Battery musings

Discuss IOM design, building an IOM, information on suppliers, tuning an IOM, results of recent events, etc

Moderators: GaryBoell, Pedro Egea

Post Reply
Colin Helliwell
Posts: 24
Joined: 18 Jun 2014, 18:44
Location: UK

Battery musings

Post by Colin Helliwell » 26 Oct 2017, 19:25

A few questions on battery power for receiver+servo/winch - inputs would be received with interest:
  • What battery capacity (and voltage) do people use?
    NiMH, or LiPo?
    What peak current is needed?
    LiPo has a better energy density than NiMH - are there 'power packs' available which will fit in a typical radio pot?
    If so, do they have a simple built-in charging socket? e.g. USB
    If not, would it be an attractive thing to be able to buy...?!

Hiljoball
Posts: 270
Joined: 06 Jan 2006, 00:47
Sail number: CAN 307
Design: V8
Location: CAN

Re: Battery musings

Post by Hiljoball » 27 Oct 2017, 17:39

Hi Colin,
There are many answers to this question. If you use an RMG winch then you can use 2S (2 cell) LiPo or LiFe batteries, as the RMG has a built-in voltage regulator that provides 5 or 6v to the Rx and rudder servo.

LiPo 2S battery voltage is too high for normal Rx and standard servos. But if you have the high voltage Rx and servos, then again Lipo is ok.

LiFePo4 chemistry is usually considered safer than LiPo for use near water. LiFe 2S has a lower nominal voltage that LiPo and may be ok with the standard Rx and servos if you do use a standard servo based arm winch servo.

As you want to use a pot, this limits the size and capacity for the battery, but also it puts the battery higher in the boat and so a lighter, but lower capacity battery is preferred - but requires more frequent battery swap.

For Lipo and LiFe you need a special charger. LiPo and Life have higher power density that Nimh are are prefered. They also provide higher power longer, but drop off at the end as they discharge, compared to Nimh.

With an RMG winch, I get about 5 hours of racing out of a 1300mh 2S lipo. I carry 3 battery packs and can do a two day regatta without the need to recharge anything.

Here are some batteries that will fit the pot. The first is a flat pack lipo, and the second is a brick Life.

https://hobbyking.com/en_us/turnigy-130 ... -pack.html


https://hobbyking.com/en_us/turnigy-nan ... -pack.html

John
John Ball
CRYA #895
IOM CAN 307 V8
In my private capacity

Bruce Andersen
USA NCA Officer
Posts: 759
Joined: 25 Nov 2003, 00:06
Sail number: USA 16
Club: Famous Potatoes Sailin Club
Location: USA 16

Re: Battery musings

Post by Bruce Andersen » 31 Oct 2017, 21:57

I also like LiPo's due to their energy/weight ratio. Rather than fill the radio pot with a big battery high in the boat an alternative is to use smaller batteries in an attempt to lower the weight. Probably of minimal significance at most of our performance levels but if it makes you feel like you're faster - that's good.

I use 860's which are pretty small and change them mid-day.
Bruce Andersen - USA 16

Post Reply