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btrayfors 04-10-2007 01:07 PM

Sizing a Battery Charger for Windlass Battery
Having dealt with the problem of charging a dedicated windlass battery bank located forward under the V-berth for some years now, I'd like to pass on a couple of things I've learned.

The basic design evolved when I installed the windlass some 10 years ago while in the Caribbean. In order to avoid a long run of very heavy battery cables, which would have been about 60' in my case, I chose to locate a dedicated anchor windlass battery bank forward, near the windlass itself. The windlass is a Lewmar Concept 2. The battery bank consists of 2 Trojan T-105's.

Over the years, I've managed to murder several sets of these batteries, through both inadequate engineering and neglect. I used to be away from my boat for several months at a time, and used a small solar panel to keep them charged. The panel was inadequate, there was no controller, etc., etc.

Wising up a bit, I decided to install a small battery charger. I got a good deal on a ProMariner 10-amp smart charger which fit nicely between the V-berths under the step. That little charger is still there, and still does a good job keeping the battery bank fully charged.

However, there are three problems. First, I'm an active ham and that charger is incredibly noisy in terms of RFI (like every other ProMariner product I've seen). Therefore, I turn it off when using the SSB. In the past, I've forgotten to turn it back on....sometimes for weeks or even months. And, as could be expected, I managed to kill another set of T-105s. This "last kill" is still in my basement where for the past 9 months or so I've tried to revive them with all manner of interventions. They still have only 60% capacity.

The second problem is that the little charger doesn't have the ability to do an equalization cycle...i.e., to hit the batteries periodically with 15.5 volts or more for a few hours to avoid plate sulfation.

The third problem isn't so much a problem, but a "would be nice" factor. The windlass operates very well from the batteries alone. Sometimes I think it would be nice, however, to be able to help them with a higher voltage when pulling in 200' of chain and a 60lb anchor under some load. The little battery charger doesn't have enough oomph to do the trick.

Solution for all three problems: install a smarter, quieter, larger battery charger, not because it's needed to charge the batteries but because it would solve all three of the above-cited problems.

Happily, there's a good and not very expensive solution somewhere in my future. As some may know from my earlier posts, I'm a big fan of Iota chargers. Industrial strength, very smart designs, very compact, and very affordable. I could replace the little ProMariner charger with an Iota 55A charger which is about the same physical size for about $165. See current eBay listing: eBay Motors: 55 AMP BATTERY CHARGER RV MARINE REMOTE CONTROL NEW (item 260106436855 end time Apr-19-07 23:00:52 PDT)

These chargers use PWM technology, and with the IQ-4 smart charge option ($35) are multistage, pulsing, and periodic equalizing chargers. I've been using one in my ham shack for over 2 years to maintain a similar bank of 2 T-105s with excellent results.

Bottom line: size the charger larger than needed to just charge the batteries, anc choose a charger which does everything you want, including not interfere with your radios.

Sorry to ramble on so long. Anybody want a lightly used ProMariner 10-amp "smart" charger? :-)


Cruisingdad 04-10-2007 03:12 PM

Hiya Bill,

How are you? Thanks for sharing.

Just a comment or two as I dissagree a bit: another option would be to move your battery further back in the boat at a location that would allow it to feed into the main house bank (charge from there also) and run cabelling to it and feed the house bank also.

As I said before, it is a real pain to run large cabelling (I just finished with 4/0). However, no more than a windlass is used and the potential to put other large draw sytems in the V, why not go ahead and bite the bullet and run the cabelling? Put a switch on it to feed other systems, like a wash down or a water maker or a bow thruster or a spot light. It would be VERY easy keep these systems from running at the same time... and most of them would never be run at the same time even if they were not switched. In housing, we would run a sub panel to different areas of a house and feed off of it. It allowed from great expansion, fewer runs, and minimal loss.

Just thoughts. Initially, it will be a real pain the butt (and expensive) to run the cabelling. But afterwards you have increased the house bank (which really gets used) and have the potetial to feed other large draw systems.


- CD

btrayfors 04-10-2007 03:53 PM


Interesting thoughts.

In my case, however, there was absolutely no possibility of locating the battery bank further back. It was either under the V-berth, or back with the other house batteries in the aft end of the boat.

