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Author Topic: nicad or gel help needed  (Read 4540 times)

tugs62

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nicad or gel help needed
« on: July 16, 2012, 07:24:05 pm »
ive got some nicads but they dont seam to last very long on a 600 motor would i get any longer if i was to use a 6v gel battery ive spent a small fortune so far on 5000mah battery and even paid 80 quid for a ansmann charger


thanks Brian
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boatmadman

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Re: nicad or gel help needed
« Reply #1 on: July 16, 2012, 07:38:58 pm »
Brian,

More information is needed before a proper answer can be given.

Avoid nicads - old technology, go for Nimh, or lipo

How old are your nicads? They dont last forever and can build up a 'memory' which reduces capacity

What boat is it for?

What size prop is it?

What is the voltage rating of your installation?
Nimhs are lighter than gel cells, so for equal capacity batteries, the Nimhs should last longer - less weight to drag around.

Gel cell batteries are best suited to relatively low current drain over longer periods, a good nimh gives better high load performance.

A battery charger for Nicads will also charge Nimhs ok.

Ian
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grasshopper

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Re: nicad or gel help needed
« Reply #2 on: July 16, 2012, 07:40:04 pm »
Are you after more speed, a longer run time or both?  Can we assume from your 'handle' that you're sailing displacement hulls rather than racing boats?

You could get a bigger capacity gel cell than your 5000mAh Ni-mH (?) cells but Gels tend to be a lot heavier - and depending on voltage you wouldn't get as much performance. It's all horses for courses but you don't give us much info ....
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john s 2

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Re: nicad or gel help needed
« Reply #3 on: July 16, 2012, 08:18:04 pm »
Please remember that gel cells dont take kindly to being run down to far. John.
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tugs62

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Re: nicad or gel help needed
« Reply #4 on: July 16, 2012, 08:31:55 pm »
iam trying to run a 600 motor in a 34inch crash tender i had the same trouble with a sea commander but ive put  a brushless in that now but cant aford to do the same with the crash tender props i was looking at 30m or 35 i dont want to bust any speed records but want it to look some thing like
 


thanks Brian
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Mad_Mike

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Re: nicad or gel help needed
« Reply #5 on: July 16, 2012, 09:22:51 pm »
what run times are you getting?
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tugs62

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Re: nicad or gel help needed
« Reply #6 on: July 16, 2012, 10:05:22 pm »
run time with nicads is 5min max not tried the gel yet going down the lake on thursday if weathers ok
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Mad_Mike

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Re: nicad or gel help needed
« Reply #7 on: July 17, 2012, 08:24:35 am »
thats pretty bad, either excess amp draw or your batteries had it.

how old are your batteries?
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Netleyned

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Re: nicad or gel help needed
« Reply #8 on: July 17, 2012, 08:38:32 am »
Just a thought,
We have a member at our club who was having the same problem
with a Robbe Seadoo.
Two or three mins on a 7.2 racing pack.
Changed everything to no avail until Eureka!
His charger was programmed to a very low
trickle charge and after leaving them on for a day
there was hardly any charge.
Reprogrammed the charger and all ok :-))

Ned

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tugs62

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Re: nicad or gel help needed
« Reply #9 on: July 17, 2012, 08:41:57 am »
ive tried two different chargers now and still the same ive 4 batterys and 2 are new and the others are 12 months old after charging them ive put a volt metre on and it says there fully charged i should have stuck to ic engines  {-) {-)
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Netleyned

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Re: nicad or gel help needed
« Reply #10 on: July 17, 2012, 08:49:20 am »
Is the motor a Johnson 600 Nasty?
Is it the same motor you had in the
Sea Commander with the same
problem.
The Johnson is sold very cheaply on
fleabay but is very power hungry and
all those in the know avoid them.

Ned
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essex2visuvesi

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Re: nicad or gel help needed
« Reply #11 on: July 17, 2012, 08:49:33 am »
Daft question.... but have you tested the current draw of your system (rather than relying on manufacturers specs)
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nick_75au

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Re: nicad or gel help needed
« Reply #12 on: July 17, 2012, 10:02:40 am »
5000 mAH will most likely be a NiMH, Ni-cads in sub 'c' went up to about 2000mAH or so. Very high capacity Ni-MH are not designed to have a high discharge rate, there are exceptions but are considerably dearer and will have a maximum capacity of about 4200 mAH. the gel cell will not handle high current, even less than a High capacity Ni-mh( there are high current versions available, Cyclon and Optima cells, very expensive.)

What version of the 600 are you using and what voltage, 7.2 volt I guess.

30-35 mm prop could draw anything from 10-30 amps depending on voltage and motor version (Graupner speed 600 7.2 for example)

Nick
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tugs62

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Re: nicad or gel help needed
« Reply #13 on: July 17, 2012, 01:32:45 pm »
sorry yes its a graupner 600 ive put a 6v gel in and had it on the bath and it seems powerfull enough ive been looking on flebay at some cheap brushless and yes its me being old fashioned i still think of nimh as nicds same as still think in inchers  {-) will the nimh run brusless motors



thanks Brian
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Mad_Mike

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Re: nicad or gel help needed
« Reply #14 on: July 17, 2012, 04:52:47 pm »
yes they will as long as you dont pull silly amps, you will need turn the LVC off though. Brushless these days is a lot cheaper than brushed anyway.
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