What Lipo batteries are people using for the RRC3?

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4kids49

4kids49

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What Lipo batteries are people using for the RRC3? I am new to Lipos, and have read a lot on TRF. I have a very small av bay application where a Lipo might be useful to me. The Lipo sold by Adrian at Featherweight looks interesting but is 3.7v I believe. Jim Amos suggested that 7.4 v might be better for the RRC3, but I did not specifically ask him about the Tenergy Lipo. I am doing a straight dual deploy with JTek ematches, no air starts or anything complex yet. Any thoughts would be appreciated. Thanks.

Chris
 
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Ah I am interested in this as well. I can easily figure out the 9v. LiPo though - I am clueless. I stickied the thread on lipo for the stratologger and I am still not completely sure.
 
For bigger rockets gonna stick with 9v

For smaller diameter may use a pair of those smaller 3.7 volt lipos bought for another altimeter , but want to wire in series . From what I hear is not required but I will feel more comfortable being closer to the optimum voltage.

Kenny
 
I use these https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=28648 with a strattologger. They are pretty small but capacity for a modern altimeter isn't normally an issue. For example the RRC3 pulls 6 ma of current running, so a 180 mah battery should power the altimeter for 30 hours (not including short bursts of power to fire charges), which is sufficient for a weekend of flying before recharging. At 7.4V the voltage is within the 3.5-10 volt acceptable range. Here is where it gets tricky. These batteries are rated to provide over 7 amps (40C) burst, and could supply even more in a short circuit, which exceeds the 5 amp maximum specified in the user manual.

I've used the batteries on a strattologger which is rated to 10 amps output, but I can't say for sure if I am exceeding the SL100 specs when I fire an e-match, although no damage has been noted. Even the batteries that Adrian sells are capable of 9 amps output. I simply bought one of the smaller 7.4 LiPo's made in order to try to minimize the max current output, and ground tested to make sure that they worked together.
 
COrocket said:
I use these https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=28648 with a strattologger. They are pretty small but capacity for a modern altimeter isn't normally an issue. For example the RRC3 pulls 6 ma of current running, so a 180 mah battery should power the altimeter for 30 hours (not including short bursts of power to fire charges), which is sufficient for a weekend of flying before recharging. At 7.4V the voltage is within the 3.5-10 volt acceptable range. Here is where it gets tricky. These batteries are rated to provide over 7 amps (40C) burst, and could supply even more in a short circuit, which exceeds the 5 amp maximum specified in the user manual.

I've used the batteries on a strattologger which is rated to 10 amps output, but I can't say for sure if I am exceeding the SL100 specs when I fire an e-match, although no damage has been noted. Even the batteries that Adrian sells are capable of 9 amps output. I simply bought one of the smaller 7.4 LiPo's made in order to try to minimize the max current output, and ground tested to make sure that they worked together.
Click to expand...

Thanks Chris. I am reading the manual with LiPo batt. in mind. I figure that there are enough people out there with RRC3's that someone must be using one with a LiPo. Adrian had some good explanations in posts of why the ones he sells are good. I am not in a rush, so will see what comes up. Thanks.

Chris
 
Interesting battery. What do you use to charge it? What type of harness? It has 3 connectors.
 
You need a LiPo balancing charger for multiple cell packs. Most LiPo packs have a 2-wire output connector and a N+1 balancing connector. I like batteries with a Molex output connector are preferred as you can buy Molex connectors from any electronics supply house but if not simply buy several sets of connectors from the company you purchase the batteries from. Make sure your charger has connectors or adapters that match your battery and I would purchase an AC/DC charger so you can recharge at home and at the field from your car battery. https://www.hobbyking.com/hobbycity...y=86&LiPoConfig=3&sortlist=W&CatSortOrder=asc is a good place to buy LiPo batteries and chargers.
 
Ok,,,,,,,,,,
Here ya go,,,,,,,,,,,

First,,,, I'm flying with an Eggtimer altimeter,,,,,,,,,
It's been working fantastic,,,,,, I have nothing but positive to say about it..........
The Eggtimer altimeter uses a separate battery to power the chip and the pyro outputs,,,,,,,
so it's much less likely to brownout the chip in flight,
this is a good thing,,,,,,,please don't ask me how I know..............

