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Selecting a new portable generator - confused on features


StevenG's Avatar
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01-19-09, 07:18 PM   #1  
Selecting a new portable generator - confused on features

After going 6 days without power during the New England ice storm, we would like to purchase a decent sized portable generator. Something in the 6.5kW-8kW range. We had a smaller one during the storm, but I wanted a larger one now and I will have it properly wired in with a 200A disconnect safety switch to keep it isolated from utility power.

My question is this though - what are the more important features to have, specifically, what is more important, a unit being brushless (my understanding is that they produce cleaner power (less THD) over their brush based competition), or one with automatic voltage regulation? I assume both is best, but in the $800-1200, I can't seem to be able to fit that order, unless it's a unit made in China.

Generac has told me their XP line has an alternator that is brushless and produces a steady voltage and THD less than 5%, but it does not have AVR. So how can it produce a steady voltage without AVR?

I've found many brush based units (by Briggs and Stratton) that have AVR though, but I can;t help with thinking brushes are bad and that the THD is going to be closer to 10% (bad for electronics).

I'm thinking brushless trumps AVR, but I can't get my mind off thinking both are equally important. I'd like to be able to run things like a plasma tv, computer, etc, during an extended outage (as well as the normal stuff like a fridge, heat, and some lights, etc), without worrying that I am doing damage. I understand I can't light up my whole house with it, just selected stuff.

Keeping in mind that I'm trying to spend no more than around $1200 (which puts Hondas and the like out), what brands should I be looking at? I checked out out Briggs and Generac (a B&S company) for the most part, but can't really find others that fit the order.

On Generac, I liked the GP7000E or the XP6500E, but was shocked to see that they recommend the valves be checked/adjusted every 100 hrs. Seems really frequent. And the issue with both of these is no onboard AVR.

Anyway, if anyone could help make heads or tails out of those two features, for the purpose I have, I'd appreciate it.

Thank you.

 
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01-19-09, 07:34 PM   #2  
sorry but for that price range you are not going to get a really good unit. you really would be better served by at least a 10K unit and if you are going to need it for very long a water cooled unit will be a better unit. i would go with a brushless unit all other things being equal, also try to look for a pressurized oil system. most of the less expensive units will need very regular valve adjustments. and any units with L head engines will need carbon cleaning at about 100 hour intervals also.

Murphy was an optimist

 
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01-20-09, 01:52 PM   #3  
Posted By: Speedwrench sorry but for that price range you are not going to get a really good unit. you really would be better served by at least a 10K unit and if you are going to need it for very long a water cooled unit will be a better unit. i would go with a brushless unit all other things being equal, also try to look for a pressurized oil system. most of the less expensive units will need very regular valve adjustments. and any units with L head engines will need carbon cleaning at about 100 hour intervals also.

Murphy was an optimist
Thanks. considering this is only for a backup in case of power loss, I wasn't looking to go crazy. But the Generac XP line is brushless with full pressure lube and spin on oil filter. Cast iron bore, etc. Rated at 3,000+ hrs.

sounds like either the 6.5kW or 8kW model is the winner for me. I just didn't know if passing on AVR to get brushless was the better swap.


Last edited by StevenG; 01-20-09 at 01:57 PM. Reason: typo
 
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01-20-09, 08:24 PM   #4  
then the Generac xp line would be my choice within those price constraints. get the biggest you can afford you won't be dissapointed with bigger.

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01-21-09, 10:57 AM   #5  
There is a point of diminishing returns though right? For example, the XP8000 has an L14-30 outlet on it. So even though the genny can put out more than 30A, that outlet and the breaker will limit it to 30A. So unless I put in a 50A inlet, and buy a genny with a 50A outlet, anything greater than 7200 watts really wouldn't be utilized unless I was plugging directly into the 20A outlets. Is that correct?

Thanks for all your help.

 
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01-21-09, 08:49 PM   #6  
Hi StevenG,

I think you might get better advice for the electrical aspect of a generator from the electrical forums here. I'm not really qualified to answer the question, but I would agree with your train of thought. If your hookup is limited to 30 amps, then there is no need to buy a generator that is well beyond that. Buying a little larger is good, however, if you think you will be using nearly all the amperage it can create for any substantial amount of time. If you're pulling 6500 watts from a 7000 watt generator for more than a few minutes, you're working it hard. Working it hard shortens the life of the engine and electrical components. It makes diodes and windings hot and holds them at their limits. If you're pulling that same 6500 watts from a 9000 watt generator, you'll be working the machine more comfortably and not taxing it. It's always better to get more generator than you think you need if you possibly can.

If it means buying a chinese generator, nevermind. I'd shop for a used one before buying one of those....

I prefer brushless for sure. I use a 7000 watt coleman with a briggs vanguard. It has been a good machine for a long time, and still is. I don't run electronics with it though, so I am not even aware of THD or how important it is. Is there a device you can plug your equipment into to stabilize the current and optimize it for use with electronics?


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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01-24-09, 11:35 AM   #7  
I suppose you could use a nice quality UPS with a line conditioner. That would clean the power up.

I've decided on the Generac XP8000E. Now I just need to locate one at Lowe's, as they by far have the best price for this unit, at $1349.

 
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