-
Welcome to RCCrawler Forums.
It looks like you're enjoying RCCrawler's Forums but haven't created an account yet. Why not take a minute to register for your own free account now? As a member you get free access to all of our forums and posts plus the ability to post your own messages, communicate directly with other members, and much more. Register now!
Already a member? Login at the top of this page to stop seeing this message.
7.6v
- Thread starter Frank211
- Start date
MattySlimz1987
Rock Crawler
Could be a typo?? Adding .1 volt to each cell I guess could be possible. I dont know the resistance specs of the cells, so... ??
Also, HV. Never saw that before either..
Also, HV. Never saw that before either..
MattySlimz1987
Rock Crawler
Cool, new to me. Guess you learn something new everyday.
robert@castle
Quarry Creeper
There has been a few brands of the HV cells out recently. The chemistry is supposed to maintain it's voltage better than the standard cells, so it drops below 3.2v later in the charge. The theory with them is that even if you only charge them to the normal 8.4v the pack will last the same amount of run time and will handle quite a few more cycles because you are never pushing it's limits. Quickest way to kill a lipo is to overcharge it.
https://www.rcjuice.com/lipo-batter...-2s-hv-100c-hardcase-shorty-lipo-battery.html
100c shorty 5600mah ??
100c shorty 5600mah ??
2S, blech...
I guess fine for onroads, which is what that's aimed at.
Here's a better choice for rock crawling:
3S 100C 3600mAh Shorty
https://www.amainhobbies.com/protek-rc-3s-100c-silicon-graphene-hv-shorty-lipo-battery-11.4v-3600mah-ptk-5116-17/p662759
Just don't need that much mAh, crawlers have very long runtime...
I guess fine for onroads, which is what that's aimed at.
Here's a better choice for rock crawling:
3S 100C 3600mAh Shorty
https://www.amainhobbies.com/protek-rc-3s-100c-silicon-graphene-hv-shorty-lipo-battery-11.4v-3600mah-ptk-5116-17/p662759
Just don't need that much mAh, crawlers have very long runtime...
Last edited:
Hydrocarbon92
Rock Crawler
Don't get a HV/7.6V based on price, only buy it based on long-term reviews. The majority of HV batts sold appear to be normal chemistry Lipo's that are just binned for higher quality.
Capacity loss over time is considerably higher, or directly on-par with what you'd expect from a normal non-HV batt overcharged to 4.3v/cell. Unfortunately many hobby lipo's aren't even "normal quality" IMO.
Capacity loss over time is considerably higher, or directly on-par with what you'd expect from a normal non-HV batt overcharged to 4.3v/cell. Unfortunately many hobby lipo's aren't even "normal quality" IMO.
What's the average runtime you get from that battery? Its not a Lipo, is it better than a lipo?
Is there a thread in here telling you the difference between the 2 ?
Don't get a HV/7.6V based on price, only buy it based on long-term reviews. The majority of HV batts sold appear to be normal chemistry Lipo's that are just binned for higher quality.
Capacity loss over time is considerably higher, or directly on-par with what you'd expect from a normal non-HV batt overcharged to 4.3v/cell. Unfortunately many hobby lipo's aren't even "normal quality" IMO.
I like charts, gives me a better understanding... Thanks for the visual !
I don't have one, but a handful of regular Ascender guys have - and they love 'em.
Very good runtime is what I've heard - average runtime depends on too many factors to really say, vehicle type/motor kv (turns)/gearing, etc.
If you compare 2S to 3S batteries with the same mAh rating there is typically a noticeable increase with the 3S.
If you've got at least decent control of your throttle finger!
Basically, the only reason to run 2S is if your electronics can't handle more, in my opinion.
Shorty LiPos were typically used in race vehicles bound by rules to 2S, and used so that they could be moved around for weight distribution and also because of the ease of packaging all the electronics around them.
The Vaterra Ascender stock battery tray is configured to use them, somewhat of an odd choice - but it's a nifty battery tray in that it's low, centralized, and partly unsprung weight.
But, again, it's been traditionally hard to find 3S shorty packs.
The same for high mAh shorty packs, because when racing all that excess mAh is not used, just swap in a freshly charged pack for the next heat.
So, your high mAh LiPo is somewhat of a find, but - again, crawlers are not typically going to burn through a lot of capacity very quickly.
Very high capacity LiPo packs are typically used in go-fast bashers, because they are run at high speeds and are relatively inefficient.
Witness all the high-capacity packs that come with Traxxas connectors on them. Who wants to constantly swap batteries while bashing?
There's a company that makes a 12000mah 2S pack for standard Traxxas battery trays (gotta use an expansion kit, like you would for a 7-cell MiMh).
It's as expensive (or more!) as the Traxxas you'd install it in.
Whatever....
Hell, that same company makes a 6000mAh "Shorty" (in name only) pack that is 68mm x 45mm x 51mm, specifically to install in the Ascender.
That's practically a cube, and does WONDERS for a crawler's center of gravity... (sarcasm definitely intended, what a bunch of twats)
Last edited:
Hydrocarbon92
Rock Crawler
That's still a lipo, but 3 cells instead of 2. A nominal 11.1v or 46% more volts than a HV 2S. Most electronics that handle a HV can handle 3S.
