Sounds good to me
It's the kind of stuff you wish you knew from the start. I'm amazed at how little anyone I talk to on the cut knows about batteries.
Oh yes. There are people with good systems whose batteries have lasted over a decade - yet there's people on the forums buying second-hand ones off Vince for £25 because they die every 6 months.
Here goes.
A battery management system does several things, depending on what you have installed. Adverc, Sterling and Victron are the best known, and they all do similar things in slightly different ways. The following description is based on Adverc's system but the principles will be similar for all of them.
The primary component is, surprise surprise, a battery management system. This tricks the alternator into giving more charge than it was designed to; ensures that the starter battery is given priority whilst sending all the excess to the domestic bank; prevents overcharging of batteries (which ruins them very quickly).
A battery isolator prevents the starter and domestic banks from discharging into each other in a costly suicide pact.
Shunts can be fitted to measure the demand from 12v and 240v electrical systems (together or separately, depending on how many shunts you have fitted and how they are connected). The information is sent to a visual monitor which can tell you what's going in when charging, what's going out when appliances are in use, as well as the current voltage of the bank. The monitor will have a low voltage alarm - ideally audible as well as visual - to warn you when the batteries are at 50% (on the default setting). Discharging below 50% too often will reduce battery capacity over time.
It takes more and more energy to charge a battery as it gets close to full. Ideally the batteries will be charged to full, or near full in reality, at least once a month but need not be charged up beyond 80% (when it starts getting expensive) on a daily basis. Ideally you will have a battery bank more than 3 times bigger than your maximum daily requirement of them, so that you can charge to 80% only and not need to discharge below 50%.
The cables connecting the batteries in the bank must be beefy enough to take the input provided by the alternator with minimal losses - bearing in mind that you might wish to upgrade your alternator to reduce charging times.
The cables connecting the batteries must all be the same size and length to put the same load on all batteries in the bank and should be as short as possible to minimise losses.
The input and outputs should be connected at diagonally opposite ends of the battery bank, rather than having them both connected to the same battery.
3000 is about optimal for revs at the alternator - more than this will give more charge but at a substantial additional cost in fuel. Less than this will give suboptimal amps for the fuel used. The revs at the alternator may be calculated from the engine rev counter by considering the ratio of the outside diameters of the engine and alternator belts. If it's 2:1, you need to run the engine at around 1500 revs for optimal charging.
That's a brain dump - think it's all there within the limits of my understanding and memory. Feel free to amend in any way you see fit, or correct any obvious nonsense - this is all based on a couple of hours discussion of our needs at the Adverc offices with our electrician.
We decided to go for some shit hot batteries in the hope that they will last for a very long time. Will report back in 2, 5, 10, 15 years depending.
but we got a very good deal from Adverc.
