Battery Charging Day

Having had a cup of tea at 5:30 am because we woke early, come breakfast we had no 240V power – oh well no coffee.

Opps – we had run the batteries flat and the Inverter had powered down as it should.  I knew the batteries were low, but declined to run the generator the afternoon before because our neighbours were enjoying the sun and the peace fishing off the bow of their boat, and I thought we would do it today instead, and let them enjoy their afternoon.

We ran 3 cells out of 32 – 100% flat – opps not the best thing to do for longevity, but once in a while is OK with our batteries, but something I intend to ensure does not happen again.

It has given me the chance to check the state of all the cells, and assess the state of balance, and we now have a fully charged battery, and I have lots of measurements for each cell.

I am installing electronics that will monitor the batteries all the time, and will eventually start the genset automatically if they get too flat, but I have not installed that yet – ironically I was going to make a start today.  This will also keep an track of exactly how much power we have left.

Normally it is best to keep LiFePO4 batteries between 10% and 90% charged.  The normal practise of charging Lead Acid batteries to 100% and float charging them is a really bad thing to do to Lithium Batteries, so I have been very careful not to charge them too much.

Still it has been a nice day – and we have a nice view over the wide’s – with pairs of Geese being very territorial, and chasing the swan away.



Ran out of water today

Today we ran out of water, quite deliberately, as we wanted to measure the tank capacity and get a feel for how the water gauge relates to the amount of water we have left.

Our water tank is in what is usually the Gas Locker.  For none boaters that is the very bow of the boat.  This means it has a complicated shape which is small at the bottom and large at the top.

As we filled the tank I measured the voltage from the water sensor every 5 minutes and noted how  full the tank gauge read.

It turns out that when the gauge says we are half full we are in reality a quarter full, and when the gauge reads a quarter full we are very close to completely empty.  To give you an idea of how extreme this is, the gauge read nearly a quarter full after filling for 5 minutes but it took 1 hour and 50 minutes to fill the tank.

This graph illustrates how quickly we run out of water once the gauge shows a quarter left.

CHart showing water level

Of course, the aim is never to run out of water, so todays measurements will help us manage our water supply and to plan when we stop at water points to take on more water.

Water points are distributed along the canals and clearly marked on canal maps.  As we intend to continuously cruise (move on every few days) we should be passing water points every few days as we go.

Fuse goes POP

Fuse goes POP – ooops.   This was fun when I was at university, making the lab technicians jump, but on my boat – well not what I wanted at all.  No satisfying POP in this case, not even a sound or a flash.  At university the fuses were loud when we deliberately made them pop; louder than any firecracker I have ever heard a really sharp bang – VERY satisfying.  Ok what amused me at 18 is less than amusing when over 50 and on my own boat, and where I have to figure out why and find a solution.

I tried a larger fuse 16A instead of 10A – well who doesn’t and to be fair the higher rated fuse was still more than adequate to protect the cable.  Well my 16A fuse also blew instantly on a circuit that had no load where it should have only used 0.05A at most. Ok, time to start to think what is going on, especially when these fuses are £5 a pop, literally per pop.

Our boat has a 48v propulsion battery that connects to the motor and Victron Quattro inverter via 225A and 400A fuses.  It also supplies the 24V DC system for the lights, water pump etc. via DC/DC converters that turn the 48V battery supply to 24V.  So far so good; this saves having a separate 24V house battery and battery charging system.

Under normal canal cruising conditions our batteries need to supply about 50A and when cooking less than 100A (yes we have an electric oven and electric induction hob like one would normally use in  a house).  Even our 3KW Electric kettle only requires 60A.  But, our batteries can deliver over 2,000 amps as a continuous load, around 5,000 amps for many minutes and perhaps 20,000A for tens of seconds into a fault.

The fuses I had selected are capable of interrupting a 200,000A fault current without rupturing or creating a source of ignition, but now I know will blow instantly when it should only draw 50ma (0.05A). Oh!

Time to get back home and let the boat builder do the final fettling before we move on board later in the month, while I consider what to do next.