All Bob said is correct,,,,,but I just learned a valuable lesson to add,,,,,,
I have a computer charger for years now,,,,,
I've used it to charge everything from lead acid motorcycle batteries
to lipo's, to nicad's and nickle metal hydride,,,,,,,
it's a balancing charger, thats a must,,,,,,,it works great, I love it.....
It does from 2s thru 6s lipo

The Eggtimer uses a 2s on the pyro outputs and a 1s to power the chip,,,,,,,
My charger won't charge the 1s,,,,,,,

So here's the charger I wish I had right now,,,,,,,,
and don't forget,,,,,, I paid near $150 for my charger, and I need a 12v power supply on my bench to run it,,,,,,,,,,

https://www.hobbyking.com/hobbyking...AC_Charger_Discharger_1_6_Cells_GENUINE_.html

This charger will run on your car batt at the field, (you probably wont have to though )
it has a built in power supply, plug it into 115V. AC,,,,,,,,
it will accomodate 1s thru 6s lipo's,,,,,,,,,,,
It will charge any battery chemistry your ever gonna need,,,,,,,
and very important it WILL save you money by keeping your batts in
good shape- it charges,, discharges,,, and cycles ,,,,,

this 2s batt I'm using on my Stratologger now,,,,

https://hobbyking.com/hobbyking/store/__23135__Turnigy_nano_tech_180mah_2S_25_40C_Lipo_Pack.html

This 1s I'm using to power the chip on my Eggtimer now,,,,

https://hobbyking.com/hobbyking/store/__23313__Turnigy_nano_tech_200mah_1S_15C_Round_Lipo_.html

These are the JST connectors the 2s battery comes with from th4e factory,,,,,,
so that is what I'm using where nessasary in my altimeter bays,,,,,,,,

https://hobbyking.com/hobbyking/store/__9682__Male_JST_battery_pigtail_10cm_length_10pcs_bag_.html

https://hobbyking.com/hobbyking/store/__9683__Female_JST_battery_pigtail_12cm_length_10pcs_bag_.html

When you place an order,,,,,,get everything you need in one shot,,,,,,,it'll be a while before you get it.........
And be forewarned,,,,,,,,your not going to like the shipping costs,,,,,,,,,
You can reduce them by placing the order in the USA warehouse for what they have there,,,,,,,,,
but it won't be everything,,,,,,,,,

Teddy
 
COrocket said:
When I ordered my batteries I got this charger https://hobbyking.com/hobbyking/sto...3S_Balance_Charger_Direct_110_240v_Input.html there are more expensive chargers that can do more cells and charge quicker but for altimeter batteries it is perfect. I've been using it without issues and it is simple to use.
Click to expand...

That charger is not the best for that 180ma Lipo. It will charge that battery at 3.6C, 2C is the max for that battery and most experts recommend charging a LiPo at 0.5 to 1C for good life time. A better inexpensive charger for that battery is this one with adjustable charge current.
https://hobbyking.com/hobbyking/store/__14633__HobbyKing_E4_Balance_Charger_.html
 
Thanks for all of the expert advice. This makes things a lot easier for me.

Chris
 
jderimig said:
That charger is not the best for that 180ma Lipo. It will charge that battery at 3.6C, 2C is the max for that battery and most experts recommend charging a LiPo at 0.5 to 1C for good life time. A better inexpensive charger for that battery is this one with adjustable charge current.
https://hobbyking.com/hobbyking/store/__14633__HobbyKing_E4_Balance_Charger_.html
Click to expand...

+1 for that charger and don't forget to buy the accessory cigarette lighter adapter for $2.26 for your car.
 
Viperfixr said:
If I've done the C rating thing correctly, this 180mAh/25C & 40C battery can put out 7.2 amps in burst and 4.5 in constant. The burst exceeds the RRC3's capacity/limit of 5 amps per output. Is this correct?
Click to expand...

The C rating is not what it will put out, but what it can safely put out without blowing up.

Most lower-specced LiPo batteries can easily output current greater than their C rating, but at the expense of degrading performance over time.
 
I went back and forth a lot with tech support at Perfect flight over this issue,,,,,,
The people I dealt with were fantastic,,,,,, patient,,,, explanatory,,,,,
This was in reference to a Stratologger.......
They want you to use an alkaline 9V. and nothing else.....
The reason is that if you have a mistake / error on the output circuit,,,,
where you make the connections to an ematch or Q2G2 as I use,,,,,,,
If you have a dead short on these contacts a 9V battery is not capable of
putting out enough current to damage the output transistors on the altimeter......
This 2s lipo IS very capable of frying those transistors.......

I make my E charge cannons out of 1 1/2" of 1/2 copper with a pipe cape soldered on,,,,,,,,
Theoretically,,,, On a high enough G launch,,,,
the edge of the copper cannon could cut through the insulation on the Q2G2's wire where the wire goes over the edge of the cannon and down into the cannon,,,
shorting the Q2G2 and making the Q2G2 not fire and damaging the output transistor on the altimeter,,,,,,if you using a battery like I do,,,, the 2s 30 - 40c lipo
No matter which altimeter you use.........I am mindful of this when I load my charges and take steps to see it can not happen........

