Ctek or Sterling?

[Colvic Watson]

We spend about 70 nights on board a year and have the charger running the whole time we are on board and connected to shorepower. I want to fit a 20 to 25 amp battery charger but was worried that having it running 24/7 like that will keep the batteries at a constant 14.4v as there is always a current draw. I saw that the Sterling Pro charge has a power pack function, does that mean it stops charging, rests the batteries and supplies the juice itself? Does the Ctek M300 do the same? The Ctek is the same price but has 5amps more output and comes with a free trickle charger for the starter, not a big deal but useful.

Thanks for any advice.

 

[dt4134]

I've a 30A Sterling charger that came with the boat. I've also got a battery monitor so I can see what it is doing. It certainly doesn't sit at 14.4V (for a start I flicked the switches to get it to peak at 14.8V).

Anyway, when it has gone through its cycle and gets to trickle mode, or whatever it calls it, it will feed a tiny current through the batteries. If a load comes on it'll correct over about a minute or two to go back to a small trickle current, if you take that load off you'll notice an increase in the charging current that will ease off over a minute or two back to just the trickle current. So it seems to cope pretty well with charging a battery bank that is being used.

No experience of the Ctek.

 

[Deleted member 36384]

I fitted the Sterling Pro Ultra and it has performed very well: no fan noise, goes into standby mode after a period of inactivity from the batteries (i.e. after a float period). Shop around because the prices vary. I leave my boat unattended for a considerable time when away and leave it switched on. My batteries are lead acid and I would say they are in better shape now than before I had a mains charger. Also if I change the battery type I can change the charging profile. I charge two battery banks with the possibility of charging 3 from the device. I recommend it as a good battery charger.

 

[davidwf]

I had the Ctek M300 and looking at the manual when it is in float mode it will provide a max of 25 amps at 13.6V for 10 days after 10 days it starts its cycle again by testing the battery etc See http://www.ctek.nu/Archive/ProductManualPdf/M 300_EN.pdf You can contact them and ask the question directly through their contact pages as well on http://www.ctek.nu/gb/en/page/contact .

I thought it was a fantastic bit of kit and would fit one again anytime, I particularily liked the small charger for the starter battery as it kept the two batteries charging regimes totally separate.

 

[concentrik]

.

We spend about 70 nights on board a year and have the charger running the whole time we are on board and connected to shorepower. I want to fit a 20 to 25 amp battery charger but was worried that having it running 24/7 like that will keep the batteries at a constant 14.4v as there is always a current draw.

I believe you are right to have concerns. Having just gone through a similar decision making process I opted for totally seperate DC power (DCP) and battery charging systems. When shorepower is available the 3 stage charger charges the batteries and a switch mode power supply does the DCP. They have no influence upon each other and function entirely independently.

I saw that the Sterling Pro charge has a power pack function, does that mean it stops charging, rests the batteries and supplies the juice itself?

It can't do this. Unless I totally misunderstood the designer when I spoke to him the answer is no. The Sterling is 'intelligent' if the only load is a battery. If you apply a parallel load (DCP) it will 'think' it is connected to a discharged battery and act as a current-limited constant voltage source. Put simply, a parallel load makes a smart charger dumb. I am making an assumption here: that you want your DCP to be uninterrupted, not pulsed (at any frequency) or corrupted by any 'charge state sensing' malarky. Others have posted that they are completely satisfied with the way such chargers both charge the batteries and supply power. My point is that you don't need a smart charger to do this, any 14v supply with sufficient current capacity can do this.

This issue seems to have become my pet subject! I'm expecting "Concentrik will be along soon to prattle on about it again" before long. I am very open to alternative explanations of how such systems behave under these circumstances.....

Does the Ctek M300 do the same? The Ctek is the same price but has 5amps more output and comes with a free trickle charger for the starter, not a big deal but useful.

Thanks for any advice.

Unless you discharge your batteries very deeply you won't need the extra 5A. In any case it would only be useful in the first minute or so of charging I'd expect, so I'd ignore it as a 'feature comparison'.

If it's of interest, I installed a 63A changeover switch (shore/sail), a 3 stage charger and a single 30A SMPS. I may add another 30A SMPS later.

 

[sailorman]

We spend about 70 nights on board a year and have the charger running the whole time we are on board and connected to shorepower. I want to fit a 20 to 25 amp battery charger but was worried that having it running 24/7 like that will keep the batteries at a constant 14.4v as there is always a current draw. I saw that the Sterling Pro charge has a power pack function, does that mean it stops charging, rests the batteries and supplies the juice itself? Does the Ctek M300 do the same? The Ctek is the same price but has 5amps more output and comes with a free trickle charger for the starter, not a big deal but useful.

