bigal.nz 59 Posted September 5, 2019 Share Posted September 5, 2019 It would have to be a violent movement... The real answer is not to use wet cells. Gelled VRSLA or AGMs dont have this issue. Acid Stratification Prevention Acid stratification can occur in conventional flooded cells. During charge, acid is released at the plate surfaces. During discharge, acid is consumed at the plate surfaces. Since the concentration is not uniform, diffusion (spontaneous mixing by random molecular motions) begins. If this mixing occurred rapidly, stratification would not occur, but it is relatively slow, allowing lighter parts of electrolyte to “float” toward the surface and heavier parts to “sink” toward the bottom. The top portion of the plates do not perform as well in contact with lower concentration electrolyte. The bottom portion of the plates do not perform as well with the higher concentration and will corrode prematurely. High voltage “equalization” charging is sometimes used in flooded batteries to make gas bubbles that remix the electrolyte. Immobilized gel or separator-absorbed electrolyte will not“float” or“sink” within itself when a non-uniform concentration exists so it cannot stratify. Therefore, no high-voltage equalizing charge is necessary. Simply recharge at the recommended recharge settings. This means longer life and consistent performance. Is AGM or GEL better for Yachts? Quote Link to post Share on other sites
Island Time 1,235 Posted September 5, 2019 Share Posted September 5, 2019 IMO gel VRSLA is best for our apps, or lithium. KEY BATTERY BENEFITS GEL AGM Premium maintenance-free design Yes Yes Spillproof construction, won’t leak if turned sideways Yes Yes Minimizes terminal corrosion Yes Yes Superior deep cycle life and resiliency Yes Yes to deep discharge damage (Best) (Good) Operates at severe angle or on side (won’t leak or spill) Yes Yes Low to no gassing Yes Yes Ideal for use around sensitive Yes Yes electronic equipment Extended shelf life Yes Yes low self-discharge rate Yes Yes Enhanced recharging efficiency Yes Yes AGM (Absorbed Glass Mat) batteries The electrolyte in AGM batteries is completely absorbed in separators consisting of matted glass fibers. This causes them to be spillproof, meaning they don’t leak acid like a flooded design if tipped on their side. The glass mats in AGM batteries are wrapped around the positive plate, which helps prevent damage from vibration and extend cycling. The battery’s groups are packed tightly in the case partitions also protecting its power producing components. AGM battery designs can have over twice the cycle life of a conventional flooded product in the right application. Gel or Gelled Electrolyte batteries The electrolyte in a Gel battery is permanently locked in a highly viscous gelled state instead of the traditional liquid form. Because there is no liquid-type electrolyte, it will not leak out of the battery if tipped on its side. The thick, gelled electrolyte and tightly packed groups also protect the battery’s power producing components. Gel battery designs have a superior deep discharge resiliency and can deliver over two to three times the cycle life of an AGM product in the right applications. 1 Quote Link to post Share on other sites
Fish 0 Posted September 5, 2019 Author Share Posted September 5, 2019 Sorry about all the drama you are having Fish. I will ansewer the care for FLA question first. By the way, apart from ensuring the batteries remian topped up both with water and with charge, you are doing nothing else wrong. 6 months Warranty?? come on manufacturer. In fact I would be steering clear of any deep cycle battery that has only a 6 month warranty. It means it is not fit for purpose. Thanks wheels, it is nice to have someone validate that we are doing the right things to care for the batteries. And its not really any drama, I mean, if I didn't have technical issues to work through and projects / problems to resolve, I might get bored and need to go sailing or something... Quote Link to post Share on other sites
Fish 0 Posted September 5, 2019 Author Share Posted September 5, 2019 Damn you auto correct. Dust I meant. We don't get dust. But our engine is brand new, with a factory aligned alternator. That and our alt is only 70 amps. Our old engine had an 85 amp alt, if we got any dust we would either check the alt alignment, or tighten / replace the belt asap. As has been stated, any alts over about 80 amps are too big for one belt, and will stuff the belt / slip / produce dust quickly. Quote Link to post Share on other sites
bigal.nz 59 Posted September 5, 2019 Share Posted September 5, 2019 We don't get dust. But our engine is brand new, with a factory aligned alternator. That and our alt is only 70 amps. Our old engine had an 85 amp alt, if we got any dust we would either check the alt alignment, or tighten / replace the belt asap. As has been stated, any alts over about 80 amps are too big for one belt, and will stuff the belt / slip / produce dust quickly. Yes - that sounds about right we have a Balmar 90 Amp alternator. Plenty of dust. I intend to derate it. Quote Link to post Share on other sites
