Having a problem using the washing machine heater

[trebby91]

Hi, All.

Having a problem when using the washing machine heater.

THE SYSTEM

525 Ah battery bank, Traction

Sterling Battery management system

Two Alternators 1X 80Amp 1 X 110 Amp wired in parallel

All battery cables are doubled up.

Sterling 2500 amp Inverter/charger.

400 amp fuse between the batteries and the inverter.

THE PROBLEM

With the engine running.

When the washing machine heater switches in the management system reports “Low voltage “ and a buzzer sounds until the heater turns off also the inverter beeps.

The washer continues to run normally throughout.

The battery state of charge never drops below 95% ( fully charged on start of wash)

The washer requires 2000 watts.

Is the 400amp fuse high enough?

Any other suggestions?

Edited December 29, 2013 by trebby91

[Ex- Member]

I suspect the washing machine requires more energy than your inverter produces.

 

Our very energy efficient washing machine requires a 3kva inverter, which also has a 6kva start up boost, so never been an issue.

 

The washing machine wouldn't run from a 2.6kva Kipor generator though it would stall the genny when the "you guessed it" water needed heating up.

[trebby91]

Just checked the washer manual and it states the heater is 2000 Watts

Is this to high for the inverter?

Edited December 29, 2013 by trebby91

[Ex- Member]

Just checked the washer manual and it states the heater is 2000 Watts

Is this to high for the inverter?

 

That's probably right ours is the same I recall, but I believe it's the initial pull of energy that will exceed 2kw as like motors do. Others will know better, my input is from experiencing similar, some of the techy members will be more specific.

[Phil Ambrose]

2kw heater coupled with whatever other power the machine is drawing may be putting your inverter on its limit as has been suggested.

Phil

[Detling]

The heater will take more current when cold and drop to 2000 watts when the resistor wire has heated up (1/2 a second perhaps) the inrush current, as it is known, for a heater is typically 2-3 times the running current (for comparison an incandescent light bulb is 7-10 times the running current). Thus for a fraction of a second your washing machine will overload your inverter, and I suspect the management system is picking up this surge. You say the washing machine carries on OK so the fuse etc. are coping with the load,but whether repetitive use will do long term damage I don't know.

[jelunga]

The very high 12v current demand is causing large volt drop in the battery cables and the systems is sensing this as flat batteries. You are really pushing it past its limits I feel. .

You are drawing something like 170 amps at 12v which is wag above the batteries 10hr rate so the internal resistance of the batteries will also significantly drop the volts out.

I have a 3kw inverter (nominal) and a 550 ah battery bank. Just trying to run a 1kw kettle for 5 mins makes the system groan.

[Robbo]

The very high 12v current demand is causing large volt drop in the battery cables and the systems is sensing this as flat batteries. You are really pushing it past its limits I feel. .

You are drawing something like 170 amps at 12v which is wag above the batteries 10hr rate so the internal resistance of the batteries will also significantly drop the volts out.

I have a 3kw inverter (nominal) and a 550 ah battery bank. Just trying to run a 1kw kettle for 5 mins makes the system groan.

 

He's running the engine tho, so my guess rather than batteries is undersized cables or alternator not giving enough amps (not enough revs).

[nicknorman]

Sounds like too much resistance in the 12v cables between the batteries and the inverter. Maybe a poor connection somewhere (can be determined by feeling all the connections with the washer on heat cycle - but don't burn yourself! - a hot spot indicates high resistance). Or inadequate size of cable for the distance. What length of wiring run is it between the batteries and the inverter? For even a shortish distance, I would want to be using 70mm^2 cable.

 

If there is a battery isolator between batteries and inverter, this could be the source of the high resistance (again, it getting warm under load is an indication)

 

To put it in perspective, we happily run a 2kw kettle from 440AH batteries and a 2500w inverter, even without the engine running.

 

As an interim measure until you fix the problem, you could consider adding hot water to the drum when you switch it on, that way there will be less or no heating to be done.

Edited December 30, 2013 by nicknorman

[PaddingtonBear]

If you want a house go sell your 'floating cottage' and buy one

[Robbo]

To put it in perspective, we happily run a 2kw kettle from 440AH batteries and a 2500w inverter, even without the engine running.

 

 

This matter's what type of batteries your using, leisure can give amps quickly where as traction can't.

If you want a house go sell your 'floating cottage' and buy one

 

It's a washing machine, a very useful item for keeping clothes clean. Just because some boaters don't want items that have been around for decades to make life a little easier in the domestic chores doesn't mean the rest don't.

Edited December 30, 2013 by Robbo

[by'eck]

The spec of your system should be able to cope with your washing machine. If the Sterling battery management system is wired correctly, it will sense voltage close to the batteries. As nicknorman suggests check the battery wiring to the inverter, particularly any mechanical connections, but your report suggests to me that the batteries are not supplying sufficient current, possibly due to old age/diminished capacity (despite the SOC reading), and the combined alternator output is not enough to compensate.

 

Your 400 amp inverter fuse is correct BTW, and unless it blows, has no bearing on this issue.

