Older Em650....voltage variance, safe to use?

[doughpat]

I picked up a somewhat vintage Honda EM650 off of craigslist for free.
Just needed fresh oil and fresh gas, started on the fifth pull . Seems like a sweet little generator for doing the bulk absorption phase of charging my lead acid battery. I have read that the older generators were not voltage stable. It sounds like depending on the load, the voltage changes. I guess they did not have the same circuitry to smooth out the voltage that the newer ones do. I have read, “ be careful what you plug into them“ .

I was planning to use the generator in the morning to bring the battery back up to mostly charged, then use a suitcase solar to trickle in the last bit.

Like most generators, there is a 120 V output, as well as 12 V DC. I wonder if maybe it would be safer to use the 12 V DC output and hook it directly to the battery, bypassing the converter?

Also, curious what type of wiring you were intended to use with the 12 V set up. There are two flat female receptacles that have clamps, looks like you were meant to put some kind of specialized connector in there and clamp them down?

[uncle_bob]

Hi

You very much do *not* want to use the 12V output. No matter how much people moan about the converter chargers, they will do a much better job than the poorly regulated 12V out of a generator. Also, it only puts out 8A max at 12V. It will take a *long* time to charge up your batteries that way. That is not a knock on this specific generator, they all pretty much are in the same boat.

At sea level / in good shape / on a fine day, the unit is rated to put out 550 VA. There don't seem to be any waveform or noise specs in the manual. It's a pretty good bet that it is not the nicest looking waveform. No idea if it meets the current National Park noise regs or not. It should put out enough to charge batteries. You don't want your fridge going over to "electric" while doing so though.

Looking at the manual, it could be > 20 years old. They seem to want the fuel line replaced every 2 years. I suspect doing so on yours would be a pretty good idea. Beats spewing gas all over the place

Bob

[doughpat]

As always Bob, your input is greatly appreciated.

Why would poorly regulated power into a battery matter? Isn’t a battery relatively immune to noisy power? Over/under voltage I could see being problematic, but other than that...?

[uncle_bob]

Originally Posted by doughpat

As always Bob, your input is greatly appreciated.

Why would poorly regulated power into a battery matter? Isn’t a battery relatively immune to noisy power? Over/under voltage I could see being problematic, but other than that...?

Hi

It's not the RFI (spikes) on the output that get you with the battery and the 12V output. It's the voltage "wandering" up to who knows where that is the problem. With the limited current output that's not always a gotcha (current limits first). If indeed you *did* run the generator long enough to fully charge the battery ( .... 100 AH at 8 A is 12.5 hours ...) then indeed the voltage going to 15 or 16 V would be an issue.

Spikes on the 120V output (and maybe a not so sine wave looking output) do bother modern electronics. Exactly what's in a "modern" converter is a bit unclear. If they do power factor correction, then they do care about sine wave input. My guess is that they don't do PFC.

Lots of fun !!!

Bob

[emelaich01]

These are fun little generators; i've got the 1000W version but you'll find that unlike an inverter generator, the voltage and frequency are a product of engine rpm's; on your Honda, it's 3600 rpm to achieve the rated 8.3 DC amps or 4.6 AC amps. That means no 'idle' speed even when peak power is not needed so the noise may be an issue. It will charge your battery just fine but you might also check into the power requirements of an AC-powered battery charger like Schumacher's 15- or 20-amp models for a more efficient use of your generator's capabilities.