Now I'll go out on a limb,,,,,,,,,
I have tested many Q2G2's in my backyard,,,,, exposed,,, not covered by a charge or anything else......
In my opinion,,,,,,,
Since the higher the voltage the faster the nichrome element heats and then burns through and then "opens"......
And also since it's the current that heats the nichrome,,,,,,
What I've seen in these igniters going off is the lower voltage lipo makes the igniter pop more assuredly then the higher voltage 9V.....
Be aware there is only about a 1V difference between the 2 ,,,,,,

Lastly,,,,
The lipo is half the weight and is rechargeable,,,,,, making them much less expensive........
I've got a couple of months now,,, eliminating as many fail points as reasonably possible,,,,,,
with JST connectors and these 2s lipos,,,,,,,,,
I like this method very much it's working great for me.........

Teddy
 
Teddy, I cannot argue with your success using a Lipo and a Stratologger--sounds like a great combo. I am still searching for that suitable Lipo for an RRC3.

Is there a Lipo that puts out between 2-5 Amps, max? Seems like that would be the one to have.
 
Viperfixr said:
Teddy, I cannot argue with your success using a Lipo and a Stratologger--sounds like a great combo. I am still searching for that suitable Lipo for an RRC3.

Is there a Lipo that puts out between 2-5 Amps, max? Seems like that would be the one to have.
Click to expand...

Get the tiny 110 mAh ones from SparkFun.
 
Viperfixr said:
Teddy, I cannot argue with your success using a Lipo and a Stratologger--sounds like a great combo. I am still searching for that suitable Lipo for an RRC3.

Is there a Lipo that puts out between 2-5 Amps, max? Seems like that would be the one to have.
Click to expand...


Mark,
I've been using lipos for a pretty long time now.......
What "we" are using for rocketry was definitely made for something else,,,,,,
after all HP rocketry is such a "niche".
I used the mostly in aircraft,,, but a bit in buggy's and trucks......
There's one very important point in that industry......
The "c" rating on a lipo denotes the constant amount of amps
it's capable of putting out (at it's voltage of course)......
So when you want more power from your plane or truck you
be certain your speed control and electric motor are rated for it and you go buy
a battery with a higher "C" rating,,,,,your motor runs stronger and more powerfully........
Well the manufacturers to be price competitive with each other make high quality batteries and not so good batteries.........
The cheaper batteries to manufacture have lower price tags,, lower "c" ratings,, and higher fail rates........
Hobby King stocks such a large selection of batteries I'm sure you could find one that would be OK
to use by the manufacturer of an altimeter,,,,,, but I think that makes it a cheaply made battery.......
I know that's not what you want.....
Mark,
I've been flying the Eggtimer Altimeter......
I use a 1s lipo from Hobby King to power the chip.......
I use a 2s lipo from Hobby King to power the pyro outputs........
Since the 2s battery comes with a JST conn on it,,,
and I like that on both male and female JST conn's the conductors are not exposed,,,, (so you have to try harder to short the battery accidentally).......
Mark, we are all a product of all of our personal experiences.
A 9V. battery clip losing contact for a split second cost me a very important rocket......
The JST conn's are pretty solid when you "make" them,,,, then I secure that with a piece of tape......
No more clips for me,,,, just shiny solder joints and solidly taped JST conn's........
Please don't jinx me,,,,,
I haven't had a failure of any kind since implementing this method........

To each his own........
This is working perfectly for me.........

Teddy
 
Viperfixr said:
Teddy, I cannot argue with your success using a Lipo and a Stratologger--sounds like a great combo. I am still searching for that suitable Lipo for an RRC3.

Is there a Lipo that puts out between 2-5 Amps, max? Seems like that would be the one to have.
Click to expand...

Mark,,,
I don't want to get anyone mad at me,,,,,,
But Stratologger,,, RRC3,,, or Eggtimer,,,,,
for me it's the same 2s lipo,,,,,,,
The only difference is for the Eggtimer you also need a 1s to power the chip........
On the RRC3 and the Strat there's one battery to power the whole thing........

Teddy
 
cwbullet said:
Interesting battery. What do you use to charge it? What type of harness? It has 3 connectors.
Click to expand...


Actually it only has two. One is the JST charge/discharge connector which is what you plug into the circuit. The other is the balance connector which is used by the charger to monitor and balance each cell in the LiPo stack. Since it's a 2s battery with two lipos in series, the balance connector has three wires. A 3s battery is three cells, 4 wires. etc.

