Generator-Charger mis match

Submitted: Sunday, Oct 23, 2022 at 11:36
ThreadID: 144974 Views:4519 Replies:7 FollowUps:8
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I bought an inverter generator which has a maximum output of 800w and constant output 700w.
I wanted to use it to power my 240v 30amp smart charger. Specs for that are Input Voltage 210-240V, Input current approx 1.6 amps, Output current 0.5-30 amps, Continuous Power output 120-360W.
BUT the generator overload light comes on and it stops running.
The charger is connected to 2 x 100ah AGM’s
Where did I go wrong?
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Reply By: Member - LeighW - Sunday, Oct 23, 2022 at 12:24

Sunday, Oct 23, 2022 at 12:24
There can be a considerable power surge with some chargers when they are first connected and this can cause small generators to overload. Enerdrive for instance indicate a 1kVA generator for their chargers upto with an ouptut of upto 40A and 2kVA for their 60A model.
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Reply By: Allan B (Sunshine Coast) - Sunday, Oct 23, 2022 at 13:54

Sunday, Oct 23, 2022 at 13:54
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Michael, as Leigh said, possibly starting surge. There are a couple of things you could try......

1) Unpair your batteries and try charging one at a time.
Or:
2) Start the generator, then power-up the unconnected charger, lastly connect the battery to the charger. This gives the generator time to bring the the charger up before applying the battery load and may reduce the inrush surge.

What brand is the charger?
Cheers
Allan

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Follow Up By: Member - Michael H54 - Sunday, Oct 23, 2022 at 15:07

Sunday, Oct 23, 2022 at 15:07
Hi Allan,
I did try just one battery and got the same result.
Also, my charger instructions said that the smart charger had to be connected to the battery before being switched on so it knows what sort of battery it is connected to so I didn't try connecting it last of all.
I was so Pis**d off I sold the generator but since I still had all the specs that I used to make the decision to purchase I just wanted to ask you guys where I went wrong.
So I don't make the same mistake next time.
Oh! and it was a Gentrax.

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Follow Up By: Allan B (Sunshine Coast) - Sunday, Oct 23, 2022 at 15:28

Sunday, Oct 23, 2022 at 15:28
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Ah yes, I forgot about the common need to have the battery connected before power-up. There is a way around that though. The charger merely has to 'see' a battery voltage before it will boot-up so if you connect a resistor (say about 36W 12v lamp) in series with the charger negative lead it will see the battery voltage but limit the current. A switch connected across the lamp can then be closed to commence charging. Yes, messy I know, but if desperate...?
I actually asked the brand of the *charger*.

I don't think you "went wrong". It is an often encountered problem with power supplies and generators that they are too quick to respond to brief surges and so trip.
Maybe next time, negotiate with the supplier to trial the genny before committal. Not possible with online purchases however.
Cheers
Allan

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Follow Up By: Member - Michael H54 - Sunday, Oct 23, 2022 at 16:58

Sunday, Oct 23, 2022 at 16:58
Yes it was an online puchase Alan.
The charger brand is iTechworld 30
Thanks for your input.
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Follow Up By: Member - Michael H54 - Tuesday, Oct 25, 2022 at 15:07

Tuesday, Oct 25, 2022 at 15:07
FYI I contacted the manufacturer of the charger. Here is their response.
I have also asked for specs re the starting surge. If they reply I will post again.


Hi Michael,

Our 30a 240v charger uses 384w on input.

Any generator which is larger than 384w will run this battery charger.

