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RE: SV27 Battery Thread - 11/26/2006 4:55:03 PM   
Waterlogged


 

Posts: 159
Joined: 10/2/2006
From: Eugene, OR, USA
Status: offline 		Yes, might just oil the motor at the same time we lube the flex cable.

-I oiled the motor bearings at the same time interval as flex cable lube time (every 2-3 runs or at the end of the day). Motor had about 19-20 runs.

-WL

(in reply to Blackjack52)
       Post #: 176

RE: SV27 Battery Thread - 11/27/2006 9:17:05 PM   
ctonez


 

Posts: 320
Joined: 9/18/2006
From: Seattle, WA, USA
Status: offline 		I have been reading this thread for awhile now and plotting which NiMh packs to get for my SV for the 2007 racing season...but last weekend the club voted to go to Lipos in P-Mono Class, so now I have to take the lipo plunge to remain competitive.
The limit is 4s2p 15V maximum.
Benmat and the others that have used lipos, do you use 2-2s1p packs? Is your ESC stock? or is there a better configuration of batteries/ESC I should consider? what mAh per pack are you running?
Should I start a new thread, or are you guys cool with talking lipos here as well...?

Regarding the cost issue:
According to the other guys in the club, if you're racing, your NiMh packs will last 1/2 season before they start to degrade and show a drop in performance. The guys using lipos are only recharging once (if that) per day and the batteries last 1-2 seasons. So in the long run, especially if you run alot or are on a racing schedule, it costs a similar anount of money to run lipos. That doesn't take into account charger costs (mine charges all types) or other associated costs, but it still leaves you in the same ballpark after one year of running doesn't it?

If I weren't intent on competing, I'd probably stick with NiMh's. Less complexity/hazard/cost.

_____________________________

For best boating results, the Surgeon General suggests you Check Temps Often!

(in reply to Waterlogged)
       Post #: 177

RE: SV27 Battery Thread - 11/27/2006 9:44:31 PM   
Blackjack52



Posts: 1203
Joined: 9/20/2006
From: Madison, AL, USA
Status: offline 		Doesn't surprise me since Namba will be most likely allowing lipos starting Jan 1.

_____________________________

Splittin' them Hydrogen Atoms
38.4mph 12cell SV

(in reply to ctonez)
       Post #: 178

RE: SV27 Battery Thread - 11/28/2006 12:18:16 AM   
benmat



Posts: 156
Joined: 5/1/2005
From: Metairie, LA, USA
Status: offline 		Ctonez:

This post may help you. http://www.rcuniverse.com/forum/fb.asp?m=5009408

Also you may want to check this source. http://www.maxamps.com/index.html?lmd=38519.529109 Their New 20C MaxAmps Lipoly 4000HV 2S 7.4V Pack $69.99 seems ideal. They also offer an optional 300 cycle warranty.

I charge and run my packs several times per outing and they perform flawlessly. At the end of a run the packs are cool and when they are charged to peak they are cool (No waiting).

For a low voltage cutoff circuit Dimension Engineering is working on a CellShield just for our setup. I use their present version of the CellShield but it's not ideally suited for ground use. For now their LipoShield, which is not as compex, should work fine. http://www.dimensionengineering.com/ServoSense.htm These are great folks and shipping is $1.

Goodluck!

Ben

(in reply to ctonez)
       Post #: 179

RE: SV27 Battery Thread - 11/28/2006 1:09:47 AM   
ctonez


 

Posts: 320
Joined: 9/18/2006
From: Seattle, WA, USA
Status: offline 		Thanks Benmat. I guess I need to search more thoroughly.


_____________________________

For best boating results, the Surgeon General suggests you Check Temps Often!

