Lipos for offroad use? - RC-Monster Forums

Scott711 · **Lipos for offroad use? -** 01.06.2006, 07:23 PM

So as I draw closer to making my first lipo purchase a concern came to mind. It seems that most of the lipo manufactures state the batts are for use in plane or heilos. Is this something I should be concerned about? Those who are using lipo already how have you mounted/protected you batts from the abuse that is delt out buy off road vehicles? Is it even an issue or am I being a worry wart? I get the impression that lipos aren't very tough and need allot of tlc, true or false? I would hate to drop $200+ on batts only to see them destroyed by a cartwheel:cry. Let me know what you think. Thanks.

MetalMan · 01.06.2006, 07:52 PM

As long as the batteries can't really bounce around, you should be fine. My 3s 3300mah battery has seen HUGE offroading in my Rustler, like getting 10+ ft. of air and then landing on the body... let's just say that the velcro battery stripped on that landing... But, that Lipo is still going. I've also done numerous other things with my Rustler and that battery, and it was purchased back in March. I do like to put a piece of foam padding under my batteries just for some slight protection, but otherwise they are good.

Just make sure that the battery is strongly secured, as it could very easily be damaged if it flew out of your vehicle. Lipos do need a bit of care/maintenance, and that mainly comes from not overcharging or overdischarging.

Scott711 · 01.06.2006, 11:10 PM

Thanks for the reassurance MetalMan. I've spent a fair amount of time this past week reading up on lipos but still need to pick your brain a little more. I understand that voltage gives you power and mHa is your capacity (run time) but the series vs parrall is still messin me up. I would like to have high mHa (3700 or more) and high voltage (18.5 - 22.2) I know this will cost big dollars but humor me anyways. Also if someone could give wiring diagrams for the various setups along with the advatages of each it might really bring this thing full circle for me. I'm still not sure what the p and s stand for either. enlighten me please. Thanks.

Scott

MetalMan · 01.07.2006, 01:21 AM

Okay, parallel (p) vs. series (s):

Standard NiMh cells that are used are put in series. This is where the positive of one cell is put to the negative of another cell. Series is just taking the + from one cell (or pack) and putting it to the - of another cell/pack, and using the remaining + and - leads to get the voltage of both cells/packs added together:
IE, a 4 cell pack (4.8v) put in series with a 6 cell pack (7.2v) is 10 cells (12v). This works EXACTLY the same with Lipos (5s=18.5v, 6s=22.2v). The "s" stands for series, so 3s means 3 cells in series. In the case of Lipo, 3cells = 3 x 3.7v=11.1v. Just think of series (s) as adding up voltage.

Parallel is pretty much the opposite the opposite of series. It is taking the positive of one pack and joining it with the positive of another. The same thing is done with the negatives. What this does is it adds up capacity. BUT, the voltage of 2 cells/packs put in parallel MUST be very close to exact (with Lipos). For example, putting 2 3s (11.1v) 3000mah packs in parallel will give 6000mah. To give a description of this "new" pack, you would say it is 3s2p. If this still doesn't make sense, I can try some more.

As for a recommendation, which vehicle and motor do you want to ue/are using?

Scott711 · 01.07.2006, 01:54 AM

Thanks for clearing that up MetalMan that very much makes sense. I'm using a 9920/8xl in a supermaxx truck. I have yet to wire everything up, I'm waiting untill I can make up my mind about if I want to go with a single series pack or two packs and parallel them. I think the esc would need to be wired different depending on which way I go. I guess ultimately its up to me to decide if I want more power or more runtime. Don't really have the extreme dollars it will take to get both from one pack.

MetalMan · 01.07.2006, 10:41 AM

Instead of getting 2 packs and putting them in parallel, it would be best to get 2 packs and put them in series. For example:
-If you want 6s Lipo, you could get 2 3s packs and put them in series.
-If youw ant 5s Lipo, you could get a 3s pack and a 2s pack and put them in series.

On either setup, it would be good to have a Lipo rated at about 50amps continuous (or more) to handle the amps that your truck might need.