Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Batteries & Chargers => Topic started by: J90 on November 20, 2014, 02:55:54 pm
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Hi everyone, I want to change the current 12v 7amp SLA in my boat for a NiMh battery pack. The boat has two graupner 600 motors and one 30 amp electronize speed controller. Can you recommend an equivalent NiMh battery pack to the 12v SLA. If it can be done I'll be able to put a spare pack in the boat as ballast whilst the other is being used for power. I do not want a Lipo power pack, NiMh battery pack recommendations please.
Thanks, Chris
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Why do you want to change from your sla?. The link below has several 12v nimh packs on. Anyone will be suitable I think but id go for the bigger capacity. Instead of putting a spare battery as ballast why not wire both batts up to give you double capacity. http://www.componentshop.co.uk/batteries/radio-control/large-power-packs/96v-above (http://www.componentshop.co.uk/batteries/radio-control/large-power-packs/96v-above)
James
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You already have all the numbers, just a question of finding a 10 cell pack with as near as possible the same AH number. It will probably be a 5000mAH pack. In theory, it should not give the same run time, but in practice, due to the pack weighing less and being better able to handle the current, it might come very close.
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Component shop do a 12v 9Ah pack which will fit
in place of a 12v 7Ah sla.
It's a kilo lighter though and £60 heavier on the pocket.
Unless there is a compelling reason for a change, why
change the status quo ?
Ned
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The problem is that the Speed 600 motors will want to take more current than a SLA battery is happy giving. Unless they have been specially made for regular cyclic use (so-called "leisure batteries") then SLA's are happiest putting out a steady low current and being trickle charged. You'd be lucky to obtain 4AH from the 7AH battery before it wanted recharging, whereas a NiMH pack can deliver a helluva lot more current and give up more of its rated capacity. I would be tempted to fit another speed controller and run each motor/ESC from its own NiMH pack i.e. two of everything. There's little point in carrying round an extra battery and not using it. That also gives you the choice of "splitting" the throttles (or using a mixer if you only have 2 channels) for better steering response.
DM
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Hi Chris.
no body has asked the pertinent question, what boat have you got it in. Going by the fact its got a 30esc its possibly a powerboat.
Frank
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Going by the fact its got a 30esc its possibly a powerboat.
Frank
I would think that's the most likely, Frank. Speed 600 motors on 12v in a workboat would be plain silly unless they were highly geared down. In which case it makes even more sense to switch to a better power/weight power supply. My heart sinks whenever I see a Huntsman or Perkasa plodding round a lake like a narrow boat because the owner "wants the battery to last longer". It won't, but it will sure seem like it!
Dave M