(in reply to benmat)
       Post #: 180

RE: SV27 Battery Thread - 11/28/2006 3:23:09 AM   
benmat



Posts: 156
Joined: 5/1/2005
From: Metairie, LA, USA
Status: offline 		Ctonez:

One nice feature of lipos is that they run well from the first charge. I chose 3700 mah packs because they run about the same length of time as the nimh of the same rating and are much lighter. The decrease in weight is what makes them faster and handle better in the turns. You can pick higher mah rated packs but they weigh more. For racing the ideal is to pick lipo batteries just large enough to safely finish the race and not carry any more weight than necessary. You also need packs that will carry the current. The new 20c packs make that selection easy as a 3700 mah 20c pack can run at 74 amps continuously. There is some debate as to how truthful that 20c rating is but even if it was only 15c it could deliver 55 amps which is plenty.

Ben

(in reply to ctonez)
       Post #: 181

RE: SV27 Battery Thread - 11/28/2006 9:53:02 AM   
Waterlogged


 

Posts: 159
Joined: 10/2/2006
From: Eugene, OR, USA
Status: offline 		Let's see the tally

24cells El-4500's and parts for packs= $200
24cells GP3300's and parts for packs= $180
An extra Astroflite 112D charger= $130

Hind sight sucks sometimes, Could have bought 4 of the 7.4V-8000mah packs after all this time. Which comes out to the same run times as 4 sets of NiMH would have been, lighter and half the battery changes for the run time.

Does this mean it's time to upgrade to Lipos? In the immediate future the move to Lipos will be old news, just like the old days of NiCads.

I'm seriously thinking of the Lipo move. As I under stand it, draining the Lipo packs only half way increases their charge cycles even higher than twice the amount. If 300 near empty cycles is the norm, would think there would be on the line of 750-1000 cycles if only pulling 40-50% out of a pack (eg 8000mah packs would be the same as 5 minutes on an IB4200 set....... This would mean that recharge time between packs is only 30 minutes to reload that 1/2 capacity that was used.

8-10min run times at 35+MPG.... SWEET!!!!



Would welcome your guy's input on the rational for the move to Lipo Batteries. I am one of those that find a good rational for change/ no change is sometimes harder than just paying for the goods. $300-500 is probablly what most of us have paid for 4-6 NiMH sets (2x 6/7cell packs for the SV reference) and chargers in the past 2-3 years anyway.

LiPo Tech/prices are now about even.... With weight gains and half the charge times (based on running 8000mah pack to 1/2cap.... and then charging 8A for 30-35min).

It's money for sure........ Good God I have to pay $575/mo on my Durango-Neon autos a month...... x 72 Months...

Asking 1/72th in car payments for the sake of the Hobby we all LOVE seems so, Trivial

That damn Hindsight
-WL

P.S. Wounder what a boat with 4x 7.4V-8000mah (30V@160A 4750watts!!!!) can do for 3 minutes! Scary

Oh oh! That smell! Smells like crapped shorts R-R-R

< Message edited by Waterlogged -- 11/28/2006 10:16:43 AM >

(in reply to benmat)
       Post #: 182

RE: SV27 Battery Thread - 11/28/2006 10:03:51 AM   
Waterlogged


 

Posts: 159
Joined: 10/2/2006
From: Eugene, OR, USA
Status: offline 		BAD BOY!!!!!! for suggesting... BUT Use at your own discretion. I'm not sure I can suggest something like this, just offering a rational for those of us who have the means, so to speak to make the leap to Lipos w/o hurting the needs of the Family Body. You know what I mean, anyway....

If you have auto loans thru a Credit union, they all as a standard in the industry let members Defer an auto payment 3 times in the life of the loan, with no fees or credit hits. You do end up paying a full month of interest Free to them (CU) so it's like a built-in fee..

I only bring this up because I owe only $3k on my Durango and a month of interest is $23 bucks for a $375 payment. I have the option of doing a $23fee to help fund a new set of 4x8000mah packs and a charger/balancer.

Makes the brain and chest hurt to think how easy this sounds.

-WL

< Message edited by Waterlogged -- 11/28/2006 10:41:23 AM >

(in reply to Waterlogged)
       Post #: 183

RE: SV27 Battery Thread - 11/28/2006 10:33:35 AM   
Waterlogged


 

Posts: 159
Joined: 10/2/2006
From: Eugene, OR, USA
Status: offline 		Making the move to 8000mah packs seems imminent for me.

