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Running washing machine without engine on - will I have wrecked my batteries??


Floating Guye

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Hi everyone,

 

My first post here.

 

So yesterday my partner put a washing machine cycle (65 minutes, 40 degrees) on in our widebeam and (since she's new to boating) she didn't know that you need the engine to be running at the same time in order to provide enough power output! We have 2x 240w solar panels, but it was an overcast day, so very little juice will have been coming in from them. Before the cycle, the batteries were at about 12.8V, but after the cycle, they were down to 10v!!

 

We subsequently put the engine on to recharge the batteries, and they seem to have refilled, and SEEM to be working as before.

 

My question is: will this episode have irrevocably damaged the batteries? And will the damage be significant? Or would a small episode like this not cause too much serious harm?

 

Another important bit of context might be that we just did a 1hr cruise before mooring and putting the washing machine on (I'm wondering whether, by generating hot water from our cruise, we may have mitigated the overall power draw required by the wash cycle, since our calorifier would have been recently topped up with hot water)... I am not sure, however, whether water from the calorifier is actually connected up to go into the washing machine.

 

Anyway, all help would be gratefully appreciated.

 

Thank you!

 

Chris

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I very much doubt that you have done much detectable damage to your batteries, as long as you more or less FULLY recharged them. That will take many hours, say 10 hours plus from 10V.

 

The question about the hot water depends upon if the washing machine is a hot and cold fill or, as is now more usual, a cold fill only. If it is just cold fill then IF the washing machine supply has been fitted with a thermostatic mixing valve AND you set the machine to a cold wash then it would have stopped the heater, the big battery load, from working. I suspect this is not the case.

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Assuming the batteries were in good condition before running the washing machine on them, then taking the batteries down to 10.5 volts (100% discharge) ONCE is unlikely to shorten their lives much PROVIDING you immediately recharged them back to 100% (2% of battery capacity tail current at 14.2 volts or higher).

 

Keep doing it and you will quickly kill the batteries.

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17 minutes ago, Mike Tee said:

You realise this could be a mind game by your partner? I reckon you will be doing all the laundry from now on!

It's called Strategic Incompetence. If you don't like doing a particular thing, you make such a pigs ear of the task the first time you are asked, that you are never asked to do it again. 😆

Edited by Jen-in-Wellies
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22 minutes ago, Jen-in-Wellies said:

It's called Strategic Incompetence. If you don't like doing a particular thing, you make such a pigs ear of the task the first time you are asked, that you are never asked to do it again. 😆

 

Indeed, soon after we married my wife asked me to iron a top of hers. Due to a moment's inattention on my part it ended up with a black triangular burn mark on it. For some strange reason in the 44 years we have been married she has never asked me to iron again. 😅

Edited by cuthound
Phat phingers
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1 hour ago, Jen-in-Wellies said:

It's called Strategic Incompetence. If you don't like doing a particular thing, you make such a pigs ear of the task the first time you are asked, that you are never asked to do it again. 😆

That definitely works! When Iain and I bought a house together, his first attempt at hanging wallpaper was his last 🙂 . It saved him over 30 years of decorating!

 

haggis

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20 minutes ago, haggis said:

That definitely works! When Iain and I bought a house together, his first attempt at hanging wallpaper was his last 🙂 . It saved him over 30 years of decorating!

 

haggis

Funny you should say that.

Decorating our first house kitchen just before we were married and moved in, I hung the paper and then SWMBO absolutely insisted in trying to rub the normal air bubbles out with the inevitable result of lost of torn patches on the paper. It worked well for her and less well for me.

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2 hours ago, Mike Tee said:

You realise this could be a mind game by your partner? I reckon you will be doing all the laundry from now on!

Only reason I know this, back in about 1975 I was on leave and my wife asked me to dig over the veg patch at a house we had just moved into. How was I to know she had already transplanted a load of tomato plants, even staking them out. Since then (46 years) all I have ever done in the various gardens we've owned is cut the grass! One evening of venomous looks and a couple of days of snide comments about 'staked out weeds', and I get excused gardening duties for life.

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A washing machine doesn’t use much power apart from to heat the water. Probably less than 1kwh which is about 100Ah from a 12v system. If this has taken your batteries from pretty much fully charged, to flat, it tells us that either you have a very small battery bank, or they are way down on capacity.

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3 minutes ago, nicknorman said:

A washing machine doesn’t use much power apart from to heat the water. Probably less than 1kwh which is about 100Ah from a 12v system. If this has taken your batteries from pretty much fully charged, to flat, it tells us that either you have a very small battery bank, or they are way down on capacity.

 

Unless he is doing cold fill without doing something to disable the heater.

