DC Voltage supply - Refrig

[Blitz]

MaineSail and others;

Over the past many years I've abused my house batteries and reserve batteries by always having my old Raritan charger powered on all the time at the dock. It was on most of the time to keep the batteries topped off but also to keep the refrigerator on and cold - as many people do.

As my previous questions and posts have noted, I recently changed out all of my primary wiring, installed a Battery Monitor, installed a new Victron Centaur 12/30 battery charger, have a Blue Seas ACR, and have two banks of batteries. My charger is wired to a fused buss for the house bank only, while the ACR takes care of charging the reserve battery.

Now that I'm looking for new batteries, I'm hoping not to abuse them as much with the charger but was thinking and am asking would it be acceptable to turn the batteries off by disconnecting the ACR and installing a separate on/off switch on the positive lead to the house batteries? This would allow the charger to work as a power supply to the DC panel and the refrigerator. I thought I read somewhere that MaineSail does this to allow lighting to work without power going through the battery bank.

I would of course to be sure that the bilge is always powered through the house bank even when the positive lead is switched off.

Any thoughts, clarifications or cautions?

 

[Don S/V ILLusion]

I've seen and read about people doing this as well. Anecdotal stories always seem to follow about people doing just the opposite (running the charger/batteries constantly i.e., 24/7) with no observable negative effect. For those who do manage their 12v systems separately as the OP describes, -

how do you KNOW it helps battery health, longevity, etc... any quantitative or empirical data to prove one method is preferable?

 

[Maine Sail]

MaineSail and others;

Over the past many years I've abused my house batteries and reserve batteries by always having my old Raritan charger powered on all the time at the dock. It was on most of the time to keep the batteries topped off but also to keep the refrigerator on and cold - as many people do.

As my previous questions and posts have noted, I recently changed out all of my primary wiring, installed a Battery Monitor, installed a new Victron Centaur 12/30 battery charger, have a Blue Seas ACR, and have two banks of batteries. My charger is wired to a fused buss for the house bank only, while the ACR takes care of charging the reserve battery.

Now that I'm looking for new batteries, I'm hoping not to abuse them as much with the charger but was thinking and am asking would it be acceptable to turn the batteries off by disconnecting the ACR and installing a separate on/off switch on the positive lead to the house batteries? This would allow the charger to work as a power supply to the DC panel and the refrigerator. I thought I read somewhere that MaineSail does this to allow lighting to work without power going through the battery bank.

I would of course to be sure that the bilge is always powered through the house bank even when the positive lead is switched off.

Any thoughts, clarifications or cautions?

I would generally not recommend that with a charger but Victron could confirm better.

Using the charger as a power supply can be fine with SOME chargers for small non-motor loads but the in-rush, start up loads of a compressor and the potential for voltage transients can wreak havoc with a charger as a power supply and a fridge compressor. They often can't react fast enough and the compressor sees some VD. They also do not filter transients from a high load device shutting down or a field collapse well. Batteries in the circuit filter & smooth this out and provide for the instantaneous in-rush the compressor desires.

With the batteries kept in the loop they filter transients and can supply the current needed for the instantaneous start up loads and the compressor starts better. The same can happen with generators and this is why they often sell large start up capacitors. Most chargers do not have capacitors inside that can handle this as well as a purpose built power supply specifically designed for motor use.

A dedicated power supply designed for use with motors will have good control of over shoot and undershoot voltages. Many battery chargers that can be used as a "power pack" don't and thus can damage equipment or the charger. Their primary use is as a battery charger then a power pack, if they can do "power only" supply at all.

You can take the ACR off line with a simple on off switch in the neg lead...

That said you simply can not compare the life you got with your old charger to a newer charger like the Victron. It's like comparing a Yugo to a Lexus.

 

[Bill Roosa]

As a general rule there is a special mode you have to put the charger in to make this happen. If the charger sees no load (0 volts) it thinks the bank is dead and tries to bulk charge it. so you would also have to switch modes when you isolated the batteries.
I've left my charger on for years and have not seen any ill effects. I would note that emergency lighting systems and uninteruptable power supplies do the same and some of them operate for years on standby with no ill effects.
Why do you think leaving the charger on for extended periods huts the batteries?

 

[Steve Dion]

I have had 2 boats that both had Xantrex chargers. I have had Gel batteries on both of these boats and they also had refrigeration units.

I received 10.5 years of un-interupted service on my first set of batteries on the first boat and going into my 6th year on this set of batteries on the current boat. The only time the charger is turned off is when I leave the dock.

Battery Charging & Refrigeration running 24 x 7.

Now while I don't have any evidence that this is better or worse for the batteries, I think it works for me. The batteries are not left to sit and discharge.

 

[Maine Sail]

I have had 2 boats that both had Xantrex chargers. I have had Gel batteries on both of these boats and they also had refrigeration units.

I received 10.5 years of un-interupted service on my first set of batteries on the first boat and going into my 6th year on this set of batteries on the current boat. The only time the charger is turned off is when I leave the dock.

