Batterty charging with Honda EM500

Submitted: Tuesday, Mar 12, 2019 at 18:35
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I recently plonked 300 watt of solar on the van in an effort to be self sufficient for a few days ‘off the grid’ and in light of the past week of minimal solar energy at home after several days of overcast & rainy conditions, I have come to the realisation we may have been left a bit short if we had been camped out at the time.

I have also been given a thirty year old Honda EM500 generator – in top condition, my dad’s old unit rarely used during and since it was purchased.

If I want to use this unit as a backup in the situation where we deplete our 2 x 110 a/h batteries, I am wondering if this will be up to the job. The specs on the genset are: AC 240 v 330 VA Rated 400 VA Max 50Hz DC 12 v 100W

My understanding from threads I have seen n EO is that the preference for battery recharging from Gensets is via the 240v through a capable battery charger as opposed to feeding 12 volts directly to the batteries.

The van has a CTEK MXS25 (25 amp) charger installed on the 240 volt side so I hope the gennie would handle that charger?

Alternately I carry a Repco 9 stage 25amp charger to handle the vehicle battery if that requires a boost.

I should note that I am aware of the recall on this model genset some years back – that is when I chucked my same unit out. I guess this one was overlooked back then. It seems some people were having problems sorting out which outlets were 240 v 12 volts, but with my limited knowledge of ‘black magic’ I have got that sorted out.

I hope to trial the system next month and I just need to know if the small Honda can keep up with the job. I never actually charged batteries with my own unit – only powered my 240 v fridges and lighting.

Cheers – regards Phil
Phil 'n Jill (WA)

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Reply By: Allan B (Sunshine Coast) - Tuesday, Mar 12, 2019 at 19:17

Tuesday, Mar 12, 2019 at 19:17
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Hi Phil,

I'm not familiar with the Honda EM500 but its rating of 330VA constant should handle the Ctek 25A charger OK.
I would not use the 12vdc output of any genset for battery charging except in emergency with close supervision. It is 'brute-force' charging and could easily overcharge and harm the battery.

I note that the EM500 had some safety issue with the 12v outlet plug some years ago (see EO Thread 22511) so take care unless it has been modified. You seem to be on top of that though.

Cheers
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Follow Up By: Member - Phil 'n Jill (WA) - Tuesday, Mar 12, 2019 at 20:27

Tuesday, Mar 12, 2019 at 20:27
Thanks Allan - I can take confidence in it now. The specs are a mystery to me but figured one of you generous chaps would know for sure.

Yes - with the recall issue, I couldn't work out the problem at the time as my unit had dedicated plugs for each side and you couldn't get them wrong, but with dad's old unit I can see where the issue came up - the 12 volt side has two sides of flex with bare metal tabs to insert into the DC outlet. I wouldn't have thought they would be allowed into the country like that. I certainly won't be using them.

The 240 side is safe though and I won't be lending it.

Thanks for the help, regards, Phil
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Reply By: Bushranger1 - Tuesday, Mar 12, 2019 at 21:13

Tuesday, Mar 12, 2019 at 21:13
G'day Phil,
Been running a 16amp charger to charge a 130 amp hr battery & 12amp charger for a 90 amp hr battery using a 650watt generator for the past 10 years with no issues.
These batteries are for engel fridge, electric blanket for those 0 deg nights & lights in 2 vans onsite at our camping property.
The gennie has well over 1,500 hours on it & the whole system works perfectly. No solar hence the long run time on the gennie. Only run it during the day when out & about. Batteries been replaced due to normal deterioration.
Your setup should work fine & as said best not to use the gennie 12v output.
Cheers Stu.
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Follow Up By: Member - Phil 'n Jill (WA) - Tuesday, Mar 12, 2019 at 21:43

Tuesday, Mar 12, 2019 at 21:43
Thanks Stu - sounds like you have a great setup - tried and tested over ten years. The gennie must be a pearler.

