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Old 16-07-2015, 07:56   #1
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Best practice for desulfation battery bank

going to go through my battery system when the boat is hauled out for the season later this year (check/change ends of all cables, etc)

For the past couple years, it seems the batteries don't seem to hold 100% for very long and drain pretty fast. Moreso now that I added refrigeration!

The house battery bank is 2 rolls 262 6v , maybe 4 years old.

alternator is a balmar with 614 regulator

The system also has a Bass brand analog volt and amp meters.

off season I use this charger West marine 30a charger

During the season using a fuel cell to keep up the charge because of the refrigeration.

Several times the battery bank did go flat on me by accident. I know, not the best thing for a battery.

Was wondering if the batteries just need a good desulfation. Before I do anything of this sort.. what would be the best practice on how to do it. Would the desulfication mode on the charger I own be good to use.. or would there be something better to use?

I assume the batteries should be brought off the boat to do this.

water level is checked regularly and has never dropped to expose the plates.

Also, any suggestions on a good battery hydrometer?

What would be a good course of action to bring back the performance of the batteries?
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Old 16-07-2015, 08:12   #2
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Re: Best practice for desulfation battery bank

Yes check the specific gravity with a hydrometer. Any auto store hydrometer should be ok. To equalise you probably want to raise the input voltage to around 16V for 4 hrs or so. Keep well ventilated and monitor battery temperature as you do it as per the charger instructions.
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Old 20-07-2015, 09:45   #3
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Re: Best practice for desulfation battery bank

Thanks...

was wondering if the charger I had (link in my message) was good enough, or is there a better procedure.

Also, how can I tell if they are actually sulfated?
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Old 20-07-2015, 10:03   #4
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Re: Best practice for desulfation battery bank

Have you ever done an equalizing charge? Other than keeping the charge up that's about all you can do.
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Old 20-07-2015, 10:28   #5
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Re: Best practice for desulfation battery bank

Whether they are desulfated is determined by testing the battery capacity. Any lost capacity would be assumed to be lost to sulfation. Ideally, you will have tested the batteries occasionally from new, so that a baseline is established. I test mine yearly.

My "cheap and cheerful" test is to withdraw half the rated battery capacity, over 20 hours, determined by my amp hour meter, then measure the voltage after a resting period. There are voltage vs. charge state charts on the web.

If you search Mainesail's posts you should be able to find a more rigorous (and time-consuming) version of the test that their yard does.

My old batteries held up well for 5 years, then dropped rapidly. My new batteries (two months old) currently test at EXACTLY rated capacity. I will monitor this over their life.

It might be interesting to do this test both before and after your desulfation treatment?
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Old 20-07-2015, 10:35   #6
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Re: Best practice for desulfation battery bank

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Originally Posted by phantomracer View Post
Also, how can I tell if they are actually sulfated?
I have not worked with your brand of battery but for similar-looking (flooded, real deep cycle, etc) models from Trojan the usual criteria for diagnosing sulfation is the combination of:

- When you measure Open Circuit Voltage with 24 hours of rest after charging as normal you the "right" value as per the manual (say 6.37V for Trojans); but

- Specific Gravity is still way lower than what the manual says it should be (1.277)
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Old 20-07-2015, 10:52   #7
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Re: Best practice for desulfation battery bank

going to check the SG of each cell this week to ensure they are all pretty close. maybe there is a bad cell.

Since i have refrigeration going , i can't really get a good resting SG reading until the off season.

havent done an equalization charge yet. might do it this winter.. or maybe bring them to the rolls distributor for them to test/equalize them this winter.

I guess it is all academic until I can get the SG tested in each cell.
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Old 20-07-2015, 10:55   #8
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Re: Best practice for desulfation battery bank

Talked to the rolls battery dealer. he said it could be as simple as not getting a full enough charge..even with the balmar alternator.. even though it hits it at 14.8v for over an hour and goes through its program.. I guess it is the SG that counts.. not the voltage at the terminals.
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Old 20-07-2015, 11:08   #9
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Re: Best practice for desulfation battery bank

Here's an ebay link to a decent hydrometer:

OTC 4619 Professional Battery Hydrometer New Free Shipping | eBay

(no affiliation, just recommending a product)

IMHO, if you was to take readings that are meaningful make certain that your hydrometer has a temperature compensation scale, preferably with a built in thermometer too. This one does and is affordable enough, you can find cheaper ones shipped direct from China but for less than $13 shipped I see no need.

Also, I looked at your charger and the equalization setting should be fine.
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Old 20-07-2015, 11:24   #10
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Re: Best practice for desulfation battery bank

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Originally Posted by phantomracer View Post
going to check the SG of each cell this week to ensure they are all pretty close. maybe there is a bad cell.

Since i have refrigeration going , i can't really get a good resting SG reading until the off season.

havent done an equalization charge yet. might do it this winter.. or maybe bring them to the rolls distributor for them to test/equalize them this winter.

I guess it is all academic until I can get the SG tested in each cell.
For practical purposes you do not need "rest" for the SG. You can do it today after a full charge.

The rest is only necessary to determine if the battery is fully charged on the basis of voltage. Two usual ways to determine if batetry is fully charged without disconnecting the fridge for several hours:

- Disconnect the batteries (just need to disconnect one terminal!) and keep charger connected to the panel and all the loads. Some chargers will have a special switch position to keep voltage fixed while you do this.

- Forget about using OCV to determine State of Charge and rely instead on measuring current that goes into the battery at absorption voltage (say your 14.8V). For Trojans you can consider them to be 100% charged when current (in amps) at 14.8V or so drops to capacity in Ah times 0.01 or 0.02. For your battery this would mean that current into each battery drops to 2.6A.

