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900w generator how big a charger can I use 20a?


reg

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6 minutes ago, reg said:

I have a stephill shx1000 generator, basic specs here

Stephill sxh100 gen specifications

 

I want to charge my batteries from this but have the following question 

 

What size charger would be best suited to run from this generator?

 

bearing in mind I don't want to run it at full throttle for long periods of time. 

Different makes of chargers have different Power-Factors (efficiencies), but 900 watts should run any 20 amp charger.

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Many thanks for both replies, does anyone have any recommendations for a <=£70 decentish charger. 

 

Will not be permantly mounted and will only be occasional use, would prefer something fairly robust but not too bothered about gizmos and too much sophistication. 

 

Unfortunately I can't use my victron multiplus as gennie is below spec to run through it. 

Edited by reg
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2 hours ago, reg said:

Many thanks for both replies, does anyone have any recommendations for a <=£70 decentish charger. 

 

Will not be permantly mounted and will only be occasional use, would prefer something fairly robust but not too bothered about gizmos and too much sophistication. 

 

Unfortunately I can't use my victron multiplus as gennie is below spec to run through it. 

Doesn't the victron have a dial or some other control that allows you to turn down the charger output to suit the AC supply?

 

By the way, you'll be running the generator for ever to try and get a typical size domestic battery bank fully charged with a 20 amp output charger - assuming the batteries have been reasonably well used since the previous charge and are down to around 50 - 70% SoC.

Edited by blackrose
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9 hours ago, reg said:

Will not be permantly mounted and will only be occasional use

PLEASE install it on a permanent basis - 'temporary' use and crocodile clips lead to potentially dangerous situations.

 

You are unlikely to get a 'known name' boating brand for that budget - a quick look shows that this is probably about the best you'll get :

 

https://www.ebay.co.uk/itm/12V-20A-24v-charger-BOOST-Boat-Battery-lorry-tractor-van-car-METAL-case-large/292775719413?epid=2008917666&amp;hash=item442acaf1f5:g:pKgAAOSwHsRYD0I~:rk:15:pf:0

 

THIS IS NOT A MULTI STAGE CHARGER SO NEED HUMAN INTERVENTION

 

or

 

https://www.ebay.co.uk/itm/12V-20A-Connect-and-Forget-Leisure-Battery-Charger-Caravan-Motorhome-Boat/122314362986?hash=item1c7a81106a:g:qMYAAOSw7I5Tw788:rk:31:pf:0

 

THIS IS A MULTISTAGE 'FIT & FORGET' CHARGER.

Edited by Alan de Enfield
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7 hours ago, blackrose said:

Doesn't the victron have a dial or some other control that allows you to turn down the charger output to suit the AC supply?

 

 

I can on mine ( I think) but Ive only ever turned it up to max output and back to the default 60 amp charge max.

I do have the both the control panel and usb interface though-Ive no idea if you can do this on the dip switches.

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11 hours ago, reg said:

Unfortunately I can't use my victron multiplus as gennie is below spec to run through it. 

I tried a few 1kva gennies with our Multiplus but no luck, tried all the adjustments, eventually settled on a bigger 2kva Kipor. Didn't make any difference as to genny quality, a cheapo 3kva worked but a 1kva Honda didn't. 

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9 hours ago, blackrose said:

Doesn't the victron have a dial or some other control that allows you to turn down the charger output to suit the AC supply?

 

Unfortunately whatever settings you use on the multiplus 2500 the stephill (and incidentally the Honda eu10) are just short of meeting the required parameters. Mentioned it to onboard energy when I called in at springwood haven and they basically said "Yep can't be done with that rated gennie", which was fair enough and confirmed my findings. Frustratingly close to meeting the parameters though. 

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10 hours ago, blackrose said:

By the way, you'll be running the generator for ever to try and get a typical size domestic battery bank fully charged with a 20 amp output charger - assuming the batteries have been reasonably well used since the previous charge and are down to around 50 - 70% SoC.

Even worse with the 6a one I'm using now. Not a major issue as its just a standalone battery inside a Numax box so effectively, when connected to the gennie, it's working as a pass through box. Used primarily to charge up my tablet and to run some secondary stand alone circuit led lights. Normally charging is taken care of by solar. 

