Li batteries

[green-boat]

I was in the local computer store and they had some used HP Li laptop batteries for $20, they were 11.1 volts @ 4320ma. Nice little flat pack. Now I don't know much about Li batteries but I would like to pull the Ni-Cd's out of my Lindberg PT109 and try the Li ones. You know it's the more voltage, less weight and longer run time thing that I'm thinking of. Any thoughts on the used battery thing. I do have a charger that will do Li batteries though.

[LtDoc]

green-boat,
There are two 'biggy' questions, and probably several 'smaller' ones.
1. Will your ESC handle the higher voltage?
2. Do you have a charger specifically for 'LiPo' batteries?
If the answer to either of those is , "no". Then don't. Or, 'up-grade' the ESC and find a charger. Simple, huh?
- 'Doc

PS - You could always get the batteries and send them to me, same for the charger and 'up-graded' ESC. It's Christmas time, you know...
(sometimes, I really embarrass myself with all these 'good' ideas.)

[Umi_Ryuzuki]

Lipoly batterys can be ruined by dropping below their rated low voltage limit.

Lipoly ESC are designed to sense the battery voltage, and shut down before ruining a battery.

Lipoly chargers work the opposite way.
Except the chargers are designed to shut down before the battery blows up and burns your model boat, the car where you were field charging, or your house down.

Go to the main page and search Li poly or something similar, and you can find lots of posts, warnings, and hazard stories.

[RCheroske]

Greenboat, if you have a smaller boat where weight and size makes a difference, I would definately go Lipo. But I wouldn't mess around with making my own system from used laptop batterries.. Use the hobby grade LiPos with the hobby grade charger and be sure to excercise appropriate cautions.

[Boatfox]

I'm still not sure I want a battery that has to be charged in a "safe" box.(or the BBQ)
Maybe when the airplane guys get all the bugs worked out I'll look into them again. Another deterent is the cost of those suckers.$$$$ big money for a batt pack.

[Kmot]

I'm still not sure I want a battery that has to be charged in a "safe" box.(or the BBQ)

Up until yesterday, I had one LiPo battery. Now I have two. And that is exactly where I store them and charge them. Seriously! In my BBQ.

I won't invest much more in the LiPo's. They are dangerous batteries, even for those who take the proper precautions. Far too many incidients have happened.

There are better batteries on the horizon. Some in production already. the A123 battery for example. Won't erupt into flames.

[green-boat]

I went back and looked them over again and they are Li-Ion batteries. I don't know if that makes any difference but that's what they are. As for a charger, I have the Triton. I know that the airplane ESCs' have a low battery cut-off but have yet to see a reversable boat one.

[P_J_Glor]

I recall discussing the use of Li-ion phone batteries in models with someone, and it was pointed out that the current demands are entirely differennt than for models, which see much more current over a much shorter time. I suspect the same is true for computer batteries. Also, as we know from the recent recalls, computer batteries are also subject to overheating. Li-poly chargers are coming down in price, so if you really want to make the "leap" you should use the proper equipment.

It really doesn't make that big a difference in scale boats, unless you are racing or doing mini plastic conversions, because you will end up putting the weight back into the boat as ballast. Just my two cents. I did make the leap to a Triton for planes, and don't regret it, but still plan to use ni-cds in my boats. I have some 200 mah packs from the car people, which will last a long time at cruise speeds.

Just my 2 cents.

Pete G.

[pflumitch]

Laptop battiers have a very low C discharge rating. 2C out of a laptop battery is about all your going to get, and thats pushing it. That Laptop battery you are talking about, you would be lucky to get 8 amp discharge out of it. I use li-po and li-ion in all of my aircraft and its a great technology, you just have to be mindful of what your playing with. Just read up on the care and use of the batteries and you'll be ok.

[RCheroske]

One thing that I really like are the cellphone batterries. If you have a cellphone that is not being used anymore, just flip it over and use it for a charger. Use the battery for lighting up your LEDS. The cell phone batteries are small flat and compact and are the perfect voltage for lighting LEDS. And when they're done, plug it back into your cell phone to charge back up.