This current may be too small for any analog amp meter built into the boat, and is also small for most amp clamps. If you do not have a battery monitor connected to a shunt next to the battery then you can use a normal multitester connected in series but this requires some nifty maneuvers to make sure you do not blow the 10A fuse in the multitester. Let us know if you want help on this.

Most importantly, if you have not been diligent in taking your batteries to 100% at least once every month (or week for AGMs) then you HAVE to expect serious sulfation. After all, if you do not charge your battery to 100% once a month then every Ah of capacity that was not filled turns into a welldefined number of sulfur atoms that end up deposited on the plate as sulfate molecules and if you leave them there for too long the sulfate will "harden" and equalization will not be very effective to dissolve it.
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Old 20-07-2015, 11:38   #11
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Re: Best practice for desulfation battery bank

Quote:
Originally Posted by phantomracer View Post
it. Would the desulfication mode on the charger I own be good to use..
That WM charger shoulf be fine, at least it is fine for Trojans of roughly the same specs.

Quote:
Originally Posted by phantomracer View Post
I assume the batteries should be brought off the boat to do this.
I have never taken batteries off the boat for equalization. Just make sure there is good ventilaiton and you wear gloves and goggles.

Quote:
Originally Posted by phantomracer View Post
What would be a good course of action to bring back the performance of the batteries?
I will give you a recipe with a health analogy.

1) Equalize them now. This is equivalent to operating someone with heart disease.

2) Equalize them to 100% charge (measured as I told you; ie battery takes less less than 3-5 amps while you hold voltage at 14.8V) at least once every other week. This is equivalent to not smoking, going for a walk every day, etc. Do not let your battery monitor tell you that the batteries are full unless you have seen the amps they take at 14.8V and that is below 5 amps- Mainesail has written good stuff on this.

If you will not do 2 just do not waste your time in 1.



Replace 3 amps with a better number form Rolls if available.
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Old 21-07-2015, 08:01   #12
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Re: Best practice for desulfation battery bank

Thank you.. on a mooring.. the marina frowns upon us dragging out hundreds of feet of extension cable to the boat to run a battery charger

will do it on the off season.. or if i can get some time at the dock

I do have a methanol fuel cell keeping the bank charged.. unsure if it gets to 100% (I doubt it)

The balmar alternator does a good job of hitting the battery with a good charge and going through its several stages til it gets to float.. No doubt even running the engine all day still won't bring it to 100%. Rolls said it might take 8 hours to bring it to 80% and possibly another 8 to bring it to 100%, if the battery was totally flat. That sounds a bit long to me..

For when its on the hard, is the 30a 'smart' charger that I am using a good choice? It seems to charge it fairly fast, and keeps coming on at low amps every few minutes (assuming it is floating it to bring it up to 100% smartly). Would a regular 30-50a dumb charger be better?
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Old 21-07-2015, 08:13   #13
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Re: Best practice for desulfation battery bank

Quote:
Originally Posted by phantomracer View Post
Thank you.. on a mooring.. the marina frowns upon us dragging out hundreds of feet of extension cable to the boat to run a battery charger

will do it on the off season.. or if i can get some time at the dock

I do have a methanol fuel cell keeping the bank charged.. unsure if it gets to 100% (I doubt it)

The balmar alternator does a good job of hitting the battery with a good charge and going through its several stages til it gets to float.. No doubt even running the engine all day still won't bring it to 100%. Rolls said it might take 8 hours to bring it to 80% and possibly another 8 to bring it to 100%, if the battery was totally flat. That sounds a bit long to me..

For when its on the hard, is the 30a 'smart' charger that I am using a good choice? It seems to charge it fairly fast, and keeps coming on at low amps every few minutes (assuming it is floating it to bring it up to 100% smartly). Would a regular 30-50a dumb charger be better?
Your setup looks to me like guaranteed sulfation. You might as well not even bother to equalize. For $600 you can get two 100W flexible panels and a Victron MPPT controller that will carry the fridge and more. Add a 2-hour engine run at sunrise once a week to take it to 80% or so and let the solar top it up to 100% (which requires many hours but does not require huge current) through the day. Ten your batteries will last more than 5 years. if you have enough of a surplus from solar you may even do away without the engine run most weeks.

I do not how "dumb" a charger you are asking about, but clearly for shorepower you want a 3-stage charger and not just any of them, you need one that will switch to float at the right time for your bank, most of them will switch too early (if time based) or will never switch (if base don current at the charger and you run a fridge).
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Old 21-07-2015, 08:39   #14
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Re: Best practice for desulfation battery bank

The fuel cell puts out pretty good current (6.x a) day and night...and is keeping up with the draw without batting an eyelash. Solar is just not an option. I might get a small one to assist during the day, but don't have the real estate for permanent panels.

The dumb charger i just meant the old school ones that just pump out amps without stages like most of todays...just trying to figure out if the charger I have is a good choice or if there are better ones.

Unless I run out of methanol (only once so far) the battery never drops below low 12v (12.2 maybe) as the fuel cell kicks in and hits it with 6.x amp til it gets to 14.2v and goes into a multi stage float program. It just seems to be coming on more than I expected, leading me to my original question about best practices and keeping the system in good health.
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Old 21-07-2015, 09:28   #15
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Re: Best practice for desulfation battery bank

This fuel cell is a form of battery charger? Or is it making 6 amps of 110V power, that runs the regular battery charger?
Sorry, but as your on a mooring, I don't understand where the 110V power to run the WM charger is coming from.
Sounds like the fuel cell monitors battery voltage and comes on automatically to charge the batteries?
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