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Battery voltage dropping rapidly!


RosieR
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Hi! I have two 12V 230Ah domestic batteries with two large big solar panels, a beta marine 43 that seems to charge the battery well (I’m pretty sure it’s not an alternator problem). The issue is that my batteries seem to drain SO quickly. Just charging phones the level sits around 12.9ish but I can put my lights on (LED) for literally 3 minutes and my voltage will go from 12.9 to 12.2. I don’t have an inverter, I use a plug in 12v inverter to charge my laptop and I cant use that at all without the engine on. I turned my 12v fridge off at the end of summer as the days got shorter but as the suns put more the battery health seems worse than ever!

The batteries are 6 years old but maybe they’re just old but I’m not sure. Any comments would be incredibly appreciated! And any advice on maintaining battery health ❤️

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Edited by RosieR
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Hi Rosie,

On the face of it your batteries are probably totally goosed. The questions about how and why will probably flow thick and fast now. I'll start!

 

1) How often are you running your engine in the winter to charge them? (Or do you have shore power?)

2) What charge monitoring device do you have? (Other than that solar controller.)

3) Have you done a power audit so you know what your daily power consumption is?

4) Have you checked the electrolyte levels under those battery caps recently?

5) How long have you had the boat?

6) Do you live aboard or is it a hobby boat?

 

Regarding advice on maintaining battery health, read the battery primer pinned in the maintenance section.

 

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Not enough info for a good diagnosis.

 

How long do you charge for and at what revs?

Are the ends of the batteries bowing out?

How do you know when to stop charging?

 

First possibility - batteries not being charged enough

Second possibility - batteries lost capacity due to persistent undercharging.

Third possibility - shorting cells in a battery.

 

Batteries fully chargng fast & discharging fast = sulphated batteries

Batteries charging slowly but discharging fast = shorting cells

Battery ends bowed out = sulphated batteries

Individual cells dryer than the rest, gassing more than the rest or getting hotter under charge = shorting cells.

 

 

 

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2 minutes ago, MtB said:

Hi Rosie,

On the face of it your batteries are probably totally goosed. The questions about how and why will probably flow thick and fast now. I'll start!

 

1) How often are you running your engine in the winter to charge them? (Or do you have shore power?)

2) What charge monitoring device do you have? (Other than that solar controller.)

3) Have you done a power audit so you know what your daily power consumption is?

4) Have you checked the electrolyte levels under those battery caps recently?

5) How long have you had the boat?

6) Do you live aboard or is it a hobby boat?

 

Regarding advice on maintaining battery health, read the battery primer pinned in the maintenance section.

 

 

2 minutes ago, MtB said:

Hi Rosie,

On the face of it your batteries are probably totally goosed. The questions about how and why will probably flow thick and fast now. I'll start!

 

1) How often are you running your engine in the winter to charge them? (Or do you have shore power?)

2) What charge monitoring device do you have? (Other than that solar controller.)

3) Have you done a power audit so you know what your daily power consumption is?

4) Have you checked the electrolyte levels under those battery caps recently?

5) How long have you had the boat?

6) Do you live aboard or is it a hobby boat?

 

Regarding advice on maintaining battery health, read the battery primer pinned in the maintenance section.

 

Thank you for your response:) 

1. I run my engine between half an hour and 2 hours a day, no hook up

2. I have a very simple voltage reader mounted in the wall (pic attached)

3. The only way I’ve been tracking my daily use is on the solar controller, what else would you suggest?

4. I haven’t, I’m terrified of actually touching the batteries, I still have ALOT to learn about 12v systems 

5. I’ve had her for a year and I live on her full time.

 

thank you in advance for all your help!

704D98B1-0942-41CB-9AB7-A7B883B17883.jpeg

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15 minutes ago, Tony Brooks said:

Not enough info for a good diagnosis.

 

How long do you charge for and at what revs?

Are the ends of the batteries bowing out?

How do you know when to stop charging?

 

First possibility - batteries not being charged enough

Second possibility - batteries lost capacity due to persistent undercharging.

Third possibility - shorting cells in a battery.

