smart chargers

[JanetAnne]

Hiya everyone,

I've been asked to seek your thoughts on smart chargers/controllers for a friend of mine.

We have twin engines with two alternators (obviously ) and we have two independant engine cranking batteries along with a bank of 500 amps of domestics.

The system is currently controlled with two split charge relays and works fine but we wondered whether we could use a smart charge system to get the best out of the alternators and reduce engine time when moored etc. With both engines running we have a potential 160 amps available. Ideally it would be nice to isolate the fridge battery from the main pack but not necessary.

We wondered what other members had done or would suggest?

Choccy is available... of course!

[JawsOrca]

We would never use them JA.  Ask Robin (LR) why... ("What's that burning smell") but you know how fussy I am with electrical bits ... 

[Oddfellow]

The charger to which Alan alludes is a Victron Argofet charge splitter. It's not a smart charger as such. It's a no-loss splitter that uses Field Effect Transistors (FET) to divert the charge to the batteries rather than Diodes which incur a voltage drop. 

To be honest, any electronics are liable to fail at some point. Just like any engine. Wear and Tear happens to everything on the planet, whether it's at a solid level or nano. 

There is a mammoth amount of data, views and opinions on various forms of charging. The simplest is often the most cost effective. We are planning to move back to charge splitting relays from diodes at some point as the charging voltage just isn't good enough. 

 

[LondonRascal]

I recently wrote about this on my Blog and said:

"Consider an external alternator regulator – this will do a great deal for your charging system, and companies such as Sterling and Mastervolt produce all in one units that take care of your charging needs in a ‘smart’ manner and monitor your batteries providing them with high amperage initially and then drip feeding the amps until the batteries are full – this also helps the overall life span of the batteries in your bank.

What an external alternator controller does is override the internal regulator, and force the alternator to charge at a higher voltage. Usually in the region of 14.4 volts.  Many people think that an increase in charge voltage from 13.8 volts to 14.4 volts isn't much of a difference. It's an increase of about 5%, so it will increase the charge by 5%.

This is not so true though, firstly a wet cell battery at about 50% charge will not begin to accept any form of charge until the terminal voltage is raised to about 12.5 volts. After this point, the current starts to flow. So the starting point is actually 12.5 volts as opposed to zero volts. Now the difference between 12.5 volts and 14.4 volts, as opposed to the difference between 12.5 volts and 13.8 volts is an increase of 50% ahh you see not just 5%.

When you take into other factors like the energy going back to the battery is roughly in proportion to the square of this voltage difference not just proportional to the voltage difference the increase in performance is more like 200% what it began at."

So they are very much a helpful addition to charging larger banks of batteries and can monitor batteries needs too - so when your engine cranking battery is full it no longer needs a high amperage - so is reduced to a trickle charge automatically.

Here is an example from Sterling Power: Link

 

As for the the Argofet - I would be happy to use this sort of thing because I know issues are going to be rare, however, I certainly would not want it sighted under a berth or where some near by flammable material is because if they do decide to short they make a lot of smoke and worry!

[Guest]

1 hour ago, LondonRascal said:

Consider an external alternator regulator – this will do a great deal for your charging system, and companies such as Sterling and Mastervolt produce all in one units that take care of your charging needs in a ‘smart’ manner and monitor your batteries providing them with high amperage initially and then drip feeding the amps until the batteries are full – this also helps the overall life span of the batteries in your bank.

Quite right.

I always fit a smart regulator to all of my boats as soon as I buy them.

People often retro-fit two or more alternators to increase charging capacity in their boats, but most existing single  alternators are quite capable of much higher charging rates, but are "knoblled" by the default built-in alternator regulator.

My current boat has  a Sterling SplitR that cost just over a £100 about 5 years ago.

This also  acts as a split charger to the main and domestic batteries, and senses their levels, giving the maximum amperage possible, as and when required by each. A sophisticated electronic charging unit unleashes the potential of even standard rate alternators.

Things have come on a long way now since the simple bridging relays in earlier boats and caravans.

 

[LondonRascal]

Another fine example of good wiring on a boat.

[BroadScot]

16 minutes ago, LondonRascal said:

Another fine example of good wiring on a boat.

Agreed, Robin,

I wish I could say the same about some of the so called DIY wiring I have seen and had to repair and replace in homes and buildings! I wish I had had a mobile phone camera in those days, to show the dangers of the risk of fire then.

Iain

[LondonRascal]

At least (even in my day) we grew up knowing a thing of two about electricity, the dangers of it and how it all worked.  I know that many many fires and maybe lives may have been saved since all items had to arrived with a fitted plug on them, but in so doing it has made a lot of what wiring and electricity is 'a mystery' to so many.

The scary thing is when one combines power with boats, is for some reason people do things they would not (at least I hope would not) in a home.  I've seen 240v double sockets installed inches from the back of a sink, shore power which is just some cable wired to a 16Amp plug one end and a 4 gang socket the other through an open window  - this is not a few volts DC we are talking of here but maybe some boaters regard 'boat 240v' as not as dangerous as 'home 240v'?

 

[Guest]

Thanks guys.

Here's another photo of what I was replacing in my boat.

When I bought it, there was a thick folder of provenance from previous owners who had paid many thousands of pounds to various boat yards to maintain the boat. It didn't look like there were into DIY very much.

This photo shows the ancient relay-based split charge which was in a really cra**y state.

The trail of invoices for the two years prior to my purchase of the boat showed the previous owner chasing a so called "elusive" charging problem.

Rubbish and dangerous workmanship often manifests itself from Pros as well as DIY'ers......