I suggest just sealing the Lipo packs in large Shrink wrap with a section of sponge at both ends. That will give a 'bumper' for shock to the pack if it bumps/moves inside the boat....
as well as a buffer that will let the pack's volume swell/shrink/breathe etc....... inside. Place an oxygen/moisture absorption pack in there (Those weird pink/blue crystal pack things you find packaged in new electronic goods boxes... that say Do NOT EAT).... those things.

Water proof, able to expand, breathe and absorb any moisture inherent to the pack all at the same time.

-WL

(in reply to Waterlogged)
       Post #: 184

RE: SV27 Battery Thread - 11/28/2006 2:34:03 PM   
Blackjack52



Posts: 1203
Joined: 9/20/2006
From: Madison, AL, USA
Status: offline 		I think I'll wait a tad on the lipos. Do they have more "punch"? Yes. Are they lighter? Yes. Are they more hazardous? Most definitely.
Dangerous if not careful when used in aircraft. Much more dangerous on the water.
Load up on the fireproof storage containers.

< Message edited by Blackjack52 -- 11/28/2006 2:38:30 PM >

_____________________________

Splittin' them Hydrogen Atoms
38.4mph 12cell SV

(in reply to Waterlogged)
       Post #: 185

RE: SV27 Battery Thread - 11/28/2006 2:48:22 PM   
Stinger9d9



Posts: 395
Joined: 8/16/2006
From: Georgetown, ON, CANADA
Status: offline 		Those who haven't taken the plunge might want to wait a bit for the new Lithium Ion batteries coming our way.

RC Boat Modeler has a little write up about these new batteries which sound similar to Lipo's, but which are safer, and recharge faster. It claims they do not catch fire, or explode (even after driving a nail through a pack). Also it claims they can be recharged in 15 minutes.

Oh yeah, it also mentions "there's no danger of over-discharging packs".

Sounds like technology worth waiting for.

www.a123systems.com

They don't sell to the end user yet, and are looking for distributors, but that could happen soon.

(in reply to Blackjack52)
       Post #: 186

RE: SV27 Battery Thread - 11/28/2006 3:19:29 PM   
Blackjack52



Posts: 1203
Joined: 9/20/2006
From: Madison, AL, USA
Status: offline 		Now that's the ticket. I would most definitely take the plunge on those. Solid cell, no gell.....for boats.

Thanks for the link. I'd be willing to pay double for those just for the safety.

I haven't seen for myself the Namba rules yet on lipos, but I do hope they implement some safety into racing them now.
The reason I ask.....you have to have a prop guard in your stall right? I would hope they implement the requirement to have a fire suppression utility when using the lipos at the events. A rated fireproof container for storing and charging. Having something like this is just plain ole smart w/out having rules governing it.
I use a fireproof sack and store them uncharged in an ammo can. I have a battery powered smoke detector sitting on top of the ammo can.
Also, fire and fiberglass don't go together well. We go out and spend another $100-$300 on a radio to make our investment more secure, so why risk it even more. I know, the solid cells can catch fire too (most just overheat and smoke), but the chances are very slim compared to gells.

Off my box.


< Message edited by Blackjack52 -- 11/28/2006 3:21:16 PM >

_____________________________

Splittin' them Hydrogen Atoms
38.4mph 12cell SV

(in reply to Stinger9d9)
       Post #: 187

RE: SV27 Battery Thread - 11/28/2006 3:57:30 PM   
Waterlogged


 

Posts: 159
Joined: 10/2/2006
From: Eugene, OR, USA
Status: offline 		That sounds reasonable to me, if the new cell tech is just around the corner for the end users like Hobbyist, I can wait. Still have 4 sets of new NiMH to use up this Spring/Summer.

Spring 2008 may be a very good time

-WL

(in reply to Blackjack52)
       Post #: 188

RE: SV27 Battery Thread - 11/28/2006 4:09:01 PM