Battery Charger on 24/7 ?

[Jon magowan]

Hello all, looking for advice please re charging my battery bank !

This is my first winter owning a boat (33ft Bavaria, 10 years old).

I have a sealed, lead acid engine battery and 2 unsealed lead acid leisure batteries.

There is a small, quite old solar panel stuck to the coachroof which seems to keep the leisure batteries at a reasonable level of charge. I’m pretty sure the solar panel isn’t connected to the engine battery (which is located remotely from the other batteries).

I also have a AC to DC charger (it is supplied by shore power and has a ’boost’ and ‘float’ function).

My questions are these…..

Is there any problem in leaving the charger switched on permanently?

Is this ‘best practice’ through the winter given that I won’t be using the boat and that presumably the output from the solar panel is likely to be pretty poor?

 

[Robih]

You'll have good arguments for both the "leave the charger on" and "rely on the panel" approaches. If leaving on it has to be a quality advanced function charger. I leave my Victron permanently on (house bank), have done for the past eighteen years, no problem.

 

[Refueler]

For extended periods of non use ... I use battery Maintainers on one boat ... they are low power auto shut off - on units that just provide a low ~1A charge to keep the batterys topped up. They are designed for caravans and other leisure stuff that get laid up for long periods. But if the batterys have any 'drain' on them - these can struggle to keep up ... best if batterys are disconnected for these.

If your charger has Float function - check carefully the instructions ... as some Float chargers are not actually designed to be connected / on permanently ... but can be left for reasonable time before disconnecting.

I have a couple of Lidl Auto smart chargers on one of my boats ... designed for just this job ..... Ultimate Speed ULGD 5.0 D2 .... nothing fancy .. simple operation .. connect and forget. The batterys withe these can still have low drain such as alarm and keep up.

 

[johnalison]

I have just replaced my standard batteries after nine years of almost continuous charge, so I can only say that it works for me.

 

[Gsailor]

Leaving a battery on charge 24/7 using a smart charger is fine in my experience - but it must be a smart charger.

And if the manual says it can be left on 24/7 you have even more reason to not worry.

 

[dunedin]

I am of the preference to NOT leave the shore power / mains charger on when not on board, but instead rely on two 50W solar panels on the sprayhood. The panels work well enough for the ships batteries through a Scottish winter.
The engine battery only gets a tiny amount of draw when starting the engine when used, and is soon replenished.

 

[Gsailor]

I am of the preference to NOT leave the shore power / mains charger on when not on board, but instead rely on two 50W solar panels on the sprayhood. The panels work well enough for the ships batteries through a Scottish winter.
The engine battery only gets a tiny amount of draw when starting the engine when used, and is soon replenished.

I totally agree.

And it is free (solar)

At the moment the OP says he has a small old panel and it is not even linked to the cracker.

It does not sound as if he has 100w going through a decent solar controller.

 

[Jon magowan]

Thanks everybody.
My charger is (10 year old) Cristec CPS30EM.
I assume it’s a ‘smart’ charger because it features ‘boost’ and ‘float’. The instruction manual doesn’t make any reference to how long to leave the charger switched on.
Guess I might see how the solar copes on its own through the winter gloom. I still feel a little uncomfortable leaving this device connected and switched on, unattended for a couple of weeks at a time.

 

[Gsailor]

Thanks everybody.
My charger is (10 year old) Cristec CPS30EM.
I assume it’s a ‘smart’ charger because it features ‘boost’ and ‘float’. The instruction manual doesn’t make any reference to how long to leave the charger switched on.
Guess I might see how the solar copes on its own through the winter gloom. I still feel a little uncomfortable leaving this device connected and switched on, unattended for a couple of weeks at a time.

If you cannot access the label on the back of the solar panel, what physical size is it? That will give us an idea of its power output.

Does it go through a solar controller and then onto the batteries?

It should be easy and cheap to replace the solar panel with a new one (you will save spending money on shore power) and while you are at it, wire the crancker in (you will have to ask experts on here how to do that)

You could get an expert on here ( or teach yourself- I used to find learning new skills about my first boat fun) how to wire all 3 batteries to your current 10 year old solar panel and measure the amps output on a cloudy day.

An expert will correct me, but the starter battery should be charged as priority and then the leisure’s via a voltage sensitive relay I think..

 

[Bodach na mara]

Guess I might see how the solar copes on its own through the winter gloom. I still feel a little uncomfortable leaving this device connected and switched on, unattended for a couple of weeks at a time.

