Charging Multiple Battery Banks

[nmit5903]

What about the solar charging Andina - solar bank charges the house bank via a Steca regulator. No danger that with a combiner the starter battery will overcharge? Presumably the solar regular will detect the combined house bank and starter bank either needs charging or is fully charged.

You refer to your brand. Which is your brand and where is it available in Sydney please.

[nmit5903]

There are also some articles on other forums about the risk of excessive cycling with combiners:

"The primary functions of battery combiners, which include voltage sensitive relays and automatic charging relays (ACR), are:
Combine battery banks so that they can share the output of a single charging source such as an alternator or shore-power charger
Automatically isolate battery banks to prevent discharging of the Start battery bank
In some applications, as soon as a battery combiner closes to combine battery banks, it may immediately reopen because the load demand put on the charging source exceeds its output. This combining (closing) and isolating (opening) process may repeat over and over—it will cycle repetitively. When this cycling happens, the secondary battery bank may not receive a charge and can become discharged."

[Andina Marie]

Originally Posted by nmit5903

What about the solar charging Andina - solar bank charges the house bank via a Steca regulator. No danger that with a combiner the starter battery will overcharge? Presumably the solar regular will detect the combined house bank and starter bank either needs charging or is fully charged.

You refer to your brand. Which is your brand and where is it available in Sydney please.

Yes each charging source is responsible for its regulation of the charging voltage. It is a quite common misunderstanding that if you connect two batteries in parallel the charging current will be split 50/50 to each battery so if one is smaller or has more charge it will be over charged. That is wrong, each battery only consumes charging current in proportion to what it needs so a smaller battery or a charged battery will be drawing very little current with the bulk going to the battery that needs it.

Think of a 1000 gallon tank and a 50 gallon tank of the same height connected in parallel by a small pipe at the bottom. As you pour water into the big tank just a little water (current) flows to the smaller tank so the water level (voltage) remains equal.

You CANNOT overcharge one battery and not the other, they are at the SAME VOLTAGE. In order to overcharge the starting battery while solar charging the house battery, the starting battery would have to get to a higher voltage but that is impossible when the voltage is coming only from the battery on charge. If the voltage were to get up to 15 volts on the starting battery, the house battery too would have to be 15 volts or higher and that can't happen due to the regulator on the solar charger.

We (Yandina) ship to over 50 countries and frequently to Australia. At checkout you will be shown the shipping charges based on weight and destination.

[Andina Marie]

Originally Posted by nmit5903

There are also some articles on other forums about the risk of excessive cycling with combiners:

"The primary functions of battery combiners, which include voltage sensitive relays and automatic charging relays (ACR), are:
Combine battery banks so that they can share the output of a single charging source such as an alternator or shore-power charger
Automatically isolate battery banks to prevent discharging of the Start battery bank
In some applications, as soon as a battery combiner closes to combine battery banks, it may immediately reopen because the load demand put on the charging source exceeds its output. This combining (closing) and isolating (opening) process may repeat over and over—it will cycle repetitively. When this cycling happens, the secondary battery bank may not receive a charge and can become discharged."

Excessive cycling?? You are charging the battery through a Combiner100 just the same as charging through a BOTH switch. The fact that the Combiner100 turns on and off to limit the load on the alternator does NOT count as "cycling", there is no repetitive charge/discharge cycle on either battery, just on and off current flowing from the alternator to the second battery.

Our Combiners NEVER steal charge from another battery. They can't! The voltage of a fully charged battery is around 12.8 volts. If the voltage flowing from the alternator to the second battery falls below 13 volts the Combiner turns OFF, long before reaching 12.8 volts where capacity would be stolen from the battery on charge.

During cycling about 2 amp-hours are transferred to the secondary battery on each cycle. It is true on some installations that the load on the house battery is consuming power faster than the Combiner can replace it. We supply Combiner160s as original equipment on emergency vehicles that sit with the engine idling for hours with very heavy house loads. In cases like this it is a simple change to connect the alternator to the secondary battery with the large load and let the Combiner just top off the starting battery as needed.

