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View Full Version : Quick Review: United RC 7.4v 1660mah LiPo Pack



mpetrich
04-16-2005, 11:47 PM
Got mine today and I thought I would share a few thoughts with you guys.
Construction of the pack is top notch! Packs are covered with black shrinkwrap and look really good in the H8 chassis. Both packs are Apogee cells and I have been using them in the past (Mini T and M18) and they are fantastic and really stand up to a lot of abuse. Before installing them I was running the Team Helotes 8 cell (which is a great pack also!). The LiPo's are much lighter, slightly smaller and the performance (top speed) is identical with the bigger 8 cell GP pack. The best part with the LiPo is the LONGER run time and definitely better punch when the motor is under heavy load (a fast take off or a blast over heavy grass, etc.). I HIGHLY recommend these cells for those of you looking to go LiPo. United RC should have the 3 cell LiPo pack soon and I will definitely pick one of those up also!
Hope this helps,
Matt

lukeita
04-17-2005, 12:37 AM
Could you please take a photo of it?
Thanks!

BitHed
04-17-2005, 12:40 AM
...hmm...that good eh...AWW mAAAN :( That means i have to buy some? :D Oh what a shame LOL...

mpetrich
04-17-2005, 12:50 AM
Here's a couple of pictures with the LiPo's installed.

mpetrich
04-17-2005, 12:52 AM
Someone also wanted a picture of a comparison between the Half8 and a T4. Well, here is it.........
Thanks,
Matt

paulj2
04-19-2005, 04:57 PM
mpetrich,

I assume from the pictures, the packs fit the battery area with no modification? Also, how do you recharge with the 2 packs parallelled? Do you charge them as 3 or 6 cells?

Did you wire them in parallel or did they come prewired?

Thanks, Paul

CableMan
04-19-2005, 06:32 PM
I am a newbie to electric RC, so this may be a dumb question:

What makes the LiPo batteries better than say Energizer AA NiMH. The LiPo batteries are 7.4V 1660mAH (12.3WH) , but 6 Energizer AA's are 7.2V 2500mAH (18WH) and are only $10 at Wal-Mart. This is almost 50% more power from the cheap Energizer batteries.

I realize that the Lithium batteries are lighter, but it doesn't look like the weight would make up the difference in power output. What am I missing, because LiPo are much more expensive than Energizer batteries? Is it the "punch" that you mentioned (I assume this would be the high current that the LiPo can deliver)?

CableMan
04-19-2005, 06:37 PM
By the way here is a random link (so I could get a picture) to the energizer 2500, 2300 or 2100 mAH AA batteries:

http://www.thomas-distributing.com/energizer-aa-nimh-rechargeable-batteries.htm

I have been buying mine at Wal-Mart for about $10.

CableMan
04-19-2005, 06:47 PM
Actually, 6 batteries for the Half-8 would be about $15 (they come in packs of 4 for about $10).

mpetrich
04-20-2005, 03:11 AM
Hi Paul,
Yes, the packs fit perfect with no modification. I also removed the battery stops today and they fit even better. Since the LiPo's are two packs of two cells each, wired in parallel, you charge them as a 2 cell with double the mah. Since each pack has 830mah, you charge them as a 2 cell LiPo with 1660mah.
Hope that helps,
Matt

mpetrich
04-20-2005, 03:19 AM
I am a newbie to electric RC, so this may be a dumb question:

What makes the LiPo batteries better than say Energizer AA NiMH. The LiPo batteries are 7.4V 1660mAH (12.3WH) , but 6 Energizer AA's are 7.2V 2500mAH (18WH) and are only $10 at Wal-Mart. This is almost 50% more power from the cheap Energizer batteries.

I realize that the Lithium batteries are lighter, but it doesn't look like the weight would make up the difference in power output. What am I missing, because LiPo are much more expensive than Energizer batteries? Is it the "punch" that you mentioned (I assume this would be the high current that the LiPo can deliver)?

There is a big difference between AA NiMH and let's say GP1100 cells and then another leap to LiPo. A LiPo battery can deliver a much higher sustained delivery of current. When the motor needs a lot of juice (during a hard start, going through thick grass, etc.) the LiPo can deliver that type of output. The AA NiMH cannot. Yes, LiPo's are much lighter and for the most part smaller, so you can get more mah for increased run time in the same space. Finally, as discussed with Castle Creations (maker of the Mamba) a 7.4v LiPo pack is rated very close to an 8 cell (9.6v) GP1100 pack. All of these (plus others) are the benefits of LiPo technology. Also, when you get into brushless motors, many of them (Hacker for example) are specifically designed for the higher amp draw that only LiPo's can provide. Finally, you stated the AA NiMH have 50% more power because of the higher mah rating. The mah defines capacity of a battery, not the power. Since a AA NiMH cannot deliver the amps needed for a hot motor, the motor just runs slowly since the batteries cannot provide the amperage that it needs. On a brushless motor, many times this will cause cogging.
Hope that helps,
Matt

CableMan
04-20-2005, 12:49 PM
OK, that makes sense. What I should have said is that the AA NiMH have 50% more stored energy (capacity), but the instantaneous power is very low.

How many amps do these high performance motors pull? I did not realize that the amount of amps was that high. I was looking at some of the motors on different web sites, but could not find the amperage in the specifications, only the voltage.

paulj2
04-20-2005, 12:50 PM
Matt,

Yes, that is the exact info I needed. Did you wire them in parallel or were they prewired?

Thanks, Paul

mpetrich
04-20-2005, 03:23 PM
OK, that makes sense. What I should have said is that the AA NiMH have 50% more stored energy (capacity), but the instantaneous power is very low.

