Battery Charger Thread

[Pearo]

So I was asked in another thread about battery chargers. Given I have some design experience in this field and given I hear so much fluff circulated about chargers I though I would put a few through their paces.

I will add more detail at time goes by, but I though for now I would just post up some thoughts on 2 chargers, the CTEK the most people rave about, and a lesser known company called GSL electronics which is an aussie company.

First let me start by saying this. Battery chargers need only operate in 3 modes, constant current, constant voltage and float. Anything else is marketing drivel and snake oil. The major mode that sucks people in is desulphation, and this is questionable at best. If you battery is suffering from irreversable desuplhation that can't be resolved through normal charging the the battery is stuffed. You may extract limited life out of it, but dont rely on it for anything critical. And lets make a point here, keeping your beer cold when camping is critical..

So the three phases of charging are Constant Current, Constant Voltage and Float. Sometimes people use other terms, like Bulk charging, maintenance etc. Constant current is the first stage, where your charger is suppling as much energy as possible to the battery. When it does this, the voltage may be below your standard 13.8 (depending on battery chemistry) that you normally see. Once the battery has consumed a certain amount of energy, it will draw less current. Once this happens, your charger voltage will rise to the voltage you would expect to see when charging, this is called constant voltage mode and is the second stage. After some time in constant voltage mode, your batttery will become fully charged, and in this mode its drawing next to no energy from your charger. When the charger detects the current draw has dropped below a certain amount, it should lower its voltage to a float voltage, which is less than the constant voltage mode. The idea here is simply to supply enough energy to overcome the battery's own internal losses and keep your battery fully charged.

When I test, I am looking for several things,

• Ripple current that is bad for batteries.
• Will the charger supply its rated current in constant current mode.
• What is the voltage in constant voltage mode.
• When does the charger switch to float mode.
• What is the float voltage.

How I test. I use 4 instruments typically. A DC load tester, a DC powersupply, a voltmeter and an oscilloscope. In subsequent posts you will see some pics of some of the gear. Given I am currently waiting on DA for my shed its all a but limited. Most of my test gear is still packed in boxes from the move and I only have notes from the tests I have done on the gear so far.


I will end this part here, and my next post will a very summarised version of the CTEK, followed by another post with the GSL. Just goint to go off and cook dinner now!

[Pearo]

CTEK MSX5.0.

I am not going to put a full review up here on any charger, just a brief run down. When I get set up in my new shed, I will go back and write down all the test results and compile them into a spreadsheet.

The CTEK is a smart charger, has 7 modes that do various things. Its a pretty good charger by all accords, but has a little quirk when in constant current mode at about 4.5 Amps. Its has several charging option, for car and motorcycle, and option to charge both AGM and flooded lead acid batteries. In all modes the voltages are as expected, and there is very little ripple most of the time, about 200mVpp. But once you start loading it up, the ripple starts.

This photo is of the main setup, the top is the oscilloscope which shows some ripple at 4.1Amps.


Stepping up to 4.5 Amps the ripple increases substantially:


Then upto 5 Amps the ripple drops back for some reason:


Ripple is bad for batteries, as it causes unwanted heating, which is a good way to destroy your battery. But the ripple from the CTEK is low frequency, so I doubt it will cause any substantial issues. At first I thought it may be the charge controller switching of the charge current to measure battery voltage, but the off time is too short to make a usefull measurement, and it only does it when loaded. My guess its a design tradeoff given the size, lack of fan and higher current supply.

Good charger, yes. OVerpriced, I think so, but its pretty fool proof.

One point I will make, it this charger will not start if your battery is below a certain voltage. This is done for a very good reason. If you have a dead cell in your battery, or an internal short, then the battery will draw the maximum amount of current possible until you turn the charger off. This can cause heating and production of hyrdogen gasses. In worst case scenario this could result in a battery explosion. SO thumbs up here.

[Pearo]

GSL BC240-1210

This charger is an Aussie designed and build charger. Pretty rare to find something like this build in Aus now. I have used a bit of their gear over the years and I have never had a single failure outside of the dreaded lightning strikes. The charger I have is one I bought many years ago and has copped an absolute flogging. The only thing that has failed on it was the fuse when I once connected a battery the wrong way!

This charger is a simple one. Not a smart charger at all. Has the three modes, Constant Current, Constant Voltage. It is the only charger on the market that I have tested to date that has no significant measurable ripple at its rated current. Voltages as expected, but no no AGM mode. I have used it on an 120ah AGM I have here for the last 5 years with no issues, and that battery can still run my primus 92l mammoth for a couple of days without charging.

Here is a pic showing it running at 10 Amps. The cro is not really visible there but you will see the ripple is non existant in the next pic.


And here is the ripple at 10 Amps (none).




Is this a good charger. Yup. Best in its class. This is my go to charger for everything.

This is not a smart charger, so it will start charging regardless. So its one of those chargers that should be checked upon every for hours intially just to make sure the battery is not getting too hot. IF you know the battery is good, just forget about it.

THink of it like one of these:


IF you have ever used an old school arlec charger with no incedents then you will never have a problem with this.

[Pearo]

Was not going to worry about this one tonight, but I have some piccies so thought I would post it up.

These are the generic ebay 20 Amp chargers you find for sale through many sellers. Look like this:


Think of it as an old school arlec charger. They do the job, just not very well. I would keep it away from AGM or GEL batteries. Probably ok for start batteries, but use with caution. Bang for buck its ok. NOt a smart charger so will charge try charge regardless of battery condition. They are good for about 17Amps then shut down.

Plenty of ripple, here at 0.5 amps


And at 17 Amps


At around $30-$40 dollars they are bank for buck ok. If you do use it, just keep an eye on it every now and then.

[Pearo]

ALDI Charger.

FAiled out of the box. Will try and find the receipt and attempt an exchage. I doubt they will have one in stock at my local Aldi but I will try tomorrow.

[Glenn.Visca]

Thanks pearo. I currently have a projecta that I purchased some time ago. I just recently purchase a Haze 120ah AGM for use on my van.

I dont plan on using the projects in the van ... Where I will install a Ctek or perhaps now a GSL.

You done tests on projecta? See any issues if I use it short term?

[Grumpy John]

This is the charger I have in my van. How would you rate it?

Xantrex TC20/40

[Pearo]

Thanks pearo. I currently have a projecta that I purchased some time ago. I just recently purchase a Haze 120ah AGM for use on my van.

I dont plan on using the projects in the van ... Where I will install a Ctek or perhaps now a GSL.

You done tests on projecta? See any issues if I use it short term?

No, but I have a mate with a projecta charger, so I will lend him one of mine and test it at some point. I may even buy one to test yet.

IF you choose a GSL, I would look at their new multi chemistry stuff.

[Pearo]

This is the charger I have in my van. How would you rate it?

Xantrex TC20/40

I have use some xantrex stuff commercially and its good. Xantrex have their roots in the industrial business, so I think you would be hard pressed finding faults with their gear. I like they way they charge several batteries independantly, it allows much more precise control of charge currents, and I assume has better fault tolerance.

Not sure if you xantrex charger has the option to add a temp sensor the the batteries, but the stuff I have used in the past did. Its a worthy addition.

EDIT. Just thought I might add in here, if I were to buy a van or RV, the xantrex gear would probably be my choice.