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[firstperkasa]

Hi.
I'm after some advice for batteries for my Italeri S100.
It will be running 3x mfa 385 5 pole motors and 30mm brass props as supplied by SHG for the dave abbott build.
My esc is an Mtroniks Tio marine 30 which is Lipo friendly so I can run either nimh or lipo. The esc will run from the main battery and I'm planning on just 2 channel radio function.
What i'm after is something like scale speed with the maximum run time .
Stan has given me plenty of advice but I really dont understand Lipo's at all.
RSM is running his on 7.2v 5000 nimh but with a different prop spec and he gets 30 minutes
can anyone suggest in detail a battery that would fit the above ?
many thanks

[firstperkasa]

just had a very helpful chap with someone at overlander . I guess i will go LiPo but its just the Mah of the battery I'll need info on now. How would a 2200 mah 11.1v LiPo compare to a 5000 mah 7.2v nimh in terms of run time and power ?


Thanks

[rsm]

Put simply the higher the voltage the faster the motors run, the higher the current rating the longer the motors will run.

[rsm]

Unless size and weight of the pack are an issue I would stick to the NiMh packs as they are easier to look after and have a longer charging/discharging lifetime. Lipos are good for high discharge applications like brushless motors and where size and weight are an issue, as they can be smaller and lighter than NiMh packs.

[firstperkasa]

cheers for the input roger. This is where i'm clueless. My running gear is different to yours so I'm looking for an idea of how the batteries would perform on 3x 385 with direct drive.

[firstperkasa]

thanks for all the help. I'm going to try 7.2v nimh
cheers

[sigfortunata]

Hi don't know if this will be of any help but I've had a similar issue.


I have a RAF towing launch running 2 x  7.2V motors. I was powering it with 2 NiMH 7.2V 4200mah batteries.  i ran well but run time was an issue.


After talking with club members I'm changing to 7.4V Lipo batteries 3000mah.  as well as delivering more power it should increase run time as the weight of 2 Lipo batts is half the weight of 2 NiMH so my hull wont be hauling that weight.


On another point did I see you were running 30mm props on 385 motors? 


I first ran my boat with 2 500 motors turning 35mm props, performance was lack lustre and current draw immense.
Changing to 25mm props performance and run time was much better.
I was advised never to run a prop which was bigger than the motor diameter so you may get better run times with smaller props


Steve

[firstperkasa]

yep I've seen that advice on the props too. I went with the dave abbot spec but bigger capacity batteries. we'll see. cheers