Current battery is one that was taken down by a shorted battery in a now redundant battery bank. Just trying to put a bit of life back into it and set things up so that I can give it a boost from time to time. 

 

Main battery bank is not an issue. 

Edited by reg
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1 minute ago, reg said:

Normally charging is taken care of by solar. 

You probably already know this but for the benefit of those who don’t... if you have solar but need to put in a bit more than solar can give, especially at this time of year, then it’s best to use the genny for a couple of hours first thing, thereby doing a fair bit of the bulk charge, then allow the solar to slowly trickle the battery up for the rest of the day. 

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3 hours ago, Alan de Enfield said:

PLEASE install it on a permanent basis - 'temporary' use and crocodile clips lead to potentially dangerous situations

Like you I'm not a fan of crocodile clips so I have permanently wired up a short cable terminated with an Anderson connector. Makes it easy to just plug in if I need to run directly from the dc output. 

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1 hour ago, nb Innisfree said:

I tried a few 1kva gennies with our Multiplus but no luck, tried all the adjustments, eventually settled on a bigger 2kva Kipor. Didn't make any difference as to genny quality, a cheapo 3kva worked but a 1kva Honda didn't. 

 

32 minutes ago, reg said:

Unfortunately whatever settings you use on the multiplus 2500 the stephill (and incidentally the Honda eu10) are just short of meeting the required parameters. Mentioned it to onboard energy when I called in at springwood haven and they basically said "Yep can't be done with that rated gennie", which was fair enough and confirmed my findings. Frustratingly close to meeting the parameters though. 

Didnt realise that-even more glad I have EU 2 now then! Useful to know though.

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On 14/01/2019 at 12:18, PaulJ said:

Didnt realise that-even more glad I have EU 2 now then! Useful to know though.

Paul my multiplus is a 12v 2500/120 is yours the same? If so are you saying that the Honda  eu20i works OK with it?

Also did you have to adjust any of the settings to make it compatible? 

Just wondering as I need to upgrade my gennie Methinks, looking at researching a stephill shx2000, which has the same engine as the Honda. 

Found on victron site that they say minimum generator spec is 2.5kva but as the Honda is below this spec and appears to work they may be building in a safety factor into their calculations. 

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3 minutes ago, reg said:

Just wondering as I need to upgrade my gennie Methinks, looking at researching a stephill shx2000, which has the same engine as the Honda. 

Found on victron site that they say minimum generator spec is 2.5kva but as the Honda is below this spec and appears to work they may be building in a safety factor into their calculations. 

It doesn't matter about the size of the engine, its the size of the generator that determines how many watts are produced.

 

The Stephill SHX2000 is only 1.5Kw continuous

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5 minutes ago, Alan de Enfield said:

It doesn't matter about the size of the engine, its the size of the generator that determines how many watts are produced.

 

The Stephill SHX2000 is only 1.5Kw continuous

OK thanks. 

Although the Honda eu20i is technically below recommended specs as quoted by victron it would appear that anecdotally it works o.k.

Thought I might of been optimistic about using the Stephill, suspect it could be an expensive gamble so will stay away from it, unless of course someone has good experience of the stephill-Victron 2500/120 that would be nice(not holding my breath though). 

 

Just on the other point I previously raised about a low cost 20a charger, just taken delivery of one. Biggest heap of dangerous (insert own expletive here) known to mankind, loose screws and broken plastic pieces  rattling about inside and generally of shoddy appearance. Currently in dispute so can't say any more but basically there is no such thing as a sub £30 safe 20a battery  charger. 

One day I'll learn 

 

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1 hour ago, reg said:

Paul my multiplus is a 12v 2500/120 is yours the same? If so are you saying that the Honda  eu20i works OK with it?

Also did you have to adjust any of the settings to make it compatible? 

Just wondering as I need to upgrade my gennie Methinks, looking at researching a stephill shx2000, which has the same engine as the Honda. 

Found on victron site that they say minimum generator spec is 2.5kva but as the Honda is below this spec and appears to work they may be building in a safety factor into their calculations. 

Nope-my multiplus is12/ 2000/80.

