"Smart" Battery Chargers. Not that smart?

[Trundlebug]

I've noticed an irritating habit of so called "smart" chargers, which seems to be common to the charging algorithm of several types.

When first switched on, they all seem to have to go right through their full charging sequence regardless of the battery voltage they see when first switched on. Only the duration of each stage alters to suit the current drawn / battery voltage.

This is true of all 3 of the chargers I have on board:-
1. Sterling Alternator to Battery charger
2. CTEK M300 ("The most intelligent charger in the world")
3. Victron bluesolar MPPT solar controller.

Why, when they're first switched on and see a battery voltage of 13.9v (or even higher, it was 14.2v yesterday. The CTEK charger was on and I hooked up the solar charger for the first time) don't they just think "Ooh, that's healthy, no need to charge it any further, I'll just cut out and wait for it to drop to e.g. 12.8v"

Instead, they first go into bulk for a few seconds / minutes, then into float, then stay at float for whatever period their timer is set to (or other parameters dictate. 2 weeks float for the CTEK!) before finally cutting out as "fully charged".

It just doesn't seem very "smart" or "intelligent" to me. Or have I got it wrong?

 

[bigwow]

Perhaps they are that smart they think,
"We had better go through the motions when switched, on or our owner will think there is something wrong with us and bin us".:encouragement:

 

[BabaYaga]

I think because just a voltage reading of say 12.8 is not information enough. It could be (often is) a fully charged battery at rest, but could also be a half charged battery with some load on it that is also being fed (e.g. by solar).
If the charger when switched on instead tries to charge the battery (by bulk, absorption, float) it gets more information about the SOC of the battery.
The kind of intelligence you are looking for would require more input I think, and also the unit would have to be left permanently on.
I have the CTEK 300, there are only the positive and negative feeds (plus the temperature gauge wire) to carry information, no sense wire. Still think it is pretty intelligent – but it's only a battery charger.

 

[ianj99]

I've noticed an irritating habit of so called "smart" chargers, which seems to be common to the charging algorithm of several types.

When first switched on, they all seem to have to go right through their full charging sequence regardless of the battery voltage they see when first switched on. Only the duration of each stage alters to suit the current drawn / battery voltage.

This is true of all 3 of the chargers I have on board:-
1. Sterling Alternator to Battery charger
2. CTEK M300 ("The most intelligent charger in the world")
3. Victron bluesolar MPPT solar controller.

Why, when they're first switched on and see a battery voltage of 13.9v (or even higher, it was 14.2v yesterday. The CTEK charger was on and I hooked up the solar charger for the first time) don't they just think "Ooh, that's healthy, no need to charge it any further, I'll just cut out and wait for it to drop to e.g. 12.8v"

Instead, they first go into bulk for a few seconds / minutes, then into float, then stay at float for whatever period their timer is set to (or other parameters dictate. 2 weeks float for the CTEK!) before finally cutting out as "fully charged".

It just doesn't seem very "smart" or "intelligent" to me. Or have I got it wrong?

Perhaps its the owner that isn't smart ?

If you can see 13.9v on a battery gauge, why would you switch on a charger?

Either way I can't see what harm it does.

 

[Trundlebug]

I think because just a voltage reading of say 12.8 is not information enough. It could be (often is) a fully charged battery at rest, but could also be a half charged battery with some load on it that is also being fed (e.g. by solar).
If the charger when switched on instead tries to charge the battery (by bulk, absorption, float) it gets more information about the SOC of the battery.
The kind of intelligence you are looking for would require more input I think, and also the unit would have to be left permanently on.
I have the CTEK 300, there are only the positive and negative feeds (plus the temperature gauge wire) to carry information, no sense wire. Still think it is pretty intelligent – but it's only a battery charger.

But you're missing the point. OK at 12.8 it probably needs charging / assessing in more detail.
But when it's reading 13.8, well it's either incredibly healthy or is already being charged by something else - in which case, leave it.

But no - it has to go right through the full charge cycle regardless.

 

[Skylark]

"smart" is evidently modern day vernacular into duping the unwary into believing hype and propaganda. "Telephone" is another good example. Obsession usualy follows soon thereafter.

 

[Trundlebug]

Perhaps its the owner that isn't smart ?

If you can see 13.9v on a battery gauge, why would you switch on a charger?

Either way I can't see what harm it does.

That's like asking "Because you have money in your bank account, why do you carry on working / earning?"

The simple answer is - because you want to maintain it that way

 

[G12]

I believe they supply a current to the battery and then analyse how fast the voltage rises. A fast voltage rise indicates a charged battery, if it rises slowly then it is accepting charge. Mine certainly works like that. Once it realises the battery is charged it drops into float mode. If as someone mentions earlier there is a load then it compensates for that plus whatever else it deems required for the battery.

 

[BabaYaga]

But you're missing the point. OK at 12.8 it probably needs charging / assessing in more detail.
But when it's reading 13.8, well it's either incredibly healthy or is already being charged by something else - in which case, leave it.

But no - it has to go right through the full charge cycle regardless.

If your charger was programmed to "hold back and wait" just because it reads 13.8V, I suspect you would risk getting the battery fully charged a lot later than if the charger was allowed to start.
My point is that as long as charging current (from other sources) and loads are unknown, it is hard to tell SOC only from a voltage reading.
As G12 says, by supplying current and measuring (volts, amps, time) there will be something to analyze.

 

[noelex]

If you are leaving the boat for an extended period of time with no load it is worth lowering the absorption and float set points by 0.2-0.4v. Unless the charger /regulator will recognise a "storage" mode (very few do this).

A charger/regulator with infinitely adjustable set points has a big advantage here. For those without this feature usually the "Gel" option is best even with flooded batteries when leaving the boat with no load.

The best regulators measure true battery return amps and can this will give a more accurate charge algorithm, but this is rare and probably overkill at least for flooded batteries.