Unattended Battery Smart Charger

[Harry Brown]

I am putting this out there to get some views on leaving a Battery Smart Charger (like these www.ctek.com) ALWAYS plugged into the mains shore power, and maintain the battery safely whist away from the boat for weeks or months at a time.

Ideally a Galvanic Isolator should be use if plugged into shore power for any length of time, but that’s another post!
I also understand you could charge by other means (solar / wind) but would like to discuss this possible battery charger solution.

Now to me leaving any mains electrical item unattended for any length of time just feels bad.

However, battery banks are not cheap and these chargers are very good indeed. I have several of these hooked up to different vehicles in a garage and do leave these unattended for weeks at a time, if I have a fire in this particular garage it’s not a problem as there is nothing around to catch fire, just the charger its self and a scorched floor!

I have thought about putting a charger in a fire proof box, in the sink, with the lid open, like in the picture below.


What I am concerned about is the charger overheating inside the box, in the very hot cabin, due to the ambient summer temperatures, and then catching fire. If the charger being in a box would overheat, what about just placing the charger in the sink on its own, (water turned off!)

Has any anyone done anything like this? Look forward to you thoughts.

[a64pilot]

I leave my Marine battery charger on all the time, like I believe 99% of the boats in Marina's do.
Why not have a "real" battery charger?

[HappyMdRSailor]

Originally Posted by a64pilot

I leave my Marine battery charger on all the time, like I believe 99% of the boats in Marina's do.
Why not have a "real" battery charger?

+100...

Float.... Float... Float.... baby....

[Harry Brown]

I just worry about all battery chargers! Hence the reason to put one somewhere where it will cause the least amount of damage, IF the small chance of it ever going wrong happend. And I'm talking about leaving it somewhere for many months, hence the concern. I'm probably worrying about nothing though ;-)

[Stu Jackson]

What kind of batteries do you have? What kind of temperatures will the boat be in when you leave it?

Reason I ask: in winter, folks disconnect their batteries when they haul their boats. With low temperatures, batteries self discharge rate is very low.

You could also put the charger on a timer, set for once a week.

Enclosing it is NOT a good idea. RFTM which always says they need ventilation.

I leave my boat disconnected when I am not there. I've been gone for as long as two to four weeks and if left fully charged, the bank is just fine. I sit in 57F water year round, doesn't get too hot here too often and usually when it's warm I'm out on the boat.

Good luck.

[hamburking]

Way up here in Canada, we haul the boats before the water gets hard. I make sure the battery is fully charged, and everything (master switch) turned off. This is in October. Launch is in May, 6 months later, and the battery is usually down maybe 0.2 or 0.3 volts lower than when I left it. And this is after enduring temps of 30 below zero over several weeks. Plenty of power to start the engine, and get back to 100% after launch.

So I would say, do not charge while away...too much risk, almost no gain.

Some people disconnect the cables from the batteries to avoid any electrical risk (like varmits chewing on the wires).

[smac999]

every boat I work on is plugged into the dock 365 days a year with a charger left on. probably 6 months all winter. and for weeks or months at time during summer. (boat used a few times a year)

[Stu Jackson]

Originally Posted by smac999

every boat I work on is plugged into the dock 365 days a year with a charger left on. probably 6 months all winter. and for weeks or months at time during summer. (boat used a few times a year)

The key is the last in ()s - they don't use their boats and are killing their batteries. Sulfation occurs by leaving batteries on float forever.

"Batteries don't die, they are murdered." -- Maine Sail

[Tibor]

When not using my boat I have all electrics turned off apart from the solar panels which keep the battery topped up. No need to use my battery charger. In fact we only connect our battery charger when staying in a marina overnight. Would never consider putting a charger in a confined space and leaving it on for a long period unattended.

[patprice]

My boat in Greece is left with the solar panels keeping the batteries charged. If at some time I increase the solar capacity I may add a second controller for redundancy. I have had them fail. It is a long lay up period...7 months.

[boeing1]

I guess with the new smart chargers you might be ok, however I think I would use a timer if leaving the boat for any lenth of time. if somethink can go wrong it will.....

[HopCar]

One reason my battery charger, a Newmar, stays on continuously is that the bilge pumps can't run out of power if a leak develops.
Newmar Phase Three Battery Chargers

[btrayfors]

Lots of things kill batteries. Stu is right: batteries perpetually on float charge can sulfate. But, they sulfate even faster if left in a partially discharged state habitually.

To be kept in tip-top shape, they need to be float-charged at a high enough voltage -- for FLAs 13.4-13.8 VDC -- AND they need to periodically be "super charged" with an absorption-level voltage -- 14.4-14.8 VDC for a short time.

The higher voltage causes bubbling which tends to dislodge loose PbSO4 lead sulfate crystals from the plates, as well as helps to avoid stratification -- the "layering" of different concentrations of electrolyte.

Ambient temperature can be critical.

Example 1. You're in Canada and it's winter where in wintertime very cold temperatures occur. You charge your batteries fully, disconnect them for the winter, and come back in the spring. They'll likely be in pretty decent shape. The cold temps tend to slow the self-discharge process way down.

Example 2. You're in the Caribbean. Winter or summer...doesn't matter. You fully charge your batteries, disconnect them, and leave the boat for a few months. You come back and find that you've managed to well and truly murder your batteries. Yep, in just a few months new batteries can be destroyed by leaving them in high temperature places with no charge. Ask me how I know, having had my own boat in the Caribbean for 11 years and having had to leave it for months at a time.

Now, I tend to leave my high quality battery charger (Victron) on 24/7. It's programmed to float at 13.8VDC then 13.2VDC after inactivity, and every other day it kicks up the voltage to 14.8VDC for 30 minutes. I've found this regime works very well with T-105s and with Crown golf-cart batteries.

This year I left my boat in Maine for the winter, and there was no way I could have left the charger on full time. Nor did I like the option of having the boatyard plug the boat in every couple of weeks or so. Result: I brought my eight golf-cart batteries home to VA and put them on charge 24/7. Every month or so I kick up the voltage and occasionally equalize them.

Be sure to always use HydroCaps or WaterMiser caps to reduce loss of electrolyte, especially when the batteries are left on charge for long periods of time.

Note that all the above relates to batteries which are in good shape and in decent installations. If by contrast there is a problem, e.g., with a shorted cell, leaving the charger on and unattended for months at a time could lead to a severe problem.....like a battery exploding or a fire destroying your boat!


FWIW,

Bill

[Akapeterc]

The only problem I find with leaving my battery charger on a closed up boat is the CO detectors go off

[Capt Gill]

There are many brands of smart chargers with varying quality from the $10 cheapo H.Freight on up. The quality of the charger and of course, the installation should be a major part of the decision. My Freedom 25 charger/inverter is always on when at the marina. I leave the boat for up to six weeks w/out being on it. Seems like talking to the mfg. would be helpful.