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5 minutes ago, Tony Brooks said:

 

Unless he is doing cold fill without doing something to disable the heater.

No I think 1kwh including heating the water. Depends on the size of the washer and wash temperature I guess but our compact one is 1.6kw and the heating cycle takes about 20 minutes for a 40c wash

Edited by nicknorman
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4 minutes ago, Floating Guye said:

We did recharge the batteries (but this only took 2hrs of the motor being on, not 10). The batteries got back up to 14.7v following charging, and then we had a day of blistering sun to top it off. I imagine that will be fine and, as cuthound says, hopefully will be okay if we don't make a repeat of it!

You can’t determine the state of charge of batteries under charge by looking at the voltage. The voltage will get to 14.7v or whatever whilst there is still a lot of current going into the batteries, so if you terminate the charge at that point they will be much less than fully charged.
 

The annoying thing about lead acid batteries is that the charge current tapers off over several hours once the maximum voltage is reached. The only way to know when they are fully charged is to measure the current, and consider them fully charged once the current has decreased to perhaps 2% of the capacity.

 

Failing to fully charge batteries regularly will cause them to lose capacity big-time. OK so you have solar as well, which of course helps a lot in summer, but based on what you’ve written I think your batteries are well down on capacity. Of course that only matters if the remaining capacity isn’t enough for your normal needs.

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6 minutes ago, Floating Guye said:

We did recharge the batteries (but this only took 2hrs of the motor being on, not 10). The batteries got back up to 14.7v following charging, and then we had a day of blistering sun to top it off. I imagine that will be fine and, as cuthound says, hopefully will be okay if we don't make a repeat of it!

 

In my view there is no way you can get a sensibly sized lead acid bank from 10V to fully charged in 2 hours unless they  are very badly sulphated to the point they need changing.

 

14.7 volts  does not mean fully charged. It just means you have finished the comparatively short bulk charge period and many more hours are needed to fully charge the bank. It only says the alternator/charger voltage  realtor has started working.

 

At a pinch, it just might be a reading when the charging source has been turned off caused by surface charge, but it seems far too high for that.

 

Determine fully charged by seeing  when the charging current has failed to drop of an hour or so and the current at 14.4V ish is between 1 and 2% of battery capacity.

 

 

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Thanks for your help. I didn't understand all of it. 

 

What I have understood, however, is that just reaching 14.7v doesn't mean the batteries are fully charged (am I right in thinking this is more the "charging voltage"?)

 

So I will go back and stick the engine on for another, say, 8hrs.


When you say "The only way to know when they are fully charged is to measure the current" - how would I go about measuring the current?

 

On a final point, I wonder if my batteries are working properly (perhaps from previous such damage from previous owners) since the voltage drops quite suddenly once the sun is off the solar panels - this makes me think they are not "storing" or "holding" much charge.


Forgive my ignorance - I don't know much about all of this and am just starting to learn!

 

Cheers

 

 

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I am wondering if, since I haven't been in the habit of sticking the motor on for long periods (except when cruising) my batteries may have been being damaged for a while now. Is there a specific way of testing battery capacity? Or do you just have to sort of work it out from how quickly the voltage drops on your display?

If I were to buy a new set of batteries (4x105ah) for my widebeam, any idea what that might cost?

The boat is only 2yrs old, so it would be bad if this battery bank had been used up already!

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3 minutes ago, Floating Guye said:

Thanks for your help. I didn't understand all of it. 

 

What I have understood, however, is that just reaching 14.7v doesn't mean the batteries are fully charged (am I right in thinking this is more the "charging voltage"?)

 

So I will go back and stick the engine on for another, say, 8hrs.


When you say "The only way to know when they are fully charged is to measure the current" - how would I go about measuring the current?

 

On a final point, I wonder if my batteries are working properly (perhaps from previous such damage from previous owners) since the voltage drops quite suddenly once the sun is off the solar panels - this makes me think they are not "storing" or "holding" much charge.


Forgive my ignorance - I don't know much about all of this and am just starting to learn!

 

Cheers

 

 

Since battery power is what keeps the lights on at night /fridge working etc, it always amazes me how many boats don’t have any means of monitoring their batteries. So it’s not just you! To measure the current you ideally need some sort of battery monitor, such as a Victron BMV 700 series, NASA equivalent. However these really need to be installed by someone competent at electrics. An alternative for occasional use is to get a Clampmeter with DC current range of such as a UNI-T UT203. You have to access the battery wires and attach the meter, take a reading. So quite inconvenient for regular usage. The best long term option is therefore to have a proper battery monitor installed.

 

As to the voltage dropping, it is inevitable that voltage when not under charge will be quite a bit less than when under charge. A fully charged battery with no significant loads connected will be at about 12.7v once it has discharged slightly. A battery at 50% State of Charge will be at around 12.1v.