How many amps do these high performance motors pull? I did not realize that the amount of amps was that high. I was looking at some of the motors on different web sites, but could not find the amperage in the specifications, only the voltage.

Yep, that is exactly right on the AA NiMH. From what I understand, a high performance motor can pull as much as 40 amps (I think that is right.....).
Especially on a hard start......that's were the burst handling capabilities of the GP1100's or LiPo's make a BIG difference.
Thanks,
Matt

half8 abuser
04-23-2005, 09:02 AM
Here's a couple of pictures with the LiPo's installed.

Wow those things stick out pretty far. Do the hit the arm at all. Looks like the wire gets in the way.

mpetrich
04-23-2005, 12:54 PM
Not really. They don't stick out far at all. If you look from the bottom of the Half8, the are barely over the edge of the chassis. I removed the battery stops and then moved in even more.
Just to let you know,
Matt

RURC
04-24-2005, 02:26 PM
How many amps do these high performance motors pull? I did not realize that the amount of amps was that high. I was looking at some of the motors on different web sites, but could not find the amperage in the specifications, only the voltage.


Mpetrich is not fully correct in his 40 amp rating. I have seen (in a RC18T) of absolute peak amp draws of 130 :eek: ( I believe that CC has seen 125 :eek: in a Mini T themselves if my memory serves in conversations I have had with them). Granted this if for a few miliseconds but the measurement is still there. Castle Creations will back me on this. This is why battery cables and connectors are so important. I have stressed this many times. Others have said the I over build things and that is true, but I have not had any if the problems others have talked of in the brushless arena. So something I am doing different works period.

mpetrich
04-25-2005, 01:31 PM
Hi Mike,
Thanks for the info. I knew that 40 amp draws happen fairly regularly, but I had no idea it could go as high as 130! Thanks for the info.
Matt

CableMan
04-25-2005, 07:40 PM
Holy toledo that is a lot of current. Let's see how fast we can melt those wires!

Thanks for the info!

UNITED_RC
05-07-2005, 03:09 AM
Thanks for the review....

one thing, while it is completely up to the driver on how to install them....we build/designed the packs to be installed with the leads towards the front of the chassis...not in the rear.

To answer some more questions here..the packs come PRE-Wired, and we PREFER to install DEANS on the pack prior to leaving the shop. We also cylce the lipo packs as well to eliminate any DOA or faulty packs. The worst thing is getting a new product, and it not work or is faulty!!! :(

If anyone has any other questions, please feel free to email us @ cs1@unitedrc.com

PS: you should see a release thread on the official release in this section in about 5 min!

URC

UNITED_RC
05-07-2005, 03:17 AM
Well....here is the link to the new pack release:

Lipo Half-8 Pack Release (http://halfeight.com/forums/showthread.php?t=294)

Vad
05-21-2005, 10:49 PM
Got mine today and I thought I would share a few thoughts with you guys.
Construction of the pack is top notch! Packs are covered with black shrinkwrap and look really good in the H8 chassis. Both packs are Apogee cells and I have been using them in the past (Mini T and M18) and they are fantastic and really stand up to a lot of abuse. Before installing them I was running the Team Helotes 8 cell (which is a great pack also!). The LiPo's are much lighter, slightly smaller and the performance (top speed) is identical with the bigger 8 cell GP pack. The best part with the LiPo is the LONGER run time and definitely better punch when the motor is under heavy load (a fast take off or a blast over heavy grass, etc.). I HIGHLY recommend these cells for those of you looking to go LiPo. United RC should have the 3 cell LiPo pack soon and I will definitely pick one of those up also!
Hope this helps,
Matt


What type of charger do you use on the packs from United RC, and what is your procedure for charging?

UNITED_RC
05-22-2005, 01:17 AM
We recommend that you use an adj. digital peak charger. Two widely used chargers of this nature are the MRC 959 and the Pirahna Dig. Peak Charger.

Charging: NO MORE than 2amps
.90v cutoff

No need to discharge, as NiMH do not have memory like NiCAD.

URC

Vad
05-22-2005, 04:23 AM
We recommend that you use an adj. digital peak charger. Two widely used chargers of this nature are the MRC 959 and the Pirahna Dig. Peak Charger.

Charging: NO MORE than 2amps
.90v cutoff

No need to discharge, as NiMH do not have memory like NiCAD.

URC


Are you refering to Lipo packs here with the above chargers...?

UNITED_RC
05-22-2005, 01:16 PM
Woops...

Sorry about that...

Good catch....

For the lipos....there are many lipo chargers out there. You can pay from $50-$300.....

A great and SAFE lipo charger is the Apache 2500. It requires a Power suppply, but pretty easy to use. It does lack some nice features, but then again, it is only $46.50 (http://unitedrc.com/store/product.asp?BrandId=20&ID=112)

Another higher end lipo charger that is widely used is the Great Planes Trition Charger. This also requires a Power Supply, but has tons of nice features. It also charges, NiCAD and NiMH packs/cells too.

Please see this link for a great lipo charging, discharging and handing procedures: http://pfmdistribution.com/guidelines.htm

mpetrich
05-23-2005, 02:33 PM
What type of charger do you use on the packs from United RC, and what is your procedure for charging?

I am a BIG fan of the Duratrax ICE charger. It does a great job with LiPo's and with NiMH batteries. You can also get a temp probe which does a really good job at helping you keep battery temps in check.
Priced right and has a lot of great functions.

United RC includes all the specs for proper charging of LiPo's. With a 2cell, I am using .80amps and if in a hurry, I may bump that up to 1.0amps.
The three cell would also have a 1.0amp limit.
Hope that helps.
Matt