[Hawkmoth]

Everything seems right for it to run properly from your description of the system.

Are you putting enough revs on the engine? I'd be checking the wiring again as well. All the main DC cables, alternator to battery and to inverter should be, IMO about 75mm in cross sectional area.

As Robbo pointed out, the type of battery does make a difference as well.

Bob

[nicknorman]

This matter's what type of batteries your using, leisure can give amps quickly where as traction can't.

 

This point interests me since we currently have leisure batteries but I was thinking of fitting Trojans at some point. As you can tell, we do need a high current output at times. Can you quantify the difference between leisure and traction in terms of ability to give high current (and take it for that matter, since we have a lot of alternator power as well)?

[ditchcrawler]

This point interests me since we currently have leisure batteries but I was thinking of fitting Trojans at some point. As you can tell, we do need a high current output at times. Can you quantify the difference between leisure and traction in terms of ability to give high current (and take it for that matter, since we have a lot of alternator power as well)?

Well the throw enough amps out to start golf trolleys and disable scooters on hills. I dont know the start current for those motors under load.

[by'eck]

This point interests me since we currently have leisure batteries but I was thinking of fitting Trojans at some point. As you can tell, we do need a high current output at times. Can you quantify the difference between leisure and traction in terms of ability to give high current (and take it for that matter, since we have a lot of alternator power as well)?

I don't have any quantitative figures but true deep cycle (traction) batteries have a lesser number of thicker plates compared with, at the other extreme, starter batteries. This means there is a lesser plate surface area in contact with the electrolyte.

 

The plate thickness dictates that the chemical state created by the surface charge or discharge take time to become uniform throughout their thickness. This in turn limits current in or out of batteries and can give rise to gassing if the charge current to capacity ratio is too high.

 

In the OP's case with 525 Ah available and a likely max current draw of around 200 amps, further offset by alternators, there shouldn't be an issue.

[nicknorman]

Yes I understand the general principle, what I don't know is the extent to which this matters. In our case we have 4x110 leisure in parallel, so with the kettle on, or with available charging current of at least 200A, that is 200A in or out, divided by 4 batteries = 50A each. By comparison the CCA is 1000A per battery, so obviously well within that.

 

If we went to 4 x Trojan 105s in series/parallel, that would become 100A per battery, ie discharging at roughly the C2 rate. Of course this only lasts 3-5 minutes (the time it takes the kettle to boil), after which the batteries can recover, but I am more concerned about Trojan's ability to take 100A charge current per string. My guess is that they couldn't, even for a short while when they are low. But it would be useful to be able to quantify what charge current they actually could take.

[Robbo]

Yes I understand the general principle, what I don't know is the extent to which this matters. In our case we have 4x110 leisure in parallel, so with the kettle on, or with available charging current of at least 200A, that is 200A in or out, divided by 4 batteries = 50A each. By comparison the CCA is 1000A per battery, so obviously well within that.

 

If we went to 4 x Trojan 105s in series/parallel, that would become 100A per battery, ie discharging at roughly the C2 rate. Of course this only lasts 3-5 minutes (the time it takes the kettle to boil), after which the batteries can recover, but I am more concerned about Trojan's ability to take 100A charge current per string. My guess is that they couldn't, even for a short while when they are low. But it would be useful to be able to quantify what charge current they actually could take.

 

Trojan recommend around 10-13% of battery capacity for charging, so if you have 450ah of battery capacity it's around 58.5amp. Victron recommend a max of 20% which is still only 90amp. If you can fit another two batteries (so increasing to 675ah) then you'll be better matched for charging and be nicer to your batteries (the same is true if you keep to leisure bats.).

Edited December 30, 2013 by Robbo

[nicknorman]

Thanks Robbo. Whilst I understand the optimal charge current for Trojans, what I don't know is the consequence of deviating from it. More water consumption (not really a problem), shorter battery life (how much shorter) or perhaps simply a refusal to take the current at a sensible voltage? I don't think there is room for another pair of batteries.

Edited December 30, 2013 by nicknorman

[Robbo]

Thanks Robbo. Whilst I understand the optimal charge current for Trojans, what I don't know is the consequence of deviating from it. More water consumption (not really a problem), shorter battery life (how much shorter) or perhaps simply a refusal to take the current at a sensible voltage? I don't think there is room for another pair of batteries.

 

I'll just quote the relevant section from Victron's free book (which is worth reading!)..

 

http://www.victronenergy.com/upload/documents/Book%20-%20Energy%20Unlimited%20-%20rev%2009%20-%20EN.pdf

 

 

2.5.6. Premature aging 2. Charging too rapidly and not fully charging.

Batteries can be quickly charged and will absorb a high charge current until the gassing voltage is

reached. While charging with such high current might work well a few times, this will actually shorten the

service life of most batteries substantially (the exception: spiral-cell and some other AGM batteries).

This is due to accelerated loss of cohesion of the active material, which results in shedding. Generally it

is recommended to keep the charging current down to at most C / 5, in other words a fifth or 20 % of the

rated capacity.

