Battery chargers

[Winnie]

Hey guys, my cranking battery has died and the reason why is because my car can sit for a month or two between proper drives, the battery charge level goes up and down and has not really been looked after properly.

Before I get a new battery I want to get a proper battery charger to leave plugged in all the time so it will last a few years more. That's the confusing part.

The ctek website recommends at least a 7A charger for a battery of 120Ah, but I'm sure I've read people using much smaller chargers without a problem. I was looking at their 3.6A one which they say will do up to 75Ah, is that just marketing bull crap to make you buy the dearer one?

[the evil twin]

I run a few different configurations of Battery/Charger combinations as standby power for remote telemetry sites.

It's not marketing bull crap as such because they have to try and sort out a 'one recommendation suits all situations' figure I spose.
I use the Ctek 0.8 amp for up to 50 A/H and the 3.6 for the larger capacities up to 140 A/H which is the largest standby capacity I need of 72 hours.

I would go the 3.6 myself for a vehicle.
Yes, the 0.8 will do and that is what I have put on 70 series 6 cyl cruisers but I use the 3.6 on the V8's.
Reason?
If the Battery is charged and it is purely a maintainance charge then 0.8 will work but 3.6 is easily enough capacity for top up when first put away then ongoing maint.
The 7 amp jobbie is a spec that revolves around Ctek thinking why is the Cust using such a big battery?
There is a largish draw and probably a quickish recharge needed?
IE you don't ideally want the draw to be much higher than the charging rate for standby/maintainance situation

In your case (and mine) there is no boost charging and no large draw, just parasitic and leakage of maybe 1/4 an amp tops depending on equipment connected.

[Winnie]

Okay cool, here's another thought. I have a basic redarc dual battery system.
If I got a 3.6A charger and connected it to cranking battery, would it put in enough charge to activate the dual battery solenoid and keep both batteries at 100%?
Or should I now be looking at a higher capacity charger?

[the evil twin]

(sorry for the delay, stupid freakin Bigpond dropped out)

Nah, the 3.6 will be fine.
It will pull in the Redarc and do both batteries even tho you are prob up around 200+ AH.
Indeed that is exactly what I have at the moment on my Red Ute... (I have removed the Intervolt programmable gear for another project)

My only comment is that assumes the batteries are in a good state of charge and condition.
If you have been giving them a hiding that day say winching and then a short drive home at night then 3.6 may be a tad low

[nissannewby]

Getting the batteries out of the engine bay will also help their longeviry but is hard to cos of room constraints.

[Chimo]

I'm sort on the same wave length as the evil twin except I went the C-Tek M-300 that comes with a .08 charger in the box. The M=300 is a 25 Amp charger but is very smart. I use it to tart up tired batteries and to maintain a couple of batteries at the same time in the boat. Both batteries are the same and are linked by an Auto Battery Coupler.

The M-300 is one of the few batteries around with a 5 yr warranty and the place I got mine from rewired the ends with anderson plugs so I can change the end connections. I can also pug anderson to anderson via the plug at the tow bar on the Patrol to charge that battery and if I leave it sit the .08 can plg into the same spot.

Winnie, check them out and you can get your batteries to last for years. Some of mine are over 10 yrs old and are working fine.

Cheers

[Winnie]

Getting the batteries out of the engine bay will also help their longeviry but is hard to cos of room constraints.
Yeah, unfortunate not an option.

(sorry for the delay, stupid freakin Bigpond dropped out)

Nah, the 3.6 will be fine.
It will pull in the Redarc and do both batteries even tho you are prob up around 200+ AH.
Indeed that is exactly what I have at the moment on my Red Ute... (I have removed the Intervolt programmable gear for another project)

My only comment is that assumes the batteries are in a good state of charge and condition.
If you have been giving them a hiding that day say winching and then a short drive home at night then 3.6 may be a tad low


I'm sort on the same wave length as the evil twin except I went the C-Tek M-300 that comes with a .08 charger in the box. The M=300 is a 25 Amp charger but is very smart. I use it to tart up tired batteries and to maintain a couple of batteries at the same time in the boat. Both batteries are the same and are linked by an Auto Battery Coupler.

