Victron charger question - what happens when batteries are under load?

[George94]

This is for SmileyPete, and anybody else with superior electrical knowledge.

 

I keep refining my ideas about the best charging system for a boat. The following applies to winter, when PV power isn't enough.

 

It seems to me that one doesn't need a big generator for charging batteries because most of the time the charger is in float mode and having a big genny is just a waste of time, money, space, fuel, and ear-drums.

 

So I am coming round to the view that ideally you need two generators. One, around 3.5 kVA or a bit more, for running the washing machine and major power tools. In other words, for occasional use.

 

The second should be a baby (but quieter!) and should be on for most of the time when you need power (yes, including after 8 pm, hence the need for being quiet). That way, the batteries are never depleted by more than a small amount and won't need marathon charging sessions to get them back to 100% SOC.

 

In my case I have a problem in that my old ST1 genny doesn't provide clean enough power for my washing machine. So, it means either buying a new genset or genhead, or using the 3kVA inverter (and cold wash).

 

The question is, what happens if I run the big genny while the chargers are in float mode, and the washing machine is running? Will the chargers draw more power from the genny to compensate for what is going out, or will the batteries just get hammered? The chargers (2 in parallel) provide 600 kVA each (flat out), and the washing machine will probably want most of that.

 

Yet another possible alternative would be to attempt to clean up the act of the ST1. Would a modern AVR do the trick?

 

Thanks for any helpful advice.

 

ETA: The Lister ST1 genset is a standard Lister unit, 3.5kVA, but I have mislaid the manual and can't give more details.

Edited September 29, 2013 by George94

[nicknorman]

Well firstly I should point out that generators, even quiet ones, shouldn't be run beyond 8pm, at least if you are within earshot of another person (boat or house). Even a quiet genny will be detectable and cause annoyance.

 

If the chargers are on float and a big load is placed on the batteries, the chargers should switch back to Bulk mode and start to work flat out. That's how it is with our Mastervolt charger anyway.

[George94]

Well firstly I should point out that generators, even quiet ones, shouldn't be run beyond 8pm, at least if you are within earshot of another person (boat or house). Even a quiet genny will be detectable and cause annoyance.

 

If the chargers are on float and a big load is placed on the batteries, the chargers should switch back to Bulk mode and start to work flat out. That's how it is with our Mastervolt charger anyway.

 

Great, that's what I hoped you would say.

 

Where I am, a late-running "silent" genny won't be heard. I am not on a canal.

[bottle]

 

The chargers (2 in parallel) provide 600 kVA each (flat out), and the washing machine will probably want most of that.

 

Bl##dy big chargers and washing machine

 

600 KVA = 600,000 VA

 

 

That way, the batteries are never depleted by more than a small amount and won't need marathon charging sessions to get them back to 100% SOC.

 

but if you are running the generator to supply your needs, then you are doing the marathon bit anyway.

 

 

The question is, what happens if I run the big genny while the chargers are in float mode, and the washing machine is running? Will the chargers draw more power from the genny to compensate for what is going out, or will the batteries just get hammered?

 

If the generator is running nothing will be coming out of the batteries, the generator is running all 230v equipment so the charger will not come out of float as the batteries are not being used, unless you have 12/24v equipment running and then the charger will come out of float and run the 12/24v equipment direct, up to its maximum output.. if you exceed that maximum the batteries will then assist.

[George94]

Thanks, Bottle. Just checking that you chaps were paying attention. Obviously it's 600VA. 50 amps at 12V.

 

Yes indeed about the marathon bit, but it would be a small quiet genny, not a great noisy lump. And no extra pure battery charging should be needed.

 

My problem is that the washing machine won't talk to the Lister generator. It doesn't like the cut of its jib, or rather the shape of its sine wave. So I can only run the WM by using the inverter, and obviously I want to supply the power from the genny via the chargers, rather than drain the batteries.

[smileypete]

If the machine is on cold wash it won't use much power, at least until spin.

 

Once the batts have reached absorption charging stage then as long as...

 

batt charge current + inverter current < charger max current

 

...the charge voltage should stay at the absorption voltage.

 

Could try another AVR, cheap enough, depends on the genny head too, 2 pole ones can be tricky evidently.

 

cheers, Pete.

~smpt~

[by'eck]

Thanks, Bottle. Just checking that you chaps were paying attention. Obviously it's 600VA. 50 amps at 12V.

 

Yes indeed about the marathon bit, but it would be a small quiet genny, not a great noisy lump. And no extra pure battery charging should be needed.