 

So depending on whether the voltage decrease is worse than the above or not, you can make a call as to the health of your batteries. But as I said, my best guess is that they are quite unhealthy / way down on capacity. Although I don’t think you have mentioned what the badged capacity of the batteries is?

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13 minutes ago, Floating Guye said:

I am wondering if, since I haven't been in the habit of sticking the motor on for long periods (except when cruising) my batteries may have been being damaged for a while now. Is there a specific way of testing battery capacity? Or do you just have to sort of work it out from how quickly the voltage drops on your display?

If I were to buy a new set of batteries (4x105ah) for my widebeam, any idea what that might cost?

The boat is only 2yrs old, so it would be bad if this battery bank had been used up already!


It’s not easy to measure battery capacity, and virtually impossible without adequate monitoring equipment that measures current and counts Ah. So yes you have to work it out from how quickly the voltage drops vs how much current is being used (difficult without current measuring equipment!)
 

Cheap leisure batteries may well only last 2 years especially if you have a boat with a lot of electrical demands. You can expect to pay a little over £100 per battery for the cheapest, going up to £250 or more for the most expensive. But expensive batteries can be damaged as easily as cheap ones, so I suggest sticking with cheap ones for now until you get a full grasp of all the issues. And bear in mind that managing electrical/battery issues is one of the hardest things in modern boating!

Edited by nicknorman
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4 minutes ago, Floating Guye said:

I am wondering if, since I haven't been in the habit of sticking the motor on for long periods (except when cruising) my batteries may have been being damaged for a while now. Is there a specific way of testing battery capacity? Or do you just have to sort of work it out from how quickly the voltage drops on your display?

If I were to buy a new set of batteries (4x105ah) for my widebeam, any idea what that might cost?

The boat is only 2yrs old, so it would be bad if this battery bank had been used up already!

 

You are at the start of possibly the steepest learning curve related to boat life - battery care.

 

Around £100 or less each for leisure type batteries that my not be the best but probably are in your case with no battery monitoring.

 

Batteries ca be wrecked within weeks if they have never been fully charged and discharged regularly to below 12V rested voltage, so we can't comment on if It's bad or not.

 

There is a way of testing capacity, but probably not a good idea while you are living aboard. Fully charge the battery and then put a known load on it 9say a 21 watt car flasher light  bulb and time how long it takes to drop to around 11.8 volts. 21 watts = 1.75 amps, so the time in hours multiplied by 1.75 will give you the Amp hour capacity of the ba terry. Compare that with the label to see how much you have lost. This will tend to overestimate the capacity, but It's near enough for your purposes.

 

It may be cheaper just to fit a shunted ammeter rather than the battery monitors Nick mentioned but then you would not be misled by certain readouts but you would forgo the ability to use the Ah out and state of charge inferred from the rested voltage to calculate the battery capacity. This is probably too much to  absorb without more study.

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So I am actually slightly reassured having read your various comments. I have a MPPT Solar Charge Controller - is this not a "battery monitor"?  As shown on the picture below, it shows me the battery voltage, amps, and various other readings IMG-20210920-WA0000.jpg.c1b69b647fdcffb0755f0167dcf619bc.jpg

Also, I was very reassured by this comment 

Quote

A fully charged battery with no significant loads connected will be at about 12.7v once it has discharged slightly. A battery at 50% State of Charge will be at around 12.1v.

 

because (when not in charge) my batteries are almost always in the range between 12.7 and 12.1

Perhaps my batteries are still okay after all?!

Edited by Floating Guye
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The makers would like you to believe it's a battery monitor, but it's not. It's just a voltmeter, and voltmeters on their own and without certain procedure can not tell you the state of charge. A very sophisticated one called a Smartguage makes a very good stab at it and its % charged reading during discharge is far more accurate than most of the monitors Nick mentioned (in ordinary boaters' hands).

 

If you want to use a voltmeter you need to stop all charging and either leave the batteries to stand for a few hours or use some moderate electrical loads like a water pump for  few minutes. Then with no electrical discharge you can use the voltage reading, now known as the rested voltage, to infer the state of charge. You can use the solar controller battery voltage reading for this at night or with the panels turned off.

 

12.7 volts rested is more or less fully charged. In my view, 12.1 is a bit lower than ideal to allow the batteries to drop on a day to day basis, but it is far better than the 10V you got. I would prefer a minimum of 12.2 to 12.3V. Be aware there is very little that is defiance with batteries, one has to take a view on what is likely best practice. The meaning of the rested voltage values will vary by temperature, battery design, and probably age of the batteries. This is why Nick and my numbers are slightly different, and it is also why the whole thing seems so complicated at first.

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