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>> Home > Forum > Electrical Related > Voltage step down
Voltage step down
Author Message

Forum Posts: 13
16th Nov 2017 23:02  
>> Permalink

I know this will sound very basic to experienced members, but my question is; If I want to use an "MTroniks" Viper Marine ESC, which is rated at 12 volts, and a similarly rated brushed motor, how can I easily get 12 volts out of two 7.2 NiMh battery packs?

As you can surmise, my electronics expertise is zero.

Brian Hill.

(Fleet Admiral!)

Forum Posts: 427
17th Nov 2017 04:46  
>> Permalink

What your asking for is possible but not easy. A 12V ESC will handle an overvoltage but I cannot say how much and depending upon the current draw of your motor a voltage regulator can be expensive. The simple solution is to get a 3s LIPO However you do need a special charger and have to make sure you do not discharge a LIPO to too lower voltage.

if your interested in going LIPO have a read about the care and feeding of them.

"that's not a bug its just an undocumented creature."

Sir Terence David John "Terry" Pratchett, OBE (28 April 1948 - 12 March 2015)
Dave M
(Fleet Admiral!)

Forum Posts: 1527
17th Nov 2017 09:40  
>> Permalink

Hi Brian
For your purpose I doubt if you can find a solution that will deliver enough amps for the motor.
You can buy 12v NiMh batteries which may be the easiest option if you do not want or require the performance provided by a LiPo which will only give you 11.1v (3s) or 14.8v (4s).
If you do decide to change to LiPos I agree with Haverlock and you do need to read and research how to use and care for the battery.

Live long and prosper

(Fleet Admiral!)

Forum Posts: 1394
17th Nov 2017 10:34  
>> Permalink

Agreed Dave👍
A 10 cell NiMH would be my solution, or depending on type of boat; size, weight, performance demands, motor current etc possibly a 12V SLA or 2 x 6V SLA.
I use the latter very happily in my 140cm destroyer and 100cm submarine and can tap off 6V for various low current ancillary functions.
Will also do the same with my Graf Spee and Belfast refits - provides useful ballast as well 😉
Cheers Doug 😎

Young at heart - slightly older in other places 😉 cheers Doug

Forum Posts: 13
17th Nov 2017 10:38  
>> Permalink

Thanks, Dave,
That shows how little I know of these things,.....a 12 volt NiMh is obviously the way to go,

Thanks a lot.

Onward and upward!!


Forum Posts: 13
17th Nov 2017 10:52  
>> Permalink

Battery ordered, and a charger, from Component Shop.

Thanks for the guidance.


(Fleet Admiral!)

Forum Posts: 549
17th Nov 2017 10:58  
>> Permalink

Hi Brian, I would suggest 2 x 6volt NimH cell packs with a parallel 'Y' lead, the reason is you can use each pack to alter the trim of the hull. with a big hull like the Fire Boat, you could even put 4 x 6v cells in for longer duration. a single 12v does not give you a lot of maneuvering room regards balance etc.
I have just changed my 48" Fireboat to 3s lipo's from 7.2v NimH packs, this is with Graupner 700bb motors with twin 50mm 3 blade brass props, not tested yet due to poor weather and shift patterns, but it sounds great on the bench.

Etherow Model Boat Club

Forum Posts: 12
17th Nov 2017 13:57  
>> Permalink

Just a thought-
The component shop does do a voltage reducer rated at 6 Amps power draw, and will drop from DC (10.5-40v to 1-9v) I thought about using one of these to run a 6v volt Marx Hectoperm motor from a 12v source, to save buying a new battery. As long as your motor speed controller setup doesn't draw more than say 4~4.5 Amps. I'm my case the tug had 4 x 6Ahr 6v batteries wired in parallel giving 16Ahr and 2-1/2 hours running time @full speed. These batteries have since all died due to age.
I wanted to use just 1 x 20Ahr 12v battery instead and keep the added ballast I need anyway. This 6 amp unit is on the limit in my application.

P.S i'm tight with money and I acquired the battery free from an alarm battery swap.

Dave M
(Fleet Admiral!)

Forum Posts: 1527
17th Nov 2017 16:46  
>> Permalink

Why not use the 12v battery if the ESC is Ok for 12v. Restrict the tx stick movement so that just 6v goes to the motor

Live long and prosper