The M-300 is one of the few batteries around with a 5 yr warranty and the place I got mine from rewired the ends with anderson plugs so I can change the end connections. I can also pug anderson to anderson via the plug at the tow bar on the Patrol to charge that battery and if I leave it sit the .08 can plg into the same spot.

Winnie, check them out and you can get your batteries to last for years. Some of mine are over 10 yrs old and are working fine.

Cheers
Thanks for the advice gents

[Clunk]

Used to have one of these before it shit itself, worked well and charge rate was pretty good........ http://www.supercheapauto.com.au/online-store/products/Projecta-Pro-Charge-Battery-Charger-12-Volt-2-8-Amp.aspx?pid=292792#Recommendations. Stupid me didn't check to see how it was doing, so battery eventually didnt' have enough juice to start the Q.

Called the RAC to get me going, so bought one of these 4A jobbies http://rac.com.au/motoring/batteries/battery-chargers and does the job

[my third 256]

what about a small sola pannel to top up the batteries

[mudnut]

They are so simple, and have a diode in them so there is no leakage overnight, and only 30 bucks. I have wired up a plug at the front of the vehicle so I can connect the panel without opening the bonnet.

[Rossco]

I just bought repco 8 stage 8 amp one. Should have got one ages ago, works great, very happy with it.

Mines pretty much same scenario as you winnie, can be weeks between a decent drive plus i often work in the shed with the car radio going. Yeah i just leave it on most the time then cranks awsome when your ready to go. The redarc kicks in reasonably early so assume it's keeping that one toped up too.

[Cuppa]

With ctek you have to be careful if buying one intended for a smaller battery bank beause there is a chance it will overcharge the battery if left unattended. I had a ctek 7 amp charger on 300Ah of batteries & this was a problem. It has to do with the how ctek chargers 'check' the battery every 10 days when in float mode. My ctek had a 'Supply Mode'. I got around the problem by montoring the battery until it was full, (ie. dropped into float mode) & then switched the charger to 'Supply mode' which I could leave indefinitely. If buying ctek I'd suggest it is best to stick with the models suited to your battery capacity.

I had a 0.8A smart charger (not a ctek)supposedly intended for 'permanent' connection plugged into a wet motorcycle battery years ago. No mention in the instructions to regularly check & top up the battery fluid. It killed a new battery in less than 12 months, being plugged in whenever the bike as in the garage.

Whichever smart charger you buy, you will still need to check the battery fluid regularly & top up as needed (if a wet battery) or risk it dropping the fluid level below the plates, or even boiling it dry. This can happen with many smart chargers as the battery will bubble & gas when close to full charge, & can do so in float mode. Shouldn't be a problem with a correctly sized ctek though.

Personally if getting a new battery I'd suggest you get an AGM battery which don't suffer the same problem because of their recombination technology. Additionally AGM's have a far lower 'self discharge' rate than wet batteries & if fully charged when you park up can happily be left for a month or more at a time without needing to be on a charger. I had no problems with YellowTop Optima batteries, although there are cheaper AGM's suitable for starting duties.

[dom14]

Getting the batteries out of the engine bay will also help their longevity.

How do you do that?

[dom14]

With ctek you have to be careful if buying one intended for a smaller battery bank beause there is a chance it will overcharge the battery if left unattended. I had a ctek 7 amp charger on 300Ah of batteries & this was a problem. It has to do with the how ctek chargers 'check' the battery every 10 days when in float mode. My ctek had a 'Supply Mode'. I got around the problem by montoring the battery until it was full, (ie. dropped into float mode) & then switched the charger to 'Supply mode' which I could leave indefinitely. If buying ctek I'd suggest it is best to stick with the models suited to your battery capacity.

