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-   Batteries & Chargers (https://www.wattflyer.com/forums/forumdisplay.php?f=6)
-   -   Hard to find (https://www.wattflyer.com/forums/showthread.php?t=81852)

Jackstone 09-15-2021 02:34 PM

Hard to find
 
Why is it so hard to find a 4500mah, 6s, 15c lipo battery?

crxmanpat 09-15-2021 07:35 PM

Why do you want such a low C-rating? What application are you wanting to use it in?

solentlife 09-15-2021 08:17 PM

I agree with Pat ... BUT :

As we go up in C rating - many packs also get heavier ... I have used the Capacity x C rating to determine if I can use a lower rated C and save a bit of weight ... not much saving on the smaller packs but as we get to larger - the weight difference can be saved or use a higher capacity pack ..

quorneng 09-16-2021 12:52 AM

I agree high C rating can add a bit of weight but can you trust the claimed C rating? The danger is a 15 C rating battery is using 'old' chemistry technology so could actually deteriorate faster than a better battery even at a low C discharge.
My rule is to measure what the full power discharge is and convert it into a C discharge rate and then double it to specify the C rating for the battery!

Jackstone 09-16-2021 12:54 AM

Ecalc results suggested 4500mah 12s1P 15c...using on 50cc Revolver gas conversion. 90 in wingspan, 20lbs. I bought a Rimfire 1.60 motor, with a Castle Creations Talon HV 120 Esc, and two Venom 5000 mah, 6s, 50c Lipos. I think that is overpowered, so I went to Ecalc.

Jackstone 09-16-2021 05:30 AM


Originally Posted by Jackstone (Post 1031196)
Ecalc results suggested 4500mah 12s1P 15c...using on 50cc Revolver gas conversion. 90 in wingspan, 20lbs. I bought a Rimfire 1.60 motor, with a Castle Creations Talon HV 120 Esc, and two Venom 5000 mah, 6s, 50c Lipos. I think that is overpowered, so I went to Ecalc.

So, am I overpowered with my setup; should I go less this and more that; or are 5000 mah 1c batteries available. This is my second conversion but bigger.

solentlife 09-16-2021 09:23 AM

eCalc C rating is as I understand it - the actual USED C rating ... not the battery label ! If eCalc gives 15C as minimum used ... then you need to look at having a safety margin on top ... I would be looking for at least 25C to give required 15C.

I used to go for minimum C rate but ended up replacing LiPo's too quickly as they degraded with use and their real C rate dropped off ...

Jackstone 09-16-2021 10:10 PM

I hope this set up works, Rimfire 1.60, Castle Creations HV 120, and (2) Venom 5000 mah-22.2v-50c-6s in series. ( Not an Ecalc configuration ) Expert opinions welcomed

crxmanpat 09-16-2021 10:44 PM

I think battery C-rating is the least of your concerns here (the C-ratings are mostly all fake, and most of them only produce a constant 15-20C anyway). What you want to pay attention to here is making sure you use the correct prop for the motor and amps to produce enough thrust for the weight of the plane.

But I have to ask, what specific model number of the Rimfire 1.6 did you get? I just looked one up and it is only capable of max 5S. 6S may burn it up if it's the same as the chart I just looked at. And if you use two batteries, you would do them in parallel to keep the same voltage but double the mAh (so 6S 10,000 mAh). Putting them in series would be 12S 5000.

Jackstone 09-17-2021 01:44 AM


Originally Posted by crxmanpat (Post 1031207)
I think battery C-rating is the least of your concerns here (the C-ratings are mostly all fake, and most of them only produce a constant 15-20C anyway). What you want to pay attention to here is making sure you use the correct prop for the motor and amps to produce enough thrust for the weight of the plane.

But I have to ask, what specific model number of the Rimfire 1.6 did you get? I just looked one up and it is only capable of max 5S. 6S may burn it up if it's the same as the chart I just looked at. And if you use two batteries, you would do them in parallel to keep the same voltage but double the mAh (so 6S 10,000 mAh). Putting them in series would be 12S 5000.

Yep that's the same motor, and I did see the 5s max. i'll downsize the batteries, and is the HV 120 a good choice or should I go with a 90 to 100 amp esc, like the instructions on the motor suggest?

crxmanpat 09-17-2021 03:24 AM

Yes, go down to 5S on the batteries and make sure you put them in parallel, not series. The HV 120 ESC is overkill since you will only be running 5S, but it will work fine and has a 20A BEC built in to power your RX and servos, so that's good. Since you have it already, stick with it.

ron_van_sommeren 09-17-2021 12:35 PM


Originally Posted by Jackstone (Post 1031208)
... is the HV 120 a good choice or should I go with a 90 to 100 amp esc, like the instructions on the motor suggest?

That would not be necessary if your setup only draws say 50A.
A setup draws the current it has to draw, even if it would lead to destruction of battery, controller or motor.
At full throttle ESC has no affect on current and power drawn, current is proportional to torque.


Originally Posted by Jackstone (Post 1031206)
... (2) Venom 5000 mah-22.2v-50c-6s in series. ...

Current drawn is proportional to voltage≤ :eek::eek:
Power drawn is proportional to voltage≥ :eek::eek::eek:

Even seemingly small changes in power system (pitch, #blades, voltage, velocity konstant Kv/gearing/⌀wheel and ⌀prop) can have surprisingly expensive effects https://static.rcgroups.net/forums/i...milies/eek.gifhttps://static.rcgroups.net/forums/i...milies/mad.gifhttps://static.rcgroups.net/forums/i...es/redface.gifhttps://www.rcgroups.com/forums/imag...s/smiley35.gif

The relationships luckily are very simple.
Some expensive realistic https://static.rcgroups.net/forums/i...lies/frown.gif and some extremely silly https://static.rcgroups.net/forums/i...es/biggrin.gif examples, hopefully instructive as well.

ron_van_sommeren 09-17-2021 12:43 PM

Motors can handle any voltage in RC land, as long as rpm and current don't get too high.
Wire insulation lacquer/resin is tested up to several hundred volt.


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