Easy rider

Hi guys,

I recently made the switch from NiMh to lipo cells and I notice the lipo's get rather warm , to warm really. I'm using the lipo's in my outrigger. It's best to keep them below 60°C and I thinck mine are doing 80°C. My lipo's are maxamps 6000 with a continues discharge rate of 20 C. My rigger pulls about 50 to 60 amps continues so that's not the problem at all , the batteries should be able to take it.

Have you got any idea how to keep lipo's run cooler in a closed hull ( no ventilation )

Thanks.

CadillacDTS2001

you should not have to cool the batteries at all.
you must 2P them and max amps lipos are not very good.
I would run a 2P set up
so say you have
3000,20C7.4 lipo
buy 2 of them ( not maxx amps) and parallel them to make 6000 MAH at 40C, 7.4 volts
that is the best way. people at our club an a 1P set up and there boats SUCKED big time. 2P or go home

Wheelnut

My Feedback: (81)

Does 2P mean 2 packs? or what?

CadillacDTS2001

it is paralleling your cells.
say you have a 6 pack of GP 3300's and you put them in 2P which will make it 6600's
like that but lipo terminology

Easy rider

Maxamps are good cells for the price. i'm using mine for over a year without a problem (in my cars ). I just tried them for the first time in my boat without ventilation and that's where the problem is. I have 3 Maxamps 6000 packs wich I could solder in parallel of only I had the space available in the boat.

In fact Maxamps 6000 are 2S1P batteries , not 2P , you're right about that but they are rated at 120 amps continues so I don't get the problem. I'm not putting to much load on the batteries at all.

I also used my Team Orion 4800 Platinum's ( Kokam cells ) with the same prob , so it's not because they're Maxamp's.

Right.??

CadillacDTS2001

max amps are not very good to other batteries. they are better then nimh but not very good in the lipo scene.
you may not notice the diffrence because you have not compared them to EVO or poly RC packs.

you will need to 2P them it may say 120 amps but like i said they are not very good. they would not be able to draw that amount of amps. i have lipos that say 140 amps 1P set up. but they are not worth a damn unless they are paralleled. and I'm only pulling a max of 100 amps.

2P you will need to buy 2 smaller batteries. 3000mah POLY RC cells
scroll down till you see the 7.4 volt 2500 MAH and then 7.4 volt 3700 MAH. . pick either one that will fit in the hull times 2

http://www.toddsmodels.com/Batteries/POLYRC/polyrc.htm

Raydee

My Feedback: (3)

Ugg, I was just about to order those exact Max Amp cells and have had racers in my ear telling me its a mistake. I figured that they are just not good enough for racing but if they are running hot in your hull and you are only pulling 50-60 amps then I am bummed. My rigger setup should pull about 80 amps or so , I am guessing those cells won't handle that load very well either. Can you give us more info on your setup....motor, prop and esc? Are you sure you are only pulling 50-60 amps?

CadillacDTS2001

Raydee. good thing you held off
go with the poly RC or the thunder power EVO
both are great batteries.

jongscx

...get some cheap northbridge coolers from radio-shack and get them to stick out the bottom to get some water-cooling?

I dunno, I'm running a cheap S/L with stock batteries, and even that does get warm...
just my 2 cents I guess.

Raydee

My Feedback: (3)

Taylor, I am glad I held off now too. Here is my problem, I want to use the same cells in my boat that I use in my Electric onroad cars. With that said my cars use 2s batts and my boats use 4s. Now my boat draws between 80-85 amps so I am thinking a set of 2s 5000mah TP Extreme cells in SERIES for 4s5000mah in my boat should be ok. Then that way I can use them in my cars at 2s5000mah. I hate being poor and having so many hobbies

What do you think? Will 5000mah at 110amp continuous be enough for a play boat?

CadillacDTS2001

it depends on how much of a play boat you want.
regardless if you have a 2s1p set up for your car. . . for argument sake say you have a 2s1p 3000 MAH
and you want to run 4s in your boat.
you will need to buy 2 more of the batteries you run in your car. 2P everything. so if you have two 2s1p 3000 mah. you will need to buy 2 more. to make it 4s1p.
remember when you buy the batteries make sure they are the exact same as the previous ones you bought. do not mix and match.