If it's a Ctek smart charger, it should cut the amps as the battery reaches it's full state of charge.
As much as to almost zero if the battery is "100%" full. If a smart charger overcharges a battery, that defeats the purpose of a smart charger, I reckon.


I had a 0.8A smart charger (not a ctek)supposedly intended for 'permanent' connection plugged into a wet motorcycle battery years ago. No mention in the instructions to regularly check & top up the battery fluid. It killed a new battery in less than 12 months, being plugged in whenever the bike as in the garage.

Ideally it shouldn't, if it's a properly working smart charger.
But, I don't leave them plugged anyway. I reckon it's a waste of electricity(not money. :) )
I charge the battery once a month with a mains electricity smart charger and a pulse charger.
Appears to be doing a really good job by keeping the battery going lot longer than it normally does.


Whichever smart charger you buy, you will still need to check the battery fluid regularly & top up as needed (if a wet battery) or risk it dropping the fluid level below the plates, or even boiling it dry. This can happen with many smart chargers as the battery will bubble & gas when close to full charge, & can do so in float mode. Shouldn't be a problem with a correctly sized ctek though.

If the smart charger does what it says it does, then ideally it shouldn't push excess current into the battery. But, I haven't tried leaving a smart charger plugged in indefinitely to see how it goes.


Personally if getting a new battery I'd suggest you get an AGM battery which don't suffer the same problem because of their recombination technology. Additionally AGM's have a far lower 'self discharge' rate than wet batteries & if fully charged when you park up can happily be left for a month or more at a time without needing to be on a charger. I had no problems with YellowTop Optima batteries, although there are cheaper AGM's suitable for starting duties.

[Cuppa]

Hi Dom,
I was pretty sure someone would post what you have in reply to what I wrote. It is what I would have expected too, but my experience suggests different.

I have learned over the years that there are smart chargers & smart chargers! Not all work the same. ’Smart’ can mean different things.

All smart chargers will be multi stage chargers, & it is not unusual to see the term smart charger used to just mean multi stage charger. All should when fully charged drop into float mode, generally providing a constant voltage between 13.3v & 13.8v (with a 12v charger) with little to no current

Most will have a voltage threshold below which the charger will switch back into bulk charging mode. Some will drop back into float mode when a voltage threshold is reached. Some will just remain in bulk charging mode for a set period of time. This runs a risk of overcharging.

The 7 amp ctek I had automatically changed from float to bulk every 10 days regardless of battery voltage. This would have been ok if the battery capacity had matched the charger, but as the charger was too small somehow the charger always thought that the batteries needed charge & if left in float mode would have overcharged them. Essentially the charger was ’too smart’.

If the ctek was left connected to my batteries when the vehicle was outside the solar regulator would periodically show a high voltage disconnect error, whilst still logging the battery voltage from the ctek. On occasions this would rise to as much as 16.1v leading to concern about the possibility of thermal runaway & even fire. This was a result of mismatched charger to battery capacity. I can’t recall more specific details, but had correspondence with Ctek at the time & am confident the charger was not faulty. They suggested I test it on just one of the 150ah batteries (instead of the two of them together) & there was no problem. Together 300Ah was a different story. I had expected that a smaller charger would just take longer to charge them, but there is clearly more to it than that.

[nissannewby]

How do you do that?

Buy a ute...

[lhurley]

Snip.... I had expected that a smaller charger would just take longer to charge them, but there is clearly more to it than that.

With my mains charger this is the case. It's a 4amp one can't remember the brand (procharge I think) and it will just keep chugging away until full. It will time out bulk charge mode after 24 hours though. So I learnt after my first camping trip with a new deep cycle battery. The charger also will sit in float indefinitely to maintain charge of a battery. Can find specific model if required.

[Cuppa]

With my mains charger this is the case. It's a 4amp one can't remember the brand (procharge I think) and it will just keep chugging away until full. It will time out bulk charge mode after 24 hours though. So I learnt after my first camping trip with a new deep cycle battery. The charger also will sit in float indefinitely to maintain charge of a battery. Can find specific model if required.

