Trickle Charger for batteries

Chris · 14 January 2007, 20:44

Is this a good idea if the boat is not going to be used for a couple of weeks?

http://cgi.ebay.co.uk/Marine-Leisure...QQcmdZViewItem

It is a trickle charger that I think you just plug in and leave charging the battery continuously at 0.2amps.

Chris

al40 · 14 January 2007, 23:17

Depends if you have anything left connected to the battery when boat is not being used. With the battery isolated (ie with proper isolation switch), you probably don't need to charge it between use, especially if using the boat every couple of weeks. I can't remember the self discharge rate for lead acid batteries but it's not huge. When I was involved in sailing, a yacht battery left all winter without being charged could still easily start the engine. Doesn't harm to keep it topped up tho as it does mean it's always ready to go and will ensure the battery actually reaches 100% charge which it may not with normal alternator cct.

Car batteries go flat faster due to static current of all the electronics. In "off" state, a car can still draw 20mA or more on the battery with clock, alarm, remote entry system etc.

AndrewH · 14 January 2007, 23:38

Alternatively I seem to remember a thread a while back about a little Maplin solar jobbie that could easily have been fixed to the A-Frame and I'd have thought that this is a sensible way of keeping the batteries topped up for free

I'm sure a quick forum search should turn it up

Andrew

Matt · 15 January 2007, 08:17

If it's flat after a couple of weeks you'd be better of fixing the source of the drain, or replacing the battery if it's just shagged. If you're talking about a couple of months or more, then yeh, I use 1 of these on the kit car, and a pair on the boat and I reckon they're great.

I'm not convinced by the solar ones - how much power do you reckon they produce in the winter? I'm not sure it'd be enough to make a difference, but I've never tried them myself.

BogMonster · 15 January 2007, 08:25

Depends on how it works, a proper one will sense battery voltage and pulse on and off as required to keep the battery topped up. I have one like that made by Maypole which I think cost a bit under £20. One that puts a constant current into the battery, not such a good idea unless you have constant drain on the battery (my RIB has a master disconnect which is always off unless I'm pumping out water or something)

I think a solar one would work ok in winter if there are no loads on the battery - you really don't need much to keep a battery topped up if the only enemy is internal self-discharge. I haven't charged my boat for about six months and it only gets used every two or three weeks for a couple of hours.

Matt · 15 January 2007, 08:36

Not sure I agree - but I might also be wrong and about to learn something.

IMVHO with a decent sized battery 2-300ma as a maintenance charge is perfectly fine. Either way, the car's been on charge for about 12 months, boat for about 3 and both are in a good state

This is the (overpriced) draper jobbie. Says suitable for 30-140Ah.
http://www.draper.co.uk/Pages/Pagesource/p67.pdf

Rodan · 15 January 2007, 08:43

maplin solar jobbie works very well. mine is left with just a pump connected for long periods (3 months recently) with no problems.

BogMonster · 15 January 2007, 09:12

Quote:

Originally Posted by MadMat

Not sure I agree - but I might also be wrong and about to learn something.

IMVHO with a decent sized battery 2-300ma as a maintenance charge is perfectly fine. Either way, the car's been on charge for about 12 months, boat for about 3 and both are in a good state

This is the (overpriced) draper jobbie. Says suitable for 30-140Ah.
http://www.draper.co.uk/Pages/Pagesource/p67.pdf

Your car will have drains on it though, maybe only a clock and an alarm but still draining a small amount.

0.2 amps is putting 1700Ah into a battery in a year which is the equivalent of charging a big (Td5 Discovery sized) battery from flat 15 times or about every three weeks

It may well be fine I'm just saying I wouldn't do it.

codprawn · 15 January 2007, 15:34

Quote:

Originally Posted by Rodan

maplin solar jobbie works very well. mine is left with just a pump connected for long periods (3 months recently) with no problems.

I wonder just how much help the solar panel is giving? My boat has been standing for 2 months now and we have had more rain that most of the UK so the auto pump is working overtime. My battery is still fine and has had no charge at all in that time. Started the engine yesterday and it still had enough power to start easily.

al40 · 15 January 2007, 19:03

I guess panel must be doing something. I looked at these in Maplin and they claimed to still produce enough on a cloudy day to input something to the battery (unlike my cheap garden solar lights!).

Charging enough to run the pump in recent weeks is good going tho :-)

codprawn · 15 January 2007, 21:28

Quote:

Originally Posted by al40

I guess panel must be doing something. I looked at these in Maplin and they claimed to still produce enough on a cloudy day to input something to the battery (unlike my cheap garden solar lights!).

Charging enough to run the pump in recent weeks is good going tho :-)

I also have a similar panel from Maplin - bought it in a 1/2 price sale. Just haven't bothered fitting it because it will prob just blow away and get smashed - when I look at how dark and gloomy it always is here with permanent rain it makes me wonder if we are actually in Iceland without the ice!!!