When a battery is charged with currents exceeding C / 5, its temperature can rise steeply. Temperature

compensation of the charging voltage then becomes an absolute necessity (see sect. 2.5.9).

My own experience is that charging a 50 % discharged 12 V 100 Ah flooded battery at 33 A (C / 3)

results in a temperature increase of 10 to 15°C. The maximum temperature is reached at the end of the

bulk phase. Bigger batteries will become even hotter (because the amount of heat generated increases

with volume and the dissipation of heat increases with the available surface) as well as batteries with a

high internal resistance, or batteries which have been discharged more deeply.

[MtB]

The most important information of all seems to be missing.

 

Is this washing machine a new installation which you can't get to work, or has it been working fine for ages until now?

 

MtB

[smileypete]

Maybe plug a 2kW kettle or fan heater into the inverter and measure the 12V under load right at the inverter terminals.

 

Batts like Trojans will need correct charge voltages and regular eq to get the best out of them, their website will have details. If they don't get this and 'sulphate' they won't perform so well under heavy load.

 

For a 2.5 kW 12V inverter the cable from the batts should be 80mm² or more, but 70mm² will probably get by OK if the distance between isn't so great.

 

 

If you want a house go sell your 'floating cottage' and buy one

 

You sound like a bitter and twisted person, is there type or group of boaters you don't have a go at?

 

cheers, Pete.

~smpt~

Edited December 30, 2013 by smileypete

[Phil Ambrose]

If you want a house go sell your 'floating cottage' and buy one

I am so glad that everybody does not have your unique take on life.

Sad, so sad.

 

Phil

[Paul G2]

THE SYSTEM

525 Ah battery bank, Traction

Sterling Battery management system

Two Alternators 1X 80Amp 1 X 110 Amp wired in parallel

All battery cables are doubled up.

Sterling 2500 amp Inverter/charger.

400 amp fuse between the batteries and the inverter.

 

The washer requires 2000 watts.

 

Any other suggestions?

 

 

2500 amp inverter, eh? What you need to do is to put up a notice in the small village you are powering and tell everyone they need to charge their electric cars elsewhere. That should take care of your problem.

 

"But Captain Kirk, I'm an electrician, not a comedian. You can't expect miracles, Jim!"

 

Obviously you meant a 2500 Watt inverter. That inverter, any inverter, is happiest running at no more than 80% of rated power. (That's a real good rule of thumb for everything electrical btw.) Your inverter has a surge rating that far exceeds its 2,500W rated capacity, but surge is usually measured in milliseconds, sometimes as long as a second or two, and surge power is never meant for extended use.

 

Just checked the washer manual and it states the heater is 2000 Watts

Is this to high for the inverter?

 

In a word, yes. Check out the ratings on the motor and the ratings on the controls (if the controls are electronic, their current draw is minimal) and add that to 2,000W for the heater and you'll probably be over what the inverter is rated at.

You really don't want to go over a 2,000 Watt load on your inverter. You can exceed that load, but then you are operating in the safety margin. Bottom line is that both your inverter and your washing machine will both wear out more rapidly.

You really should consider having an electrician look at your boat, assess your system needs and recommend an inverter that is properly sized to the demand you want to put on it. It sounds like you have a really nice 240V system there, you are simply asking too much from it. If your inverter is relatively new, it probably has a fairly good resale or trade-in value.

Meanwhile, you should quit using the heater in the washer and either wash in cold water or heat some water in a kettle and then put that in the washer. It's a PITA, I know, but it sounds like you shelled out pretty good money for a nice electrical system and it would be a pity to suffer the consequences of overloading it - and make no mistake, running it at capacity is overloading it.

BTW - I admire your decorum in your reply to PB. Personally, I probably would have replied in a more construction-kinda-guy way. lol

[by'eck]

Thanks Robbo. Whilst I understand the optimal charge current for Trojans, what I don't know is the consequence of deviating from it. More water consumption (not really a problem), shorter battery life (how much shorter) or perhaps simply a refusal to take the current at a sensible voltage? I don't think there is room for another pair of batteries.

I think the longevity benefits of traction batteries are only achieved with lowish charge/discharge currents and regular full charging. IMHO only under those conditions can their increased price be justified.

 

If your boat electrics are optimised for quick charging (say C/3) and you have regular or even occasional heavy current draw from inverter (driving washing machine for example), then the middle of the road, cheaper leisure type are to be preferred, reducing the likelihood of plate surface shedding mentioned by Robbo. I appreciate that battery bank size has a bearing on the current drain issue though.

 

I note that Googling for marine batteries rarely brings up Trojan T105 golf cart batteries although they provide an excellent solution for some boat owners who's use dictates reliability but with modest power drain - a sailing yacht on an ocean crossing for example.

 

I was certainly pleased today I was using leisure batteries when I accidentally tripped the 16 amp shore power breaker and the inverter automatically but briefly kicked in before blowing its 500 amp fuse. A historical power audit revealed a 2kW fan heater and 1.6kW washing machine were running but it drew the line when a 2.2kW kettle was turned on as well The inverter didn't stand a cat in hells chance of supporting that load although a new fuse had it working fine again - lesson learnt