Topic: advice needed from wiser heads!

[Ironclad]

Hello all.... been a little while since I was on here with my ASR build(which is now mostly complete!).

I recently had the opportunity to pick up a revell 1:72 snowberry flower class corvette model (for only ?40.00 too!) and as it is such a lovely large roomy hull have set about converting it to RC as its pretty easy to do. But one question I have is that unlike the ASR which was a heavier model and therefore didnt need much ballast, this one is very light and I was thinking of using lead acid batteries as they would supply both power and ballast at the same time!

So the question is: do I go for 6v as this can power the receiver too or would 12v be better. Also: should I get one with a high ampere hour rating or is something like 2.4 Ah ok and what the hells the difference?

Any advice would be greatly received!!

Ironclad

[colin]

personaly i would go for the 6 volts, and probably the 4 Ah would fit... if not then two, 2 Ah.. 

[Manxman1831]

I'm not entirely sure about the hull size for the Revell 'Flower' class corvette, but does a hull size of about 2 foot long by 6 inch with a depth of 2 inches sound about right?  This is about the same size as the old HFM ocean tug that was available until the mid-90's, in which case I can probably help.

For this hull, we used a 6-volt motor as supplied with the kit (roughly the same size as a Mabuchi 365) with a Bob's board (how many remember them?) as speed controller.  The kit recommended using NiCad's space evenly on each side of the hull by the motor, which wouldn't have worked due to the steering servo positioned in the same place.  I 'cheated' and slid a 6-volt, 2.4Ah lead-acid under the rear decking alongside the steering rod.  Trimming was done using stones picked up off the then local beach and it ran for many years with this set-up, before the battery deteriorated due to age.  The replacement is a Ni-MH pack with 7.2 volts, 3600mAh.  Same weight surprisingly, so not had to do too much to the trim.

The higher the Amphour rating, the longer the running time for your model.  Try not to connect batteries in parallel (side-by-side), from my own experience this has led to batteries being damaged if one of the pair is heading towards the end of its life, regardless of how many charges it has taken.  In theory, rechargeable batteries can last up to 1000 charges, but this depends a lot on usage, charging and storage.

[mikearace]

Revell/Matchbox FLowers do need a fair bit of ballast to get to a right level on the waterline.  Have built two over the years and as Joe rightly says a 6v would be ideal preferably a 4ah SLA as this would take you down very close to the wl with a little bit of additional ballast too.   This coupled with a MFA 400 motor would be in my view a good combination.

[Ironclad]

Thanks folks.... that's great.

@Manxman....this bugger is a big one...its 3ft long and about 6"deep....its a real bucket! I know what you mean about the charging issue too....I have decided that a twin lead acid battery set up will be suitable but I will leave the charge connectors separate so that they can both be charged separately....bit of a faff but means that the batteries should be safe.

So I will order two SLA's with a 4.5 Ah rating I think and see how she sits in the water....I have attached a pic below to show the hull so far.

Ironclad