 

Batteries fully chargng fast & discharging fast = sulphated batteries

Batteries charging slowly but discharging fast = shorting cells

Battery ends bowed out = sulphated batteries

Individual cells dryer than the rest, gassing more than the rest or getting hotter under charge = shorting cells.

 

 

 

Hi! Thanks for your response:)

I charge between half an hour and two hours at 2800 rpm.

I’m not sure what you mean by end of the batteries blowing out, is that a physical change? I haven’t touched the physical battery I don’t think I know enough to move anything 😂 I’m getting tired of being scared of it though so I’m ready to learn as much as I can!

I’ve experimented with different charging times and it hasn’t seemed to make a difference.

I’ve only let the battery drop below 12v twice in the year I’ve been on it according to the solar reader so I hope it’s not persistent undercharging!

 

it sounds like “sulphated batteries” how do I trouble shoot that?

thank you again for your help

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1 minute ago, RosieR said:

1. I run my engine between half an hour and 2 hours a day, no hook up

 

Ok, this may well not be enough. I suspect the batts have been slowly degrading from chronic under-charging and now you've reached the point where they hold hardly any charge. 

 

 

3 minutes ago, RosieR said:

2. I have a very simple voltage reader mounted in the wall (pic attached)

 

That's probably a passable volt meter but to really track and understand the battery state of charge, you need an ammeter (current meter) too. Something like a Victron BMV712.

 

 

 

4 minutes ago, RosieR said:

3. The only way I’ve been tracking my daily use is on the solar controller, what else would you suggest?

 

 A Victron BMV712, along with a long day spent reading and inwardly digesting the battery primer I linked to above. It explains batteries beautifully and clearly, in proper depth but not so much depth as to be overwhelming.

 

 

7 minutes ago, RosieR said:

5. I’ve had her for a year and I live on her full time.

 

Ok, so your charging regime is probably not a long way short of enough, but in winter the solar harvest tumbles and probably caused you to persistently under-charge. 

 

What does that voltage meter read now? (Now it's dark outside and the solar is not producing.)

 

 

 

(All these questions help build a picture of what is happening. Some positive advice and suggestions will follow eventually. Probably!!)

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In short, your batteries are dead and need replacing.

The problem you have is :

1) Why has it happened &

2) What are you going to do differently to stop it happening again.

 

It very much sounds as if you have been undercharging for a long time - as a very rough guide you should be looking at running the engine for 4 hours per day and 8 hours per day at the weekend.

This may not be sufficient, or it may be excessive, but it gives you a base line to work to until you can get an understanding of how to manage your batteries, and, how to do a power audit (comparing how much electricty you need to generate to replace what you have used.

Edited by Alan de Enfield
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The batteries are definitely past useful life. At 6 years old this is not surprising. But when (or preferably before) you get new batteries, please read up about the issues with lead acid battery charging. It is easy to kill new batteries fairly quickly (months or even weeks) by undercharging them. Unfortunately lead acid batteries are very reluctant to fully charge, and yet failing to fully charge them regularly is the number one cause of battery damage.

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38 minutes ago, RosieR said:

The batteries are 6 years old but maybe they’re just old but I’m not sure.

 

Six years is actually a pretty good life for lead acid batteries. They've done well even if it turns out they need replacing now.

 

 

 

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2 minutes ago, Alan de Enfield said:

It very much sounds as if you have been undercharging for a long time - as a vety rough guide you should be looking at running the engine  for 4 hours per day and 8 hours per day at the weekend.

 

Unless of course, you have a decent solar installation.

 

With my own solar installation I need to run my engine for 0 hours per day in the week, and 0 hours per day at the weekend for 9 months of the year. Rosie also has a solar installation.

 

Rosie, solar works great from March to November. For the three winter months it dips to near zero. This is probably what killed your batts.

 

 

 

 

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4 minutes ago, RosieR said:

Hi! Thanks for your response:)

I charge between half an hour and two hours at 2800 rpm.