The Honda runs way better than the Hyundai 2000 I have and is smaller and lighter too.

Havent had to change any settings other than on the Digital Multiplus control panel (when running gennie), which I set to 6.5 when I use my washing machine (its 2,300 watt) 

Really pleased with my setup-2000 watt is more than I need most of the time-just except for when I need to do washing-power assist is a cheap way of getting few more watts..

Edited by PaulJ
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My experience of charging using  a portable generator is the amps  going into the battery are less than than when using a mains supply. I have only done  this very occasionally.  A very inefficient means of charging a battery. 

 

As for portable chargers I have a small one from Aldi which is unfortunately no longer available but it gives an idea of something that may be available

https://www.aldi.co.uk/auto-xs-car-battery-charger/p/097043233607400

However as  said a fitted charger would be the solution for regular use .

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Based on a very elderly Sterling 40 A charger, three 110A leisure batteries and a now expired 1000w Yamaha genny; this setup worked most times, but if the batteries had taken a tanking, I would sometimes have to run the engine for a few mins just to get things moving.
Using the 1.5kW genny that we now have, no probs whatsoever.
Based on this experience, and playing safe, I would estimate 30A charger max for the OP's genny.

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14 hours ago, PaulJ said:

Nope-my multiplus is12/ 2000/80.

The Honda runs way better than the Hyundai 2000 I have and is smaller and lighter too.

Havent had to change any settings other than on the Digital Multiplus control panel (when running gennie), which I set to 6.5 when I use my washing machine (its 2,300 watt) 

Really pleased with my setup-2000 watt is more than I need most of the time-just except for when I need to do washing-power assist is a cheap way of getting few more watts..

OK thanks for that info, unfortunately mine is the 120a charger version so suspect I wouldn't get away with it, certainly would be an expensive gamble to find out. Added to that I have found that victron specify a minimum of a 2. 5kva generator to pair with my model. 

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28 minutes ago, reg said:

OK thanks for that info, unfortunately mine is the 120a charger version so suspect I wouldn't get away with it, certainly would be an expensive gamble to find out. Added to that I have found that victron specify a minimum of a 2. 5kva generator to pair with my model. 

In theory you could get away with a 1500w generator IF the charger was 100% efficient (ie had a Pf of 1)

 

Basically Power Factor is how efficiently the input power is used - a battery charge with a Pf of 0.5 will use (lose) 50% of the input power to produce its output.

 

Many chargers have a Pf of around 0.75-0.8 , some as low as 0.6. with Ebay 'cheapys' as low as 0.5.

You can electronically achieve a Pf of 1 but it is expensive.

 

As an example :

If a cheap charger has a Power factor (Pf) of 0.5 then it will require 2x the power to 'work' than one with a Pf of 1.

So if your Victron had (I'm not suggesting it has) a Pf of 0.5 you would require a 1500w generator in theory, but in reality would require a 3000w generator.

Edited by Alan de Enfield
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4 hours ago, MartynG said:

My experience of charging using  a portable generator is the amps  going into the battery are less than than when using a mains supply. I have only done  this very occasionally.  A very inefficient means of charging a battery. 

 

As for portable chargers I have a small one from Aldi which is unfortunately no longer available but it gives an idea of something that may be available

https://www.aldi.co.uk/auto-xs-car-battery-charger/p/097043233607400

However as  said a fitted charger would be the solution for regular use .

Has anyone else found this?

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On 14/01/2019 at 11:56, WotEver said:

You probably already know this but for the benefit of those who don’t... if you have solar but need to put in a bit more than solar can give, especially at this time of year, then it’s best to use the genny for a couple of hours first thing, thereby doing a fair bit of the bulk charge, then allow the solar to slowly trickle the battery up for the rest of the day. 

That makes sense and is probably the strategy I'll adopt, thanks. 

 

Update On the delivered faulty charger issue previously mentioned I have now received a full refund for this without the need to return it, so I can't really complain about that. However I would reiterate that there is no such thing as a quality sub £30 20a charger, without going into details, easy enough to deduce if on ebay, I would say dangerous looking bit of tat which awaits a meeting with my lump hammer. Hope the new one I have ordered fairs better. 

Thanks for all the help. 

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