Lithium Batteries 2 - The Drifted Thread!

[PaulRainbow]

PCUK, I've seen a few adverts for the Aptivolt Battery Management systems | Autonnic on the back of PBO recently and I am considering it as part of rewire on my boat. With its prioritised charging, this solution may meet your requirement for a separate battery for the fridge. Hopefully there is a formite out there who has installed it and can advise.

I have fitted Autonnic equipment and find them a good company to deal with, but i have not fitted this system. It does look interesting, if the particular installation would benefit from the features that this offers.

I might have been tempted to fit one of these to my own boat next Spring, when i install the new solar panels, but it is a bit restrictive in some respects, i may be fitting more than 20a of solar and my boat is 24v.

That said, i agree with Tranona in post #20, it's far too complicated and expensive for the OPs needs.

 

[dankilb]

That said, i agree with Tranona in post #20, it's far too complicated and expensive for the OPs needs.

Absolutely... you'd want to know whether/how the possibilities of something like Victron 'smart shunt' (or equiv) for monitoring and straightforward common sense in the design/management of the system had been fully exhausted before being convinced of the need for a more complicated system.

I was thinking about this separate house batteries thing and it occurred to my that my grandfather did something similar on his Westerly Berwick back in the day: He'd use up the first (newer) house battery before switching to a backup once the voltage was low. Whether he'd have opted for that (as a smart guy and engineer) - over combining them in a bank - if he'd had a shunt and a modern battery monitor is another question.

 

[Spirit (of Glenans)]

From the above, Lithium makes no sense for you.

As mentioned in the other thread, it's not a good idea to separate the house batteries, neither is it a good idea to have a separate fridge battery. Firstly, using one battery at a time will mean that the single battery will get cycled more and die sooner. Secondly, charging one battery at a time will make very poor use of the 150a alternator.

In my opinion, your system needs to be a nice, simple one. A single battery for engine starting and 3 leisure batteries for domestic use. Both banks kept separate from each other, with a 3rd switch for emergency starting. Alternator connected to the engine battery, other charging connected to the domestic bank, with a VSR between the two banks.

Fit a decent battery monitor to keep an eye on things and don't discharge the domestics past 50%

The following schematic should suit you well, just ignore one of the domestic batteries.

Strangely, the attachment was not visible to me on the original post and only appeared in the quote when I started writing this reply?