 

My problem is that the washing machine won't talk to the Lister generator. It doesn't like the cut of its jib, or rather the shape of its sine wave. So I can only run the WM by using the inverter, and obviously I want to supply the power from the genny via the chargers, rather than drain the batteries.

 

Hi George - sorry but your chargers need to put out their full rated current at nearly 15 volts so with inefficiences that going to be closer to 1700 watts for the two 50 amp units you have.

 

Your solution of running the washing machine from the inverter sounds fine as long as its within its capabilities. The two chargers running will offset the current drain from the batteries which on average is not that much spread over a complete washing cycle. Max power will be drawn for a relatively short time in heating mode and again when in spin. The two chargers should get ahead in charging the batteries in between and shouldn't take too long to get batteries back to 100% SOC after machine cycle has finished.

 

Can I suggest that a suitcase inverter/generator might best suit your needs. The auto-throttle will leave it quietly running at idle whilst batteries are charging on float but will have enough grunt to cover the demand of both chargers when given low batteries or with washing machine running. The Honda EU20i may not be up to running the two chargers flat-out so a Kipor IG2600 (2300 watts continuous) might suit better.

[George94]

 

Hi George - sorry but your chargers need to put out their full rated current at nearly 15 volts so with inefficiences that going to be closer to 1700 watts for the two 50 amp units you have.

 

Your solution of running the washing machine from the inverter sounds fine as long as its within its capabilities. The two chargers running will offset the current drain from the batteries which on average is not that much spread over a complete washing cycle. Max power will be drawn for a relatively short time in heating mode and again when in spin. The two chargers should get ahead in charging the batteries in between and shouldn't take too long to get batteries back to 100% SOC after machine cycle has finished.

 

Can I suggest that a suitcase inverter/generator might best suit your needs. The auto-throttle will leave it quietly running at idle whilst batteries are charging on float but will have enough grunt to cover the demand of both chargers when given low batteries or with washing machine running. The Honda EU20i may not be up to running the two chargers flat-out so a Kipor IG2600 (2300 watts continuous) might suit better.

 

Thanks, By'Eck,

 

In fact I already have a Honda EU10i for normal use and light battery charging using one of the two chargers (that's why I have two). It's packed up at the moment, but I am getting it repaired. I would run the washing machine from the inverter while using the other genny connected to both chargers (it has the power, but not the nice sine wave). The inverter also needs repair - I haven't used or needed all this stuff for a couple of years, but my mooring arrangements changed unexpectedly.

 

Basically, the purpose of this thread was to make sure that I wouldn't knacker the batteries by using the inverter. My old washing machine ran happily on the generator, but the new one is more fastidious about the power it will accept.

 

I am very interested in the idea of trying to improve the generator output using a more modern AVR, but that's possibly outside the direct experience of anybody here.

[nb Innisfree]

Be wary of auto w/m running off auto throttle on inverter generators, they can keep switching continuously from tickover to full throttle as the load keeps fluctuatIing in a wash cycle. Maybe it needs a genny big enough to supply a wash cycle in tickover, throttle opening only on heating and/or spin?

[George94]

Be wary of auto w/m running off auto throttle on inverter generators, they can keep switching continuously from tickover to full throttle as the load keeps fluctuatIing in a wash cycle. Maybe it needs a genny big enough to supply a wash cycle in tickover, throttle opening only on heating and/or spin?

 

No, the WM won't be running off the inverter generator (the Honda). It will be running off the batteries via a 3kVA PSW inverter, and meanwhile the ancient 3.5kVA Lister will be replenishing the batteries. I would presume that the batteries will act as a large capacitor and shield the generator from any sudden fluctuations, but since it ran the old WM directly for many years I don't think it needs much protection.

 

But point taken.

[Robbo]

This is for SmileyPete, and anybody else with superior electrical knowledge.

 

I keep refining my ideas about the best charging system for a boat. The following applies to winter, when PV power isn't enough.

 

It seems to me that one doesn't need a big generator for charging batteries because most of the time the charger is in float mode and having a big genny is just a waste of time, money, space, fuel, and ear-drums.

 

So I am coming round to the view that ideally you need two generators. One, around 3.5 kVA or a bit more, for running the washing machine and major power tools. In other words, for occasional use.

 

The second should be a baby (but quieter!) and should be on for most of the time when you need power (yes, including after 8 pm, hence the need for being quiet). That way, the batteries are never depleted by more than a small amount and won't need marathon charging sessions to get them back to 100% SOC.

