Best Electric Generator For Back-Up Power.

[robert k]

Powermate used to make a 2.8 KW generator that was alot more efficient than their 3kw, if it's the same company. I don't think they make the 2.8kw anymore. If you are going to use it frequently, efficiency is the name of the game and at 100 watts difference at half load, I would find a way to make it work. Then too, air cooled engines are not the most efficient, they are just light weight with a good power to weight ratio. I read where a man described making his own stationary generator from a water cooled 1.3L automobile engine. Not absolutely certain but I think he used the engine and trans to drive a single phaze 240V electric motor backwards. It would be an interesting calculation to suit output shaft RPM at the most efficeient engine cruise speed to which electric motor would be suitable. Probably need a lazer level and a dial indicator to get the drive line right  with less than .001 runout. Millwrights might say less than .0001but I will gurantee that something moved whenever I worked on it and it lasted for years of continuous use anyway.

[not so old china hand]

Hi,

I was away all day yesterday and I see this thread has grown. I have been looking through the posts and will make a few quick comments and then post more detailed answers to some of the questions above.

 

Jake,

I'm afraid my quick and dirty calculation served to confuse. Battery capacity calculations are complicated by a range of factors. Not least the fact that the capacity of a battery decreases as the current drawn increasess (this is known as Peukert's Law). For example if a battery is rated as having a100 amp hour capacity at 5 amps it would provide a constant current of 5 amps for twenty hours. However if the current draw was increased to 10 amps the battery would ony supply this higher current for somewhere between 7 and 8 hours (and not 10 hours).

 

I was assuming that the battery would be depleated down to 20% of its capacity, taking 80% out. The lowest usable voltage is about 10.5 v for a 12 v lead acid battery.

 

Thomas

In many countries (including the USA) you can indeed sell power that you generate back to the electricity company: often at a considerable premium over their rates to you.

 

Site owners

I will continue to post on the topic of going off the grid on this thread if that is OK with everybody.

 

I have to head out again cheers for now.

 

Terry

[lyno 47]

I have set up a number of R/Vs with inverters and gen sets, here many like to go to remote areas and camp for a week or so.

I use 4-6 120amp hour batteries hooked up to the inverter usually with a 5000 watt inverter in the r/v I also mount a 1.5 kw solar panel on the roof of the r/v to charge the batteries during daylight hours,i also hard wire the gen set to the power inlet via a one way diode with a switch to change the gen set from 12volt charge mode to 240 volt direct power just in case there is no sun and the solar panel is not charging the batteries .

Like every set up there is limits so things like running a fridge, fans, lighting,p/c etc are o/k but running a/c will put a greater drain on the batteries.

I usually fit the r/vs out with led lights .

This system will usually keep most of the appliances running for around 4-5 days depending on your personal usage.

[not so old china hand]

I have set up a number of R/Vs with inverters and gen sets, here many like to go to remote areas and camp for a week or so.

I use 4-6 120amp hour batteries hooked up to the inverter usually with a 5000 watt inverter in the r/v I also mount a 1.5 kw solar panel on the roof of the r/v to charge the batteries during daylight hours,i also hard wire the gen set to the power inlet via a one way diode with a switch to change the gen set from 12volt charge mode to 240 volt direct power just in case there is no sun and the solar panel is not charging the batteries .

Like every set up there is limits so things like running a fridge, fans, lighting,p/c etc are o/k but running a/c will put a greater drain on the batteries.

I usually fit the r/vs out with led lights .

This system will usually keep most of the appliances running for around 4-5 days depending on your personal usage.

Hi I wish I had seen this information when I first kitted out my junk! I got close to this spec by a process of trial and error. May I ask a few detailed questions?

 

1) If I understand correctly you set up the gennie to charge the batteries with dc? Way to go. I discovered the hard way just how inefficient charging from a 220 ac genset through an inverter/charger is.

 

2) What kind of genset (fuel and capacity) do you fit and where?

 

3) Are the fridges conventional domestic fridges. If so what capacity?

 

4) Do you make any provision for charging the domestic battery bank from the vehicle's engine when underway?

 

5) What kind of batteries do you use for the domestic supply?

 

Cheers Terry

[robert k]

Terry, in the US many generators are set up to charge 12v also, some even have a usb socket for laptop or you can plug your phone charger into it.

[Jake]

Terry, in the US many generators are set up to charge 12v also, some even have a usb socket for laptop or you can plug your phone charger into it.

Hey guys,

 

This subject came full circle, back to the generator.  And I like that -- discussion of pros and cons,

Lyno47's custom made connections and cost.  Robert K pointed out the latest and greatest genset

(genny, generator) being sold on the market now.  Since Terry has nothing but accolades of Honda

brand generators, I took the opportunity to go shopping:

 http://powerequipment.honda.com/generators/models/eu3000i-handi

 

Charging a 12vdc battery, page 35 of http://cdn.powerequipment.honda.com/pe/pdf/manuals/00X31Z286100.pdf

 

They even have ports for parallel operation between the two (3KW x 2), page 30

 

I can see both of my blenders churning out pina coladas and halo-halo all day long.....he, he.

Edited May 16, 2014 by Jake
spil chek

[Thomas]

 

 

Thomas, Jake and I and not so old china hand were being off topic and talking about the related true off grid application. I believe I mentioned "off grid" 3 times in that post and I guess it just slipped past you.

