New "Smart Chargers" vs not so smart chargers

Stu Jackson · Feb 18, 2014

Bob,

"To leave the fridge on or not" has been a philosophical issue for many, many years. For those who come to their boats once a week, I still find it strange, because you're right, pick up a cold one on the way to the boat, turn the fridge on when you get there, and it'll be cold in half an hour.

One of my friends has made the point that if the shorepower goes out, and it can, then all that mayo is gonna make a BIG time cleanup required, and a stinkin' mess to boot. I find it incredible that folks still do that.

From your distance and the amount of time you're away from your boat, forgetting about the battery charging for the moment, what's the concept?

I've also made the point that the less you use your fridge, the longer it'll last. They simply aren't like household fridges, and do have a shelf life.

In your case, you could leave the batteries fully charged and completely disconnect the boat and you'd be just fine.

Yes, there are smarter chargers out there that cycle and avoid full time float, which, as you know, your charger doesn't.

However, if you follow the advice above, you can keep your combined inverter/charger.

If you buy a new charger, then yes, you can still use the inverter side. Just never have the separate charger and the inverter on at the same time.

Good luck.

PS - We have a Freedom 15, pretty much the same as yours, controlled by a Link 2000. Before I put in the Link, I ran it from the switch on the top of the housing.

Ron20324 · Feb 18, 2014

Some folks have gone to a dedicated power adaptor/supply to go from AC direct to the fridge's 12v needs. Saves the charger in the process.

Gunni · Feb 18, 2014

If your charger output is not enough to supply both the house load, and the battery charge requirement your batteries will be loaded to make up the difference. When your batteries get drawn down below the charger float charge point (say 85%), and your charger can't supply the total load (house + battery charge), they are likely to stay in absorption mode and cook off as the charger struggles to produce the required amperage.

A lot of this stuff becomes clear when you have a battery / charge rate monitor. Bottom line; you can have your cold drinks AND your battery life.

Maine Sail · Feb 19, 2014

rfrye1 said:
I was reading my latest issues of the sailing magazines and they had a good article about battery chargers. I'll admit my expertise is limited in this area. My current boat (1998 Hunter 376 with4D house batteries, and a dedicated start battery) has the OEM 1998 Heart Freedom 2000 charger/inverter. I have learned over the years that if I leave the fridge on while I'm away for an extended time (I live 400 miles from my boat), the charger senses the drain on the batteries and sometimes will overcharge my batteries, and I come back to my boat 2 months later to dry batteries. If I turn OFF everything, this seems to fix the problem. So I just bring a couple cold ones with me.

My question: is that the charger? It's 16 years old, and I assume they are smarter/better now. At $200 a piece for those 4Ds I'd like to maximize their life.
Also if a buy a new charger, can I still use the inverter?

Thanks, Bob.

Bob,

Your old Freedom charger is not very smart by today standards. It lacks a custom charging program or forced to float option. It also uses a timer based algorithm or minimum current to terminate absorption. This charging technology is akin to dinosaur saddles....

Algorithms like this often results in too short of an absorption period on larger banks and too long on smaller banks.. Really pretty dumb.. When connected to a Link 1k or Link 2k the min current option changes and is then programmed via the Link. There are many situations that can confuse the "min current" threshold so the egg timer is also thrown in... Egg timer chargers are DUMB.....

The older Freedom units are designed to not go back into absorption once float has been attained. This is what they are supposed to do. Do they always do that, sadly, HELL NO...... On top of that marina's are not known for steady power supplies and interruptions are frequent which re-sets the unit and starts absorption voltage the process all over.

I have been working on marina boats and counted as many 7 interruptions in 6 hours!!! That means a minimum of six straight hours of absorption voltage on batteries that are already chuck full.... Despite these being mere "blips" in AC supply the charger still re-sets.

There are very few options on the older Freedom's other than choosing the GEL 1 program. At least this way when it pops out of float, or power is reset, it will revert to absorption at just 14.1V as opposed to 14.4V. This will help limit gassing but as batteries age, or get contaminated, the votlage at which they gas can drop..

Good quality smart chargers today use what I refer to as "adaptive learning" algorithms. This means they monitor & calculate the time the charger was in bulk, how fast the voltage came up and then calculate the needed absorption time. (that is a really, really dumbed down explanation and they do much more) Even when in absorption they are using this adaptive learning algorithm to calculate when to go to float..

But don't be fooled, many "smart" chargers today are no smarter than they were 20-30 years ago, which is a pretty darn dumb "Egg Timer" charger.

Companies like Magnum, Mastervolt & Victron all make custom programmable inverter chargers that are also smart but not every product in each line is customizable. (some of these require a computer interface kit to properly program them)

For stand alone battery chargers the Sterling ProCharge Ultra or ProMariner ProNautic P are two of the best with 11 presets to choose from and one fully custom program. Their remote display is head and shoulders the best on the market. (The PM and Sterling chargers are identical - joint venture)

Any charger or inverter/charger that does not have a custom program that allows you tailor a specific program is not "smart" IMHO. Any charger or inverter charger that uses time only (egg timer) or min current thresholds for transitions is NOT SMART. There are LOTS of dumb chargers out there marketed as being "smart". Most of it is pure BS... Three stages of charging DO NOT make a charger smart.

My take is that a 100A plus charger has no place being used as a "stand by" always on charger UNLESS you can select a program that has a maximum voltage under 13.6V which essentially turns it into a "power supply".

This is a program that never allows the charger to exceed 13.6V, even when AC is reset, unless you manually take it out of that mode.. I call this "power supply mode" or "forced to float" mode.

These chargers can be very dangerous due to the immense current they can supply. If they boil off a battery, as yours already has, and it internally shorts, then you have 100A of current, plus the batteries it's in parallel with, to throw current into that short. This can lead to an explosion or thermal runaway condition. Limiting any larger inverter/charger to a max of 13.6V, when you are not there, is a good safe practice.

Another option is to buy a smaller charger that can supply your always on loads and have a little left over for the batteries. This charger should also be set to "forced to float" / 13.6V or use a custom program to do so.. When you get back to the boat and are there switch to a "charging" program.

If a charger or I/C does not have a forced to float switch or a custom program option that allows you to create that, spend your money elsewhere.

Another option is to use an AC to DC power supply and switch it on while at the dock to power the fridge. Newmar makes some excellent AC to DC power supplies...

I am NOT a fan of leaving any larger charger on without being forced to float when you are not there..... There are far too many reports and failures like you've experienced.......

New "Smart Chargers" vs not so smart chargers

rfrye1

.

Stu Jackson

.

Ron20324

.

Gunni

.

Maine Sail

.