I’m not sure what you mean by end of the batteries blowing out, is that a physical change? I haven’t touched the physical battery I don’t think I know enough to move anything 😂 I’m getting tired of being scared of it though so I’m ready to learn as much as I can!

I’ve experimented with different charging times and it hasn’t seemed to make a difference.

I’ve only let the battery drop below 12v twice in the year I’ve been on it according to the solar reader so I hope it’s not persistent undercharging!

 

it sounds like “sulphated batteries” how do I trouble shoot that?

thank you again for your help

 

Yes a physical change. From the photo you can probably look  down between the battery and the battery box.

 

To troubleshoot the batteries requires a hydrometer, knowing how to use it with corrosive fluids, and knowing how to assess battery state of charge from rested voltage. I fear this may be beyond you at this stage. If they charge up fast and discharge fast then they probably are sulphated.

 

You do not have t run at such high revs unless it is an old Lister SL/SR  engine. Between 1200 and 1500 rpm is usually enough, but in winter with no solar the run times are far too short, especially if you have no charging current monitoring. We usually suggest 3 to 4 hours a day and 8 hours or more each weekend. Less shoulf be OK when the solar is producing well.

 

If you want me to tell you about hydrometer testing and rested voltage assessment just ask.

 

 

 

 

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Apologies as this wont help with your current query, but I just wanted to make a suggestion that if you are a full time liveaboard, more solar panels would also be a great investment if your budget will stretch that far.

They are much cheaper to buy than they were a few years ago, and they can be installed as a DIY job (plus you will get plenty of help on this forum if you have any queries).

For about £500 you could be getting five or ten times as much solar charge into your batteries as you are now, and it could really help to keep your new replacement batteries in good shape without having to run the engine for hours and hours. 

 

 

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12 minutes ago, MtB said:

 

Ok, this may well not be enough. I suspect the batts have been slowly degrading from chronic under-charging and now you've reached the point where they hold hardly any charge. 

 

 

 

That's probably a passable volt meter but to really track and understand the battery state of charge, you need an ammeter (current meter) too. Something like a Victron BMV712.

 

 

 

 

 A Victron BMV712, along with a long day spent reading and inwardly digesting the battery primer I linked to above. It explains batteries beautifully and clearly, in proper depth but not so much depth as to be overwhelming.

 

 

 

Ok, so your charging regime is probably not a long way short of enough, but in winter the solar harvest tumbles and probably caused you to persistently under-charge. 

 

What does that voltage meter read now? (Now it's dark outside and the solar is not producing.)

 

 

 

(All these questions help build a picture of what is happening. Some positive advice and suggestions will follow eventually. Probably!!)

Thank you so much for this help it’s extremely helpful! I’ll take a look at that link and definitely invest in a better reader… and it sounds like some new batteries as well😂

right now the voltage is 12.58

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Just now, RosieR said:

Thank you so much for this help it’s extremely helpful! I’ll take a look at that link and definitely invest in a better reader… and it sounds like some new batteries as well😂

right now the voltage is 12.58

 

Whatever you do please ignore and % of charge reading on any new monitor. Unless you are fairly technical, know the manual backwards, alter the factory presets, and regularly re-calibrate and synchronise it it will tell lies and encourage you to do the same for the new batteries.this is all in that battery primer.

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5 minutes ago, Tony Brooks said:

 

Yes a physical change. From the photo you can probably look  down between the battery and the battery box.

 

To troubleshoot the batteries requires a hydrometer, knowing how to use it with corrosive fluids, and knowing how to assess battery state of charge from rested voltage. I fear this may be beyond you at this stage. If they charge up fast and discharge fast then they probably are sulphated.

 

You do not have t run at such high revs unless it is an old Lister SL/SR  engine. Between 1200 and 1500 rpm is usually enough, but in winter with no solar the run times are far too short, especially if you have no charging current monitoring. We usually suggest 3 to 4 hours a day and 8 hours or more each weekend. Less shoulf be OK when the solar is producing well.

 

If you want me to tell you about hydrometer testing and rested voltage assessment just ask.

