Solar charger without controller

[NewToTheRoad]

OK guys.  I followed conventional wisdom and went with the following:

Victron Energy Blue Solar Controller (100/15)
A 50W flexible panel that I will mount off the stern rail to get optimal sun.

My plan is to wire the controller directly to one of my two batteries (currently only have two).  If I leave the battery switch on "Both" with that effectively top off both batteries similar to how the alternator would?

Thanks,
  Bryan

[mark_53]

I believe it would. If your batteries are OEM wired, when you switch to both, you put them in parallel. The thing is your wiring runs to charge become rather long and you will see more voltage drop then if you wired them individually from the controller.

[Stu Jackson]

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........wire the controller directly to one of my two batteries (currently only have two).  If I leave the battery switch on "Both" with that effectively top off both batteries similar to how the alternator would?

Yes, it would.  You would also have your entire boat "live" (of course you'd turn off all branch circuit switches or breakers) while most of us turn our 1-2-B switches off.  The way we do this is to wire the alternator output to the house bank and use a VSR (combiner, echo charger, etc.) to deal with the second battery.

If you don't want to go there, yet, then perhaps you could consider charging one battery at a time, which would allow you to keep the switch off when you're not there.

Can you tell us more about how you use your two batteries?   Do you have a fridge?  Do you anchor out or marina-hop using shorepower?  Are your batteries generally close to full when you return to your slip or before you leave the boat?

If you can get one battery as close to full as possible you can alternate batteries connected to your panel.  If, however, you leave on at PSOC (Partial state of charge) its not good for the battery.

You can leave a full battery for a couple of weeks without recharging without damaging it.

Getting a used battery completely full (100%) takes a lot of time, usually overnight, but read these battery acceptance topics in Elec 101:

Battery Acceptance by Stu  http://c34.org/bbs/index.php/topic,4787.0.html

Why Going Into FLOAT is NOT Full

http://c34.org/bbs/index.php/topic,8216.0.html

[J_Sail]

My plan is to wire the controller directly to one of my two batteries (currently only have two).  If I leave the battery switch on "Both" with that effectively top off both batteries similar to how the alternator would?

  Bryan

The primary reason one has two battery banks is so that you have a spare if a problem develops. Leaving a battery switch in the BOTH position invites the inevitable error of leaving it in BOTH with a load running. The result is BOTH batteries being dead.  The proper solution is some form of automatic isolation that allows charging of both. Those include:
1. Echo Charger (either Xantrex or Sterling)
2. An ACR (aka automatic combiner) such as the BlueSea ACR's or Yandina.

The ACR acts like an automatic BOTH switch that engages only when it sees a high enough voltage to indicate that a charger is active. Some include support for remote override switches and indicators, which can be useful.

The echo charger senses that your primary battery is being charged and does a DC to DC conversion to charge your secondary battery with its own independent charge curve. It has the advantage of allowing your secondary battery to be of a different type than the primary rather than simply charging both sets in parallel. The drawback is that it has more electronics in it that can fail and it can only output limited current (15A for Xantrex Echo, anywhere from 3A for the tiniest Sterling up to 30-60A for their larger models, but that's plenty for recharging your reserve battery). The Xantrex should not be mounted inside the battery box due to corrosion concerns.

There are tons of postings on the issue of how to best isolate/combine battery systems, but the gist of all of them is that you want an approach that minimizes the chance that you will ever manually combine your batteries (i.e. get rid of the BOTH position). It is rarely beneficial and is a major source of ending up with both sets of batteries dead when you need them most.

