Glad to hear you have found a suitable power source. The 5000 mAH will certainly give you a bit more Oomph!
I did a quick Google search and saw an Panasonic charger advert on Amazon, so they are available. Try phoning Ian at Component Shop initially.

Well happy day!!!
Tried the boat out running the two 7.2 volt 4500 mah batteries in series giving 14.4volts.
It was very windy and choppy but I had to try it out.
The speed was very good and the batteries lasted very well. So all in all I am happy with the end result.
I have ordered two more 5000 mah batteries for a bargain price from China and my last problem is to decide how to charge two batteries at a time.

HI Dave
As I already have two 7.2 battery packs I decided to try connecting them in series. I also decided totry and neaten up the electrical layout so I used some 13mm foamex board as base and made small retaining blocks to hold things in place. I was scratching my head a bit to figure out where to put the batteries but settled for one each side held by long U shaped brackets screwed to the motor baseboard. The motor bracket serves to hold the batteries up on edge. I have tried it out in the bath and I am optomistic about the performance. Photo attached

You need to check the max voltage your ESC supports as if you exceed this magic smoke may appear and the ESC will be unwell!
Brushless motors are very power hungry and are capable of passing very high currents so any power supply needs to have a low internal resistance to meet the amperage requirement of the motor.
SLA's have the highest internal resistance and LiPo's the lowest with NiMhs not quite as low as the LiPo.
Have you checked the current being drawn with the props in the water. it is very Important that you do not exceed the max rating for either the ESC or motor so I suggest you buy or borrow a Wattmeter to check your setup. Brushless motors work best at their designed speed and do not take kindly to being overloaded by increasing current demand at quite alarming levels. I always start with a small prop and work up to a size that suits the setup and model - unlike brushed motors bigger props don't usually result in more speed, just higher current draw and the need for bigger and more expensive batteries and ESCs, plus more water cooling.
If the 7.2v NiMh worked well you could try a higher voltage as the packs are now available in all sizes and can be custom made to your requirements but you will need high capacity cells. Several club members have Perkassa models and they use NiMhs and can sail for 20 mins depending on how fast they sail. Do remember that the ballast should not be too far forward as any weigh there will need to be lifted (increased current) when the boat goes on the plane. Good luck and please post details of how you progres as other will benefit from your efforts and experience. 😀

Thanks for the reply Dave
Happily I persevered with the programming card and in the end I got the reverse function back. As soon as it worked I left well alone so I am still not sure about the rights and wrongs of programming it.
The esc is definitely for boats because it has water cooling.

I tried out my Perkasa model today and it went fine using 7.2volt battery packs as for Tamiya cars. I tried a small 12volt lead acid and it went much better but didn't last very long. I was wondering about using two of the 7.2 volt packs in series to get 14.4 volts (after checking capacities)
My EnErG brushless motor is marked as I.C. 600/670 C50-20
I will look now for the best battery option to give me at least 12 volts and a reasonable running time. (Any advice appreciated)
The boat is the 49 inch model so will take an appropriate size battery

Hi
Not familiar with the Maytech devices and the web site is not much help re setups.
Many brushless ESCs are designed for flight models and do not have reverse functions. Some are suitable for model cars and can be reversed by selecting reverse, which applies a braking effect, returning the transmitter stick to neutral then selecting reverse again. if your lucky your boat / car will then run backwards.
I have used several types and it always is a bit hit and miss that reverse selects. Works best if you have spring centered sticks and have not moved the trims from mid position.
The setup cards are better than using the transmitter and listening for beeps but are not infallible. Try repeating the process and see if you can get the ESC working in reverse. Unfortunately my experience suggests the setting can get lost between sessions so you may have to repeat the process.
The ESCs designed for cars seem to work best but usually have a fan cooler so are not so good for heavy current motors. Work OK with my 28 range of brushless but struggle with 35 range or greater. 😀