Keeping Batteries Healthy, Safely, Over Winter?

CaptainBob

CaptainBob

Well-Known Member
Joined
7 Nov 2007
Messages
1,477
Location
North Yorkshire
www.yacht-forum.co.uk
Our boat is on unattended on land for the winter and I need to work out a way to keep the batteries healthy without returning to it very often (14 hour round trip each time!).

I can leave shore-power wired to a battery charger, but am dubious about leaving it on unattended for months at a time. I also do not own a suitable mains powered trickle charger so will have to spend ££ on one.

We have 3 200 Ah, non-sealed lead-acid batteries.

Any suggestions? Recommended trickle chargers?

NB. I am wondering about putting the money towards a D400 wind generator, but from what I can gather they require the manual operation of a kill switch to stop the batteries or dump resistor from cooking should conditions become a little extreme. Also the circa £1500-£2k for an installed D400 would go a long way to buying small petrol generators and a _lot_ of petrol to run them, for when we're living aboard (in the UK) from spring next year.
 
Even in sunless UK you'd probably be better off with about 100w of PV panel attached through, preferably, an MPPT tracker or a simple controller. Costs will probably be less and results more consistent than with a wind generator.

I'd certainly not recommend a simple trickle charger, almost a certain route to cooking the batteries, but a switch-mode charger which senses the state of charge of the batteries and adjusts it accordingly.

The cheapest of all is the latter, if you have a ready source of mains electricity.
 
Everyone I know who has a wind generator has been very disappointed with it - expensive and produces far less output than promised. A solar panel costing a couple of hundred pounds (probably less) will be fine to keep your batteries healthy.

As for leaving a battery charger on shore power unattended for months - the duration really is not particularly relevant. It doesn't need weeks to overheat and catch fire - minutes will do if it goes faulty. Equally, the boat will be gutted in ten minutes if it does catch fire - so, if you would leave a battery charger running unattended for a couple of hours, you may as well leave it for six months!
 
CaptainBob said:
Our boat is on unattended on land for the winter and I need to work out a way to keep the batteries healthy without returning to it very often (14 hour round trip each time!).

I can leave shore-power wired to a battery charger,
Click to expand...

Get a timer switch, digital type, set to switch charger on say 15 / 30 minutes a week, assuming it's a multi-stage one.

Leave the boat with batteries well charged, then all you need is to give the batteries a quick charge upto 14.2 / 14.4 weekly to keep them full and healthy.

If you leave them on a trickle charger you may / will generate sulphation and other problems due to the low voltage.

Brian
 
Do the batteries really need that much charging? I have two Electrosol batteries totalling 180 Ah. and a Sterling 20A. charger. The batteries stay in the boat and I give them a 24 hour charge in December and another in April. The boatyard meter shows mains consumed in each of these sessions and it's very small - I forget the exact figure but it's about 2 or 3 kWh. which suggests to me that the batteries lose only a few % of their charge per month. I can't do exact sums as I don't know the efficiency of the charger. It works for me anyway
 
charles_reed said:
Even in sunless UK you'd probably be better off with about 100w of PV panel attached through, preferably, an MPPT tracker or a simple controller. Costs will probably be less and results more consistent than with a wind generator.

I'd certainly not recommend a simple trickle charger, almost a certain route to cooking the batteries, but a switch-mode charger which senses the state of charge of the batteries and adjusts it accordingly.

The cheapest of all is the latter, if you have a ready source of mains electricity.
Click to expand...

Hear, hear. I left my Halfords automatic charger connected up all winter believing that the float mode would keep the batteries tip top. In the spring, the batteries were wrecked and had to be replaced. However, due to lack funds, I only replaced one leisure battery 110aH. I found this was more than adequate for my type of cruising in conjunction with my 20w solar panel.
The suggestion of using a timer is a very good one.
 
Open lead-acid batteries, as a rule of thumb discharge by about 1% of their charged capacity per week.
So allowing for 40% effectiveness for 4hrs a day I make a 72watt panel as being just OK for the job - however few batteries start off in a state of full charge - as only a well-tuned switch mode charger will get the last 10-18% in and float charge all the cells.
Even smart alternator controllers don't get a chance to fully equalise - they don't usually run long enough.
A good MPPT controller, with sufficient output to back it up, will do at least as well as a switch-mode charger.
 
A solar panel (with a regulator and blocking diode) is undoubtedly the best option - safe and reliable, and will also be useful in the summer.
Many boatyards won't allow you to leave mains power connected to an unattended boat, due to the fire risk; some insurers also discourage the practice for the same reason..
 
