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[sturrock]

Hi everyone.this is my first post. I have two boats I built with my father a long time ago,one is the F C Sturrock the other one is the Sangsetia.I currently have two MFA 800 motors in the Sangsetia. I wish to change the motors as they drain the batteries very quickly the batteries are two 6v 4amp . Any help would be appreciated.

[DaveM]

Your post implies that the batteries are sealed lead-acid types. They're great for tugs and doorstops but little else.
 My first suggestion would be to replace them with Nickel-Metal Hydride cells. These will deliver higher currents for a lot longer and can be purchased in 5-cell packs (6v). Also be aware that these motors will take up to 12 volts, which would improve the performance even more.
This is a good website to look at for suitable batteries. https://www.componentshop.co.uk/batteries/batteries-radio-control/batteries-radio-control-large-power-packs/batteries-radio-control-large-power-packs-48v-60v.html
DaveM

[sturrock]

Thanks for the info,I assume I would have to invest in a different battery charger. I will have a look on the website.

[Shipmate60]

Most chargers now will charge all types of batteries excepl Lion.


Bob

[malcolmfrary]

A pair of motors pulling 5 Amps each makes 10 Amps.  A 4 A/H battery has, theoretically, about 20 minutes before it is fully discharged.  In practice, SLA are not generally suited to that level of current delivery, so probably rather less time before they give up.
Whatever the battery technology, 4 A/H is still 4 A/H, but NiMH and LiPo are better able to deliver high currents continuously.  The same weight of battery will have a lot more capacity and will give longer run times, but a lighter battery will give a faster boat.

[RST]

Keep us posted on how you get on with this please as Sangsetias are few and far between.  Mine's 17 years old now and still 95% finished!  Nothing to add apart from saying twin 777's and 3 blade 40mm props and on 8.4v Ni-Mh so far all it wants to do is empty the bath -but thats no recommendation and I only got my power meter recently and not checked what current draw is.  One thing for sure is I originally had 12v SLA's for it, but became bleedin obvious it was too heavy.  The lower voltage would make-up for the less weight for sure.  I hope to finish mine during lock-down, no excuses now!

Rich

[sturrock]

Hi Rich,
I am going to purchase some different batteries which will improve the running time and also reduce the weight.The boat runs very well it was just the running time.
Brian

[RST]

Hi Brian,

2 x 4ah 6 VSLA I imagine would have it brought to waterline, but were you running them in series or parallell?  I'd imagine you'd get a good benefit changing to Ni-Mh-sticks.  It will be a lighter model for handling also!  What type of propellers are you using please?

Thanks,

Rich

[sturrock]

Hi Rich,
I am running the batteries in series and yes the two batteries brings it down to the waterline. I have one in the stern and one just under the front of the cabin. Hopefully the different batteries will improve things. The props I am using are 40 mm three bladed navy props. My boat is also quite  old building it in the early nineties and mine isn't finished either and in need of a refit.
Brian