OR the best thing to do is just to buy your self a new set of batteries.
buy 4s1p batteries and buy 2 of them and wire them in parallel.
to make 4s2p. this way you keep your car stuff in one place and your boat stuff in another.
as for it being expensive. well it is the price you pay for this hobby. and if you cheap out well there might be consequences. especially with lipo. if not then i would go to a 2s boat and then you can run 2s2p with out having to buy batteries.

Raydee

My Feedback: (3)

Well 4 packs in my boat just won't happen SO if two 2s1p TP extreme packs in SERIES won't do the trick then I guess I will be stuck buying two 4s1p packs for the boat and 2s packs for my cars.

Ok one more question now...just for arguements sake
Lets say I buy two 4s1p 2500mah packs and run them in Parallel for 4s2p at 5000mah
Or I buy two 2s1p 5000mah packs and run them in SERIES for 4s1P at 5000mah

Will there be a difference?

CadillacDTS2001

yes. if there wasn't then this conversation would not happen.
you double the amps and the discharge rate. unlike the 1P setup.

Raydee

My Feedback: (3)

Please explain, if they are both 5000mah in series or in parallel how is there a diff? I am not saying you are wrong, I just want to be enlightened.

CadillacDTS2001

uhh ok.
2s1p 20C 5000 series them. . 4s1p 20C 5000 ( just add up the voltage) same as a 4s1p lipo

4s1p 20C 5000 parallel them 4s2p 40C 10,000 MAH ( same voltage, more runtime more amp draw)

CadillacDTS2001

Here is the MAX amps discharge chart.
these cells are suppose to be 20C cells
There own chart shows the these cells fall off at any thing above 9C
That is why these cells should not be rated at more then 10C
Therefore I would not use them above 5C
To get good power and long cell life you should not draw on cells above 1/2 of the "C" rating.
this chart shows that drawing at 15C or 60 amps you will get very short run time for what they are rated, and a very low voltage.

SO really by looking at the chart these cells should be a 9C rated cell. could you just imagine the kind of heat and low voltage you would get by pulling the 20 C

Got RPM

Taylor beat me to the punch. You are making assumptions that are not supported by facts. Assuming your rigger only pulls 60 amps (how do you know this?), if the cells get too hot then they are not true 20C cells. This is a problem with LiPo just like it was with NiMH - cheap cells are just that and if you want high performance you will have to pay for it. Independent tests have shown that many cheap LiPo packs do not deliver their rated C, sometimes they only deliver half the C before overheating.

You should never have to cool LiPo cells. If they get too hot - and 80C is way too hot!!! - then you are pulling too many amps from them. It doesn't matter what the label says - if they get too hot you are pulling too much! You will have to either prop down, run for a shorter time, get a milder motor, or run different cells.


.

Easy rider

motor : Lehner 1530/8 turn
ESC : LMT BK Warrior 2018
Prop : Graupner 37,5mm two blade carbon

Easy rider

This is gonna get expensive. Are there balance wires and connectors included with a PolyRC lipo pack ? All of my balancer wires/connectors are Maxamps compatible ( Hyperion style )

CadillacDTS2001

they should be compatible. if not then buy the leads that make them compatible.
they should be compatible .
see what mean about bad cell ( refer to the chart)

BB Modss

2p or go home...I agree... SV27 with 2 of my 4s 4000mah pack's in 2p config.

Easy rider

Yes allright , I get it ;-)

I will wire my 4000Mah maxamp packs in 2P configuration tonight and test them out tomorrow. I will keep my eyes open for some good 2P packs.

Easy rider

BB mods,

Am I wrong or did you wire your lipo's in series to become 14,8Volt ? I have to wire mine 2 X positive together ans 2 X negative together right ? I still want mine to be 7,4Volt.

Thanks.

Easy rider

Is this correct ? When you put 2 GP 3300 packs in parallel you still have 3300 Mah !!! You only get 6600 if you put them in series but you'll end up with 14,8Volt , am I mistaking here ? I just want to get it right without blowing up my Maxamps.

Raydee

My Feedback: (3)

If you series the packs the voltage doubles, voltage doubles
If you parallel the packs the capacity doubles, voltage stays the same