A word of caution on LiPos. Use the proper charger and configure it correctly for your battery. Don't short them out. They will catch on fire and burn. Even the little ones can be a potential ignition source. I've seen them burn and it isn't pretty. The larger ones can deliver hundreds of amps. That's enough for arc welding.
 
degreaser said:
Actually it only has two. One is the JST charge/discharge connector which is what you plug into the circuit. The other is the balance connector which is used by the charger to monitor and balance each cell in the LiPo stack. Since it's a 2s battery with two lipos in series, the balance connector has three wires. A 3s battery is three cells, 4 wires. etc.

A word of caution on LiPos. Use the proper charger and configure it correctly for your battery. Don't short them out. They will catch on fire and burn. Even the little ones can be a potential ignition source. I've seen them burn and it isn't pretty. The larger ones can deliver hundreds of amps. That's enough for arc welding.
Click to expand...

They are amazing aren't they..........
Lithium Polymer battery technology is what finally allowed electric airplanes that would really move......
And today,,, when you combine brushless motors and today's electronic speed controllers,,,
electric planes rival glow engines,,, it's amazing.......
The energy density in a lipo battery is so high no other battery chemistry has even come close......
I have a 50 or 60 lb iron / steel vise mounted to my workbench....
It was holding a E3 conn for a 3s 2200mah 40C lipo pack for an airplane,,,
I was soldering the conn on,,,,, I slipped,,,,,, I pushed the brass piece through the plastic,,,,
when it touched the vise (the other conductor was already in contact with the vise) it did exactly what you'd expect a car battery to do.....
And keep in mind,,, this is a relatively small pack.......

Teddy
 
markkoelsch said:
Might this be the point where we consider a current limiting resistor?
Click to expand...

I'm not sure,,,
I'd hope Bob would chime in on that,,,
but I believe a resistor would limit or reduce voltage,,, not amperage.....
To serve that purpose (to protect the output transistors) you'd have to fuse the pyro outputs.........
In which case if you had a dead short on the ematch and blew the fuse the charge is probably not going to go off ......

Teddy
 
Last edited:
onebadhawk said:
I'm not sure,,,
I'd hope Bob would chime in on that,,,
but I believe a resistor would limit or reduce voltage,,, not amperage.....
To serve that purpose (to protect the output transistors) you'd have to fuse the pyro outputs.........
In which case if you had a dead short on the ematch and blew the fuse the charge is probably not going to go off ......

Teddy
Click to expand...

Indeed, the resistor would limit the current to the ematch prior to it going off, as well as after, so it might prevent it from firing. But it might not:

On the other hand, something like a 1-ohm resistor, with a 2-ohm ematch, with a 4-volt LiPo, would still allow 1.3 amps through before the ematch lights, and at that point the circuit would allow 4 amps.
 
markkoelsch said:
Might this be the point where we consider a current limiting resistor?
Click to expand...

Might this be the point where we consider a secondary, cascaded (and simple/cheap) power transistor on a secondary board - that is fired by the RRC3 outputs. This way, the RRC3 only 'sees' the gate current of the 'firing board' - and any runaway current through the secondary power transistor would only trash that one and not anything on the RRC3 (I *think* this isolation is legitimate - but a few diodes on the gate lead should isolate the RRC3 if there was some kind of crazy breakdown that allowed current back out the gate lead) . If fried, a simple changeout of this (what? $2? $5?) component would get the system ready for the next flight. (Admittedly, some kind of logic (or test procedure) would need to be provided (or worked out) to confirm viability before flight (so that one doesn't fly a dead board)). Surely something like this would be a rather cheap insurance policy. Another component could be a solid-state relay (effectively the same).

Disclaimer: it's been awhile since I did anything with electronics - but I think the logic is sound in the above suggestion (with refinement, as needed). But, a completely separate physical component would make 'repair' a trivial matter.

-- john.
 
onebadhawk said:
I'm not sure,,,
I'd hope Bob would chime in on that,,,
but I believe a resistor would limit or reduce voltage,,, not amperage.....
To serve that purpose (to protect the output transistors) you'd have to fuse the pyro outputs.........
In which case if you had a dead short on the ematch and blew the fuse the charge is probably not going to go off ......

Teddy
Click to expand...
https://www.linear.com/solutions/1531 illustrates the use of a 2-terminal device that limits the current flowing through it to a fixed maximum, value. For this circuit, if R1= 0.33 ohms, the maximum current would be 3 amps. There are similar 3-terminal and 5 terminal device circuits that do the same thing.

There is some voltage drop associated with these circuits. You might have to use 2 LiPo cells in series to overcome the voltage drop instead of just one without it.

Bob
 

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