By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Lipo battery instead of NiMH

All Topics | Latest Posts

Search for:  in Thread Title in  
Richard King 722/11/2012 17:25:17
3 forum posts

The 700ma battery that came with my Futaba 6Ch was not looked after by its first owner and so now hardly holds enough charge for a day at the flying field even after a full charge

I have been told that a LIPO is both cheaper than a larger capacity NiMh/NICd and that a LIPO can fit within the transmitter battery bay--I know I need to remember NEVER to try to charge it with the 13A wall charger!

BUT-what battery exactly should I order? given 2000+ Ma seems worth having and it must of course have a Futaba connector

Can anyone please advise a good and inexpensive LIPO that wil fit the Futaba 6 Ch and a good LIPO seller?

Brett Armstrong05/12/2012 04:36:30
4 forum posts
3 photos

Not sure if your Tx has a low battery warning but the 10CG dose and it is set at 8.5V non adjustable.

This causes a problem, if you put a LiPo in place of the NiMh you will have to chose a 2S or 3S. The 2S is too low and causes the low battery alarm to sound constantly. On the other hand the 3S will get below the self destruction limit before the low battery alarm warns you.

In short if your Tx is built for NiMh and has a battery alarm, stick with NiMh for a new battery.

Daithi O Buitigh05/12/2012 09:50:29
avatar
1362 forum posts
49 photos

The other option (and safer) is to use a LiFe instead of a LiPo (it doesn't self-destruct if it gets too low)

John Cole05/12/2012 12:13:13
615 forum posts
24 photos

I use a low-discharge NiMH from VapexTech . Look about halfway down the page for a flat 8-cell 2500 mAH pack with Futaba plug. £12.50 delivered. I charge AFTER flying and rarely need to top-up before flying. Charge with your normal wall-charger. Takes a long time the first time but thereafter you only put back what you take out (plus a bit). Easy to live with.

Steve Hargreaves - Moderator05/12/2012 15:10:22
avatar
Moderator
6744 forum posts
191 photos

I'm a big fan of the LiFE alternative as Daithi suggests.....the voltage from a LiPo (11.1V) is just that little bit too high when compared with a NiMH pack IMHO......the 9.9 volts of a 3S LiFE pack is pretty much perfect.....

In fact this will make interesting reading.....

I fitted a 3S LiFE pack to my 10C a while ago & I've had no problems at all......it lasts & lasts (& lasts & lasts....wink 2) see here

crispin church05/12/2012 15:47:30
avatar
442 forum posts
102 photos

or go spektrum and use 2 life with a ubec works great no changing parts no high voltage needed smiley

you can change any plug to what you need why buy over priced batterys just because it got right plug on

 

Edited By crispin church on 05/12/2012 15:50:33

John Cole05/12/2012 16:15:36
615 forum posts
24 photos

Why do LiPo & LiFe chaps think these are better than low self-discharge NiMH?

Steve Hargreaves - Moderator05/12/2012 16:25:32
avatar
Moderator
6744 forum posts
191 photos

Simple really John...I find that the self discharge of LiFE batteries is much lower than that of LSD NiMHs....in fact it is just about non-existant....plus the charging regime for Lixx batteries is much simpler & can be achieved within 1 hour....none of the false delta peaks you get with NiMH....

I am currently switching all my Rx batteries to LiFEs too......wink 2

Steve Hargreaves - Moderator05/12/2012 16:28:25
avatar
Moderator
6744 forum posts
191 photos

Oh & thei voltage stability of Lixx batteries is much better too.....pull a few amps out of a NiMH pack (especially an AA cell type) & watch the voltage collapse......LiFE cells hold up their voltage much much better.....thumbs up

John Cole05/12/2012 17:11:27
615 forum posts
24 photos

1. The OP was about putting a different battery in a Tx. They draw mA not A. So no advantage for Li cells in that respect. Futaba Txs are DESIGNED to run on Ni AA cells.

2. My Vapex cells retain their charge very well. If I go to my Tx after a couple of weeks, they are still nearly fully-charged. The technical advantage of Li cells of even lower self-discharge means that you can store them over winter and they don't need charging in the spring. But so what?

3. Simple charging regime? I just plug in my wall charger and leave the Tx on charge for about as long as I've been flying or a bit more. Or I can leave it on much longer (overnight) with no fire risk. What could be simpler than that?

Using batteries with characteristics much different from those for which the Tx was designed introduces problems I can manage without.

Steve Hargreaves - Moderator05/12/2012 17:17:56
avatar
Moderator
6744 forum posts
191 photos

Well, you asked the question John....dont know...I answered according to my experience......