Fish 0 Posted September 5, 2019 Author Share Posted September 5, 2019 A similar issue, I have 4 x Trojan T105 6 volt batteries, 5 + years old, one is always wet around the caps ( and only that one) They are serviced regularly, at least once a month in the winter and often more than that. 2 solar panels keep them charged, 1 x 75w probably at least 15 + years old and 1 x 100w at 1 year old all through an Epever 20a mmpt controller. The "wet"battery doesn't show any difference between cells when checked with a hydrometer and is consistent with the "dry top ones?????? any and all suggestions welcome. We've got the same solar controller. It does an equilisation charge once a month 'automatically'. I've never been comfortable with it doing this 'unsupervised', but haven't really worried about it until now. I was just starting to notice water outside the cap on one or two cells. It was kind of annoying but I didn't give it too much thought. I might pay more attention now. My understanding is that when doing an equilisation charge, you should take the caps off(?) cause it bubbles away like crazy, and to closely monitor the water level. This is of course in the context of doing one at home in the garage, as apposed to automatically on the mooring. Is it possible your controller is giving it heaps (equalisation) that you aren't aware of / while you aren't looking? It is a plausible explanation for water outside the cap. It could also explain why my cells were going dry. The data logger that Farrari recommended for these controllers would answer the question of what is going on with the equalisation charge (I've never actually seen it occur). If I need equalisation to prevent stratification, and the equalisation may be causing my plates to dry out, I'm thinking the $50 odd for the logger may be worth while. The alternative is to disable the equalisation protocol, but then I'll have to lug the batts home for a proper equalisaton, and with best intentions, that wont happen as often as it should. Quote Link to post Share on other sites
Fish 0 Posted September 5, 2019 Author Share Posted September 5, 2019 The real answer is not to use wet cells. Gelled VRSLA or AGMs dont have this issue. Mwahahaha, yes, I am aware of batteries that need less maintenance, or are maintenance free. Apparently, you can get boats that are nice and shiny and brand new, and don't need any work done on them at all..... some even come with a seven year warranty. Unfortunately the associated cost is a critical factor. The choice is either get the batts that need the maintenance, or not own a boat at all. We researched other battery options and deliberately went with FLA on the cost basis. With a 35 yr old boat, it is very easy to over capitalise (he says after just installing a new engine, prop shaft, dripless shaft seal, rudder tube, rudder bearings etc etc). How do they say "we have to cut our cloth to suit our budget"... I'd like to think that by doing crazy things like reading the manual, understanding our batts and their limitations, and taking good care of them, we can get 10 yrs out of them, like we did the last ones. Quote Link to post Share on other sites
Island Time 1,235 Posted September 5, 2019 Share Posted September 5, 2019 I understand about operating cost. However the normal life of a wet cell batt, discharged to 50%, is about 300 cycles. An AGM VRSLA is 300-600 cycles and a VRSLA Gel is about 600-1000. Lead carbon can be 4000 or more. Cost is not just about the purchase price, but the total cost over the products useful life. Cheapest is rarely best. The wet cell units deteriorate more on float than any of the others as well... Certainly you get more life with the correct use, so its well worth reading the manufacturers PDS. Quote Link to post Share on other sites
Island Time 1,235 Posted September 5, 2019 Share Posted September 5, 2019 Oh, and that education session I'm doing at Gulf Harbour yacht club is Wed 18th at 7pm. Free for members and maybe a small donation from non members. Batteries, Types, selection and Mantenance, plus how to use your multimeter. BYO meter, best to practice with what you use. A demo circuit will be used to show voltage drop fault finding and remedies...plus some more if there is time. It's pretty casual. Tea/Coffee $2 donated to the youth sailing trust. All welcome. Quote Link to post Share on other sites
wheels 543 Posted September 5, 2019 Share Posted September 5, 2019 Interesting list of battery benefits IT. I don't disagree with any of it. Although I have always placed AGM over Gel for one reason. That is the possible creation of gas bubbles in the gel when hard charging and once bubbles have been produced, the battery is pretty much shot. So hence the use of them in standby use like UPS etc. Quote Link to post Share on other sites
