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Why You Should Not Use Trustfires

With the increase of posts asking about Trustfires and no posts to explain why they are so bad, I decided to write a thread about them.

Trustfires (or Ultrafires, they are same thing) are terrible Li-Co batteries, they are poor quality and very dangerous. To be used in Nerf, you have to use unprotected cells, the fact that these cells have no protection circuit - when they should have one - is not good, they have a protection circuit for a good reason.

Trustfires cannot output enough amps for our uses. Trustfires only output 1 amp, while your 2 stock Nerf motors will pull 4-5 amps. Rhino130s pull 8A each while Hellcat 180s pull 22A each.

As Trustfires are a Lithium chemistry, they are unstable if you try to use them to supply more amps than they can deliver.

The capacity is not true, if the seller says they have 1100mah capacity, they probably only output 600mah. This capacity is shortened even more by the low amp output for our Nerf purposes. With such low performance, it's a wonder that anyone thought that it was a good idea to use them for Nerf.

With the poor quality and the low amperage of these Trustfires, they can start a fire if you use them, you really shouldn't be using Trustfires.

Alkaline batteries will output 1.5 volts per cell and less than 1 amp. They can't run any motors better then stock.

IMRs (Li-Mn chemistry) are 14500 (AA) button top batteries (other sizes are available, just that this available size fits Nerf battery trays without modification. This is the same size for trustfires). They have the standard lithium 3.7 volts per cell output and have an amp output of 5 amps. They can run stock motors for an increase in performance, but don't have enough amps for anything else.

LiPos have the standard lithium 3.7 volt output with a varying amp output (in this case c times the capacity in amp hours, 1000mah is 1ah, equals the amp output) ranging from 15 amps to 120 amp bursts. They come in many different capacities and voltages (s=number of cells in series, 3s is 3 cells. P is the numbers of series, p times s is the number of cells; 2s2p is 4 cells). To use a LiPo, you need a good connector and a rewire using appropriate wire. You can also get Graphene LiPos which are good for high power blasters and it completely removed rev up time when you replace the motors. There is also LiHv, which are high-quality LiPos with 3.8 volts per cell if you want a few extra fps from your blaster.

Trustfires (Li-Co, easily the worst and most dangerous lithium chemistry) are a 14500 sized button top battery that are designed for use with torches. They have the 3.7 volt output but can only deliver 1 amp. They are unsafe for Nerf, they can start a fire due to you trying to use them in Nerf. Do you want to risk you and your kids with these dangerous, unstable and poorly made devices?

In summary, don't use Trustfires, use IMRs or LiPos.
The Dark Kitten

Very nice summary Dusty!  Definitely Scientific paper worthy.
Id suggest to the mods putting this in the vault?  For safr keeping and something to reflect on and to guide newcomers what is safe and what is not.
Now all we need ia a Lipo safety post, rm2 post and possibly onr on blaster safety.

Yes - well said Dusty.  Highlights all the reasons not to use batteries for a purpose they weren't designed for.  

I also agree with TDK's comments about sticking this in The Vault.  Out of interest TDK what is rm2?
The Dark Kitten

NewportNerfer113 wrote:
Out of interest TDK what is rm2?

A motor we ussed to use. We used it with trustfires and such, but it was only when someone did some data pn it did thry realise that stock motors are better at higher voltage. So now we stop using them.
But to repeat yes dusty uf science isn't a strong subject it aught to be your knowledge and then ability to find this information is very impressive and thr community will grow with contributions like this

Thanks for doing this. You've covered most of the bases but I just want to point out a few minor corrections/additions (EDIT: it looks like a lot but most of it is explanation/context).

Dustybin wrote:
IMRs (Li-Mn chemistry) are 14500 (AA) button top batteries. They have the standard lithium 3.7 volts per cell output and have an amp output of 5 amps.

Probably wording more than anything, but you can get IMR cells in sizes other than 14500 (14mm diameter, 50mm length) size and with "flat-tops" rather than "button tops". 5A continuous is maybe on the low end for a 14500 size cell but probably not a bad estimate as it will depend on the individual cell/manufacturer (I think 7A is the most I've seen for a 14500 cell). Note that larger IMR cells can supply more current (and actually aren't bad options - 18650 size IMRs can easily achieve 30-40A) but at that point you're paying quite a bit and a LiPo or NiMH pack would easily be cheaper (you'd need a dedicated high-current cell holder, or battery spot welder if you're making your own pack out of them, anyway).

Dustybin wrote:
LiPos have the standard lithium 3.7 volt output with a varying amp output (in this case c=amp output)...