Yes this is similar to how many work, (the time periods my vary) even the Ctek, except it's what the ctek does 'extra' after being in float mode for 10 days which is different.
Some will also continue to put a small current into the battery whilst in float. Depending on battery type & size, over lengthy periods of time,this can reduce battery fluid levels (wet battery), so checking now & again is wise.

[Winnie]

Thanks cuppa, for that spanner in the works. So now I'm really confused.

[the evil twin]

snip... So now I'm really confused.

Excellent, our work here is done.

Perhaps this will help make it worse.
No matter which brand you choose you are looking for a "maintenance" Charger not a "bulk/float" and even in the one brand not all are the same.

For CTEK - look for the M series (with exception of the 0.8 which have been around for yoinks)
XS 0.8 - YES for batteries up to 100 AH (manuf spec) and FWIW I use for a tad more
XS 3.6 - NO
MXS 3.8 - YES for batteries to 130 AH (manuf spec) and FWIW I use up to 200 AH when paralleled
CT 5 - NO
MXS 5.0 - YES for batteries to 160 AH (manuf spec)
etc, etc as size increases

I have maybe 20 odd CTEK 0.8 and some 3.8's in vehicles and field installations.
The field batteries are changed out no earlier than 3 years and test as "98% charge, healthy battery" on SAE testers and find their way into vehicles, boats and campers.
The vehicle batteries mainly Century and Supercharge haven't been changed out yet (nearly 3 years in service) so no hard experience.

Now... I have a MXS 7.0 as my 'home' smart Charger as my 'go to' for reco and bulk/float charging.
I still prefer the 3.8 for maint of the Ute even tho the spec is 225 AH for the 7.0
It is just a gut feel but it seems to do a better job, maybe because the Ute battery capacity is a parallel sum or whatever I don't know.
I only use the 7.0 on my camper which has over 300 AH parallel capacity (3 x 100 and the Brake System battery)

Solar - works well but relies on the battery chemistry and the best combo is large battery small panel and no reg.

[Winnie]

And this mxs3. 8 should be okay to leave plugged in for extended periods of time?

[the evil twin]

And this mxs3. 8 should be okay to leave plugged in for extended periods of time?

The first CTEK I commissioned was well over 5 years ago (XS 0.8).
Been running 24/7 ever since, still has the original batteries in it (twin 28 AH sealed)
Specifically MXS 3.8, maybe 3-4 years ago
Have yet to see one crap itself

[bazzaboy]

As others have said, what about a small solar panel? I have two small panels, I think their about 7-8 amps each. One panel is connected to my wife's car, which only gets used about once a week, and the other is on my patrol connected to the start battery. Works perfectly and ensures that both vehicles will start when needed. If the patrol is needed for a trip, I stick my 40amp smart charger on the start & second batteries to get them fully charged before heading off.
IMO doing it this way will ensure maximum battery life expectancy.

[dom14]

Hi Dom,
I was pretty sure someone would post what you have in reply to what I wrote. It is what I would have expected too, but my experience suggests different.

I have learned over the years that there are smart chargers & smart chargers! Not all work the same. ’Smart’ can mean different things.

All smart chargers will be multi stage chargers, & it is not unusual to see the term smart charger used to just mean multi stage charger. All should when fully charged drop into float mode, generally providing a constant voltage between 13.3v & 13.8v (with a 12v charger) with little to no current

Most will have a voltage threshold below which the charger will switch back into bulk charging mode. Some will drop back into float mode when a voltage threshold is reached. Some will just remain in bulk charging mode for a set period of time. This runs a risk of overcharging.

The 7 amp ctek I had automatically changed from float to bulk every 10 days regardless of battery voltage. This would have been ok if the battery capacity had matched the charger, but as the charger was too small somehow the charger always thought that the batteries needed charge & if left in float mode would have overcharged them. Essentially the charger was ’too smart’.