Island Time 1,235 Posted September 5, 2019 Share Posted September 5, 2019 Indeed Wheels, but that is why they have a max charge rate. Again,read the PDS, and follow the instructions! AGM are better for large loads over shorter time, Gel better for smaller loads over longer time. And, just to confuse matters, lead carbon are better than both! Quote Link to post Share on other sites
Fish 0 Posted September 5, 2019 Author Share Posted September 5, 2019 Back to the stratification and equilisation question, I understand equalisation has two elements to it, 1) the bubbling and physical mixing of the electrolite, so as to prevent stratification 2) bringing 'lazy cells' up to full charge by running 16 volts over all the other cells, so that the voltage can reach the lazy cell (apologies for incorrect technical terms for the concept). Being on a mooring, without shore power, and not wanting to go near one of those eWoF palava's, I'm looking for an effective way to manage / avoid stratification. I don't know if the solar controller equalisation charge has done anything, on the basis I've had issues with the batts, it would appear to be in-effective. Would it work to physically mix the electrolite in each cell with something like this hydrometer sucker / dropper? If the cells are effectively mixed, do you still need to run 16 v over them to get the lazy cells up to charge? or would mixing the cells improve performance so they take the same charge as the other cells? The other way to ask this question, is what comes first, stratification or high resistance / poor charge in a cell? Quote Link to post Share on other sites
wheels 543 Posted September 6, 2019 Share Posted September 6, 2019 To answer in reverse order, yes the equalisation charge does three different things. It helps to break sulphation crystals away form the plate surface. The much higher charge voltage (but very low current) causes the plates to charge to 2.5V/cell. This is the maximum the plate can go to and this kind of charge " equalizes" all the plates to the same equal voltage level. The last part is the stirring up of the Electrolyte. To anawer your question Fish, basically no, you would have no way of stirring the acid up enough to mix it, even by squirting the electrolyte. In fact, the sludge that falls to the bottem could be stirred up and if that gets on the plates, it will only degrade the charge and worse case it could short two plates.Doing an EQ charge monthly may or maynot be needed. A better method is to apply a fully saturated charge and then compare the specific gravity readings (SG) on the individual cells with a hydrometer. Only EQ if the SG difference between the cells is 0.030.While an EQ charge can help. it can also damage the battery. When in an EQ charge, check the changes in the SG reading every hour. When the gravity no longer rises, stop the EQ charge. No further improvement is possible and a continued charge would have a negative effect on the battery. Quote Link to post Share on other sites
bigal.nz 59 Posted September 6, 2019 Share Posted September 6, 2019 The MT50 records solar energy, KW hrs etc. Not battery max charge/discharge and max/min voltage which is what you want. IMO every boat should have a battery computer. Without one, you have no idea the state of charge of your battery. The one on the solar controller is so inaccurate as to be worse than useless, as it may lull you into a false sense of security. To get an accurate state of charge from a lead acid battery requires it to rest (no charge, no discharge) for >10 hours. No one does that on a boat. Most people discharge the batts much more than they think they do.... Just got a BMV712 up and running today. +1 the logging. I love it. Quote Link to post Share on other sites
mcp 32 Posted September 8, 2019 Share Posted September 8, 2019 lead carbon are better than both! With the exception of high drain loads causing high voltage sag. I would still use an AGM [maybe the diesel motors battery] for the windlass and would have very short runs or over sized cables to high current consumers. They can be fussy with charging, as with most new battery types. I really am on the fence about going Lead Carbon or Lithium Iron Phosphate. Quote Link to post Share on other sites
Island Time 1,235 Posted September 8, 2019 Share Posted September 8, 2019 Agreed, but then there is the debate about running windlass from house or start banks. Windlass is a high load for a short time, which is what a cranking battery is for.... The minimum charge rates for (at least some of) the carbon based batts are an issue if you have solar as well. There is currently still no perfect solution. I use VRSLA gel....but likely next time will be something completely different. Quote Link to post Share on other sites
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