Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[tomo55]

Hi , New to model boats from aero,
has any one used lipo batteries in model boats? if so how do they perform?
What are the most common batteries used in boating,
My thoughts are lead acid for large tugs etc with Nimh for quicker high planning craft (maybe Lipo),Am I on the right track?
advise welcomed
Regards Chris

[malcolmfrary]

Yes they have, and in the right kind of boat they perform very well, usually where light weight and high performance are required.
Obviously, in applications where weight is required, LiPos become a pointless expense.
Most radios were designed in the elder days with 6 volts nominal in mind, this being handy for 3 cells of lead acid, 4 dry cells or 5 NiCad.  LiPos have an inconvenient voltage for use as an RX supply, but definitely have their place in the scheme of things.

[andrewh]

Chris,

As you surmise,  the boating fraternity divides up, like Gaul, into three parts

The people who need weight, want to sail for at lease 48 hours at a charge, and tend to favour lead batteries of one sort or another

The people with need for POWER at minimum weight, volume etc (basically fast electrics and planing scale boats) - likely to use LiPo, Li-ion, Nicad and NiMh

And some people in between who often use large capacity NiMhs

If you have Lipos etc (meaning chargers and the knowledge to use them) - go for it!
I use my aircraft Lipos, Li-ions reclaimed from laptop packs and lots of other convenient battery packs
andrew

[Inkmark]

Hi Guys
I have been thinking of using LiPo batteries but I keep hearing horror stories if the voltage goes too low.
I know there are warning devices etc but what really happens when the voltage hits the floor so to speak?
Do we need sails as well?
Mark

[andrewh]

Mark,

There are ESCs which have suitable cutouts to protect Lipo batteries from dropping below the critical voltage - they usually allow you to reset the throttle and get a little power to get back home.

I have never used them - I find that the performance drops off so much as the voltage drops that I stop having fun at about 3.5 volts per cell  - which is very safe for the batteries.

You can fit a ESV* to the boat where you can see it - it would light some amber LEDs when the voltage is getting low enough to start coming home.
*Expanded scale voltmeter

The reality is prolly better than the horror stories - Lipos (and Li-ion and Saphion and Tadiran) discharged below a voltage specified by their manufacturers (usually 2.5 to 3.0 V per cell) MAY have changed chemically so that it can never accept charge again.
Many people have found that giving the over-discharged cells a LONG trickle sometimes brings them back to life and they can them be charged and used normally.

Hope this helps,

andrew

[Inkmark]

Thanks Andrew
Coming to electric from IC my learning curve is near vertical at the moment.
Cheers
Mark

[andyn]

I'm currently sitting out on the patio, lovely day, here with a lithium battery between my legs (laptop), one on the table charging, and one ready to be charged...

Shows how confident I am in Lithium batteries

If you are worried about the scare stories of lithiums, you can always get yourself some Lithium Phosphate Ion batteries (A123 or Li-Fe), which are much safer, but you have to make up the packs yourself.

Fifth generation Lithium Polymer batteries are by far the safest, you would actually physically have to try to damage them.

See http://www.kongpower.com/company_en/about.asp For more info on fifth generation Li-Po's. The english on there isn't very good, but the products are first rate.

[OMK]

You can fit a ESV* to the boat where you can see it - it would light some amber LEDs when the voltage is getting low enough to start coming home.
*Expanded scale voltmeter

Tomo, if you're okay with a soldering iron, a dead simple ESV as suggested by AndrewH, one that you can build yourself, can be found here:  http://www.pm.keirle.com/esv/esv.htm
Failing that, a dedicated Lithium monitor can be found here:  http://www.dawnmist.demon.co.uk/rcm.htm#2

Good luck.

[jonny shoreboy]

My helicopter runs on Lipo's so I have used them but I'm not an expert on them.

The one piece of advise I would give you though if you wish to use Lipos, is to buy a decent balancing charger with different charging rates to charge your batteries. They aren't that cheap, but are cheaper then replacing a battery everytime a cell fails?

[andyn]

...buy a decent balancing charger with different charging rates to charge your batteries. They aren't that cheap...

They are cheap

I have a Logic RC Fusion L50B charger, It is absolutely excellent, couldn't be more pleased. I have tested it alongside my Schulze 6-330D, which cost over £120, and although it doesn't have the same charging capacity, it's balancer is near enough spot on the same as on the Schulze, to withing .01 of a volt either way. I keep it in it's original box, with a huge collection of leads in there, so I can take it down to the lake and charge anything I get asked to with it. In fact my earlier post about charging refers to it and the Schulze charging two Li-Po's for someone else together, off the same input battery. Only reserve is that it's not that loud (beeper)

I got mine for £50 from Barry at Mainly Models in Hitchin

http://www.logicrc.com/
http://www.mainlymodels.co.uk/product_info.php?cPath=79_78&products_id=863

[jonny shoreboy]

Mine was about £50 too and works great! What I meant by they aren't cheap, is it is better to spend a bit more then £10...

[andyn]

True, yes

Stay away from Century chargers though, about a week back someone on this forum had one go up on him (nearly literally...)

[tomo55]

Re chargers Ive got a graupner 16 no problems at all,ideal for all my needs.
Just wondering if Lipos were ok for boat use really.
Ive used Lipos in aero and a rockcrawler and have not had any bother ,as long as you follow the instructions with your charger and batteries all should be well.
Chris

[red181]

if you google lipo low voltage alarm, there are plenty there alarms, and led lights etc
In rc helis, you can tell when the voltage is dropping, as mentioned earlier, overdischarge will kill the lipo, the rotor speed will start to decrease, probaly not so easy to spot in a boat. If you are not going to go fast, then its cheaper to just use nimh or lead acid, for that extra ballast if needed. Nicad have a memory effect, so need to be discharged, and charged, nimh dont, so are a bit easier to maintain as you dont have to run them flat all the time. If you go lipo, you need a specific charger, and a "baklancing" charger will be best. Expect to pay £50.00 for anything decent