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House Battery Issue


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

Its actually very rare on a balmar, and this issue (Aleana's) to me sounds like it might not be the real story. Belt rubber is, well, rubber - it insulates. It can cause overheating, and I guess if there was enough of it could cause the brushes to make poor/intermittent contact, which may explain it. BUT that much belt dust would be a sign of a poorly aligned install, unstable brackets, or the wrong belt/s.

 

Fish, old wiring itself can be the issue. Ok till you moved it, now some cable damage, a bad crimp or dodgy terminal can be the cause. It is likely not to be visible. I'll find a basic diagram and post it.

 

14.4v - I know this is what many internally regulated alts are set to. Its fine for most weekend sailors, but think about this. The batteries are spec'd to have a float voltage (usually, read the batts PDS!) of 13.5-13.7v. If you do lots of motoring on fully charged batts, 14.4v is sufficient to boil the batts. Most people don't motor long enough for this to be an issue, but it can be.

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And once again, why car batteries never get fully charged. To fully charge an FLA, you need 14.4V, but once charged, it needs to go back to 13.5/13.8 float voltage. Cars charge at 13.8 and never get above 75% full charge. But if the Alt was set at 14.4, it would boil the battery.
Just to add to IT's comments, it can also be a case of one battery getting hotter than the other due to what is around it. Once the Battery gets hot, the charge needs to be reduced. If one is getting hotter thgan the other, from say the Engine heat or against a wall or something, then it could end up getting over charged. Just clutching at straws of course. But it is so difficult for a new battery to have a shorted cell, it is hard to believe. Besides, the Voltage would be down on the battery by 1.5V.
Two 6V batteries in series should not be affected by a wiring issue either though. That kind of fault should affect both batteries.
 

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Maybe Wheels, depends on how the charge sources are connected.  Here is how it should be, IMO.

 

Basic 6v batt circuit.jpg

 

This is a basic diagram. It would be sensible to switch the batteries as well, to enable complete disconnection if required. That is required for commercial vessels. 

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I wondered if one of the charge sources, say the solar, is connected to the neg terminal (for example) of the wrong battery, hence charging it at 12v ?? I've seen that before. This is why remote diagnosis is very hard, what an owner sometimes thinks is there is not actually there.....

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14.4v - I know this is what many internally regulated alts are set to. Its fine for most weekend sailors, but think about this. The batteries are spec'd to have a float voltage (usually, read the batts PDS!) of 13.5-13.7v. If you do lots of motoring on fully charged batts, 14.4v is sufficient to boil the batts. Most people don't motor long enough for this to be an issue, but it can be.

I think this may be the issue.

 

I just want to confirm my understanding of an internally regulated alternator.

They do 14.4 v all the time.

The purpose of the regulator is to ensure they don't produce greater volts as engine revs increase.

If / when the battery is fully charged, the resistance increases, so they take less current, but the voltage is still 14.4 v.

The theory is the battery (when fully charged) wont take the current, even though the alternator keeps on trying to give it. My issues with this is the power still has to go somewhere, and is dissipated by boiling off the battery water. This is fine for short periods, but long periods or over time, I'm going to get dry battery cells, and ... stuffed batteries.

 

This would be fine in Wheels scenario, where the system is set up so the battery is never actually fully charged. With the long tail to full charge an FLA, its moderately unlikely to actually manage to get that last 20% into the battery by engine use.

 

ACCEPT, being a clever clogs, I've gone and put 180 watts of solar panel and a posh MPPT controller onto the house batteries - all set up to get them to fully charged, especially while the boat is not in use, so I can run the fridge, stereo, fans and as many lights as I want when I do go out on the boat (without the engine running).

 

It appears my new solar system is effective at keeping the batteries topped up. Every time I check it, it is at float charge (13.4 v or 13.5 ish).

So now, every time I run the engine, I'm just over charging the batteries...

 

Checked it today, batteries were 13.5 v on solar. Started the engine and everything went to 14.43 v, being the batteries, and a check of the alternator output (taken at the master switch), still being 14.43 v.

 

So if this is my issue (fully charged batteries on solar, over charging every time I run the engine) it would appear my options are:

1) disconnect the posh solar gear short term in order to save the batteries

2) retro-fit a smart charger to the alternator to resolve the over charging issues, or

3) get a Booboo spec stereo and increase the electrical load with every appliance I can find to try and balance the load and power consumption (or just flatten the batteries a bit so the dumb alternator can charge them back up...)

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For what its worth we occasionally have a similar thing happen in our off the grid set up of 15 years . typically we run two sets of 4 6v lead acid 220ah batteries  in series (24v system) with the two sets paralleled. last summer 3 of the batteries (in one bank) started needing frequent top ups but the system seemed normal in everything else.early one morning before the sun came up i noticed amongst all the 6.2s and 6.3s i had a 5.8v on one battery (less than two years old) - changed it with a new one and all is well again... By any chance Fish have you compared the resting voltage of them? I know you have a couple of guru's onto it but i thought i'd put in 5c worth anyway...

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So if this is my issue (fully charged batteries on solar, over charging every time I run the engine) it would appear my options are:

1) disconnect the posh solar gear short term in order to save the batteries
No, don't do that. They are doing their job.

 

2) retro-fit a smart charger to the alternator to resolve the over charging issues, or
Yes, best idea.

 

3) get a Booboo spec stereo and increase the electrical load with every appliance I can find to try and balance the load and power consumption (or just flatten the batteries a bit so the dumb alternator can charge them back up...)
Nope, it won't solve any problem, just create a whole heap of new ones for you and for all around you.
 

I would also look for water saving caps for the batteries to stop evaporation.
  Some reasons the battery is losing water and not the other is, maybe it's getting slightly warmer than the other and thus evaporating more, or those cells affected may have slight differences in resistance, enough to make the cells hotter during a long period at full charge.

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We have taken the batteries off the boat and are going to check the resting voltage this morning (after having let them rest overnight), I'm looking forward to seeing those answers.

 

To muddy the water a little, I have added water to the other one, but it hasn't dried it's plates. We haven't been measuring the water in, so its very qualitative, and it may just be that the one with the dry plates is because we didn't actually add as much water. I've got a posh water adding measuring device (that automatically fills the water to the same level above the plates) and I am about to put it on the boat... been in the shed for a long while.

 

On the temp thing, the battery box is well away from the engine and heat sources and is effectively symetrical. I can't see how one battery could be warmer than the other.

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