Thursday, August 01, 2019

Moving on to Banbury

We left our lovely mooring at Chisnell lift bridge on the meadows and headed towards Aynho. It was another beautiful day and we made the most of it.. We got to Aynho Wharf and a boat was just coming off the water point, touch!
We got rid of our rubbish and filled with water for 40 minutes.. We then carried on to the tricky Aynho diamond lock and from here the water levels seemed to change..

It got very shallow as we passed the Pig Farm and on to Kings Sutton lock.

It didn't get any better past the always shallow Twyford, tipping the boat over when passing another boat.

We were pleased to reach Grants lock, reaching our mooring we like..
The sun was lovely with a nice gentle breeze so we relaxed making the most of it, as the weather didn't look very good for tomorrow..

Before we left today we let our batteries drop to 55% and we cruised for 2 hours and were idle in locks for one hour.. By the time we had got to our destination our batteries were at 100% and Al had done a washing load on route which is the high red peak on the chart.. We have had to reduce the charge rate going into the lithium batteries from 60 Amps down to 25 Amps using a Buck Boost, as they charge so fast, solar was also putting in an average of 10 Amps. Our cruise looked like this on the BMS (Battery Management System)


Alan Stacey said...

Love reading your continuing blog posts, we had same issues with low water levels on Southern Oxford when we cruised down and then back up in April/May so not surprised similar issues this time of year.

I have a quick question regarding your charge rates for your lithium batteries since we are considering upgrading ourselves following our successful solar install using the brackets you recommended.

Why do you limit charge rate to only 25 amps? Our current lead acids are quite happy initially changing at up to 90+ amps when at low charge. I had understood from other information sources that lithiums were happy absorbing even higher charge rates. Have you encountered (or heard about others) that have experienced problems with high charge rates?


Del and Al said...

Hi Alan,
The charge limit is adjusted so when the management system turns off the charge to the lithium batteries, it doesn't then create a back feed to the alternator which could burn it out.. Which means its the alternator you have to worry about not the batteries.
If you have a 12 volt system then you can fit a BMS 12v/200a which you can see on the Victron site. This can be adjusted to protect:
1/ Over discharge
2/ Starter battery.
3/ It has a remote on and off switch and adjustable voltage protection for the alternator.
We couldn't have that on Derwent6 as we have a 24 volt system and had to have the expensive Buck Boost fitted, but it does a good job. We also have two lead acid dump batteries fitted to divert the alternator charge to them when the lithium's don't need it. Hope this helps! Del

Alan Stacey said...

Feedback much appreciated. We do indeed have 12V system, so appears a little more research in order. I am determined to get my head around this no matter how long it takes!


James said...

Hi All

I'm not quite getting the reduced amps either although I understand how you can't be using the 12/200 as a current limitter.

Ours is 12v and we use 2x 12/200's in parallel solely to limit the current to about 160A (they can do 80A each). I know that you mentionned battery temperature being an issue recently.

On shoreline yesterday I charged at 110A and put 50A back in in about 24 minutes. With the engine running we put back in a constant 160A until 14.2v target is achieved and charging swithches off (well it actually switches off at about 13.9v and then cycles on and off getting lower nd lower amps til 14.2v ish. Our starter battery is the only dump source.

Over winter if we're not running the workshop we'll need to run the engine 3 1/2 hours a week to replace all we use.