 

 

I agree with you. I don't see any reason to have on grind and off grind as two separate topics. Its all about providing electrical power.

Yes. My point was, when someone talked about what to do with the WASTE electricity of the own back up system, ANY* back up system can be CONNECTED to the grid to SOLVE the waste problem you where talking about for the off grid system.   So what I wrote IS related  :)

 

Yeah, let's talk about electricity that could possibly be sold back to the utility companies.  Pick any power company in the

Philippines and ask yourself the following question: do you have any confidence that your account will be credited correctly?

Or would you continue to supply unauthorized connections within your village or barrio?

I don't expect any Phil electric company will pay me anything. No need for that either, because I don't expect the production will be biger than own production TOTALY

but it can be "waste" TEMPORARY.

Concerning the violet text I ment through the public grid of the electric company. I believe it would be complicated/expensive otherwice, EXCEPT if their cable start AFTER my meter anyway, with or without my permision  :)

 

I have no idea if the Phil meters do so, but I believe the Swedish meters go BACKWARDS when deliver power to it. If it's like that in Phils too, the bill will be the REST of got minus delivered.

 

I believe the Swedish "private" producers have to get OK from the electric companies to be allowed to deliver to the public grid, because the companies want to check if the "private" deliver corect type of electricity, and perhaps they demand some stability too. But the Phil electricity aren't stable anyway...  :)

[robert k]

Thomas, I wouldn't want a bit of my power going back into the grid. The liability measured against a few hundred piso a month savings would not be worth it to me. the hot water produced from any excess energy I produced would not be wasted, it would be used in the shower, wash clothes and do dishes. Part of my personal plan to stay out of trouble is to limit the points of contact between myself and any utility entities, like electric company, water, cable or internet. The less we have to discuss the better. I can count on one hand all the stories I have heard of pleasant interactions with utility companies but have heard hundreds of horror stories. Bad news travels fast but even if there were 10 times the good interactions that went unreported, the odds of a pleasant interaction are still very small. I will just eat the couple hundred piso a month I might have saved and smile. :)

[intrepid]

I have been following this thread like others because I too would like to save any money where I can.  Since electric is a needed item it may be a place to save.  The largest users of electric in most homes is heat/air con and hot water.  In the Philippines heat is really not an issue.  Hot water for some is a must have but there are solar options.  I plan to start a new thread asking for anyone using solar hot water heater and ideas. 
As far as generators/ charging and batteries, I do have some experience also on boats.  Over the years I have tried using different batteries.  Deep cycle marine in different voltages and configurations.  I used 2 100ah but was too small.  Later I was using 2 4D gel-cells because a great buy at the time.  They had the capacity I needed and lasted quite a while and no maintenance.  But those things were heavy.  At least they only have to be set in place once and removed when bad.  I replaced them with 4 6volt golf cart batteries.  Almost he same capacity as the 4Ds and so much easier to move around.
One of the things I wanted to throw out here that has not been mentioned is 12 volt appliances.  Campers and boaters know what I am talking about.  Almost anything made for the the house that uses 110 - 220 volt can be had in 12 volt.  Fans, lights, refs, pots, TVs, blenders(Jake) and even air conditioners.  Just remember, the bigger items like refs, and air-con still use more amp hours from the batteries.    My charging system for batteries was heavy duty marine charger when at shore power and high output alt. when away from dock.  I've been away from boating about 8 years now but at the time was never thrilled about solar chargers.  Mostly because of price and slow charging.  I'm sure that has changed in recent years.  Although I had a small inverter, I rarely used it because most everything on my boat was 12 volt.  Just some more ideas for those considering going off grid.  My vote would be a large battery bank, suppling to 12 volt appliances with a small to mid sized gen set.

[robert k]

Intrepid, I see your point about 12V appliances not having to endure the loss of stepping up the voltage, unfortunaly I believe that the great majority of them are low quality or very costly for quality. 12V in the home would have one glaring weakness, 12V does not travel well. Wheras any voltage may need a larger diameter wire to carry the voltage long distance, 12V would require big wire guage from almost the very beginning and get progressively worse. You really would be better off converting to 120V or 220V and using thinner wire from that point. As an example, I have two batteries in my toyota 4Runner, the hot sides are connected but I use a multipoint body ground for the second battery. I didn't have the guage wire I wanted so I ran two 4 guage multistrand wires to the remote battery 11 feet from the one under the hood. the voltage loss with even that overkill in wire is 7/10ths of a volt. I'm pretty sure the loss would at least double if I deleted one of the 4 ga wires. Double the distance, with one 4 ga wire, you are going to be pulling alot more amps, because as the volts go down, the amps go up, the wire will heat up. If you are going to wire your house with at least 4 ga wire, I'm buying stock in a copper company. I'm talking multistrand wire too, if you used solid wire, you would need alot bigger wire to begin with as electricity flows on the outside of solid wire and would take alot more surface area to carry the energy. Nice thought though for a van or boat, maybe small kubo, otherwise I don't think it's going to reach Jake's blenders in the kitchen. I certainly wish it would work. Maybe there is a chance if you clustered all of the things you want tor run around the batteries, but I don't know how that would work.