Battery Chargers

[AtlanticAl]

I am at present re wiring my boat. I am doubling up the batteries, bought a load of stuff, including a battery A B and Both switch, buying a thirty watt solar panel, and a controler to replace the ten watt panel that is their just now.

My question is, I could pay a 150 dollars for a marine battery charger that charges two banks, on a trickle charge, , the boat will be left in the marinal for a week at a time, and both batteries need to be charged when we get to her, as we will sail for maybe thirty hours, and just have the solar panel for that time, and the motor, whch is an outboard, electric start, and does generate some power, but my wife, likes lots of power hence the two batteries, because she is not a sailor, and has never been out of electricity. but, why would i pay 150 for a marine battery charger, that can charge double banked batteries, when i can buy two trickle chargers from O'Reilly auto parts, for twenty buck each, and hook them up sepperate, and leave the batteries switche to battery one, to hande the auto bilge pump.

If your answer is waterproof, dont bother answering, as nothing is waterproof, I can make it waterproof myself by puting it in a bag, and if it really is waterproof, submerging it dosent count.

alistair

 

[Brian D]

I would think the very first reason is the $150 charger is going to be a little more intelligent than the one for 1/3 the cost. However, if you look at the specs and see that it does the same thing, by all means, purchase it. But, if your batteries boil out or for any other reason, fail, then all you have to blame is yourself. And it is waterproof.

Currently I have a small motorcycle battery and a $20 charger on my boat. Been there for almost 6 months. My wife reports no issues. However, when I return home in December, all that will change. I will be installing two Group 27 batteries and a Guest 12A (6/6) battery charger. Why? Because I feel more comfortable knowing that charger was designed for that environment. That is the only reason. And, I don't think it is waterproof.

Good luck.

 

[Ron20324]

Why isn't the solar used as a trickle charger? I went solar back in May, and have only been on shore power maybe 3 days just to use the water heater. AND, your bilge pump should be wired straight to a battery (and fuse), and not through a switch that may be inadvertantly be left off- in spite of best intentions.

 

[captstu]

The solar charger with an appropriate controller (mandatory) is a superior float charger to any 110V battery charger, marine or shore side.

There is no possibility of galvanic corrosion since the solar charger allows you to not put the boat on shore power and completely eliminates that risk.

The price of a low power solar controller is small compared to a battery charger and is a better, more risk free, solution to ensuring your batteries are topped off when you sail the boat.

It is OK to run the bank in the "both" position when at the dock and under charge. If you have a failure and both batteries are discharged, there is no added risk, just fix the problem, charge them up, and be happy. /Stu

 

[Barnacle Bill]

First of all, marine batteries are made of components that will not rust out in salt water conditions. I have seen auto store battery chargers disappear after time due to galvanic corrosion and that is no exaggeration. Secondly, any good battery charger will have a trickle auto mode so that the batteries will not over charge and boil over. So, when you need a higher rate of charge you get it and when you don't, you won't. Thirdly, when you have a battery charger that is properly installed, it will be hard wired into your shore power system, will have it's own properly (double poled) breaker on the panel. It will be permanently mounted somewhere where it will not fly around like an auto charger which is just sitting somewhere. Fourthly, you can buy a battery charger that will charge as many batteries as you have and then it is always hooked up and you don't have to unhook one and then rehook another, etc. But, to charge your batteries, the auto charger will work and if it disappears from corrosion, you can just go out and buy another.

 

[Bill Roosa]

More importantly a marine BC does not connect the neurtal 110 circuit to the 12 volt ground curcit like a shore side unit does. This is an important safety and corrosion (other boat parts not the BC) consideration.
What you really need to do is determin your energy budget and figure out what you need. The wife "likes lots of power" is not a very useful engineering term. Lots of power can be had fairly cheaply if you only want it for a few microseconds. If you want it for the full 30 hours then what constitutes "lots"?
Your 10 watt solar is only going to be giving you minimal charging and will surly not recharge the bats even given a week of no use. 10 watts at 13.6 volts is only (10/13.6=)0.74 amps and then only when the sun is "full on" Save you money for a more substantial panel(s) or invest in more batterys and a marine charger.
I went through this with Bardi Sea and developend an excel spreadsheet that can help calculate total AH used on a cruise, total AH produced and battery state of charge along the way. it's free.

 

[shemandr]

I can attest that the spreadsheet is a good place to start making an energy budget

 

[AtlanticAl]

I think from the advice, i will just avoid a battery charger, and see how the bigger solar panel gets on with charging the batteries. If it dosent work, i can fit a 110 battery charger at a later date.
The chargers i looked at in O'Reilly auto parts, were the type that were designed to be fixed to a wall, so would be ideal for a boat, they were also just trickle chargers, that were automatic, so i think they would be the type of thing i was looking for. I am not so sure about the corrosion risk, most of the sailing i have done has been in the sea, and the corossion in salt water, is extreme, because the salt water is acting as an electolyte, but on a fresh water lake, corossion should not be such a problem, howevor, i have never really had a boat on fresh water for any lenghth of time, so i dont really know.

 

[Maine Sail]

I think from the advice, i will just avoid a battery charger, and see how the bigger solar panel gets on with charging the batteries. If it dosent work, i can fit a 110 battery charger at a later date.
The chargers i looked at in O'Reilly auto parts, were the type that were designed to be fixed to a wall, so would be ideal for a boat, they were also just trickle chargers, that were automatic, so i think they would be the type of thing i was looking for. I am not so sure about the corrosion risk, most of the sailing i have done has been in the sea, and the corossion in salt water, is extreme, because the salt water is acting as an electolyte, but on a fresh water lake, corossion should not be such a problem, howevor, i have never really had a boat on fresh water for any lenghth of time, so i dont really know.

These types of chargers do not completely isolate the AC side from the DC side and can lead to corrosion issues. Good quality marine chargers use an AC/DC isolation approach inside the charger, usually an isolation transformer, to prevent these issues and minimize the risk of corrosion..