Appreciate the feedback, cheers - Phil
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Follow Up By: Bushranger1 - Tuesday, Mar 12, 2019 at 22:13

Tuesday, Mar 12, 2019 at 22:13
Actually the gennie is a cheap GMC 2 stroke that was $100 bucks!
I bought 2 thinking it would die but still got the spare new in its box. I just cant kill this thing!
Runs for minimum 6 hrs or more at a time every 2 days. Sometimes for a month or more when doing wildlife surveys.
Chucked out the crappy "torch" spark plug & use NGK plug at service interval. Use good quality 2 stroke oil & fuel stabilizer.
Dont use stale fuel & in your case change the oil & it will just keep on going.
I guess also the reason my cheapie keeps on going as it is just running a constant load (2 battery chargers).
Cheers Stu.
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Follow Up By: chris a - Wednesday, Mar 13, 2019 at 08:37

Wednesday, Mar 13, 2019 at 08:37
Good day STU
I have one of the little GMC It seems to blow a hell of a lot smoke and ratels
like a old train I have heard some bad things about theses things but it keeps going
What oil are you using and how munch It getting a bit hard to start
Thank mate
Chris
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Follow Up By: Bushranger1 - Wednesday, Mar 13, 2019 at 08:54

Wednesday, Mar 13, 2019 at 08:54
Hi Chris,
I use Penrite semi synthetic but have used other low smoke oils mixed at 50:1. Does not blow any smoke but of course still smells like a 2 stroke.
Make sure you use fresh fuel as petrol goes off pretty fast these days. I also run fuel system cleaner thru it every so often.
Couple of times mine got hard to start I took off the muffler & scraped all the carbon out of the exhaust port. The port size had been considerably reduced due to the carbon. Since using FC or FD rated oils I have not had to decarbonize the port. This is due to higher detergent content of the better rated 2 stroke oil.
Hope this helps.
Cheers Stu
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Follow Up By: Bushranger1 - Wednesday, Mar 13, 2019 at 09:07

Wednesday, Mar 13, 2019 at 09:07
One other thing Chris.
2 stroke engines like to run under medium load so I have a 150watt light plugged in so that as the 2 battery chargers reduce output a load is kept up to the gennie.
Cheers Stu.
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Follow Up By: chris a - Wednesday, Mar 13, 2019 at 09:26

Wednesday, Mar 13, 2019 at 09:26
Thank Stu
Approximately how munch stabilizer goes in to the full tank Or do you mix it in a
bigger container first thanks
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Follow Up By: Bushranger1 - Wednesday, Mar 13, 2019 at 19:18

Wednesday, Mar 13, 2019 at 19:18
I use Stabil brand & mix it in the 5L container so it protects all the fuel.
From memory I think its 10 ml per 5 Litres.
Anyway you can get it from Supercheap & it tells you on the Label.
Sorry but I cant get the bottle as its in the shed at our camping property.
Cheers Stu.
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Reply By: eaglefree - Tuesday, Mar 12, 2019 at 22:45

Tuesday, Mar 12, 2019 at 22:45
I own a Honda ex350 generator. I inherited it. Also 2 stroke it has 6amp 12v charging port like yours. It also has AC

I connectef a good quality smart charger to the AC outlet and it fried the charger. I read up it was due to the genny not having pire sine wave.

So I have two options to charge my AGM batteries 1/use the DC outlet and keep an eye on the voltage or b/ use the AC outlet on an old type charger.

I have a 2700mah old type charger but I know I can run up to a 20amp one.

I have a alternator charging set up and solar so the genny is just for emergency.

Are you aware your charger could be square sine wave and not compatible for a smart charger?
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Follow Up By: Member - Phil 'n Jill (WA) - Tuesday, Mar 12, 2019 at 23:05

Tuesday, Mar 12, 2019 at 23:05
Hi eaglefree, thanks for the heads up on that aspect - I hadn't taken into consideration the matter of differing types of power generation - although I have seen quite a few references over the years about 'pure sine wave' vs square waves.

I don't know how sensitive the CTEK, or Repco chargers are, but I might have to resort to another 240v / 12v transformer I pulled out of a previous van if it looks likely to be a problem. As usual I hang onto all the old gear 'just in case' - you never know when it might come in handy as we tell the missus.

