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Old 24-03-2014, 18:58   #16
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Re: Replacing batteries

We use Lifeline AGM but I can get them UPS direct to my receiving dock door at OEM rates. Good service so far 5 years.

Here is a link to Bob's Blog. There is a lot of experience and good advice here on batteries and extending their life. Very long read but worthwhile. Handy Bob lives off-grid, is an electrical engineer who had enough of battery and solar systems that didn't work as advertised.

https://handybobsolar.wordpress.com/
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Old 24-03-2014, 19:00   #17
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Re: Replacing batteries

Any examination of AGMS shows a poor fit for a boat, they have many good characteristics that can't be accessed or are not applicable. And several bad characteristics that do affect boat operations.

Money is better spent on good open cell Flodded La.

gels are even worse, way to easy to overcharge. No redeeming features.

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Old 25-03-2014, 01:22   #18
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Re: Replacing batteries

My nightmare scenario is battery acid sloshing around in engine bay. Otherwise I wouldn't even think about Gel-s or AGM-s. Perhaps not a very likely situation to occur so.

Thinking of it one really should skip gel and AGM technologies when going up from open lead-acids and start to use LiFePO4 cells.
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Old 25-03-2014, 01:31   #19
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The thing is you only need half the capacity of lifepo4s than your lead acids. Lead acids should not be discharged more than 50% but lifepo4 can be discharged down to 20% SOC. The price isnt really that bad when you do the math
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Old 25-03-2014, 02:51   #20
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Re: Replacing batteries

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The thing is you only need half the capacity of lifepo4s than your lead acids. Lead acids should not be discharged more than 50% but lifepo4 can be discharged down to 20% SOC. The price isnt really that bad when you do the math
It's pretty bad if you do your math right Generally you have to budget in all the additional electronics starting from cell balancers or whatever they were and finishing with all the charging and monitoring equipment unless you already have the newest gismos. However, I would change to LiFePO4-s without any hesitation if I could reason the cost. But then again, I'm quite technically minded person and some other may feel that manufacturers of LiFePO4 batteries and -equipment are not ready for an average client yet.
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Old 25-03-2014, 03:49   #21
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Replacing batteries

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The thing is you only need half the capacity of lifepo4s than your lead acids. Lead acids should not be discharged more than 50% but lifepo4 can be discharged down to 20% SOC. The price isnt really that bad when you do the math

Yes but they are not a drop in for LA at present

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Old 25-03-2014, 04:53   #22
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Re: Replacing batteries

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My nightmare scenario is battery acid sloshing around in engine bay.

Have you heard of battery boxes?
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Old 25-03-2014, 05:05   #23
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Re: Replacing batteries

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Have you heard of battery boxes?
I actually prefer acid draining to bilge from where it's quick task to pump out with manual bilge pump. Lots of flushing to do afterwards of course. And sodium bicarbonate (baking powder) helps a lot. Have thought about it but still would not like to live through it.

My battery box has drain holes.
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Old 25-03-2014, 05:08   #24
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Re: Replacing batteries

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I actually prefer acid draining to bilge from where it's quick task to pump out with manual bilge pump. Lots of flushing to do afterwards of course. And sodium bicarbonate (baking powder) helps a lot. Have thought about it but still would not like to live through it.

My battery box has drain holes.
WOW, is your post here missing a joking smiley face?
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Old 25-03-2014, 05:12   #25
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Re: Replacing batteries

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WOW, is your post here missing a joking smiley face?
Never too serious

Well, it's like Mr. Amel designed it. And I admit I agree with him. Simple and efficient.
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Old 25-03-2014, 13:39   #26
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Lifepo4 dont need bms at the C rate we use them at. Your alternator just needs its voltage tweeked and a li solar controler is not more expensive than a normal la one. Battery monitors are usuly already existing on your boat. As LiFepo4 gets cheaper, people will stop ranting on how fragile lifepo4s are. They are actualy very tough batteries and can accept a charge amperage of three times its capacity. They dont sulfate up if left to low, and they dont loose water because they dont have any.
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Old 25-03-2014, 14:01   #27
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Re: Replacing batteries

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Lifepo4 dont need bms at the C rate we use them at.
The BMS has nothing to do with "C" rate but has lots to do with protecting against over discharge and over charge of the cells which can ruin them.

You may not ever need to use a battery management system to balance, if staying well within the knee range, but you really should have low and high voltage protection or risk a big fat hole in your wallet.. A LA battery can survive over charging and over discharging but a LiFePO4 will usually be irreversibly damaged if pushed too far.

The most beneficial part of any BMS is protecting against an HVE and LVE, not cell balancing, but people get confused and assume a BMS is all about cell balancing, it is not. For people who insist on using LA charge voltages on LiFePO4, then you really will want cell balancing. Charge to a max of 14.0V, and never go below 20% SOC, and you will likely need to top balance less than you equalize flooded batts. Push these cells over 14.2V on a regular basis and you will require more frequent balancing.
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Old 25-03-2014, 15:21   #28
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Ok then. A simple monitor and relays for low voltage cut and high voltage cut can be used. Lead acid batteries should also have this system. How that fancy name BMS comes here I do not know. Maybe BMS should stand for Balancing management system instead :0
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Old 26-03-2014, 01:14   #29
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Re: Replacing batteries

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Ok then. A simple monitor and relays for low voltage cut and high voltage cut can be used. Lead acid batteries should also have this system. How that fancy name BMS comes here I do not know. Maybe BMS should stand for Balancing management system instead :0
That's exactly what I meant. Mass use equipment is not ready. One has to be technically minded to deal with Lithiums. Or, buy from Mastervolt -- hugely expensive.
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Old 26-03-2014, 01:57   #30
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I find Lead acid more complicated IMHO
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