"Roll up" trickle charger with two battery leads

[Sea Hunt Video]

I've decided I want to install a "roll up" trickle charger. I recently installed two AC Delco Voyager batteries (Group 27). The batteries are installed in parallel.

From what little electrical knowledge I have, if I want to use just one "roll up" trickle charger, I think I need to have one with two leads - one for each battery. Does anyone know of a "roll up" trickle charger that comes with two leads

Since the batteries are in parallel, I think I could use only one "roll up" trickle charger if I was willing to leave the battery switch on "ALL". I am not. The trickle charger will be primarily used to "top off" the batteries when I am NOT on board. I think it is probably a bad idea to leave the batteries "ON" when I am not on board.

I guess I could add a wire to the one lead on most trickle chargers and come up with a dual lead "roll up" trickle charger. I would like to avoid this, if possible. If not, wire strippers, connectors and heat shrink are at hand.

Thoughts, suggestions, recommendations will be much appreciated.

Thanks in advance.

[Terry]

There are chargers designed for battery banks, such as we use. Battery Tender has a unit that will work on AGM and wet cell. I think there is also a Battery Minder unit for two wet cell batteries, that is cheaper than the bigger Battery Tender unit.

Amazon has some units, if you buy from Amazon. Marine suppliers also carry them.

Another way is to use two units, one for each isolated battery, I suppose. Especially if all you want is a trickle charge on the batteries. You would HAVE to remove the chargers prior to switching the batt switch, however.

Some where I saw an on-board unit that managed charging of batteries without actually having to remove it when you pull out the dock power. This would make it easy, and somewhat fool proof.

All the best. Terry

[Steve Laume]

Raven has the house bank set up parallel with a start battery on an echo charger. The solar panel goes to a cigarette lighter socket that has it's own breaker wired independent of the main battery switch. This goes directly to the house bank at the selector switch.

The problem you have is combining the batteries. I may be wrong but I believe, if you were to tie the batteries together with a shared solar charger, it could be disastrous. You will have created a very small wire connection that would attempt to carry house and start up loads between the two batteries. I am not certain what effect a diode in the charger would have.

Some possible solutions would be to use two chargers, each going to it's own battery. Another would be to install a small toggle type selector switch the would direct the charge to one battery at a time. It would have to be an on/off/on type switch. Set up that way, you could never combine the batteries. You would have to select one or the other battery to charge each time. This would have the additional advantage of being able to charge the battery that needed it the most. If you are alternating the use of your house batteries, you would also alternate which one went on the trickle charge when you put the boat away.

My understanding is that unless you are using identical batteries and always keep them tied together, you do not want to leave them that way for very long. The problem is that the more fully charged battery will discharge into the lesser. The cycle will go on forever until it pulls the entire bank down. This is one more reason to rule out leaving the main selector switch in the combined mode.

So now things have become a lot more complex than the old Typhoon days. You are going to have so much fun messing around with your new love, Steve.

[Carl Thunberg]

I don't pretend to be an expert on solar chargers, and batteries in general, but I can tell you what worked successfully on my boat. I had a house bank of two Group 27 wet cell batteries, and a dedicated starting battery. I also had a relatively small solar panel (rigid) which I connected to only one house battery, which ran the bilge pump. It was always the same battery. I relied on the alternator to charge the second house battery. It was a very simple set-up and it worked fine. Again, I'm no expert on this stuff, but I'm a strong believer in keeping things simple and more-or-less foolproof. No switches to mess with.

Since the rigid solar panel was always in the way and prone to getting stepped on, I simply disconnected the solar panel and stowed it safely out of the way whenever we got under way. This arrangement would never work for a live-aboard cruiser, but for the majority of us who primarily day-sail or do coastal cruising for a couple weeks at a time, it should work fine.

Edit: forgot to mention that my batteries were isolated from each other.

[Maine Sail]

I've decided I want to install a "roll up" trickle charger. I recently installed two AC Delco Voyager batteries (Group 27). The batteries are installed in parallel.

From what little electrical knowledge I have, if I want to use just one "roll up" trickle charger, I think I need to have one with two leads - one for each battery. Does anyone know of a "roll up" trickle charger that comes with two leads

Since the batteries are in parallel, I think I could use only one "roll up" trickle charger if I was willing to leave the battery switch on "ALL". I am not. The trickle charger will be primarily used to "top off" the batteries when I am NOT on board. I think it is probably a bad idea to leave the batteries "ON" when I am not on board.