Thanks for any advice.

Simon if you see "Little Stewie" (while escort van) about the yard ask him what he doesnt know isnt worth knowing. he is ex foxs electronics & now freelance.
if you contact "Wingdiver" he will get his phone No for you

 

[LittleShip]

I've a 30A Sterling charger that came with the boat. I've also got a battery monitor so I can see what it is doing. It certainly doesn't sit at 14.4V (for a start I flicked the switches to get it to peak at 14.8V).

Anyway, when it has gone through its cycle and gets to trickle mode, or whatever it calls it, it will feed a tiny current through the batteries. If a load comes on it'll correct over about a minute or two to go back to a small trickle current, if you take that load off you'll notice an increase in the charging current that will ease off over a minute or two back to just the trickle current. So it seems to cope pretty well with charging a battery bank that is being used.

No experience of the Ctek.

Nice simple explanation of how the Sterling works for us that think it's all smoke and mirrors...

The Sterling can also be used for power when the Batteries are disconnected from the system.

I have had one for about 6 years I leave it on constantly and would,... like others recommend one. Like all chargers powering batteries you will need to check water in the batteries occasionally.

Tom

 

[concentrik]

Originally Posted by dt4134 View Post
I've a 30A Sterling charger that came with the boat. I've also got a battery monitor so I can see what it is doing. It certainly doesn't sit at 14.4V (for a start I flicked the switches to get it to peak at 14.8V).

Anyway, when it has gone through its cycle and gets to trickle mode, or whatever it calls it, it will feed a tiny current through the batteries.

If a load comes on it'll correct over about a minute or two to go back to a small trickle current,

How can it go back to a small trickle current when you have applied a parallel load? Remember there is only one conductor from the charger to the battery/load. If the charger decides for some reason to supply only a trickle current (which it would have to effect by reducing the output voltage) that is the only current available to share between load and batteries - unless the batteries themselves supply some current, but then doesn't that defeat the object?

if you take that load off you'll notice an increase in the charging current that will ease off over a minute or two back to just the trickle current.

So after it has eased back off to a trickle current, say 500mA, what is powering your 12W cabin light? It can only be the batteries.

I don't doubt that the sterling charger is doing something but fail to see how it can distinguish between the current demands of a discharged battery and a parallel load. Still waiting for enlightenment.....

 

[Deleted member 36384]

Concentrek, first of all I am out my depth on this subject, but I understand that the Pro series don't trickle charge. I think they just go into a standby mode for quite a while and then wake up again to perform some maintenance charge. On my charger (Pro Charge Ultra) it appears to be in standby mode for quite a while (as displayed, 0 amps) when I checked it during a day on the boat without using power. I have read that batteries don't like long term constant charging regimes. So perhaps Sterling took this into consideration when programming his Pro series. Anyway, just a thought.

 

[concentrik]

Concentrek, first of all I am out my depth on this subject, but I understand that the Pro series don't trickle charge. I think they just go into a standby mode for quite a while and then wake up again to perform some maintenance charge.

Thanks Boots; seems completely reasonable if the charger is connected only to the batteries. Goes to standby when the charge current drops below a preset level (or when the terminal voltage rises to a preset level) - waits, monitoring the terminal voltage (TV) maybe - then when TV drops due to self discharge, starts the process again. The trouble begins when you start demanding current which is not going to the battery...

On my charger (Pro Charge Ultra) it appears to be in standby mode for quite a while (as displayed, 0 amps) when I checked it during a day on the boat without using power. I have read that batteries don't like long term constant charging regimes. So perhaps Sterling took this into consideration when programming his Pro series. Anyway, just a thought.

And thank you for it....

 

[Trundlebug]

We spend about 70 nights on board a year and have the charger running the whole time we are on board and connected to shorepower. I want to fit a 20 to 25 amp battery charger but was worried that having it running 24/7 like that will keep the batteries at a constant 14.4v as there is always a current draw. I saw that the Sterling Pro charge has a power pack function, does that mean it stops charging, rests the batteries and supplies the juice itself? Does the Ctek M300 do the same? The Ctek is the same price but has 5amps more output and comes with a free trickle charger for the starter, not a big deal but useful.