On Sun, Oct 23, 2022, at 09:48 AM, Michael *****wrote:

Product Question ------------------------------- What size generator do i need to run your 30 amp smart charger?
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Follow Up By: Member - Warren H - Tuesday, Oct 25, 2022 at 15:36

Tuesday, Oct 25, 2022 at 15:36
It is interesting how issues persist despite advances in tech. In the 1990s a group I worked with needed very clean 12V power to run instruments and dataloggers for extended periods, so the batteries needed charging. The tech designed a system whereby the generator fed (pretty noisy) 240V to a 36V battery charger connected to 3x12V deep cycle lead acid batteries. To get the ripple and spike free power, he pulled the 12V off the middle battery. I did get an explanation of the details of why this was the way to go but it has faded from memory.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Oct 25, 2022 at 17:08

Tuesday, Oct 25, 2022 at 17:08
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Warren,
The tech was possibly aiming to utilise the two outboard batteries as an impedance to filter-out the ripples and spikes. The concept has some merit.
Cheers
Allan

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Reply By: Nomadic Navara - Sunday, Oct 23, 2022 at 15:59

Sunday, Oct 23, 2022 at 15:59
Way back we used to connect a 60 W incandescent globe across the generator output. This produced a bit of load to settle the generator down before you applied the inductive load.
PeterD
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Follow Up By: Member - Michael H54 - Sunday, Oct 23, 2022 at 17:01

Sunday, Oct 23, 2022 at 17:01
Thank you Peter that's a trick worth remembering :)
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Reply By: qldcamper - Wednesday, Oct 26, 2022 at 10:38

Wednesday, Oct 26, 2022 at 10:38
Your generator wouldnt happen to be a gentrax from outbax would it.
Track history of over rating products.
Have you ran anything else off the generator that requires 600 plus watts?
AnswerID: 641920

Follow Up By: Member - Michael H54 - Wednesday, Oct 26, 2022 at 20:43

Wednesday, Oct 26, 2022 at 20:43
Yes Gentrax. Not from Outbax.
I lost my patience with it and it has gone to a new owner.
The only other thing I powered from it was a 12 volt fridge which it handled without a problem.
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Reply By: Geoff (Newcastle, NSW) - Wednesday, Oct 26, 2022 at 11:46

Wednesday, Oct 26, 2022 at 11:46
Hello Michael,
All of the information you have been given is spot on and valuable.
I have only one more thing to add and it's something the average person has no access to.
It's the "quality" of the output from this cheaper inverter style equipment.
Attached is an image of the output of a 1,500 Watt pure sine wave inverter at 1,500 Watts and a purely resistive load. In this case a domestic bar radiator. An inductive load such as your battery charger will most likely change the output again.
Some of the cheaper "inverter" generators have a square wave output. All bets are off on how your battery charger would see that supply and load it up.
The mains power is included for comparison.
Geoff,
Landcruiser HDJ78,
Grey hair is hereditary, you get it from children. Baldness is caused by watching the Wallabies.

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Reply By: Bushranger1 - Wednesday, Oct 26, 2022 at 13:58

Wednesday, Oct 26, 2022 at 13:58
G'day Michael,
Maybe your Gennie is not putting out the rated watts?
I bought a cheap GMC 800w Gennie in 2010 to charge 3 independent batteries using 3 separate multi stage chargers.

Batt 1 is 120ah with 16 amp charger.
Batt 2 is 120ah with 12 amp charger.
Batt 3 is 80ah with 8 amp charger.

So total of 36 amps plus I run a 240v150w spotlight at the same time to keep the gennie loaded as the chargers "throttle back" when the batteries get near full charge. The cheap gennies tend to run more evenly by keeping a load on them.

Have never tripped the overload & the system gets run for 6 hrs + at a time.
I guess the only difference with my system is that the load is applied as each charger is switched on rather than 36 amps in one go.
Cheers
Stu

AnswerID: 641922

Reply By: StormCamper - Friday, Oct 28, 2022 at 01:33

Friday, Oct 28, 2022 at 01:33
If the 240v charger has a rather poor conversion effiency, and power factor, and the cheapo generator is, well cheap, that might explain it. Amazes me how many buy dirt cheap gennies and then wonder why they get problems. Filthy little things, get your self an Esky and ice so you can be more happy
AnswerID: 641931

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