Also, I have no intention of installing a washdown pump or a bow thruster or whatever. I already have a searchlight: it doesn't draw much current at all and runs from the ships 12V wiring system via any outlet on the boat. Ditto on a washdown pump: minimum amperage draw.

One other concern these days: the price of copper wire has skyrocketed. I can't imagine how much a 60- or 70-foot run of 4/0 or larger marine cable would cost. Together with the cost of an additional breaker or fuse'd need one at each end of this humongous'd be looking at a lot of bucks.

Even further, charging would be a bit dicey, since even with a 4/0 cable the forward batteries wouldn't be at the same potential as the main house battery bank. It would probably be best to install an EchoCharge...another $100 or so. Or a combiner. Or a huge switch with a combiner/echocharge, etc. Not good solutions, to my mind.

Nope, for me the completely separate forward battery bank works, both in theory and in practice. Admitedly it ain't for everybody.

BTW, this battery stuff is a problem. Just ran into a friend at the marina who was trying to help out a buddy on a new-to-him 46-footer. Seems the yard looking after this boat had left the inverter on with no AC to the boat over a period of several months. The load was refrigeration and a few other things. Predictable result: a bunch of very dead 4-Ds! Ouch.

Cheers to all. It's almost time to get out there on the water again (I believe the last below-freezing night in the Chesapeake region was last night).


Cruisingdad 04-10-2007 03:58 PM

I understand Bill. A little different set up for you. I just wanted to point out for others that might be in this situation.

Take care. See ya.

- CD

CapnHand 04-10-2007 06:14 PM


Thanks for the advice on the Iota charger. My charger is undersized for the batteries I have so I'm upgrading.

Jack Rabbit Marine has that charger for sale on ebay at $175, includes the 1Q4 controller and free shipping.

Anyone want a Xantrex 10TB charger?

btrayfors 04-10-2007 09:12 PM


Thank YOU for the reference. I hadn't seen Jack Rabbit's ad on eBay.

This is a heck of a deal: $175 for the DLS-55 with the internal IQ-4 controller and free shipping. I just bought one! They have 9 of them, according to their ad.

One other thing: they are apparently under the impression that these chargers are only for flooded batteries because they aren't temperature sensing. That's not right. They use a technology which works equally well with flooded, gelled, or AGM batteries, and without temperature sensing.

Among other benefits of these chargers I haven't previously mentioned is their wide tolerance for variations in input voltage and cycles. This makes them really good for use with onboard generators, as well as with shore power.

And, speaking of power, these Iota's often put out a LOT more battery charging energy than do other brands of equal ratings. They are industrial-rated for 100% duty cycle, and carry a 2-year guarantee, while the rest of the industry usually has 1-year guarantees and their equipment isn't rated for 100% duty cycle.

Now, anybody REALLY want a used ProMariner 10A smart charger?


sailaway21 04-10-2007 09:37 PM

Try Cam. He's getting ready to fill up a garage with all the stuff he doesn't want to sell with his boat. The charger will blend right in.

SVDistantStar 04-10-2007 10:05 PM

Ive got about the same issue going on. My current set up is what came with the boat. The bank is made up of 2 deep cycle marine batteries and a starting battery that was for the motor. There is no real charger in the system, just a AC-to-DC converter. In the year ive had the boat, the bank has always stayed charged up and will run my load for about 2 days before dieing. Now since we will be heading out to anchor soon, im going to put off buying a charger and just geting my Air-X wind gen going. Ive got 4 golf cart batteries to use for my bank. I know the Air-X isnt going to keep the bank fully charged since ive got 3 large 12v(house style bulbs) lights to light the boat and a small TV that runs on 12v(love that since our marina is the main target of power outages). Ive got a 700watt Kawasaki generator that i can use to help keep the bank up. The boat did come with an older car battery charger that ive used before to get the bank in shape before going out for a trip. It works decent, but is junk, its about to rust apart.

camaraderie 04-11-2007 12:35 AM

SVDS...just a caution...don't leave that auto battery charger alone on the boat. I had a hunter in a slip next to me burn to the waterline some years ago due to the use of one.

SVDistantStar 04-11-2007 12:43 AM

I dont use it often, very rare use. Mostly for topping up the battery for the skiff. I think one like it is what burnt up a Hunter 2 slips from me.

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