[gspeak]

Originally Posted by nmit5903

What about the solar charging Andina - solar bank charges the house bank via a Steca regulator. No danger that with a combiner the starter battery will overcharge? Presumably the solar regular will detect the combined house bank and starter bank either needs charging or is fully charged.

You refer to your brand. Which is your brand and where is it available in Sydney please.

Unlike many others on CF, I am no expert, however, I also wanted to upgrade my charging systems. In my case (a catamaran) I have a 3 bank battery setup (2 starting batteries & a house bank). Charging is by 2 alternators, a 3 bank charger when on shore power & 327W Solar via a MPPT controller.

Initially, the only combining was done when the motors were running via 2 ignition switch triggered solenoids, which always ran very hot. Of course when on shore power the 3 bank charger looked after all the banks. However, when on solar only, the house bank was the only bank being charged. Not ideal.

After emailing Andina & sending her a diagram of what I had, she advised how I could check how it was all wired via the solenoids, & then confirmed that my plan would work fine. I purchased two combiner 160's directly from her online. Delivery to North Queensland was about a week & a half.

I basically replaced the two solenoids with the combiners. This has worked out extremely well. All banks now receive charge no matter which & how many charging sources are running, no switching, no very hot solenoids.

The batteries seem to be much happier!

Just a happy camper.

Dave
Seabreeze L380 #241

[sailinglegend]

Originally Posted by Andina Marie

.......You CANNOT overcharge one battery and not the other, they are at the SAME VOLTAGE......

I've corrected you on this point in previous posts but you don't seem to accept that a small starter battery when parallel with a large service bank can be overcharged by over gassing. The starter battery may be fully charged in 20 minutes but a large service bank may be at absorption and gassing voltage for maybe 6 hours. On long motoring trips if the engine is stopped during a lunchbreak then the service bank will go back into the absorption and gassing stage for another 6 hours until the regulator cuts back to a float voltage. When banks are combined the starter battery may be accepting no charging current, but if it sits at its gassing voltage when fully charged it will gas more violently - not good for sealed batteries.

You can get the same problem when on shorepower when the microwave or air con switches on and the shorepower charger may just reset itself and the 6 hour absorption mode will be repeated

I repeat below one of my previous postings on the problems of too high a voltage for too long:

The current to the full second bank maybe zero, but it's the voltage that is doing the harm. This is basic, sorry advanced, battery chemistry which can be found via Google. In absorption mode all the batteries are going to be at the gassing voltage. (They like to gas a little bit). The second bank could be very expensive Bowthruster batteries not a cheap starter battery. Some clever battery combiner/followers, like Balmar DuoCharge, can have a boost voltage input of say 14.6 volts - well above battery gassing, but the output voltage to the second bank can be set to 14.1 volts which is below the gassing voltage. This setting can automatically be reduced further by a battery temperature sensor. Balmar's regulators are even more clever. For AGMs they set the Boost voltage to 14.38, hold that for a while and then reduce it below the gassing voltage to 14.18, for the duration of the absorption stage. They then drop to an even lower Float Voltage. Why do they do this? To stop the batteries gassing too much.

I've just quizzed Balmar on these gassing issues and had some very helpful feedback which confirms exactly what I have said above. They also gave me the following feedback:

"The ability to reduce the charging voltage to the standard flooded battery by half a volt has resulted in far fewer failures on the starting battery side as a result. I've heard that from the folks at Hinckley and Island Packet in regard to substantial reductions in warranty claims for starting batteries after they began to install Duo Charges instead of battery isolators in the early to mid 2000's." - BALMAR

I understand your Combiners do have, as you call it, a "Clever" voltage limit feature which you can turn on and limit the voltage transferred to 14.2. Not so clever because it doesn't LIMIT as you suggest, but appears to disconnect, so the second battery stops charging when 14.2 volts is reached. This means it will never charge properly. You say you do this to limit over-voltage on GEL batteries - which you also wrongly call AGM batteries.