Thanks for any advice.

I was in exactly the same position as you when I was looking to install a charger two years ago. Like you I whittled it down the same decision, Sterling or CTEK.

In the end, I decided they were both reputable and fairly equal on performance, although I liked the way the Sterling was a single unit rather than two, but the CTEK had higher capacity.

In the end it just came down to price, the CTEK being marginally cheaper, although there's not a lot in it really. I also watch what it's doing on my BM1.

I have found the CTEK seems to keep on float charge of 14.4v for much longer than I expected, initially for two to three weeks after installation before it cut out and went to "pulse" maintenance, where it senses the battery voltage and cuts in at around 15v for 30 secs occasionally when the voltage drops to about 12.8v.

It's never stayed on float charge as long as that since, but still remains on it for far longer than I would expect, usually about 10 days, regardless of how little current is being put in (down to 0.1A for much of the time). I thought that was a bit stupid for a charger that claims to be the "most intelligent in the world" although I don't exactly claim to be a world expert myself.

When disconnected, even for a second or two, it goes through the whole sensing cycle and then goes back on to float charge 14.3-14.8v(depending on temperature) for another 10 days even if the batteries were already fully charged and conditioned. Again, this didn't seem very intelligent to me.

Despite that, the batteries haven't needed topping up at all since I fitted the charger. To me that says it's doing its job well, and not overcharging as much as I feared.

Weekend use of the boat with lights, water pump etc do sometimes cut the charger back in to float mode, but not always. Sometimes it just continues to pulse, but more frequently to top up and replace the drain on the batteries. I haven't figured out why it sometimes does one thing and sometimes another, but I've stopped worrying about it - although it remains a curiosity. The obsessive side effect of having a BM1 !!

Overall I have no complaints with the M300. It's done some things I wouldn't have expected, but I'm sure the Sterling would perform very similarly and either way you won't be disappointed. It'll boil down to price, installation space and size in the end.

 

[Fr J Hackett]

Can't help with the Cetec or Stirling kit but used to run a Mastervolt odn a similar duty cycle to yours never had a problem with it for 10 years so my vote and reccomendation would be to look at Mastervolt, not the cheapest though.

 

[Colvic Watson]

Getting complicated! With so many days/nights on board connected to shorepower, the last thing I want is large periods of time with very high battery voltage. I had hoped it could sense the need to supply power without running at 14+ volts. What I do when away from the boat is switch the charger off to 'rest' the batteries but we have an auto bilge pump and alarm, last weekend the pump failed and ran constantly, if that had happened during the week, we'd have come back to dead batteries.

I'm not sure what to do! The 20 or so nights a year we spend on mooring buoys mean that a 25amp charger is a lot better than a 20amp because we run a genny to heat the water and charge the batteries - we are very power hungry even with all LED lights - most of the time we are using 100+ amps a day and even in "mooring mode" as we call it we use about 60 a day. Maybe I should stick with what we've got and put a 50w solar panel in but we've nowhere really shade free. If I was convinced that Sterling really were intelligent and could tell the difference between domestic current draw and a partially charged battery I'd go for it.

 

[dt4134]

How can it go back to a small trickle current when you have applied a parallel load? Remember there is only one conductor from the charger to the battery/load. If the charger decides for some reason to supply only a trickle current (which it would have to effect by reducing the output voltage) that is the only current available to share between load and batteries - unless the batteries themselves supply some current, but then doesn't that defeat the object?



So after it has eased back off to a trickle current, say 500mA, what is powering your 12W cabin light? It can only be the batteries.

I don't doubt that the sterling charger is doing something but fail to see how it can distinguish between the current demands of a discharged battery and a parallel load. Still waiting for enlightenment.....

The battery monitor measures the current going into the battery and measures the voltage at the battery. Based on that, what I described is what is happening to the battery. The charger is providing more that because it is covering whatever domestic load there is plus the charge going into the battery. It's behaved like this for even quite significant loads.

The behaviour I described means the charger is adjusting its output over a minute or two whilst it is accommodating changes in the domestic load to keep the trickle current through the battery pretty even. In fact, in that mode it'll just be reacting to a drop or increase in voltage as the domestic load comes on and off.

It's quite simple really, I suspect you are overcomplicating things.

 

[iowman]

Cetec

Over 2 years ago I installed the Cetec M300 to look after the 'house' batteries together with the small free unit on my engine start battery,

Both batteries kept fully charged with minimal current taken from the mains.