If your way works for you then I'm very pleased & I think you should definitely stick with it........thumbs up

Allan Bennett05/12/2012 21:56:34
1603 forum posts
44 photos

One thing I would be wary about with LiFe packs is the way they hold their voltage for a long while, and then suddenly go down. By the time the trannie's low voltage alarm (if indeed it's valid for LiFe) realises the voltage has dropped, it may be too late.

Also, LiPo batteries don't like being stored fully charged -- their life will be shortened doing that, so do you discharge them down to storage voltage after every flying session, and then recharge them on your flying day?

For me there's nothing simpler than putting a NiMh pack on slow charge the night before flying day, and the capacities available these days are plenty for my day's flying.

JC06/12/2012 12:38:54
avatar
283 forum posts
53 photos

Hobby King do a direct replacement LIPO for transmitters. I use them in mine and they work a treat and last for ages. I too was fed up with nimh btys lasting ten minutes at the field. The Turnigy TX btys remain charged for weeks dependent on use and are very cheap. obviously you need to remove them for charging. At about 14$ each get a couple. Still cheaper than one Graupner TX nimh.  Just keep an eye on the voltage. Having said that the TX will stop working long before the LIPO is dangerously low. As for keeping a LIPO fully charged for too long just use the  cycling funtion on your charger occasionally to keep the bty in good nick.

**LINK**

JC

Edited By JC on 06/12/2012 12:41:54

Allan Bennett13/12/2012 08:03:55
1603 forum posts
44 photos

LiPos don't benefit from cycling (full discharge followed by full charge) ... in fact all it does is add one more cycle to their usage history. They do benefit from being discharged down to 50% capacity or less, if they're going to be stored (i.e. not used) for more than a few days.

Richard King 720/12/2012 09:22:01
3 forum posts

That is helpful thanks Alan

Martin Harris20/12/2012 10:16:07
avatar
9161 forum posts
229 photos

I'm a definite fan of LiFe cells - as receiver packs. Like John, I'm very happy with low self-discharge MiMH in transmitters though. I prefer the margin of warning that they give on low voltage (although given the choice I'd have stuck with Nicads) over lithium cells and that a cell failure (short circuit) will allow a reasonably small drop which will be signalled by the low voltage alarm. I've known this to happen on more than one occasion with Nicads and NiMH. My Jeti receivers do appear to function adequately on less than 3.4 Volts (as I found out when I lost a cell in flight in a Nicad pack recently so if a cell fails short circuit on a LiFe receiver pack (hopefully a typical failure mode?) then I should be able to get down OK.

The 2000 mAH Sanyo Eneloop transmitter pack in my 10C will last for several sessions of reasonable duration over several weeks and then I re-charge it in less than an hour when the voltage drops below around 9.8V and although not best practice, the 1200 mAH Nicad in my rarely used 35 MHz transmitter holds a reasonable charge for months.

 

Edited By Martin Harris on 20/12/2012 10:16:47

MaxG20/12/2012 10:33:07
161 forum posts
3 photos

There was a very good article in the latest BMFA news on this topic. Worth a read.

Also if you put a LiPo in your TX are you sure you want to charge this in the house? In fact are you sure you want to charge it in the Tx as well.

Lots of issues and inconveniences there.

How does your Tx low battery alarm work with a LiPo in the system. Thje alarm voltage is likely to be wrong for a LiPo.

Stick with Eneloops and be safe.

brfc720/12/2012 10:39:32
avatar
401 forum posts
140 photos

I've read loads of posts recently about lipos in Tx's and everyone going on about the low battery alarm. I've been flying 15+ years and can't remember my Tx's alarm ever going off. I know when I've last charged it and I look at the displayed voltage before and after every flight. I honestly can't see this being a problem.

baz

Martin Harris20/12/2012 12:27:50
avatar
9161 forum posts
229 photos

The point is that a lithium battery's voltage will drop very quickly from a reasonable voltage to no meaningful power and the concern is that the low voltage alarm won't give you sufficient warning to get down safely.

I agree there shouldn't be a problem if you maintain a good charging regime and conduct regular testing of the cells but not everyone does (or is capable of doing so).

brfc720/12/2012 17:27:51
avatar
401 forum posts
140 photos

One thing I do as my Tx (Futaba 7cap) has a time on the screen for total time switched on. So everytime I charge the battery I reset this back to zero and then I know how long it has been powered on.

baz

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Support Our Partners
Cambridge Gliding Club
CML
Wings & Wheels 2019
Slec
electricwingman 2017
CADMA
Sussex Model Centre
Advertise With Us
Sarik
Latest "For Sale" Ads
Has home isolation prompted you to start trad' building?
Q: The effects of Coronavirus

 Yes - for the first time
 Yes - but Ive bashed balsa before
 No - Ive existing projects on the bench
 No - Im strictly an ARTF person

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us