I'm afraid your writings are fully of errors and bad engineering ideas.

[Stu Jackson]

legend, you might want to reconsider, and avoid those nasty comments.

Overcharging with Combiners or ACRs The MYTH:
Overcharging Batteries with a Combiner or ACR

Most folks completely miss the point that combiners ONLY combine WHEN THERE IS A CHARGE SOURCE present. They also fail to understand battery acceptance.

Our combiner has worked flawlessly since 1998. I have NOT boiled out my reserve bank.

Please, be nice.

[Maine Sail]

Originally Posted by sailinglegend

I've corrected you on this point in previous posts but you don't seem to accept that a small starter battery when parallel with a large service bank can be overcharged by over gassing. The starter battery may be fully charged in 20 minutes but a large service bank may be at absorption and gassing voltage for maybe 6 hours. On long motoring trips if the engine is stopped during a lunchbreak then the service bank will go back into the absorption and gassing stage for another 6 hours until the regulator cuts back to a float voltage. When banks are combined the starter battery may be accepting no charging current, but if it sits at its gassing voltage when fully charged it will gas more violently - not good for sealed batteries.

You can get the same problem when on shorepower when the microwave or air con switches on and the shorepower charger may just reset itself and the 6 hour absorption mode will be repeated

I repeat below one of my previous postings on the problems of too high a voltage for too long:

The current to the full second bank maybe zero, but it's the voltage that is doing the harm. This is basic, sorry advanced, battery chemistry which can be found via Google. In absorption mode all the batteries are going to be at the gassing voltage. (They like to gas a little bit). The second bank could be very expensive Bowthruster batteries not a cheap starter battery. Some clever battery combiner/followers, like Balmar DuoCharge, can have a boost voltage input of say 14.6 volts - well above battery gassing, but the output voltage to the second bank can be set to 14.1 volts which is below the gassing voltage. This setting can automatically be reduced further by a battery temperature sensor. Balmar's regulators are even more clever. For AGMs they set the Boost voltage to 14.38, hold that for a while and then reduce it below the gassing voltage to 14.18, for the duration of the absorption stage. They then drop to an even lower Float Voltage. Why do they do this? To stop the batteries gassing too much.

I've just quizzed Balmar on these gassing issues and had some very helpful feedback which confirms exactly what I have said above. They also gave me the following feedback:

"The ability to reduce the charging voltage to the standard flooded battery by half a volt has resulted in far fewer failures on the starting battery side as a result. I've heard that from the folks at Hinckley and Island Packet in regard to substantial reductions in warranty claims for starting batteries after they began to install Duo Charges instead of battery isolators in the early to mid 2000's." - BALMAR

I understand your Combiners do have, as you call it, a "Clever" voltage limit feature which you can turn on and limit the voltage transferred to 14.2. Not so clever because it doesn't LIMIT as you suggest, but appears to disconnect, so the second battery stops charging when 14.2 volts is reached. This means it will never charge properly. You say you do this to limit over-voltage on GEL batteries - which you also wrongly call AGM batteries.

I'm afraid your writings are fully of errors and bad engineering ideas.

Here is a real world example of an actual Yandina Combiner. Our boat, previously owned by my friends parents, spent 5 years on a 24/7 world cruise (98% of the time on the hook). Because of engine driven refrigeration and lack of wind, cruisers do often have to motor, the engine run time over that 5 years was 2800 hours!!

The owner, an EE, never converted to external regulation, did not believe in it. The alt was set for 14.4V. The only real modifications to the charging system were that the alt was fed direct to the house bank and the Yandina combiner was added. It also had a solar panel with a controller set for 14.4V. This means the start battery was combined for charging with a dumb regulator set at 14.4V for at least 2800 hours but when you add solar combining I can't even begin to guess but thousands and thousands more hours spent combined over that 5 years..

When we bought the boat the batteries were 6 years old. The start battery tested far better than the house bank (conductance testers). All that had been done is to keep the water topped up.

