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  1. #1
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    Default Why Are People So Down On Gel Batteries?

    I'll warn you now, I am going near-mad trying to decide on what maintenance-free batteries to go for to replace our SLAs. I'm getting completely conflicting reports on battery types and their performance so I figured liveaboards are probably the best people to ask.

    According to the figures, gel batteries appear to be the most obvious choice for a liveaboard. Their longevity is second to none, yet I am told I should be looking at AGMs. However according to the West Marine catalogue, AGMs can only be deep cycled 300 times, versus gels which can cycled 1,000 times.

    The ever polite and comprehensive Charles Sterling said this of gels:

    i would not use gel batteries as the are over sold, expensive and useless
    Having recentlly bought one of his products I was very grateful for this really useful insight.

    Assuming I have a comprehensive charging system and ensure I don't over-charge them, what is the reason not to go for gels? Someone on PBO has just told me he's done 12-15 years on his gels. Doesn't that say it all?
    Last edited by demonboy; 11-01-12 at 07:15.

  2. #2
    macd is offline Registered User
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    I'm no battery expert, although there are some on the forums so I hope you get the advice you're looking for.

    I've certainly read on here that Mr Sterling's notions on gel batteries are somewhat out of date (and possibly a little self-interested). He also seems to think that 'maintenance-free' as applied to batteries is an oxymoron. He is very clearly of the view that the only type of domestic battery that should be installed on a boat is a true traction battery (such as a golf-cart battery).

    You might be interested in this thread, especially post #33: http://www.ybw.com/forums/showthread.php?p=2800787

  3. #3
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    Gel batteries like to be charged and discharged slowly. Most boat owners want to discharge batteries slowly but charge them fast. Large alternators, battery sensing alternators, Charge boost systems such as Sterling, all will reduce gel batteries life thus mitigating any cost benefit. Gel batteries also seem to be particularly sensitive to being incorrectly wired - parallel with positive and negative from opposite ends of the parallel lines is essential. Many boats (including proffesionally fitted) do not have this but if not so fitted the warranty is voided on some makes.

  4. #4
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    vyv_cox is offline Registered User
    Location : North Wales, sailing Aegean Sea or Menai Strait
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    I bought a three-year old motorhome with a gel domestic battery. This duty is pretty similar to that of a boat but the charging system is more sophisticated than many and the engine runs more often. The battery was totally dead. I realise that this is a long way from being a controlled evaluation but it is significant that the original flooded acid starter battery was perfect for some years afterwards.
    Answers to some technical queries at http://coxengineering.sharepoint.com

  5. #5
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    Well, having done further research since my OP, and also finding a possible supplier of AGMs, I think I'll knock gel on the head anyway and plmup for AGMs. I don't trust myself with this careful charging of the gels and it sounds like monitoring them would be as time-consuming and painful as topping up open lead-acids, which defeats the whole object. I guess I should go with what a lot of people are saying on these forums about AGM.

    I do find Mr Sterling's responses aggresive and childish, especially as he knows I am a new customer of his having just laid out over two hundred quid for one of his bits of kit, but I digress...

  6. #6
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    Again, and opinion from me, as there are people on here that know far more about the finer chemistry of batteries, but I did do a fair amount of research before deciding on mine.

    I ended up going for a 200ah AGM. It was a Lucas from the local battery shop. Not marine specific, and cost me 200 notes.

    So, here's why I decided to go AGM.

    AGM is a bit more robust. It has a lower internal resistance, so charges more efficiently. If you are using solar cells, this is obviously helpful as you don't want your precious charge being resisted. They can be used for big power draws, so you could, in needed, use any of your domestics to crank the engine. Finally, they have more "usable" capacity, so pound for pound, you get a bigger battery - i.e. if you needed to (probably not advisable) and AGM will discharge way further than a gel or flooded battery.

    Somebody is probably going to come along and argue, as is the nature of a forum, but that's what a couple of weeks of pondering led me to understand.
    http://onkudu.com 4 years living on a 21ft boat. 1 month on a 32ft.

  7. #7
    macd is offline Registered User
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    Quote Originally Posted by demonboy View Post
    I do find Mr Sterling's responses aggresive and childish...
    You're not the first. He can be nice as ninepence, but then...

  8. #8
    Blue5's Avatar
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    Quote Originally Posted by demonboy View Post
    I do find Mr Sterling's responses aggresive and childish, especially as he knows I am a new customer of his having just laid out over two hundred quid for one of his bits of kit, but I digress...
    Sounds like you spoke to him on a good day, he is very good on his subject sadly his customer service skills need to be honed.

    The good thing about forums like this if you are pre warned about his nature you can make allowances....

  9. #9
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    OK, thank you all for your comments. I appreciate the comparisons and the experiences too, it's reaffirmed what I said in my previous post. Despite wanting to carry on the discussion about a certain electronics manufacturer I think I have the answer I was after.

    Thanks, all

  10. #10
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    Quote Originally Posted by demonboy View Post
    According to the figures, gel batteries appear to be the most obvious choice for a liveaboard. Their longevity is second to none, yet I am told I should be looking at AGMs. However according to the West Marine catalogue, AGMs can only be deep cycled 300 times, versus gels which can cycled 1,000 times.
    If you want high number of cycles, traction batteries will far out perform gels. look at this range - http://www.exide.com/Media/files/Dow...ic%20Solar.pdf

    I've tried AGM and found they're not worth the extra cost, now back on bog standard 110AH leisure, cheap and easy to source. Wouln't put sealed or gel near my boat, want to charge quickly when the need arises and keep everything simple. Golf cart would be best but I'm restricted on "footprint" area to get them in.

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