Running a 3S that's 2/3 the capacity of a 2S will usually net the same run time, as they contain the same watt-hours of juice. The motor is actutally a little more efficient on 3S, which usually is offset by the occasional full-throttle stabs. A 2/3 capacity 3S is also virtually the same volume, although typically they're taller with a smaller footprint.
Personally I love running 3S and even 4S when possible. I have monster 4S batts for my boat, some cheaper 3S for my bashers/crawlers, and 2S for my track truck.
Don't get a HV/7.6V based on price, only buy it based on long-term reviews. The majority of HV batts sold appear to be normal chemistry Lipo's that are just binned for higher quality.
Capacity loss over time is considerably higher, or directly on-par with what you'd expect from a normal non-HV batt overcharged to 4.3v/cell. Unfortunately many hobby lipo's aren't even "normal quality" IMO.
Very interesting. May I ask where that chart comes from?
Sent from my iPhone using Tapatalk
Hydrocarbon92
Rock Crawler
If comes from here I believe: How to Prolong Lithium-based Batteries - Battery University
I believe they've collected data from various sources, but NASA and the US Military have published lots of test data that many places use. NASA claims to get 8yrs+ from lipo's that are in constant use simply by charging to only 3.9V, but not fully discharging will also increase overall life. For instance two half-discharges (50% depth of discharge) uses the same energy as one complete discharge, but you can get twice the life out of the battery. That's one reason I tell people to stop draining their phones to 1% lol.
I believe they've collected data from various sources, but NASA and the US Military have published lots of test data that many places use. NASA claims to get 8yrs+ from lipo's that are in constant use simply by charging to only 3.9V, but not fully discharging will also increase overall life. For instance two half-discharges (50% depth of discharge) uses the same energy as one complete discharge, but you can get twice the life out of the battery. That's one reason I tell people to stop draining their phones to 1% lol.
Hydrocarbon92
Rock Crawler
The specific chemistry used for that graph (LiCoO2/graphite; Choi, S. S., & Lim, H. S. 2002 study) is actually what's used in most soft lipo's (inc the iPhone, which is labeled "Li-Ion" but is clearly a Lipo cell). 4th paragraph: Li-polymer Battery: Substance or Hype?
Lipo is just a term for any lithium-based battery in a soft pouch, while Li-Ion is a generic term for several chemistry types rolled into a cylindrical case. In any case that chemistry is considered 3.7v nominal & 4.2v max charge.
Digressing from split hairs, virtually all high-amp lithium chemistries follow the same deterioration schemes. In every single case, under-charging or partial discharging will vastly prolong the life of the battery. Charging a NMC "Li-Ion" 18650 or a LiFe 0.1v above it's normal max will reduce the number of effective cycles by a surprisingly similar amount.
Lipo is just a term for any lithium-based battery in a soft pouch, while Li-Ion is a generic term for several chemistry types rolled into a cylindrical case. In any case that chemistry is considered 3.7v nominal & 4.2v max charge.
Digressing from split hairs, virtually all high-amp lithium chemistries follow the same deterioration schemes. In every single case, under-charging or partial discharging will vastly prolong the life of the battery. Charging a NMC "Li-Ion" 18650 or a LiFe 0.1v above it's normal max will reduce the number of effective cycles by a surprisingly similar amount.
And why I charge to 4.15 and 4.3 on HV, always and immediately store at 3.8 to 3.85. LVC at 3.2.
Mine aren't old enough to report longevity, but these are the numbers purported to maximize life.
For crawler use they seem happy.
I do like the extra punch going to 3s from 2.
I also cycle a new battery several times to 50% discharge and low amps in and out. Supposedly this conditioning also promotes longevity.
Mine aren't old enough to report longevity, but these are the numbers purported to maximize life.
For crawler use they seem happy.
I do like the extra punch going to 3s from 2.
I also cycle a new battery several times to 50% discharge and low amps in and out. Supposedly this conditioning also promotes longevity.
Hydrocarbon92
Rock Crawler
Lipo's really only need 1 full cycle for break-in, and that's only to maximize capacity after storage. LiFe chemistry do seem to suffer if not not broken in.
Deep discharges below 3.5v are a bad idea for lipo's, HV or regular. I only go down to 3.6v, partly for life and partly so my truck/boat is always near max power. I beat the living piss out of my first 3S Turnigy packs going down to 3.2v LVC and they puffed after 3 months. My 4S Turnigy were run on a diff ESC with a 3.4v cutoff but I used a separate beeper set to 3.6v, and they're still good & ~5.5 mohm each.
I really don't get why ESC's have such low LVC's. I'm thinking about making my own LVC with an Arduino that can be set all the way up to 3.8v & multiple "steps" of throttle reduction for different voltages.
Deep discharges below 3.5v are a bad idea for lipo's, HV or regular. I only go down to 3.6v, partly for life and partly so my truck/boat is always near max power. I beat the living piss out of my first 3S Turnigy packs going down to 3.2v LVC and they puffed after 3 months. My 4S Turnigy were run on a diff ESC with a 3.4v cutoff but I used a separate beeper set to 3.6v, and they're still good & ~5.5 mohm each.
I really don't get why ESC's have such low LVC's. I'm thinking about making my own LVC with an Arduino that can be set all the way up to 3.8v & multiple "steps" of throttle reduction for different voltages.