C ≠ Max discharge rate in Amps unless the capacity of the pack is 1000mAh (1Ah) - the max discharge rate of a lithium pack is it's C rating multiplied by it's capacity. The C rating is effectively a standardised measure of performance (or quality*) of the chemistry of the pack rather than the pack itself - graphene packs, for instance, tend to have higher C ratings so even lower capacity graphene packs can provide more current than a "standard" LiPo. Motors running on a pack with a higher discharge rate may perform slightly better (higher discharge packs often also have a lower internal resistance) but, for the most part, a higher discharge rate doesn't really matter as long as it meets or exceeds the current demands of the motors (for example, if you're powering a pair of Hellcats there should be minimal performance difference between a 3S pack that can output 50A and a 3S pack that can output 100A - the motors will only ever draw up to 44A, and only for a very short period of time, anyway). More isn't a bad thing although if you have the choice between C rating and capacity (e.g. a 1000mAh 50C pack or a 2000mAh 25C) I'd go for the extra capacity - more capacity means greater max Amp output and a longer run time. It might be worth adding that capacity in mAh (milliampere hours) is the amount of current in mA (milliamperes/milliamps) that the battery can supply continuously for one hour on a full charge i.e. a rating of 2200mAh implies that the battery can supply 2.2A continuously for 1 hour before needing to be recharged. In reality though, the Ampere-hour rating varies depending on load and battery condition - one of the reasons LiCo cells like Trustfires never seem to achieve their Ampere-hour rating is that they're often tested at ridiculously low current draw and the results converted back to a unit hour (they often can achieve their specced capacity but only at something like 0.1A current draw). Going back to internal resistance, another reason to avoid LiCo cells (and even IMR cells in the higher current applications) is voltage sag under load especially when you are near or exceeding the max output of the cells (LiCo cells may have a 3.7V nominal voltage but that can sag by as much as 0.5V per cell under load with stock motors, more so with anything aftermarket that draws more current).

This is verging on pedantry but it's worth noting that S is number of cells in series. A 3S pack may have 6, 9, 12 or even 15 cells total, the additional cells being in parallel in order to increase the capacity (and therefore the discharge rate in Amps). This would normally be noted as 3S2P, 3S3P, 3S4P 3S5P etc. but since you don't see it that often (even though most packs you buy will be in this sort of series-parallel configuration) it probably doesn't matter too much.

For most motors using LiHV shouldn't matter too much either. You might get a minor spin-up boost from the 3% voltage increase (more voltage = more stall current and torque for a given motor) but the velocity should be largely unaffected. The motors will be spinning around 3% faster but the top speed of most aftermarket motors is such that they're already spinning fast enough on "standard" LiPos to achieve, and even surpass, the critical velocity for a given flywheel/dart setup (that is to say they're already spinning fast enough that even slowing down under load shouldn't reduce the velocity significantly). This is why Honey Badgers on 2S don't perform any better as flywheel motors than Rhinos on 3S even though the former has a 30% speed advantage at no-load (if anything Honey Badgers are too fast for most flywheel setups).

NewportNerfer113 wrote:
Out of interest TDK what is rm2?

Adding to TDK, this is a (Solarbotics) RM2 (IIRC it stands for "Regular Motor #2"). It was originally jumped on as a motor to use with a standard tray of 4 AA alkaline cells but fell out of favour quite quickly when people found that they tended to destroy themselves just as quickly due to their stamped sheet copper brushes (after not much use they end up looking like the set from a Rayven motor on the left of this image). Even then you could get better performance with stock motors on 3 IMR cells. You can replace the brushes with a carbon set, which would also let you run them on a higher voltage supply, but you could do the same with stock motors and achieve the same thing and, especially with the motor options nowadays, at that point you've almost spent as much as a much better, more powerful motor like a MTB Rhino. To be fair it was originally intended as a repalcement motor for Solarbotics' "GM" series of gearboxes which themselves were probably originally meant for robotics use where the motors wouldn't have to run continuously but only for short bursts.

SSGT wrote:
(or quality*)

* If you see two packs from the same manufacturer with similar dimensions and voltage/capacity/number of cells, but one has a higher C rating that the other, it's quite possible that the cells came from the same process but the cells that performed worse in testing were "binned" into a lower performance level than the higher performing cells. There's nothing wrong with the cells they just don't perform as well as some of the others due to normal manufacturing variance. The cells in each pack also tend to be selected/matched so that all the cells in the pack have very similar performance/capacity to prevent, among other things, uneven discharging - something many don't consider when throwing 2-3 individual cylindrical cells together.

This all gives excellent further reading to FDS's battery guide.  I know that it all has been really useful at trying to claw back the knowledge I used to have about the properties of electricity and how they work in circuits.

Thanks SSGT, I have corrected some of the information there.
daniel k

Finally, somewhere clear and easy for me to refer people to!

A&M do we want to consider this for The Vault? Dusty's folded in a fair bit of SSGT's information and it's pretty accurate. Smile

Dusty, where were you two weeks ago? Could have saved me tenner.
Well at least I know now.
Crying or Very sad  Crying or Very sad  Crying or Very sad

This post actually answers a question I was about to ask as the recent influx of new members has brought the Trustfire issue to the fore again. I originally bought some trustfires a few years back (in the days before I discovered Britnerf) and I was wondering what they were ACTUALLY used for.

Turns out they are used in torches, cool, I've now found a use for my trustfire's I have stuck in my Nerf toolbox gathering dust.

TBH IMRs make more sense in most torches these days too, and it still makes sense to avoid trustfire as a brand just because they're so widely bootlegged, you never really know what you'll get

(trustfire were basically the first widely known, half-decent chinese lipo brand- very popular for torches and bike lights. I had quite a few of their 18650s in packs. But I wouldn't buy them now. Too many stories of "protected" cells with no actual protection, of large cells that are actually smaller ones padded out to larger size, and lots of low quality, specs missed etc.)

Northwind wrote:
TBH IMRs make more sense in most torches these days too, and it still makes sense to avoid trustfire as a brand just because they're so widely bootlegged, you never really know what you'll get

Completely agree, and I wouldn't use them if I didn't already have four sitting around doing nothing.

Are we moving this to the vault then?



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