I guess I could add a wire to the one lead on most trickle chargers and come up with a dual lead "roll up" trickle charger. I would like to avoid this, if possible. If not, wire strippers, connectors and heat shrink are at hand.

Thoughts, suggestions, recommendations will be much appreciated.

Thanks in advance.

Two batteries if physically wired in parallel are ONE battery. Connect the + lead to one end of the parallel bank and the - lead to the opposite end.

Just remove two batteries from the bank pictured below and connect your solar panel as shown, across the bank..


Be aware that with most "roll ups" you will BARELY sustain the banks self discharge, let alone "top up". Anything bigger than a "trickle/maintainer" and you'll need a charge controller.

This is how to correctly wire a parallel bank:


This is how to incorrectly wire a parallel bank:




PS.. If you bank is only wired in "parallel" via the battery switch then they are not technically wired in parallel...[/img]

[Steve Laume]

Thanks Maine Sail. I was assuming Robert's batteries were combined at the selector switch as he has the two battery set up.

I have both house batteries tied together at a "pre-selector" switch before the get to the main selector. This will allow me to break the house bank apart but they are normally left connected. The start battery is on the second side of the main selector switch.

The tidbit you gave about coming off of opposite battery terminals is something I was not aware of. It is very logical.

Thanks again, Steve.

[Russell]

I think Robert is misusing the term parallel, given his reference to having to set the battery switch on "both" to share the charger. His batteries are isolated from each other via the switch (this is what I get from his post).

The easy solution to this problem is to add a battery combiner, essentially an automatic "both" switch that combines the batteries when a charging voltage is sensed (from any type of charger: alternator, solar, "roll up" etc). They are not expensive and easy to install.

I use two of these for charging my start battery and my windlass battery:

http://bluesea.com/productline/overview/387

Here is a good article on how they work:

http://bluesea.com/viewresource/1366

[Terry]

Oh, I get it. A roll-up solar panel.

Might as well use two. An isolator will work, but costly.

Terry

[Steve Laume]

The price of an isolator is almost as much as another panel. It would seem like a much better idea to have two. The problem is finding a good location for both of them.

Raven has a semi flexible panel tied to the sea hood. This is not the optimal location for generation but it is out of the way and does contribute nicely.

I still think a $10.00 switch would work very well for the situation Sea Hunt has on his new boat. Use one of your batteries for house loads and switch the charger to that battery. Next trip out; switch to the other battery for the house and transfer the charger to that one.

For that matter you always have your trusty battery meter to check the state of each battery so you could put the panel on whichever happens to be lowest. the combiner is nice but it is a lot of money to spend on a modest solar charging system, Steve.

[Russell]

Keep in mind isolators and combiners are not the same thing (and I cant imagine why someone would opt for an isolator). A simple combiner is about $70, I have a hard time imagining a boat owner calling that expensive.

As well, this setup will work for all current and future charging systems, eliminating entirely the need to mess around with the 1/both/2/off switch or having to remember to do so. In fact I strongly recommend people throw those old style switches away and replace them with the on/off/emergency parallel switches, with all charging sources going to the house bank and charging start bank via combiners and engine start wired directly to start bank (able to start off house via emergency paralell switch). This is the way boats are wired in this day and age and changing over is a rather minor investment for a much better and more intuitive system (the cost of a switch and a combiner, but just getting the combiner gets you there).

[Sea Hunt Video]

My apologies to all for the delay in responding to so many great posts. I spent the day giving S/V Bali Ha'i a thorough bath. Scrub, wash, scrub, REPEAT. As I am sure many know, it is amazing how much dirt, grease, grim, etc., you can get from a boatyard in just 11 days.

Now, to the issue at hand. Unfortunately, I believe it is time for me to once again remind everyone how truly dumb I am in so many things. I am not without skills. Unfortunately (or fortunately), they do not transition well to my current lifestyle.

Much of what has been posted is beyond my knowledge level. You guys forget who you are dealing with. I am DUMB.

Now that we have re-established this fact, here is how my electrical system is set up.