 

 

 

 

Both of the batteries are fully encased so can’t get to them without taking them out of the box I think.

yes that does sound a bit above my knowledge, I’ll have to rummage the internet to try and understand the system better! It sounds like I’ve also been undercharging severely if 3-4 hours is advised… with the rpm, that’s the rpm of my engine, I’m not sure how to change it without coming out of neutral, is that something I can do directly on the engine?

thanks again for your help 

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Have you ever checked the level of the liquid in the batteries?  It may be a bit late now, but about once a month it is a good idea to unscrew the round black knobs on the top of each battery and check that you can see the fluid is above the plates inside.  If it is getting low add distilled or deionized water (from Halfords) until the water is about 10mm above the plates, or on the level indicator if there is one. You need to do each knob individually as they are separate cells.

If/when you buy replacements try to get ones where you can check and replenish the levels. 

 

N

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17 minutes ago, MtB said:

 

Six years is actually a pretty good life for lead acid batteries. They've done well even if it turns out they need replacing now.

 

 

 

That puts my mind at rest a bit! I’ve tried searching everywhere for how long batteries should last and the results are really varied some saying 10 years! 

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Just now, RosieR said:

That puts my mind at rest a bit! I’ve tried searching everywhere for how long batteries should last and the results are really varied some saying 10 years! 

 

Ten years would be quite exceptional! I struggle to wring four years out of a cheap set, and I like to think I have a rough idea what I'm doing with them nowadays!! 

 

 

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7 minutes ago, MtB said:

 

Unless of course, you have a decent solar installation.

 

With my own solar installation I need to run my engine for 0 hours per day in the week, and 0 hours per day at the weekend for 9 months of the year. Rosie also has a solar installation.

 

Rosie, solar works great from March to November. For the three winter months it dips to near zero. This is probably what killed your batts.

 

 

You are spot on- solar is an absolute game changer for a liveaboard, for most of the year anyway. 

This is just showing my rear panels, not the front ones.

There were a couple of rotten overcast days, but generally I'm starting to find that I get enough on the good days to power me through the rubbish days.

In fact for the last two days I've topped up the batteries, heated up the water tank, and still switched the panels off by early afternoon to avoid overcharging the batteries. 

I love the sun so much I think I might have Aztec blood in me.

 

 

Screenshot_20220305-220056.jpg.bd64d7d206a28e3e6d618759e21e9cc1.jpg

 

 

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12 minutes ago, Tony1 said:

 

Apologies as this wont help with your current query, but I just wanted to make a suggestion that if you are a full time liveaboard, more solar panels would also be a great investment if your budget will stretch that far.

They are much cheaper to buy than they were a few years ago, and they can be installed as a DIY job (plus you will get plenty of help on this forum if you have any queries).

For about £500 you could be getting five or ten times as much solar charge into your batteries as you are now, and it could really help to keep your new replacement batteries in good shape without having to run the engine for hours and hours. 

 

 

Great idea thank you! Do you know how long solar panels last as well?

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4 minutes ago, RosieR said:

It sounds like I’ve also been undercharging severely if 3-4 hours is advised… with the rpm, that’s the rpm of my engine, I’m not sure how to change it without coming out of neutral, is that something I can do directly on the engine?

 

If you have a Morse or Teleflex single lever control, there is usually a button somewhere (often in the middle of the pivot) that you can press in whilst moving the lever forward to raise the engine speed.  Holding the button in prevents the gear from engaging, so the propeller does not rotate when you speed up the engine.

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3 minutes ago, RosieR said:

Great idea thank you! Do you know how long solar panels last as well?

 

They last decades. They do degrade but it's really slowly.

Oh, except the flexible 'stick-on' solar panels. Keep well away from them. They have a terrible reputation for short life. 

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2 minutes ago, RosieR said:

Great idea thank you! Do you know how long solar panels last as well?

 

I must admit I have no idea Rosie, and it probably depends on who you buy from, but I'm sure it will be at least 10 years, and probably closer to 20 if they don't get directly damaged. 

But if you're going to be on the boat for 5-10 years, solar panels will probably pay for themselves, in terms of lower diesel fuel bills etc for the engine.

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