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House Battery Issue

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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. 

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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.

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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!

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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?

61BH100.jpg

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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.

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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.

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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.  

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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.

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