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House Battery Issue


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#1 Fish

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Posted 13 August 2019 - 08:58 PM

I've got new (18 month old) FLA house batteries. 2 x 6v. One has started boiling it's cells, so twice now we've found the cells 'dry' (being the tops of the plates are out of the liquid). The other battery has taken water, but has never dried a cell (3 cells each battery). 

They are Exide 220 amp hrs.

 

Is this a sign the battery is stuffed, or a possible over charging issues? They are still within warranty.

 

We have 2 x 90 watt solar panels going through an MPPT controller. I was very careful in setting up the controller exactly as the battery manual said. The engine alternator is 70 amps, internally regulated. I don't actually have the details on the internal regulator regime. The batteries have had very little use since installation, and very little load demand put on them. I have noted that the cells are slowly bubbling with the engine running (i.e. normal charging), although the solar controller indicates they are fully charged, or close enough. Start battery is AGM, and is on a separate solar float charger.

 

We are on the verge of diving in and sussing everything, and our initial thought is an issue with how we've set up the new engine alternator, but given its only one battery boiling cells dry, wanted to ask the collective wisdom if this sounds like a battery fault and not a charging issue?


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#2 Island Time

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Posted 13 August 2019 - 09:19 PM

It could be either. Is the battery with the water being used all the cells in the battery, or a couple? If its all, then its a load balance issue - that batt is doing all the work. If thats the case, then there is likely excess resistance in the system. This can be in a battery,  a wiring problem, a terminal, or a connection. A proper voltage drop test it required to identify the issue. 

The battery cabling MUST be that the positive cable to the distribution loads comes from one batt, and the neg from the other, with no other cables to the terminals. 

A wiring diagram is required to be sure whats going on. It is not likely to be any alternator issue, but where the engine neg is connected, and how the B+ terminal of the alt is connected could potentially be charging that batt at 12v!!

Cant say much more without looking.


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#3 wheels

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Posted 14 August 2019 - 05:22 AM

Adding to IT's comments. There is one other possible.
Do you have any kind if water recovery caps fitted? If you do not, then it could be simply a case of water depletion due to evaporation. It is normal that water evaporates and requires constant refilling. The charge voltages are much higher than Vehicles, so as the battery gets fully replenished. But this leads to the battery evaporating water.
However, exposed plates can cause the plates to be damaged. This then can cause a charge imbalance and one battery can end up taking a greater charge current over the other, which then starts a cycle of more evaporation, more damage, more current more evap......and the situation spirals.
Recovery caps can usually be fitted. They stop the water from escaping from the cell, but the gasses can still get out.
The other possible is that the batteries need an equalization charge to equalize the cells. This should be done at least once per month for batteries sitting unused over Winter and then both Batteries will draw the same charge current. Hopefully a top up and equalization charge will restore them if not too much damage has been done to the plates that have been out of the water.
And finally, if they are still under warranty, top them up to proper level, give them a charge and then call the marine sparky (or return them to where you bought them) and have them tested. If one is reading badly enough, then you might be able to get a replacement under warranty.
 


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#4 Fish

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Posted 14 August 2019 - 08:41 PM

Thanks for the help guys.

The battery supplier has offered to take the batteries (we drop them off) and assess them for a warrantee issue. We will go down that path and have the batteries checked, and rule that in or out, before we dive off and check everything else on the charging side. There is nothing obvious on the charging side. We figure we need to take them off the boat to do a descent equilisation charge and suss voltages and resistance etc anyway, so this option looks straight forward.

 

Yes, the cells going dry are all on the same battery. The other battery hasn't had any go dry (we do top up the water as per usual FLA maintenance).

 

Ironically, we have contacted a couple of auto lectricians to investigate changing the alternator from internally regulated to externally, so we can set up a smart charger. They are all telling us that the alternator is too small and likely to get fried (heat dissipation capacity)... Where as the problem I'm addressing is a possible frying of the batteries, not the alternator... argghh. I'll park that issue until I have alternator issues (gotta love boating).