If the ctek was left connected to my batteries when the vehicle was outside the solar regulator would periodically show a high voltage disconnect error, whilst still logging the battery voltage from the ctek. On occasions this would rise to as much as 16.1v leading to concern about the possibility of thermal runaway & even fire. This was a result of mismatched charger to battery capacity. I can’t recall more specific details, but had correspondence with Ctek at the time & am confident the charger was not faulty. They suggested I test it on just one of the 150ah batteries (instead of the two of them together) & there was no problem. Together 300Ah was a different story. I had expected that a smaller charger would just take longer to charge them, but there is clearly more to it than that.

Hi Cuppa,
Yeah, I agree. Makers of smart chargers can muck around with the meaning of "smart charging".
Yeah, I meant it as a multi-stage charger, preferably controlled by a microprocessor, otherwise it wouldn't be that much of a smart charging.
Ideally, smart charger should take the battery voltage into account and adjust it's output accordingly.
It's suppose to do that at the time you connect the charger to the battery.
If the smart charger doesn't do that and relies on an internal timer to dictate the bulk, adsorption and float charge stages, then it can't be that smart.
Let's say you have a battery that is 98% charged. And you connect your "smart charger" and it immediately charges that battery on bulk stage. And that can't be good and bound to end up overcharging the battery.

The idea of "smart charging" is that it has to be smarter than alternator regulator.
Alternator never overcharges a battery, 'cos the regulator does the job of taking the input from the battery voltage and
adjusts the output voltage(or amps) of the alternator.
The only thing alternator does not have is the so called "smart charging" capacity to charge a battery to 100%, 'cos the smart charging process break down the charging process to stages to suit the battery chemistry, which is an average alternator(unless it's a smart alternator controlled by a dedicated microprocessor or the ECU) can't do.

So the microprocessor in the smart charger must take the battery voltage into account and adjust it's float charge accordingly, effectively preventing the battery from overcharging.
If the so called smart charger can't do that and solely rely on an internal timer to regulate the stages of smart charging, then IMO, if I'm correct, it's no smart charger at all. On the contrary, as in your case it can end up cooking the battery.

If you can't leave your smart charger plugged into the battery all the time and it kills the battery by overcharging it(regardless of batter AH rating), then I think it's a good idea to be really careful about leaving them plugged in all the time.
Even though I agree with "smart charging process" in principle, I'm still suspicious of the smart chargers that they might end up cooking the battery. Hence the reason I don't leave my three stage smart charger(20A) connected to the battery for too long(definitely won't leave it plugged indefinitely).

So, if your 7amp Ctek smart charger switches to bulk stage every ten days(regardless of the battery SOC), then IMO it's not a smart charger and should be careful with using it as a full time plugged in smart charger.

I'm not that all aware of the different Ctek chargers(with different amp setting) for different AH batteries.
I thought, the charger should ideally adjust the charging process to different AH rating batteries.

I also have trouble with the idea of smart charging with 3.xx A rating smart chargers.
My smart charger is rated 20A, which means at bulk(or boost) stage it can allow 20A maximum current.
A smart charger with 1 - 3A maximum during bulk stage, doesn't look all that bulk( or boost) to me.
In other words, it may be missing the boost stage of smart charging altogether.

[Winnie]

Update... so in the end I got the CTEK MXS3.8
When I plugged it in the other day, it jumped straight to charging stage 3 and pulled the Redarc in not long after that so both batteries are charging and I'm happy with that.

[dom14]

Update... so in the end I got the CTEK MXS3.8
When I plugged it in the other day, it jumped straight to charging stage 3 and pulled the Redarc in not long after that so both batteries are charging and I'm happy with that.

Sounds like it comes with electronics to assess the battery SOC the moment you plug it and it chooses the charge state accordingly.
Microcontroler controlled smart charger, by the sound of it?