Just a word to put things into perspective.  The capacity of a battery is a measurement of its a ability to hold charge, i.e. current.

So a 5000mah battery can hold enough charge to supply 5a for an hour.  When you go to the pond in the morning you need to know how much charge is actually in the battery so you have enough for the day’s sailing. So if your 5000mah battery has only 2500ma charge in it it will only provide 5a for half an hour or 2.5a for an hour.

For the majority of the discharge process a battery should provide a reasonably constant voltage.  It will be slightly higher when fully charged and it will drop off as the battery discharges but mostly around the quoted voltage.  That constant voltage is important as it determines the speed the motor rotates at but not to be confused with capacity.

Richard is right in that you need a fully charged battery and an understanding of how many amp hours it can hold and consequently how long it can run the boat for. These meters can basically only measure the battery voltage to give an indication of the state of charge. This is critical when it comes to LiPos but the NiMH batteries have a very flat discharge profile so the meter will show whether it is fully charged or discharged from the voltage but are not much use in telling you anything in between. With NiMH cells, charge them up the night before and then if they are in good condition they will deliver most of their normal capacity.

Just out of interest, I recently replaced my car battery. It would still start the car OK but the stop start function was taking longer to kick in which suggested that it was getting a bit marginal. I did a resting voltage test which confirmed this as it was down to 12.4v as opposed to the recommended 12.7v. I have a holiday coming up where the car will spend a week at the airport. On my car, as on most modern ones, if the car doesn’t like the battery voltage it refuses to crank the engine unlike older vehicles when you used to be able to keep cranking until the battery was dead.

At nearly 8 years old, it is doubtful if the battery would have lasted through another winter, quite apart from the airport risk,  so the obvious solution was to replace it. £240, but better safe than sorry and I’ve had my money’s worth out of it as the usual battery life is quoted as 3-5 years.

Colin

I think this is the user leaflet:

https://www.overlander.co.uk/pub/media/downloads/Overlander_Design_Capacity_Meter_Manual.pdf?srsltid=AfmBOopdi0_YJv4LGp6C9b_DCbFdzrGyQW-04J7j3_5BL80ERcfkhI5R

Colin

Usually the lead needed to plug in NiMH batteries is a standard RX connector. It will only give you a voltage which is of limited use though.

Colin

I think there is another socket next to the Lithium one which accepts an RX type lead. This is used to measure NiMH voltage as well as supplying power for analysing some Lithium battery parameters.

Colin

Whilst buying a smaller battery for my Faun I thought I’d get one of these as apart from testing the voltage etc. it has uses with ESC and servo testing.

Chris