This represents approx 28 years of charging at "coastal cruiser" engine hours of approx 100 hours per year. We retired the house bank but the FLA start battery went on to start my brothers power boat for another 4 years, 450 HP worth of outboards... I had no reason, at that point, after six straight years and thousands of hours of combined charging to get rid of it because it was still perfectly fine...

I have yet to see a single situation where an ACR/VSR caused an early demise of a start battery, especially one in warranty. I will have to talk with Rick or Dale about that comment.. I do find it rather interesting and contrary to what I see out here daily..

I even have boats where the Bulk 1 is set well above 14.6V. Of course I actually use expensive testers to confirm what I see or don't see. I simply do not see overcharging of start batteries by using either BOTH or a combiner and I have a large n=XXX to pull data from.. I also do not see it with Echo Chargers or Duo Chargers..

We can't forget that automobiles use the same battery technology we use and run around year after year after year for thousands and thousands of hours at 14.2V - 14.6V. Our two cars are set for 14.4V & 14.5V. My wifes car has 160k on the factory installed 2005 FLA battery. It is still going despite being "over charged" for 160K miles.

Theories are good but I work, test and measure batteries on actual boats and have yet to see a single case of overcharging that I can even begin to hint at being caused by a combiner.. In most instances the start batteries almost always outlive the house banks despite often being of cheaper construction.

Our recently retired start battery (7 years) was retired when we converted to LiFePO4. It is still testing at better than new spec on Midtronics and Argus analyzers. Compared to new (actual baseline) it comes in at 96%. It was combined via solar for 7 years and a dumb regulated alt for 6 of the 7 years and then a smart reg pushed to 14.7V in absorption for the last year... The house bank is testing in the 92% - 93% range..

For 7 years I did little other than use my battery switch as an on/off switch and let a combiner do the rest batteries are about as perfect as one could expect including the start battery.....

By far the biggest concern we have on sail boats is chronic under charging. Over charging, in my experience, is very, very rare.

When I see it it is usually with an unregulated solar panel, failed battery charger, failed regulator or old single stage ferro charger left on at absorption for months and months at a time and the electrolyte never checked..

I just recently worked on a 41 footer with installed Gel batteries and a combiner (optional equipment package). It also had a properly set up voltage regulator for the gel batteries. Both the start gel and gel house bank are now 11 years old.... Pretty hard to blame the combiner for much of anything at 11 years old....

I have piles of cases I can point to with similar results. One customer who just did the great loop (power cat) with twin Volvo diesels with dumb regulated alts and a Blue Sea ACR.. Don't know how many thousands of hours on those engines but it is a power boat. Batts are still going strong....

BTW the Balmar Duo charger does NOT do float independent of the charge source, as you implied it does. It is a simple voltage follower with some programmable voltage parameters such as the "ON" voltage and the second banks voltage limit...

[transmitterdan]

Originally Posted by sailinglegend

I'm afraid your writings are fully of errors and bad engineering ideas.

Legend,

That last statement is not fair or accurate in my opinion. I have not read all of the posts by the manufacturer but as an EE I can say what I have read is not "fully of errors and bad engineering ideas".

There are very few reports of batteries being killed by overcharging. There are simple steps that one can take to prevent it. Don't buy a charger that sits blindly for 6 hours at absorption. Don't mix wildly different battery types in a system. Pay attention to the charger voltage to be sure it isn't too high for too long. The last one is what killed some batteries for me. I had a Xantrex multi-bank charger decide to equalize all my batteries while I was away for a few days. I have never heard of the typical VSR style combiner damaging batteries. If your main charger is smart and programmed for the bank battery type it is highly unlikely to overcharge any battery in the system. If you fear this put the charger's temperature sensor on the smallest battery.

I am sure it is possible for someone to contrive a battery bank that is nearly impossible to charge correctly. But we should not disparage a proven device or quality supplier on the basis of outlier cases. We should be glad there are some manufacturers willing and able to produce a high quality component that helps cruisers in the real world. There are numerous examples of poor quality components and suppliers in this market. Let's make it easier for the good ones to succeed and also easier for the bad ones to disappear.