The battery is nothing special - just BIG. Bought it for my Defender but when I found out the boatbuilder had stuck a duff battery on and it's all I had around at the time. Fits the battery box perfectly and cost about £50.

Simon B · 18 January 2007, 10:48

I had been considering rigging up a caravan "S" type socket to plug in and charge at 12v when I'm towing, tucked away in the console somewhere. Has anyone else done this?

al40 · 18 January 2007, 13:22

That sounds like a good way of giving your battery a top-up before using the boat.

Do you have an accessory socket on your RIB? I'm not sure on the current that the standard caravan charge sockets can deliver (may be more than the accesory socket or fuse / cabling can cope with) but that could be a possible way of connecting the cable to the RIB battery

I guess if the RIB battery was mostly charged, the current would not be that huge anyway.

jyasaki · 18 January 2007, 16:54

Quote:

Originally Posted by BogMonster

0.2 amps is putting 1700Ah into a battery in a year which is the equivalent of charging a big (Td5 Discovery sized) battery from flat 15 times or about every three weeks

That sort of neglects the self-discharge rate of the battery, though. Not sure what that number is, but given that a disconnected battery will be dead (well, maybe not dead, but discharged to a non-useful state) in about 3 to 4 months, I can't see 200mA being a problem.

And, since most chargers are rated to their max current (the 200mA), and the battery voltage increases as it's charged (i.e. the battery voltage approaches the charger output voltage), as the battery charges, the amount of current is going to fall off anyway.

jky

Poly · 18 January 2007, 23:05

Quote:

Originally Posted by Simon B

I had been considering rigging up a caravan "S" type socket to plug in and charge at 12v when I'm towing, tucked away in the console somewhere. Has anyone else done this?

http://rib.net/forum/showthread.php?...uble+electrics

Aidan · 19 January 2007, 00:02

Good idea Polwart.

If you blow the Car engine management system tho, warranty is shagged,

Nick Hearne · 19 January 2007, 07:42

Quote:

Originally Posted by jyasaki

Not sure what that number is, but given that a disconnected battery will be dead (well, maybe not dead, but discharged to a non-useful state) in about 3 to 4 months, I can't see 200mA being a problem.
jky

I have no problem leaving batteries for over 4 months & still being in tip top condition!

jyasaki · 19 January 2007, 16:47

Quote:

Originally Posted by Nick Hearne

I have no problem leaving batteries for over 4 months & still being in tip top condition!

Not saying you don't Nick, but most of the evidence points to the contrary:

from http://www.corrosion-doctors.org/Bat...lf-compare.htm

>>>>>>>>
Self discharge of batteries
Function of temperature
Self-discharge is the electrical capacity that is lost when the cell simply sits on the shelf. Self-discharge is caused by electrochemical processes within the cell and is equivalent to the application of a small external load.

Lead-acid and nickel-cadmium batteries lose their charge very quickly. For example, a lead-acid battery stored at 30oC would lose half its initial charge in about 3 or 4 months while, for nickel-cadmium, this would only take about 6 weeks. In normal use, this might present no real problem, as these types of battery can be recharged, but such batteries are clearly unsuitable for "fitting and forgetting".
<<<<<<<<<<<<

Note that I snipped stuff about other technologies, as they don't really fit the conversation.

One other site I glanced at put the self-discharge rate of lead-acid batteries at between 1 and 60% per month (nice that they're so generous.) I filed this site under "useless".

Apparently, self-discharge rate is pretty quirky, and is affected by manufacturing tolerances, number of cycles the plates have seen, ambient temperature, etc. But, it does occur.

I've got a second truck which sits in the driveway for months at a time. It usually requires a charger session before it will crank. Once started and run for an hour, it's good for a couple more months.

Hope that your system is more robust than mine.

jky

Poly · 19 January 2007, 19:23

Quote:

Originally Posted by Aidan

Good idea Polwart.

If you blow the Car engine management system tho, warranty is shagged,

not my idea - i just recalled the previous discussion. but since (as I understand it from my fortunately limitted caravan knowledge) this is exactly the purpose of double electrics when towing a caravan. I can't see why it would damage the eng. man. sys. nor necessarily invalidate the warranty.

Simon B · 19 January 2007, 22:58

That's it then I'm off to "Caravans R Us" the morra and wearing my cunning Rogue Wave mask will purchase 2 plugs and a socket of the "S" type chuck in a fuse somewhere I did wonder if I needed a diode I'll ask my radar software mate and see what the guru says.

Where we live its at least 3 hours to the sea so it will recieve a little top up before we launch. I suppose I could use it as an accessory socket if we leave the diode out.

OK then that'll be all the cara-wacka kit and a 10 million candle power dragon beam to send morse to codders & co. Next time we are in Wales I'll look him up I might have the engine mods done to the 4.6 by the turning it into the beast.