? For some the simplicity of a single pack is without a doubt the way to go.
06-28-2020, 08:53 PM
#12
Missed you at the track today Bill. Raced for the first time in a while. Those batteries I "thought" were good still weren't. Out of the two one started to puff slightly (so we're getting rid of that one) and the other, though fine, just didn't have the punch it used to and one of the cells seems to have an issue. It occasionally gave me an "abnormal connection" on my charger cause one of the cells wouldn't charge past 4.17v while the others were at 4.21v. Gonna order some replacements tonight and get rid of the old ones.
Batteries will also tend to go bad from old age too
Those bad connections can be a faulty connector on the charger too... especially if you are using "cage" style bullets, I try to use "slotted" bullets so that I can spread the bullet with a mini phillips screw driver to increase the bite. Also those 2mm bullets (for the balance port) only come with cage style connectors and they need to be replaced every year or so, I guess it depends on how often they are used.
1/8 Buggy will do fine around 5Ah, go 6.5Ah if you want some cushion, the extra weight will make it more stable anyway.
1/8 Truggy at least 6.5Ah to 8Ah if you more than enough cushion
I haven't raced TC in years, I assume you're gonna race at N-Control?
I know a 5Ah shorty will do fine for any of the stock classes, but wouldn't be surprised if folks are running 8Ah packs for mod, I would talk to Paul on this thread here just to see what most of the guys are running these days over there:
Bringing the track back on RCFiles - RCFiles Forums
06-29-2020, 10:18 AM
#13
Normally I would've been at the track, but my sinuses were already jacked after the dust storm hit on Friday, no way I was gonna be able to be outside for more than a couple hours at a time this weekend... I plan to be there next week for sure!
Batteries will also tend to go bad from old age too
Those bad connections can be a faulty connector on the charger too... especially if you are using "cage" style bullets, I try to use "slotted" bullets so that I can spread the bullet with a mini phillips screw driver to increase the bite. Also those 2mm bullets (for the balance port) only come with cage style connectors and they need to be replaced every year or so, I guess it depends on how often they are used.
1/8 Buggy will do fine around 5Ah, go 6.5Ah if you want some cushion, the extra weight will make it more stable anyway.
1/8 Truggy at least 6.5Ah to 8Ah if you more than enough cushion
I haven't raced TC in years, I assume you're gonna race at N-Control?
I know a 5Ah shorty will do fine for any of the stock classes, but wouldn't be surprised if folks are running 8Ah packs for mod, I would talk to Paul on this thread here just to see what most of the guys are running these days over there:
Bringing the track back on RCFiles - RCFiles Forums
Batteries will also tend to go bad from old age too
Those bad connections can be a faulty connector on the charger too... especially if you are using "cage" style bullets, I try to use "slotted" bullets so that I can spread the bullet with a mini phillips screw driver to increase the bite. Also those 2mm bullets (for the balance port) only come with cage style connectors and they need to be replaced every year or so, I guess it depends on how often they are used.
1/8 Buggy will do fine around 5Ah, go 6.5Ah if you want some cushion, the extra weight will make it more stable anyway.
1/8 Truggy at least 6.5Ah to 8Ah if you more than enough cushion
I haven't raced TC in years, I assume you're gonna race at N-Control?
I know a 5Ah shorty will do fine for any of the stock classes, but wouldn't be surprised if folks are running 8Ah packs for mod, I would talk to Paul on this thread here just to see what most of the guys are running these days over there:
Bringing the track back on RCFiles - RCFiles Forums
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