 

In my case I have a problem in that my old ST1 genny doesn't provide clean enough power for my washing machine. So, it means either buying a new genset or genhead, or using the 3kVA inverter (and cold wash).

 

The question is, what happens if I run the big genny while the chargers are in float mode, and the washing machine is running? Will the chargers draw more power from the genny to compensate for what is going out, or will the batteries just get hammered? The chargers (2 in parallel) provide 600 kVA each (flat out), and the washing machine will probably want most of that.

 

Yet another possible alternative would be to attempt to clean up the act of the ST1. Would a modern AVR do the trick?

 

Thanks for any helpful advice.

 

ETA: The Lister ST1 genset is a standard Lister unit, 3.5kVA, but I have mislaid the manual and can't give more details.

 

The Victron can power boost any source, so for washing machine or tools, you don't need as big as generator as you first thought. It can also reduce the amps to the charger to match the generator max power and how much AC load there is...

 

Read this.. http://www.victronenergy.com/orderbook/

 

So if you have a Combi, then you only need a small generator, not two as you first thought.

Edited September 30, 2013 by Robbo

[George94]

 

The Victron can power boost any source, so for washing machine or tools, you don't need as big as generator as you first thought. It can also reduce the amps to the charger to match the generator max power and how much AC load there is...

 

Read this.. http://www.victronenergy.com/orderbook/

 

So if you have a Combi, then you only need a small generator, not two as you first thought.

 

That Victron book is the clearest exposition of batteries and charging that I have seen. They now need to do one for solar PV!

 

I already have all the kit; I just needed to know whether what I had would work to power the washing machine using the inverter, and without drawing too much energy from the batteries. The reason I have two 50A chargers rather than one larger one is that 50A seemed to be the maximum that one could ask the Honda to handle (along with a few lights etc.).

 

Thanks for all the replies.

[Robbo]

 

That Victron book is the clearest exposition of batteries and charging that I have seen. They now need to do one for solar PV!

 

I already have all the kit; I just needed to know whether what I had would work to power the washing machine using the inverter, and without drawing too much energy from the batteries. The reason I have two 50A chargers rather than one larger one is that 50A seemed to be the maximum that one could ask the Honda to handle (along with a few lights etc.).

 

Thanks for all the replies.

If you have the combo and the remote (can also set on the machine) you can dial down the number of amps it will use.

[by'eck]

 

No, the WM won't be running off the inverter generator (the Honda). It will be running off the batteries via a 3kVA PSW inverter, and meanwhile the ancient 3.5kVA Lister will be replenishing the batteries. I would presume that the batteries will act as a large capacitor and shield the generator from any sudden fluctuations, but since it ran the old WM directly for many years I don't think it needs much protection.

 

But point taken.

 

Actually it won't be so much the batteries that shield the generator output from the washing machine as the inverter. This especially as it uses a fair bit of conditioning circuity on its AC output.

 

Unfortunately its a myth that a battery load will iron out high frequency voltage fluctuations.

[nb Innisfree]

It's also a myth that Victrons improve the waveform from a genny, it can only mimic it.

Edited October 1, 2013 by nb Innisfree

[Robbo]

 

No, the WM won't be running off the inverter generator (the Honda). It will be running off the batteries via a 3kVA PSW inverter, and meanwhile the ancient 3.5kVA Lister will be replenishing the batteries. I would presume that the batteries will act as a large capacitor and shield the generator from any sudden fluctuations, but since it ran the old WM directly for many years I don't think it needs much protection.

 

 

You can either charge batteries or discharge batteries, you can't do both at the same time.

[nb Innisfree]

 

You can either charge batteries or discharge batteries, you can't do both at the same time.

You can with a trilithium modulating feedback particulator circuit.

[George94]

Perhaps I expressed myself badly. I think it is fairly obvious that you can't charge and discharge a battery at the same time. All I am trying to do is use the genny to reduce the energy taken from the batteries.

 

And I am not suggesting that the batteries will in some way smooth the generator output. All the power going to the washing machine will go through the inverter, which produces a pure sine wave.

 

By "shielding the generator", I meant providing power for sudden peaks, such as the motor starting.

[Phil Ambrose]

NB Innisfree, a what!!?

Phil

[nb Innisfree]

NB Innisfree, a what!!?

Phil

One of them...

[Phil Ambrose]

Oh I see (not really but I'm trying)

Phil

[bottle]

It is not one them, it is one those.

 

 

No wonder you're confused.