charging deep cycle batteries
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Category: General Forums
Forum Name: The Boat Shed
Forum Description: Discuss all things boating.
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=58699
Printed Date: 09 Jun 2026 at 12:37am
Topic: charging deep cycle batteries
Posted By: ripfishnbust
Subject: charging deep cycle batteries
Date Posted: 18 Oct 2010 at 11:26am
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Howdy gents,
got a deep sycle battery that needs recharging. I put it on my usual 12v charger. Left it on 12 hours or so. All seemed ok, all charging light on the charger lit up. Then I unplugged it and a little later checked the charge int he battry - only 3/4 full. Damn, I thought, put it on for another 12 hours, maybe more. Still the same amount of charge - but this time I could hear a bubbling noice coming from inside the top of the battery.
What gives? Did I mess it up? There's an indicatore on the battery that shines different colours - green for charged, black for needs charging and no sign which means the battery's knackered and needs replacing. Before charging it was black - now it's either black or there's nothing there! Any one know what I should do?
Cheers.
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Replies:
Posted By: Catchelot
Date Posted: 18 Oct 2010 at 11:31am
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How old is it?
Have you checked the fluid levels?
Can you measure the battery voltage with a multi-meter?
Rule of thumb; full charged 13.2v Half Charge 12.5v less then 11v...buggered!
Perhaps also get a hydrometer and measurre the specific gravity, can be a bit more accurate than voltage tests. ------------- "The sea, once it casts its spell, holds one in its net of wonder forever." - Jacques Cousteau |
Posted By: tas-tackle
Date Posted: 18 Oct 2010 at 11:42am
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Do all of the above (hi al) as well as after about an hour or so on charge, visually sight down each port to see if bubbles are rising.. if one is not, then that one may be sulphated.. Was talking to a manager in a well known battery shop as I was about to change my wifes car battery.. Talked about charging batteries at home and he said... "You guys with your 4, 6, 8 amp chargers dont leave them long enough, they should be left charging for 48hours and not overnight as most folks do" Have done that ever since How often has this battery been brought up to full charge... ??? ------------- http://postimage.org/" rel="nofollow">  http://www.tas-tackle.co.nz |
Posted By: ripfishnbust
Date Posted: 18 Oct 2010 at 2:02pm
| mmm interesting thoughts guys. For starters, it's only 1 year old. I've only been using it over the past 6 months so this is the first time it's been brought up to full charge. And I've checked - it's only a 4 amp charger. I'll whack it back on and keep an eye to see if any bubbles ARENT rising, right? (and here I was thinking bubbles rising was a problem!). If I've still got concerns after what - 24 hours? - I'll just take it into my local auto electrician I think Catchalot as the stuff you suggest I do sounds far too tricky for me! Thanks heaps for the advice guys, keep it coming! |
Posted By: tas-tackle
Date Posted: 18 Oct 2010 at 2:16pm
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take all the screw plugs out anyways to allow the battery to "breath" while charging... firstly, ensure the plates are covered with water... I use clean rainwater... You WANT to see bubbles rising from each cell after about 2-3 hours or so.. you should be charging all of your batteries to full charge for a period of 48 hours every 3 months... then when fully charged a trickle charger applied to avoid sulphating... I just use a solar charger...cheap as chips... ------------- http://postimage.org/" rel="nofollow"> http://www.tas-tackle.co.nz |
Posted By: Catchelot
Date Posted: 18 Oct 2010 at 3:40pm
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Yep as Fisher says...bubbles is all a normal part of the charging chemistry...gases...
And if you do need to top up the fluid levels just don't use tap water...chorinated water is no good, the best is de-mineralised or distilled...but rain water is fine. ------------- "The sea, once it casts its spell, holds one in its net of wonder forever." - Jacques Cousteau |
Posted By: Brooook
Date Posted: 18 Oct 2010 at 9:22pm
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Same with my battery.
Took it to the autoelectrician and he measured everything and it looked good. Then he charged it up and still looked good. After a while it lost voltage and looked only fair. He said it was borderline. I decided to buy a new one.
Deep cycle batteries (he said) are designed to go flat and charge up repeatedly. He said if you were to leave it over winter you should charge it up on your home charger every couple of months otherwise it sulpherises or oxidises (or some such word) and will never quite be the same again.
As for the borderline battery, he said it wouldn't be the right battery to start the Commodore but would be OK for the Toyota (except it doesn't fit, LOL). Deep cycle doesn't have the big amps to start a big engine, rather a steady amp drain like all the eqipment on the boat, tilt, starting outboards etc. ------------- Give a man a fish and he will eat for a day.............Teach a man to fish and he will sit in a boat all day drinking beer, |