That could be a curly one to take into consideration as the old Honda is fairly old and I don't know if they had invented 'pure sine waves' back then.

I shall have to ponder that one.

Cheers - Phil

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Follow Up By: RMD - Wednesday, Mar 13, 2019 at 08:38

Wednesday, Mar 13, 2019 at 08:38
Phil 'n Jill
I agree with eaglefree as to the generator output. If the output isn't near a sine wave or the frequency is way off the mark, then a modern switchmode power supply designed for 50 or 60 HZ, heats up or doesn't start/run anywhere near efficiently. All these chargers are similar technology. It doesn't know how to handle food which isn't compatible. Similar situations with laptop power supplies. With a resistance load like a globe or maybe some LED lights the crappy waveform may be ok.

I know it is only for emergency use, but the 12v side has to have the engine running near or at full normal revs to create 12v or a bit more. You need more voltage than that as smart chargers do provide and so the voltage of the generator 12v side will try and reach it's maximum, but the applied current will diminish as the battery charges. That means a long run with 8amps if your lucky output, which results in long time of charge/engine run to do a bit of charge.

If the output 240v waveform isn't compatible with a smart charger,ie, switchmode dc unit it is, a plain normal cheap old conventional battery charger which takes advantage of any 240v ac input, may be the best thing for a top up. Just have to monitor charge level/time and applied battery voltage.
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Mar 13, 2019 at 08:45

Wednesday, Mar 13, 2019 at 08:45
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Oops, I should have thought of that and addressed it.

The ac output of that old gennie may be not too pure.
It would not be an "inverter type" system but would be producing the ac directly as a sine wave but may have a few "artefacts" in the way of distortions and spikes in it. Also, the frequency output will be directly related to the motor speed and if too far off 50Hz may cause problems within the connected loads.

"Square wave" and "Modified sine wave" characteristics are produced by the actions of inverters changing 12vdc to 230vac. Rotary generators produce essentially sine waves (of a sort).
Cheers
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Follow Up By: eaglefree - Wednesday, Mar 13, 2019 at 09:40

Wednesday, Mar 13, 2019 at 09:40
Yes I was naive also, a $240 smart charger up in smoke.
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Follow Up By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 10:53

Wednesday, Mar 13, 2019 at 10:53
Thanks gents - being forewarned is forearmed as it has been said.

Would there be any simple test to assess the type of output this genset produces do you think?

I actually have an auto electrician due this morning to run new wires to my Anderson plug. He may be of some help in that regard...

Cheers - Phil
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Mar 13, 2019 at 11:02

Wednesday, Mar 13, 2019 at 11:02
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Phil, the only way to objectively appraise the output waveform of the genset would be with an oscilloscope instrument. It is unlikely that an auto electrician would posses this. It is the tool of a electronic technician.

The output frequency in Hz could be assessed using a multimeter, many of which incorporate this function.

Both such tests require the usual precautions of dealing with the hazards of working with live 230 volts.

Cheers
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Follow Up By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 15:45

Wednesday, Mar 13, 2019 at 15:45
Hi Allan - you are right - the auto chappie not only didn't have the gear - he didn't want to know about gensets full stop, nor what happens when it gets to the van from his vehicle wiring - too many variations for him. Can't say I'm surprised from what I have read here on EO from time to time.

Thanks for the followup - greatly appreciated.

Regards - Phil
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Follow Up By: Bushranger1 - Wednesday, Mar 13, 2019 at 15:57

Wednesday, Mar 13, 2019 at 15:57
Hi Phil,
As I was using a cheapie generator I wanted to check out the waveform so I got the electronics guy at work to set up his digital oscilloscope to perform the waveform check then took the scope home.
Stuck the probes in the gennie socket then took a "snapshot" of the waveform form for him to look at.
You dont know someone that can do the same for you do you?
Turned out I had a standard sinewave with a bit of "noise" but was all good.
Cheers Stu.
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Follow Up By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 16:38

Wednesday, Mar 13, 2019 at 16:38
Thanks Stu - not that lucky but I will ask around though.