My batteries are wired "in parallel" - at least how I understand the words "in parallel" when talking about batteries. The positive (red) terminal of battery #1 is connected to the positive (red) terminal of battery #2. These batteries are then connected to the alternator via another red wire and grounded to the engine block.

I have a Perko "OFF" "1" "ALL" "2" switch.

In my mind (often a difficult place to live ) I think of battery #1 as the "start" battery and battery #2 as the "house" battery.

I really tried hard to figure out the way that Maine Sail recommended the battery bank be set up so that I could avoid having to think of "start" and "house" etc. and switching back and forth, etc. Our Commodore even sent me an email explaining how he did it on his Cape Dory 25D using Maine Sail's method. Unfortunately, for me it is not meant to be (at least not yet) as I still do not get it. I am in the middle of reading a book Maine Sail recommended (Boatowner's Illustrated Electrical Handbook by Charlie Wing). Maybe by the end of the book........

I think that for the short term I will buy a relatively inexpensive "roll up" trickle charger and do as some posters have suggested - alternate attaching it to battery #1 and battery #2.

Sails get "bent on" tomorrow. Yippee

[Russell]

Robert,

As you describe, your batteries are indeed installed in parallel then. In which case, your charger can connect and charge them both with only the single leads and no combiners/isolators/second panels.etc. Just take the red from the panel to one of the batteries red, and the black to the other batteries black (as Maine Sail described) and your done.

Though unless you have a third battery, your 1/both/2/off switch is not doing anything except for the 1 and off positions.

If thats the case, I would consider adding a third battery as a dedicated starting battery(or separating your existing two batteries into separate banks). The whole reason behind separate banks is that if you accidentally discharge your batteries too far, you always have a separate fully charged battery to get the engine started. Though I assume you have no 12v fridge, in which case discharging two g27 batteries that low is unlikely, but I would still personally want the peace of mind of a dedicated starting bank.

To be clear, you cannot have your batteries installed in parallel AND have two separate banks, your batteries are a single bank and your battery switch does nothing more then on and off.

[Russell]

By the way, I would recommend reading through (and understanding) Don Caseys Sailboat Electrics Simplified. Maine Sails book recommendation is very good, but Caseys book is much easier to wrap your head around first if you are new to this stuff, then move on to the more thorough books.

[Maine Sail]

Robert,

Unless you have more than just those two batteries on your boat the bank should ideally be re-wired. As it is now it seems you only have one bank.


The most basic way to wire your switch is as follows.

Battery #1 + post to switch terminal #1

Battery #2 + post to switch terminal #2

"C" post of switch to house DC panel and starter


As for the trickle panel how many watts are you considering?

[Sea Hunt Video]

By the way, I would recommend reading through (and understanding) Don Caseys Sailboat Electrics Simplified. Maine Sails book recommendation is very good, but Caseys book is much easier to wrap your head around first if you are new to this stuff, then move on to the more thorough books.

Have it; read it (twice); 19%-21% comprehension. I did like page 120 where Mr. Casey diagramed "A Better Way". Unfortunately, I did not show this to the electrician. Also, I do not think there is room on CD 25D to install three (3) separate switches (house, start & paralleling) as diagramed in his book.

I will reconfirm tomorrow the battery wiring routing I currently have on board. I know I said that Battery 1 and Battery 2 were connected in parallel. I "THINK" they are. I was helping the marine electrician install the new batteries and that is how I believe they are connected.

However, (there is always a "however") if connected in parallel the Perko battery switch makes no sense. It is either both batteries "on" or both batteries "off"; both batteries being charged from the alternator or both batteries NOT being charged from the alternator.

As I think about it more, I seem to recall the electrician (a knowledgeable guy) suggesting I should separate the batteries and connect them in parallel through the Perko battery switch. I know this disagrees with Mr. Casey's book.

I am still in the process of labeling everything. I can barely get into/out of the portside cockpit locker (too much linguini ). I want to put labels on each battery wire - as suggested by Mr. Casey. I also need to label the wires behind the electrical panel.

If possible, I would also like to find time to do a little sailing. S/V Bali Ha'i is much, much bigger than S/V Tadpole with a lot more canvas. I need to learn how to manage this single handed.