If you don't want to visit, perhaps once a month and do a top-up charge, then I'd agree with PRV and say take them home.
I definitely wouldn't leave them on trickle all winter, in my experience that doesn't do batts any good at all.
For what it's worth, mine stay on board and I make a point of topping up the charge once a month in the winter when I'm there doing something else (I use 'cheap' caravan shop batteries and they have done extremely well) but then my round-trip is one hour, not 14.
 
CaptainBob said:
Our boat is on unattended on land for the winter and I need to work out a way to keep the batteries healthy without returning to it very often (14 hour round trip each time!).

I can leave shore-power wired to a battery charger, but am dubious about leaving it on unattended for months at a time. I also do not own a suitable mains powered trickle charger so will have to spend ££ on one.

We have 3 200 Ah, non-sealed lead-acid batteries.

Any suggestions? Recommended trickle chargers?

NB. I am wondering about putting the money towards a D400 wind generator, but from what I can gather they require the manual operation of a kill switch to stop the batteries or dump resistor from cooking should conditions become a little extreme. Also the circa £1500-£2k for an installed D400 would go a long way to buying small petrol generators and a _lot_ of petrol to run them, for when we're living aboard (in the UK) from spring next year.
Click to expand...

A Sterling multi stage mains charger will take care of your batteries over winter and during the summer when afloat and shore connected. Or something similar. Cost about £230 for a minimal output (20 amp) somewhat more for a 40 amp. Check web prices. I have the 20 amp unit for a bank of 350 amph. Easy DIY installation.

Halfords trype units are a lot cheaper and deliver a lot less, so really unsuitable for unattended maintenance.

PWG
 
Can't bring them home unfortunately. Liking the solar idea.

Do you think I could use that Maplin 120W panel in conjunction with a Marlec HRDi controller unit? I like Marlec's gear and the HRDi will support wind power if we add that at some point, and has the added benefit of showing you accurate battery voltages and current supply.
 
I think that the sealed multi stage chargers which are made for a maintainance charge for motor bikes are great for your task.

I got a couple from Lidl/Aldi and find them very good.

The two chargers I bought from Halfords at much greater cost have both given up the ghost.

I also have a solar panel and wind generator as I do not have continuous shore power.
 
Have a look on ebay they have lots of panels at good prices i paid just short of £300 for two 80w panels. They are working fine.
Maurice
 
reeac said:
Do the batteries really need that much charging?
Click to expand...

No.

When I made charger's, late 90's we had a maintainance cycle it went into when the boat was not being used. It would turn on the mains, and charge the battery as required based on battery state, then turn it's self off. It would run with full batteries for seconds a day, so 15 minutes a month is adiquate. The main problem, for a general answer is it depends on charger and battery state, so 15 minutes a week is a safe basis to work.

Brian
 
Advanced Battery Charging - An Excellent Upgrade To My Yacht

PeterGibbs said:
A Sterling multi stage mains charger will take care of your batteries over winter and during the summer when afloat and shore connected.....
Click to expand...

I was going to post something similar but PeterGibbs has beaten me to it.

I purchased a Sterling Pro Charge Ultra (PCU) for similar reasons as CaptainBob. My batteries are standard wet cell types which require electrolyte levels to be checked.

The PCU has been left on continuously for at least 3 months this year due to work commitments. The batteries have remained in good condition and the electrolyte level has not required topping up since late spring.

I am confident that the level of protection via the shore power circuit breaker, the boats 240 V consumer unit circuit breaker (sized for the PCU), the PCU fuses (power circuit, charging circuit) and PCU control system, that the risk of an incident is as low as possible such that its not worth bothering about. The boat is well ventilated and any gassing risk is negligible.

With a compliant installation and adequate ventilation it is possible to have confidence in shore powered advanced battery chargers to be left on for long periods of time.

Below is a section from the Sterling site which may help to balance opinion on the risks of over charging: -

http://www.sterling-power.com/support-faq-1.htm

I have a wind generator (Air-X) which has sat in the automatic "feathered" position since I installed the PCU as it senses the voltage in the battery banks being above some set point. Before I installed the PCU the wind generator (Air-X) ran constantly i.e. it never got the batteries fully charged. It did keep the domestic batteries charged at an acceptable level (but not fully charged) over the winter before I purchased the PCU.

There are alternative advanced charging units to Sterling Power devices.
 
CaptainBob said:
Any suggestions? Recommended trickle chargers?
Click to expand...
Neat little charger and cheap too buy a couple or three even.

UK_66292_01_b.jpg
 
If you go for relatively small solar panels, don't spend a lot on charge controllers - Maplins sell perfectly good low-power (up to several amps) modules for about £20 - I fitted one on our previous boat and it worked very well.
 
Last edited:
You must log in or register to reply here.

Other threads that may be of interest

W
Battery suicide
Replies
17
Views
625
Refueler
Refueler

Share this page

Top