 

On a practical point, what is it best to do with the solar panels when I take the batteries off? I assume just disconnecting them breaks the circuit, but surely they are still producing ergs, and the ergs need to go somewhere? We are pondering taking them off for a bit, since we aren't actually using them / needing the power, while we sort issues and its not hot summer / fridge running / cold drinks drinking season yet (oh, the dream, a cold drink in a calm bay on a long summers evening, with no phone, jetski's or any other hassles)


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#5 Island Time

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Posted 14 August 2019 - 10:00 PM

Hmm, Fish, if the batts don't test ok, then it could be the wiring that's the issue. It could be the root cause, and can damage the batts. You (or anyone else) can't test the wiring without the batts in place. Battery and cable voltage drop can only be properly tested under load. What it does without load is irrelevant. If they do test ok, the problem is in the installation/cabling. If it were an alternator issue, both batts would be dry.

Heat dissipation in an alternator is a big problem. That's why real marine alternators are hot rated - they can run at or near their rated output indefinitely. Automotive alts can and do melt and fail in apps that drive them hard. Some external regs, like the balmar ones, can have temp sensors on the alt, and back off the current if it gets too hot.

You can safely disconnect the solar panel cables, with no connection they have infinite resistance and no current will flow. The voltage between the cables will be higher than usual, so tape them so they can't short.

Again, I'll state, the best thing you can do is draw out the wiring of the batt/alt/charging circuit. Its a reference that all boats should have aboard, and if you post it here we may find the answer. Be certain to draw what is actually there, not what you think is there!

Simple mistakes can cause issues like this.


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#6 Aleana

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Posted 15 August 2019 - 08:36 AM

I had a long running complex and baffling similar issue that took months and loooots of $$$s to suss involving replacing every component in the system. Ultimately the rogue component turned out to be nearly new alternator that had accumulated belt dust through the cooling vents resulting in shorting within the case - and spurious charging including voltage spikes (16+) which fried my batteries. Luckily all my electronics were new enough they had auto shut-off to avoid damage.

We found this out by sending alternator away to a test specialist where problem was diagnosed and fixed - via dismantling and cleaning.
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#7 Island Time

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Posted 15 August 2019 - 08:51 AM

I'm sure that sort of thing happens quite often Aleana, at that is an unusual fault. In this case though, if it were a voltage issue (caused by the alt) it would effect both batteries. As it is uneven, it has to be a resistance or cabling fault.
What sort of crap alternator fails due to belt dust - a Hitachi?
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#8 Aleana

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Posted 15 August 2019 - 09:13 AM

Balmar 150a
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#9 lateral

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Posted 15 August 2019 - 09:25 AM

Not the first complaint I've heard on Balmar alternators.


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#10 Fish

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Posted 15 August 2019 - 09:35 AM

Hmm, we have a brand new alternator on a brand new engine, still under warrantee.

But we paid extra to get the posh instrument panel and have a voltage meter in the cockpit. Its never moved from 14.4v. Strangely.

 

The wiring etc has been inplace for well over 10 yrs and didn't give issues. That was an 85 A bosch alternator, external Balmar smart charger (with temp sensor and wind back if its cooking) going to 260 Amp hr batteries. I am curious exactly what, if any wiring we changed with the new engine install. At most one lead may have been extended, I need to check (my father did all of the lectrical work).

 

As a note, we haven't re-installed the balmar smart charger yet. Initially it was because we haven't gotten aroundtoit, and it would void the warranty on the new alternator etc, but we've just worked out the new alternator wont cope with external regulation, the frame is too small and unlikely to cope with heat dissipation. Additionally, it sounds like it would be cheaper to get a new purpose spec'ed marine grade and larger alternator than to muck around with the one we've got. Its a Slovenian thing, been in production since 1996 apparently, does the job and nothing else.

 

On the wiring diagrams, that stuff normal results in my brain scrambling itself, a very good example of why to pay someone with specialist knowledge (aka a consultant / professional) to sort it for you, in a fraction of the time and without the screw ups if doing it yourself.

IT, do you have an example of a simple engine to battery side wiring diagram?


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