Meanwhile I will also look for what us old farts would probably call an old 'solid state' battery charger. Should imagine one of the family will have one on a shelf - bit surprised I don't - but I was forced to have a clean out a couple of years ago when shifting and I did manage to salvage a few trunks full of gear....

Regards - Phil
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Reply By: RMD - Wednesday, Mar 13, 2019 at 13:23

Wednesday, Mar 13, 2019 at 13:23
Phil 'n Jill
I see you have 300w of solar on the van, that sounds good but unless the panels are really good quality panels, their actual output compared to the rated, on the specs panel output will be far less. If you get 200w of actual power from them I would be surpised. Last week I fitted 3 x 160 panels to my ute roof/canopy. and although same size as a good 80w panel they each don't produce a great deal more. Rated 9amp at operating voltage but maybe 6amp each.
If reading amp flow to check the system, the amps in the solar line will be lower than the amps in the battery charge line if using an MPPT charger unit. Mppt holds the panel voltage to gain higher difference for it's inverter, ie, switchmode unit. The higher energy level is more efficient.
If wanting charge during lower light conditions, in fact any light conditions, having the panels in series, ie, double the panel voltage, and running that voltage into a decent quality MPPT regulator which can accept the input voltage, will see your batteries being charged when other systems voltages are often too low in potential difference to do anything much at all.The switchmode unit in the MPPT charger just converts the energy/whatever energy is available into the required battery charge profile.
A friend has recently done that with 2 x 250w panels through an Enerdrive DC DC dual input charger. Now he sees batteries charged like never before.
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Follow Up By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 15:55

Wednesday, Mar 13, 2019 at 15:55
Thanks RMD - I may be lucky on this one - the installer - RV Solutions in Rockingham - did fit An Enerdrive unit and voltage being produced seems ok in it's present static situation. I will be keeping notes when we put the system to work eventually.

Cheers - Phil
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Follow Up By: RMD - Wednesday, Mar 13, 2019 at 17:26

Wednesday, Mar 13, 2019 at 17:26
Phil
Not sure what you mean "voltage being produced seems ok".
If the panels are in parallel which is ok, but in low light you will still get some voltage but current flow intensity is vastly reduced. You previously mentioned low sun conditions.
If in that situation, or even with a series/parallel switch to link panels in parallel or series, when linked as series the Enerdrive, (smart unit it is) can use the current flow offered but it now has then got much higher voltage, ie, double what parallel would have at that moment and the Enerdrive can make more use of it for much longer as the daylight diminishes. Normal system will have konked out at that point.

The series linked panels begin charging earlier and later with the energy level available being able to be converted by the Enerdrive unit.
This may suit your purpose if often in or concerned with low sun/daylight conditions. Good sun, no problem with either way.
Just a consideration.
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Follow Up By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 19:05

Wednesday, Mar 13, 2019 at 19:05
I appreciate the feedback RMD. From my observations of the readings, the panels are producing 18v and it feeds in at 13.7v as it stands in the driveway.

I will be monitoring it throughout the day when camped to see what levels the batteries are, both on the Enerdrive screen readout and with my trusty hand meter for comparisons.

Meanwhile I shall also ask RV Solutions if the system is in parallel or series - something worth knowing I guess.

Thanks again - regards Phil
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Follow Up By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 20:06

Wednesday, Mar 13, 2019 at 20:06
Hi RMD - I finally fathomed out what you were trying to tell me - went over my head first time round.

The switch FROM parallel to SERIES will boot it up in really poor conditions. That is pretty smart as long as it gets switched back when the solar picks up again.

Handy technology, I shall go and read the INSTRUCTIONS and that doesn't happen too often - thanks.