Various links (first two are excellent quick primers by MaineSail, the third is a longer article)
http://www.sailnet.com/forums/3054617-post5.html
http://www.sailnet.com/forums/3054689-post7.html
https://forums.sailboatowners.com/index.php?threads/1-both-2-off-switches-thoughts-musings.137615/
https://forums.sailboatowners.com/index.php?threads/question-about-battery-combiner.176679/

C34 link:
http://c34.org/bbs/index.php?topic=7986.0

Echo Chargers
https://www.amazon.com/Xantrex-82-0123-01-Echo-Charge-Systems/dp/B0016G8RT8
http://www.defender.com/product3.jsp?path=-1|328|2289962|2295772&id=2086407

ACRs
Blue Sea:
   https://www.bluesea.com/products/category/35/Automatic_Charging_Relays
   https://www.bluesea.com/resources/1366
Yandina
   http://www.yandina.com/

[NewToTheRoad]

Thanks Guys.

I am assuming original, 2 battery configuration.  I just bought the boat in Sep and then it went immediately into Winter storage.  So, I don't have any practical experience.  My #1 reason for the solar is because I intend to keep it on a mooring.  There is no fridge or inverter and minimal electronics.  All interior lights are LED and I don't expect to be using running lights.  Toilet is elec.  My expected usage will be day sails and maybe some weekends.

Yes, my only reluctance was that everything is left live, but I can live with that for now.  This is somewhat of an interim solution.  After reading most of the elec mods my plan is to go to a dedicated starter and house setup before next season.  My plan was to add a dual or echo charger at that time.  I did just purchase a dual purpose Group 24 battery at West marine to keep as a on-board spare and eventually become my starter.

[NewToTheRoad]

Thanks for some great feedback J_Sail.  That is definitely the direction I need to be going.

bryan

[NewToTheRoad]

I believe it would. If your batteries are OEM wired, when you switch to both, you put them in parallel. The thing is your wiring runs to charge become rather long and you will see more voltage drop then if you wired them individually from the controller.

Mark,
  I may have misunderstood you but the controller has a single positive and negative connection to the battery.  If I were to wire them individually from the controller wouldn't that wiring essentially put the batteries in parallel and negate the 1, 2, both switch?  My understanding is that I would need a device between the controller and battery(s), such as a xantrex echo charge, to keep them both isolated but allow charging of each.
Bryan

[J_Sail]

I believe it would. If your batteries are OEM wired, when you switch to both, you put them in parallel. The thing is your wiring runs to charge become rather long and you will see more voltage drop then if you wired them individually from the controller.

Mark,
  I may have misunderstood you but the controller has a single positive and negative connection to the battery.  If I were to wire them individually from the controller wouldn't that wiring essentially put the batteries in parallel and negate the 1, 2, both switch?  My understanding is that I would need a device between the controller and battery(s), such as a xantrex echo charge, to keep them both isolated but allow charging of each.
Bryan

Yes, but with a few clarifications:
1) Yes, if you were to try to wire the controller directly to both batteries, you would  be tying them together permanently (which we all know would be bad).
2) I suspect that Mark probably meant to say the wire length needed via the 1-2-Both switch is longer than if you wired the controller directly to your house battery and used some other approach for getting the charge current to your second battery (echo or combiner).
3) Your statement that, "I would need a device between the controller and battery(s)", is just slightly off. You wire the controller directly to the house battery and then add a device (echo or ACR) from the house battery to the second battery for the charge pathway.

[Stu Jackson]

........................
........................ My plan was to add a dual or echo charger at that time.  I did just purchase a dual purpose Group 24 battery at West marine to keep as a on-board spare and eventually become my starter.

1.  Specificity helps here.  [Just a danged engineer speaking! ]  You do NOT want a dual charger, or as Balmar calls it a duo charger.  They have "issues" that have been discussed elsewhere.  If you want me to find some discussions let me know, but if I convince you to ignore it, then it's a moot point.     You want either an echo charger or a combiner.  If your house bank is larger than your reserve bank, an echo charger would work just fine.  A combiner is less expensive.  The warning about the echo charger installation manual is in the Elec Systems 101 topic, as are further discussions about the differences between the devices in addition to Jeremy's fine presentation.