[Maine Sail]

Originally Posted by Maine Sail

BTW the Balmar Duo charger does NOT do float independent of the charge source, as you implied it does. It is a simple voltage follower with some programmable voltage parameters such as the "ON" voltage and the second banks voltage limit...

Quoting myself here.

Sorry to SL but I missed the part where it was said "Balmar's regulators". It was all in the same paragraph with discussion about the Duo and I read too fast. What I said above is accurate but not based on what I quoted and thought I read. SL did not imply the Duo did independent float and was referring to Balmar regulators not the Duo...

But just to reiterate the Duo Charger is simply a voltage follower with adjustable max output voltage and adjustable turn on voltage set points. It will not do float independent of the charge source. The literature is misleading on this and thus why I bring this up...

[sailinglegend]

Originally Posted by Maine Sail

......All that had been done is to keep the water topped up.......

I'm very sorry this subject causes so much emotion - but I did specifically say that gassing is not good for sealed batteries,. Your example was for FLAs.

I do not retract any of what I have said -batteries do gas - that is why multi-stage chargers drop down to a float voltage below the gassing voltage. If you have a sealed starter or bowthruster then there is a chance that it can be over-gassed. This is fact.

Car alternators are designed to supply power to the cars electrical system and not charge a heavily depleted service bank. They may be set to 14.4 volts but was that voltage monitored all the time. The chance is that most of the time it never achieved 14.4 volts. Some have temperature compensators that cut the voltage down to below the gassing voltage - that is why cars and trucks can run all day without problems. You can't compare starter batteries in car with batteries on boats.

Originally Posted by Maine Sail

...BTW the Balmar Duo charger does NOT do float independent of the charge source, as you implied it does. It is a simple voltage follower with some programmable voltage parameters such as the "ON" voltage and the second banks voltage limit...

Thanks for correcting yourself on that one. As you say it is a smart voltage follower - it will also allow you to set a float voltage of your choosing. This is very confusing and does suggest it is a multi-stage regulator. Balmar say they are looking at producing just such a beast.

Originally Posted by transmitterdan

.....Don't buy a charger that sits blindly for 6 hours at absorption......

You should buy a charger (shorepower or alternator regulator) that you can programme to suit your size and type of battery bank. I choose to set mine to 6 hours because I have a 1000Ah service bank and a 27 Ah Red Flash Starter battery.

Originally Posted by Stu Jackson

....Overcharging with Combiners or ACRs The MYTH:
Overcharging Batteries with a Combiner or ACR.

You keep posting links to c34's site that I can't log on too - I have tried repeatedly and failed.

[nmit5903]

.......the weight of argument seems to be coming down in favour of a combiner though there are arguments against - with which others disagree based on the actual incidence of failure of starter batteries. Is that a fair summation?

[sailinglegend]

Originally Posted by nmit5903

.......the weight of argument seems to be coming down in favour of a combiner though there are arguments against - with which others disagree based on the actual incidence of failure of starter batteries. Is that a fair summation?

May I add a few more comments.

I have no problem with combiners for Flooded Lead Acid, but Sealed batteries can suffer with over gassing and in most cases lost water cannot be replaced. Some batteries like my Lifeline AGMs have very low water loss because over 99% of any gas is recombined.

In a short thread like this there are not enough for and against arguments - check out Google for some long academic papers on the problems of gassing. My point is that ANY procedure that could quicken the death of our batteries then be avoided. As Maine Sail says "batteries don't die they get murdered". I respect everything that he says on these Forums - but we disagree on this subject. He may not see on a daily basis "evidence" of combiners causing excess gassing, but I suspect he doesn't cut open each battery to see the cause of failure. Balmar have said they perceive a need for a better "combiner" and may produce a multi-stage battery to battery charger, but they are worried that the customer may not be prepared to pay the high price. Starter batteries are cheap so most people are not worried or prepared to pay for an EchoCharge or a DuoCharge, but an expensive AGM bowthruster bank could justify an expensive Balmar piece of kit that does the job with no potential gassing problems.