Regards - Phil
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Follow Up By: RMD - Wednesday, Mar 13, 2019 at 20:27

Wednesday, Mar 13, 2019 at 20:27
Phil.
The system can always be a series panel connection as that gives the earlier start and later finish. Although the amp from the panels are not added together for the Enerdrive and will be same maximum amps flow, the system is inputting at twice the voltage level and so has same energy available. The Enerdrive input can( please check of course) use the higher voltage any time early, midday or evening. It converts it into what the charging requirements are for you batteries. Overall it has the capacity to deliver more AH of charge everyday ‘cos it starts early, runs input at higher voltage which the Enerdrive can convert and delivers for longer in the afternoon. No need to switch it from parallel to series or back, just leave as series. Alan may have a viewpoint of the performance too.
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Mar 13, 2019 at 22:15

Wednesday, Mar 13, 2019 at 22:15
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Yeah, sure. Providing your MPPT controller can handle the input voltage, going to series connection is always better. Not only for the benefit of capturing the low light levels at early and late hours and also on overcast days, but also with the higher voltage and accompanying lower input current there will be less energy loss in the cables from the panels to the controller.

I should note that you would not use a series connection with nominal 12v panels when using a PWM controller. Any excess voltage so generated is simply discarded and the energy thus lost.

Cheers
Allan

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Follow Up By: RMD - Thursday, Mar 14, 2019 at 08:22

Thursday, Mar 14, 2019 at 08:22
G'day Allan,
If Phil's charger is the same Enerdrive unit as my friend has, he purchased it specifically because it could accept the higher voltage, whereas some others cannot take two panels in series.
He is a broadcast radio tech and understands energy levels quite well.

The good thing about the Enerdrive and other similar units is, they work with the available higher voltage, less amps but same energy level and can switch/convert for a distinct advantage.
With his system now delivering around 38v to the Enerdrive with only same as one panel current, it sees the batteries being charged far better than with two panels in parallel. Infact, he has just been away for a few days and it is the first time he hasn't been complaining about the batteries being too low.

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Reply By: Member - Phil 'n Jill (WA) - Wednesday, Mar 13, 2019 at 15:51

Wednesday, Mar 13, 2019 at 15:51
Thanks to all contributors - amazing how many aspects have to be considered in these matters. I appreciate the discussions and feel sure a few other followers are better informed as a result.

Regards - Phil


P.S. If I work out how to EDIT - I will fix my gaffe in the title or I won't be able to find the thread again on a search for 'Battery' ;o))
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Follow Up By: Bushranger1 - Wednesday, Mar 13, 2019 at 15:58

Wednesday, Mar 13, 2019 at 15:58
Oh no. Not a spelling mistake :-)
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Mar 13, 2019 at 16:07

Wednesday, Mar 13, 2019 at 16:07
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Phil, maybe that is what prevented it from turning into the usual "battery thread" fracas?
Cheers
Allan

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Follow Up By: Genny - Wednesday, Mar 13, 2019 at 17:42

Wednesday, Mar 13, 2019 at 17:42
What's that? Did I hear smelling mistake?
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Follow Up By: chris a - Tuesday, Apr 09, 2019 at 12:35

Tuesday, Apr 09, 2019 at 12:35
G day guys If a fuse was placed in the lead from the gen to the charger would stop damage to the charger
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Reply By: Member - Phil 'n Jill (WA) - Monday, Apr 15, 2019 at 11:59

Monday, Apr 15, 2019 at 11:59
Hi people – I know everyone is just hanging out for an update on the outcome of our test runs for the new solar gadgetry and various bits of gear tacked into the van – as promised.

Summary of trial run - overnight Sunday at Bunbury, three nights at Albany and two at Walpole with batteries relying on 300 odd watts of solar plus the DC-DC charger proving adequate without any 240 volt charger whilst travelling from Sunday through to Thursday when the skies started to close over. Whacked the 240 volt charger on when batteries were at 12.5v at 5pm and no sign of much further solar input for the next couple of days due to shady parking spot and cloud cover increasing.

There seemed to be no issues with the two charging methods (solar + DC-DC) feeding the batteries during this period.

I was considering the DC-DC investment may have been superfluous whilst there was an abundance of solar charging available, but the last couple of days reminded me that we will always be subject to changing conditions, and the ‘belts & braces’ backup system is now considered a worthy investment.

The little Honda remained in reserve and not put to the test, but it will be used when necessary, linked into an old school charger to the batteries.


A big thankyou to all contributors

Regards - Phil
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