Battery Charging & Refrigeration running 24 x 7.

Now while I don't have any evidence that this is better or worse for the batteries, I think it works for me. The batteries are not left to sit and discharge.

But properly cared for GEL batteries are some of the longest lasting batteries you can buy. 10.5 years on GELS is not out of the question. I have one customer with a 13 year old bank... You rarely see that in wets unless they are Rolls/Surette and I don't think you ever see that with AGM.


Personally I am not a huge fan of 24/7 charging as I see too many failures of chargers which can then take out the bank when they do fail. Dock power is anything but reliable and because of this, and other reasons, I still see lots of well made chargers fail...

In a "perfect world" there should be no issue with 24/7, IF, you have a good charger and a good source of power.. The Victron is an excellent charger.

Most of today's "marine" chargers, made by reputable manufacturers, are far different and far kinder to batteries than the chargers of 20 years ago. They can be left on without issue or until the charger craps....

That said taking out a fridge compressor will likely be more costly than an inexpensive bank of wets in the event the charger were to fail, in a battery killing mode.

 

[Blitz]

So basically it is done in practice (like many things) but not recommended even for an Excellent charger like a Victron.

Then, is using the charger as a power supply for lighting in the winter or at the dock is ok? As long as it's not motors like compressors or fans?

 

[cephius (Dave)]

DC Power Supply added

I had the same issues with a much smaller battery bank.

Here is my solution:
http://forums.hunter.sailboatowners.com/showthread.php?t=121841&#post742606

 

[Blitz]

A dedicated power supply designed for use with motors will have good control of over shoot and undershoot voltages. Many battery chargers that can be used as a "power pack" don't and thus can damage equipment or the charger. Their primary use is as a battery charger then a power pack, if they can do "power only" supply at all.

That said you simply can not compare the life you got with your old charger to a newer charger like the Victron. It's like comparing a Yugo to a Lexus.

MaineSail - thanks for moving the thread.

So, I guess most boats don't have power supplies at the dock to run their DC power refrigerators and are in essence killing their batteries some by constantly being on a charger. Is the only solution an AC/DC refrig? or do you recommend a DC power supply you've seen used safely?

 

[Maine Sail]

MaineSail - thanks for moving the thread.

So, I guess most boats don't have power supplies at the dock to run their DC power refrigerators and are in essence killing their batteries some by constantly being on a charger. Is the only solution an AC/DC refrig? or do you recommend a DC power supply you've seen used safely?

Blitz,

They are only killing their batteries IF they have a poor quality charger, whihc many still do. A good charger like the Victron should not damage your bank. Battery chargers have come a LONG way in recent years. Most boats do not have a dedicated 12V power supply for the fridge...

 

[Ron20324]

My Xantrex has a switchable option to go into a mode that provides a constant 13.5 volts. There have been threads here in which a suitable power supply uses shore AC, but putting out the DC to run the fridge at the dock- and not using the batteries.

 

[gettinthere]

Don't forget the value of the battery bank as back up to shore power for power outages. Nothing like coming to the boat & finding rotten food in the frig!

 

[Blitz]

I got some answers from Victron which basically agrees with the forum:

MaineSail and others;

Over the past many years I've abused my house batteries and reserve batteries by always having my old Raritan charger powered on all the time at the dock. It was on most of the time to keep the batteries topped off but also to keep the refrigerator on and cold - as many people do.

As my previous questions and posts have noted, I recently changed out all of my primary wiring, installed a Battery Monitor, installed a new Victron Centaur 12/30 battery charger, have a Blue Seas ACR, and have two banks of batteries. My charger is wired to a fused buss for the house bank only, while the ACR takes care of charging the reserve battery.

"Yes that's possible but not needed, the charger goes into float after the battery has been charged and thats the same as acting as power supply, the battery will not be boiled then"

Now that I'm looking for new batteries, I'm hoping not to abuse them as much with the charger but was thinking and am asking would it be acceptable to turn the batteries off by disconnecting the ACR and installing a separate on/off switch on the positive lead to the house batteries? This would allow the charger to work as a power supply to the DC panel and the refrigerator. I thought I read somewhere that MaineSail does this to allow lighting to work without power going through the battery bank.

I would of course to be sure that the bilge is always powered through the house bank even when the positive lead is switched off.

" yes it can but only when there is still a battery connected to one of its outputs to give it a reference on voltage , so switching all battery's of is not a good idea "

 

[Maine Sail]

I got some answers from Victron which basically agrees with the forum:




"Yes that's possible but not needed, the charger goes into float after the battery has been charged and thats the same as acting as power supply, the battery will not be boiled then"



" yes it can but only when there is still a battery connected to one of its outputs to give it a reference on voltage , so switching all battery's of is not a good idea "

Interesting that the Victron Centaur needs a reference voltage to work as a power supply? I have a customer with a different one, Phoenix maybe, that worked fine without batteries but I only used it to power the lights...