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Fish

House Battery Issue

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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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