2.  Please save oodles of your $$ and never buy a battery of any kind from West Marine.  They are simply re-branded batteries made by others and you're paying twice as much for the silly label.  Scout out "real" battery vendors in your area via Google, Yelp and the yellow pages, then comes back and ask us before you buy.  What you have will work as a reserve bank, but a simple auto start battery would have been a lot less.  Sorry the horse is outta the barn.    Read the link to Maine Sail's discussion about real deep cycle batteries before you buy.

Good luck, sounds like you have a plan.

[mark_53]

I believe it would. If your batteries are OEM wired, when you switch to both, you put them in parallel. The thing is your wiring runs to charge become rather long and you will see more voltage drop then if you wired them individually from the controller.

Mark,
  I may have misunderstood you but the controller has a single positive and negative connection to the battery.  If I were to wire them individually from the controller wouldn't that wiring essentially put the batteries in parallel and negate the 1, 2, both switch?

Bryan,
I was thinking there was some controller provided way of charging two separate banks.

My understanding is that I would need a device between the controller and battery(s), such as a xantrex echo charge, to keep them both isolated but allow charging of each.
Bryan

If you only can charge a single bank and you have two banks than wiring both batteries directly from the controller to each battery will not work efficiently since the controller is sensing only one voltage...but it should work.  The problem it seems with an ACR or echo charger is when you flip the 1-2-B switch to B, now you have one bank and the ACR or echo charger are hard wired for two banks.  That seems like a problem.  An alternative would be to put a voltage monitor on each bank (each battery in your case) and a switch coming off the controller.  You could manually direct the charge to each bank or use the 1-2-B switch for both.

Many of us have paralleled the batteries in the battery box to create one larger bank (1 on the 1-2-B switch) and added a start/reserve battery (2 on the switch) with an ACR or echo charger between to isolate and charge each bank separately.  In this configuration, you would only have one wire from the controller to the bank 1.

[Stu Jackson]

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1.   The problem it seems with an ACR or echo charger is when you flip the 1-2-B switch to B, now you have one bank and the ACR or echo charger are hard wired for two banks.  That seems like a problem.

2.   An alternative would be to put a voltage monitor on each bank (each battery in your case) and a switch coming off the controller.  You could manually direct the charge to each bank or use the 1-2-B switch for both.

3.  Many of us have paralleled the batteries in the battery box to create one larger bank (1 on the 1-2-B switch) and added a start/reserve battery (2 on the switch) with an ACR or echo charger between to isolate and charge each bank separately.  In this configuration, you would only have one wire from the controller to the bank 1.

1.  No problem at all.  Why?  Because when you do install an VSR (of any type) you do two things:   send ALL charging sources to the house bank so the 1-2-B switch is only a USE switch; and never have to move the 1-2-B switch to B, ever, unless your VSR breaks, in which case you ONLY go to B when charging sources are present.  B is for Backup. 

2.  Double dipping with more switching, and, right, you could use the 1-2-B switch, but if you do #1 above you turn the switch off when you leave the boat and both banks get charged.  Simpler.  No switching required.  This is the entire concept of doing this:  simplicity.  It also is healthier, 'cuz your brother-in-law won't fry your alternator's diodes by turning the damn switch off when youre motoring even though you told him DO NOT TOUCH!!! 

3.  Yup, totally in agreement with #1 and #2!   

[NewToTheRoad]

Got it.  Thanks for the clarifications.  I like the simplicity aspect and will, with time and $, move in that direction.  I have read a lot of the debate on the AB switch and there are many great points of view.
Battery was only  $99 but will definitely run it by the group when I go to golf cart batteries for the house.

My plan was to install the controller under the Nav station which is ultimately 2 ft farther than the AB switch.  So my run to the battery box is at least 6 feet( through the wet locker and behind the main panel) which I undertand will have some voltage drop.  But, it seemed to be an easy location to monitor and out of the way.  I have read where others have done the same.  Is there a better location closer to the battery?