I would also be uncomfortable. I once saw my neighbour's garden shed burnt down when a fault occured in the charger he was using to charge him lawnmower battery. By the way I have a very old charger that has boost and float settings and it is certainly not "smart". Which reminds me that I really must take a load of old stuff to a recycling centre.

 

[010169]

Some people disconnect other peoples boats from the electrical supply and leave you up a creek.
What voltage are you leisure batteries of a morning? If over 12.7 v good. What voltage at middle of day? If 13.7 V good.
Wind turbines work at night and on gloomy winter days but you need to maintain them because they have moving parts. I like solar and wind.

 

[Refueler]

I would also be uncomfortable. I once saw my neighbour's garden shed burnt down when a fault occured in the charger he was using to charge him lawnmower battery. By the way I have a very old charger that has boost and float settings and it is certainly not "smart". Which reminds me that I really must take a load of old stuff to a recycling centre.

That's where the 'Float' term gets murky ... as many 'Float' chargers do drop down to low rate for 'float' but its not sensed ... its just voltage level related and resistaince of the battery. Its not a good idea to rely on that long term. If its instructions do not mention about being left connected - then I would be wary of doing so.

A proper smart charger with sensed 'float' is called for .... or take a 'dumb charger' and connect via a sensing unit ...

I have an old Maplins solid state splitter that senses battery and determines which battery to charge and also when to shut off ... restart charge etc. Its very old and I am going to swap it out .... relegate it to bench use ... there are better units now ...

 

[Biggles Wader]

Thanks everybody.
My charger is (10 year old) Cristec CPS30EM.
I assume it’s a ‘smart’ charger because it features ‘boost’ and ‘float’. The instruction manual doesn’t make any reference to how long to leave the charger switched on.
Guess I might see how the solar copes on its own through the winter gloom. I still feel a little uncomfortable leaving this device connected and switched on, unattended for a couple of weeks at a time.

If you are only leaving the boat for "a couple of weeks at a time" I would just isolate the batteries when away and fully charge them when I visit the boat. A different matter if leaving the boat for six months.

 

[dunedin]

The other factor is the need to maintain a shore power connection when away from the boat. I much prefer to avoid a mains lead connected if possible. I may be paranoid, but just feel more risks of galvanic corrosion etc (though our boat does have a galvanic isolator).
Hence why just use solar for battery charging when away - and solar has worked perfectly.

 

[Jon magowan]

Many thanks everyone. Very informative!

 

[johnalison]

I am of the preference to NOT leave the shore power / mains charger on when not on board, but instead rely on two 50W solar panels on the sprayhood. The panels work well enough for the ships batteries through a Scottish winter.
The engine battery only gets a tiny amount of draw when starting the engine when used, and is soon replenished.

That was my policy at one time, and my 36w panel was plenty. Unfortunately, my charger sits at the rear of the cockpit locker and when I left it switched off one winter it failed due to damp, as it is separate from the dehumidified cabin. Since then I have preferred to leave it running and also use a granule damp-trap in the locker. In general, relying on a solar panel makes good sense.

 

[Mudisox]

I have 3 old 1988 solar panels [approx 14" square] that face South for most of the time, and it seems to keep all my batteries [2x 120AH leisure +2 starter batts] above 12.8 throughout the year.

 

[lustyd]

Thanks everybody.
My charger is (10 year old) Cristec CPS30EM.

I had a Cristec as originally fitted to my Jeanneay which I left on all the time for a couple of years before it popped and got replaced with a new Victron. Looking at the meter readings the Victron uses significantly less power when the battery is full. This is in the order of pounds per week of electricity usage just for charging a full battery. You could argue that the Cristec was dodgy when I bought the boat and never functioned as intended, but I suspect it was just less advanced being a couple of decades older tech. I don't think it's a good thing pumping more juice into a full battery.

Having since swapped out for a lilthium I no longer leave the charger on 24x7, but for AGMs I definitely would

 

[HunterWanderer]

I always disconnect from shore power when not on the boat. The battery isolator switch does just that so batteries are fully charged when I return.

 

[lustyd]

The battery isolator switch does just that so batteries are fully charged when I return

Doesn't work with lead though, they need a maintenance charge to remain at 100%, hence the chargers are usually connected on the battery side of the switch. A battery monitor wouldn't know that due to the way they work, so will happily pretend the battery is at full capacity.