I have a BEP VSR which has a three-way switch: OFF-Automatic-ON. If I'm leaving a marina for a long motor I can turn the combiner off - I believe the Yandina will also do that with an additional remote switch. This means you have to remember to turn it back on!!! So my KISS solution is to have a small 5 watt solar panel connected only to the starter battery. In the Med this keeps the starter battery fully charged - but never overcharged.

I also have a three-way alternator regulator switch. This goes from Balmar external regulator - OFF - Balmar internal regulator. The internal regulator is set for 14v but seldom gets above 13.8v. Great to use when motoring and I know the batteries are 100% charged.

[transmitterdan]

Originally Posted by sailinglegend

I'm very sorry this subject causes so much emotion - but I did specifically say that gassing is not good for sealed batteries,. Your example was for FLAs.

I do not retract any of what I have said -batteries do gas - that is why multi-stage chargers drop down to a float voltage below the gassing voltage. If you have a sealed starter or bowthruster then there is a chance that it can be over-gassed. This is fact.

Car alternators are designed to supply power to the cars electrical system and not charge a heavily depleted service bank. They may be set to 14.4 volts but was that voltage monitored all the time. The chance is that most of the time it never achieved 14.4 volts. Some have temperature compensators that cut the voltage down to below the gassing voltage - that is why cars and trucks can run all day without problems. You can't compare starter batteries in car with batteries on boats.

Thanks for correcting yourself on that one. As you say it is a smart voltage follower - it will also allow you to set a float voltage of your choosing. This is very confusing and does suggest it is a multi-stage regulator. Balmar say they are looking at producing just such a beast.

You should buy a charger (shorepower or alternator regulator) that you can programme to suit your size and type of battery bank. I choose to set mine to 6 hours because I have a 1000Ah service bank and a 27 Ah Red Flash Starter battery.

You keep posting links to c34's site that I can't log on too - I have tried repeatedly and failed.

I am not emotional and apologize if it appeared so. Engineering analysis will tell us what we need to know. If gassing during absorption is a concern because the charger is too small to complete that phase in a reasonable time then the obvious solution is to get a properly sized charger. Absorption can be completed in 1-2 hours with the right charger.

I don't know what a Red Flash battery is but if all the batteries are the same style such as VRLA and the charger is sized correctly then gassing will not be an issue. If gassing in the small battery is a concern then the same concern exists for the big bank. After all the big bank is just a bunch of parallel small batteries in big boxes. That issue exists whether or not there is a combiner.

The link worked for me.

[Maine Sail]

We need to remember that the vast majority of multiple bank chargers are doing the SAME exact thing. All banks get absorption voltage for the same amount of time. True "multi-bank" chargers are very, very expensive and rather rare. The vast majority of multi-bank chargers are not really multi-bank at all just multi-output / single voltage program chargers. This is no different than what a combiner does you have one charging source and multiple banks charged off that single source.... When the charger comes up to absorption voltage both banks get the same voltage for the same duration. Hundreds and hundreds of thousands of chargers out there like this.

I have plenty of AGM and GEL banks with combiners and I just went through every case I could think of where I have replaced banks.

It is almost always the house bank that fails first not the "over charged" starting battery. I have 2k worth of Lifeline AGM's sitting in my shop right now ready to be returned for core. The starter battery, a Lifeline too, is still going strong and was not replaced. It is charged via a combiner... The house bank wore out due to cycling yet the start battery is still testing just fine despite it being the one getting "over charged"..

BTW Sears sells the Die Hard Platinum. It is nothing more than an Odyssey AGM battery with the Die Hard name and case color.. It gets Sears longest warranty despite being placed into cars & trucks that can run at "gassing voltages" all day long...

4 Year Free Replacement and 100 Month Pro-Rated Warranty

Die Hard Platinum

Again the theory of over charging with a combiner sounds good but I just don't see it in the real world. I don't just work on wet cell batteries either.

With a proper charging algorithm both banks get the same "gassing" voltages for the same amount of time.