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LIPO battery VS. Racing pack


#1

Hello guys,

Recently I stumbled over this product:
http://www.sparkfun.com/commerce/product_info.php?products_id=8484

Which is a 3-cell lipo battery with 6Ah of power.

But, I would need a charger for this battery too: (I will need the speed charger for more A)
http://www.sparkfun.com/commerce/product_info.php?products_id=8293

Which comes to a total of: $39.95 + $19.95 = $59.9

Now I was wondering, how powerful are these batteries compared to a racing pack?

Let’s say we have these 2 situations, how do they compare?
[ulist]
we have 2 servos connected
we have 2 DC motors connected
[/ulist]

Both running 5V (regulated via FEZ), both connected to FEZ (servos directly, DC motors with motor shield)

Thank you!


#2

Basically the difference between that and say a R/C LiPo battery is discharge current. The batteries on SFE are high capacity but can only dump 2C in current (2x capacity - 12A in this case) vs a r/c lipo able to do up to 50C (300A for a 6Ah pack).

If you want to run a motor or servos, get a R/C lipo. If you want to run electronics, get a lithium-ion.

Servos can stall out at 2-3A, and a motor will run 5-200A depending on the motor. Therefore, if you want to run servos and motors stick with the R/C LiPos.

Also, the sparkfun battery cannot be balanced - so once your cells start getting slight voltage differences you can start putting too much voltage into one cell and end up with it going critical. (ie: burn down your house). R/C batteries on the other hand have balance leads on them and R/C chargers have balancers in them to charge your lipo’s (or any other cell) safely.

Either way, i’d recommend you get an R/C charger for charging your lipos. You can get them for the same price, they are far smarter, you can charge lead acid, nimh, nicd, LiFe, LiPo, Li-ion, LiMn on them. You can also discharge, recharge, and cycle any of your batteries (great for bringing NiMH’s back to life).

I’d recommend one of these if you’re on a budget:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11668&Product_Name=HobbyKing_Variable_6S_50W_5A_Balancer/Charger_w/_accessories&aff=19701

If you want something a little fancier (by $3), i’d highly recommend this charger:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7028&Product_Name=Turnigy_Accucel-6_50W_6A_Balancer/Charger_w/_accessories&aff=19701

For batteries, if you want insane amounts of capacity:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11939&aff=19701
Or, slightly less capacity but much cheaper:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10286&aff=19701

Or something cheap ($25) for less capacity (4000mAh)
http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=9185&aff=19701

I highly recommend HobbyKing for batteries and lipos. I have one of their quad chargers mounted to the cargo barrier in my 4WD, and 2 chargers inside. I have dozens of their batteries, and friends have dozens and dozens more.

If you’re worried about them, get one of these: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14285&aff=19701
$2 for peace of mind.

If you were looking for lipo’s for your r/c car:
4000mAh 2s: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8357&aff=19701
5000mAh 2s: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10277&aff=19701
5200mAh 2s: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=13398&aff=19701

All under $27 each.


#3

Thank you for your detailed and very clear reply! This will come in handy!
Still, these batteries with charger cost more then those from sparkfun, but you are right about voltage reduction and burning cells. I did some research on the internet regarding LIPO’s.

Although this is very detailed, could you correct the wrong links? Some links are double stated and I believe you meant to show something else…?

Thank you! ;D


#4

The Sparkfun batteries are a lot less capacity than a racing pack. That’s part of the reason.


#5

The 6000 mAh battery was my choice, but it’s only available in Europe if I pay immense shipping costs. Not an option.

If I order from the Europe warehouse this saves a lot of money.

This battery is in stock:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=13398

Is this also a good battery? It has a little less capacity. (5200mAh)
Thanks! :wink:


#6

Oh yyeah, and why is this charger more expensive? Is this even better? ::slight_smile:


#7

Because it charging a really big battery! Remember, Robert, 6Ah at 3.3V is a lot different than 5Ah at 8.4V.


#8

Since this is the only charger available in Europe, there is nothing less to do but buying this one :frowning:

Where did you read this?

Edit: Seems like the link has gotten lost?
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10452


#9

Robert, read about Ohm’s law http://en.wikipedia.org/wiki/Ohm’s_law


#10

Lol, I’ve studied electronics, I know mister Ohm :smiley:
I thought you read some difference between chargers or batteries what made a lot of difference in amperage? :smiley:


#11

Buy a good charger. The cost of the charger will save you in cost of batteries in the long run. If you wan to get your moneys worth get one that does multiple types and multiple cells with cell balancing.


#12

I’ve got an Electrifly Triton EQ and it does the job admirably well. Charges everything. Handle discharge cycles. Balancer is built in. Cost about $120. Considering a “good” LiPo battery from MaxAmps costs $130 it’s an investment well spent.


#13

So you both would advise the more expensive charger?


#14

Yes.


#15

I would advise getting a HobbyKing charger. The internals are the same as the more expensive brands (don’t worry, i’ve looked!). They use american made FET’s and are very well constructed, their software is just as good if not better than the big name brands.

The reason they can sell them so cheap is because their either a) own the factory making them, or b) Are order 10,000 direct from the factory. There are no middlemen. There is no chinese distributor, selling to a local distributor, who sells to the local wholesaler, who sells to the local hobby shop, all wanting their 40-60% markup.

The Accucel chargers are very very good, and very accurate.
HK: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7028&aff=19701
DE: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10452

Their ECO series chargers are their new ones, only at HK warehouse at the moment though.
HK: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=12104&aff=19701

The german warehouse costs more because it costs more to staff and they have to ship the goods there in the first place. If you’re buying a few things double check the price of buying both HK and DE warehouse + shipping. It might be cheaper from HK.

I don’t know how many cells you want, however guessing you’re dropping voltage to 5v - i think you want 2s. If you don’t need the battery in a hard case - ie: it’s not taking big impacts regularly, just get a normal lipo.
All of these are at the german warehouse. Prices are what i see them as logged in, so they may not be what you see.
$28.50, 5.8Ah 2S 30C: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14390&aff=19701
$18.31, 5.0Ah 2S 20C: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14376&aff=19701
$27.97, 5.0Ah 2S 30C: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14327&aff=19701
$30.03, 5.0Ah 2S 40C: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=13959&aff=19701
$23.74, 5.0Ah 2S 20C: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10365&aff=19701
$23.29, 4.5Ah 2S 30C: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=13389&aff=19701

I don’t know if you need more than 20C, check the weight and dimensions of each pack when choosing, some will fit your application better than others.


#16

Thank you!

I think my choice will be these:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14390&aff=19701

and charger:
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10452

Do you think this is a good price-value-quality pack? ;D
Thanks for your time! :wink:


#17

Good choices :slight_smile:

Do you have an old PC power supply that you can hack to make a powersupply for the charger? To charge the 2S pack you’ll need about 4.5A at 12v. I use two old powersupplies for my high current requirements (i of course have a regulated lab supply too, but it is only 3A).


#18

Yes, I should have 3 power supplies lying around on the attic. :smiley:
Have to wait a little bit, the charger is not in stock :wall:


#19

Robert, you do have a power supply for it, right?


#20

I could use one of my power supplies or just pick a old PC power supply… :slight_smile: So yes.