I am 100% happy. If we spend weekend just staying on our berth and use 12 volt heating plus light and 12 volt TV the chargers simply supply the 12 volts required,

Cannot speak more highly of the system together with the service and advice supplied by Barden from whom I bought the units,

 

[concentrik]

The behaviour I described means the charger is adjusting its output over a minute or two whilst it is accommodating changes in the domestic load to keep the trickle current through the battery pretty even. In fact, in that mode it'll just be reacting to a drop or increase in voltage as the domestic load comes on and off.

It's quite simple really, I suspect you are overcomplicating things.

It is simple, but not in the way you think! If the current source (charger) delivers a current through a single conductor it cannot assign differing controlled currents to two separate loads. In this sense it is dumb - it has no idea how the current it delivers is being split because it cannot see beyong its single connecting wire. All it can do is alter the supply voltage and/or current limit its output. Having done this, the current it supplies will be split between the loads (battery and domestic) according to the resistance (internal resistance in the case of the battery) of each. If the batteries are receiving a 'trickle charge' it is not because of anything intelligent the charger is doing - it's because the internal resistance of the batteries is high because they are fully or almost fully charged.

 

[LittleShip]

It is simple, but not in the way you think! If the current source (charger) delivers a current through a single conductor it cannot assign differing controlled currents to two separate loads. In this sense it is dumb - it has no idea how the current it delivers is being split because it cannot see beyong its single connecting wire. All it can do is alter the supply voltage and/or current limit its output. Having done this, the current it supplies will be split between the loads (battery and domestic) according to the resistance (internal resistance in the case of the battery) of each. If the batteries are receiving a 'trickle charge' it is not because of anything intelligent the charger is doing - it's because the internal resistance of the batteries is high because they are fully or almost fully charged.

I think you are confusing people on here.......

The way dt4134 explains how it works is the way mine works when I check it.

I only have 12 volts on LShip and when I'm at the dock and plugged in the charger maintains the battery level as needed.

As I stated the Sterling charger can be used when the batteries are removed from the vessel, it will only supply what is needed.

Thats the way it looks from here

Tom

 

[concentrik]

I think you are confusing people on here.......

Tom

I think you're right so I'll stop. People are going to believe what suits them, but that doesn't alter Kirchoffs Law.

Enough! (with a smile)

 

[Trundlebug]

Getting complicated! With so many days/nights on board connected to shorepower, the last thing I want is large periods of time with very high battery voltage. I had hoped it could sense the need to supply power without running at 14+ volts. What I do when away from the boat is switch the charger off to 'rest' the batteries but we have an auto bilge pump and alarm, last weekend the pump failed and ran constantly, if that had happened during the week, we'd have come back to dead batteries.

I'm not sure what to do! The 20 or so nights a year we spend on mooring buoys mean that a 25amp charger is a lot better than a 20amp because we run a genny to heat the water and charge the batteries - we are very power hungry even with all LED lights - most of the time we are using 100+ amps a day and even in "mooring mode" as we call it we use about 60 a day. Maybe I should stick with what we've got and put a 50w solar panel in but we've nowhere really shade free. If I was convinced that Sterling really were intelligent and could tell the difference between domestic current draw and a partially charged battery I'd go for it.

I really wouldn't worry about the batteries being on 14v for some time. It doesn't do anything any harm. As I said above, my batteries haven't needed topping up for 2 years since I fitted the CTEK charger. The charger clearly does not excessively gas the batteries, regardless of what you (or I) may fear.

 

[VicS]

We spend about 70 nights on board a year and have the charger running the whole time we are on board and connected to shorepower. I want to fit a 20 to 25 amp battery charger but was worried that having it running 24/7 like that will keep the batteries at a constant 14.4v as there is always a current draw. I saw that the Sterling Pro charge has a power pack function, does that mean it stops charging, rests the batteries and supplies the juice itself? Does the Ctek M300 do the same? The Ctek is the same price but has 5amps more output and comes with a free trickle charger for the starter, not a big deal but useful.

Thanks for any advice.

I have dredged this thread up again because I have just had a little play with my Smartcharger.

I charged the ( car) battery and then with the charger still connected and switched on I turned on a good load (headlights).
The charger went into "reconditioning" mode!

The Ctek M300 charger I believe has a recondition mode. Maybe the same will happen with that if you attempt to use it as a powerpack

AFAIK the Sterling charger does not have a recondition mode. It is in any case stated to be suitable for use as a power supply.

.