Using generator to charge house battery

[Noah]

Hi Folks,<br><br>&nbsp; I bought a used Honda eu2000i portable generator with a 12 volt plug used to charge a battery.<br><br>I'm wondering if I need to regulate the voltage myself to prevent overcharging the battery, or if the Generator has an on board regulator to allow me to take a nap while it's charging. <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle"><br><br>&nbsp; Worst case scenario is I buy a cheap AC battery charger to plug into the 120 plug, but it seems to defeat the purpose of the 12 volt option on the gen...<br><br>What do you think?<br><br>-Noah

 

[wrcsixeight]

The Honda output is only like 8 amps and unregulated. &nbsp;Use it but do not let the battery voltage climb above ~14.8<br><br>I don't think many utilize the 12v output on a generator, but if your batteries are low, 8 amps is not going to fill them up too quick, so you'd be safe napping, but better to have a automatic charger/ converter which starts everytime it is fed 110 to 120 volts AC from any source.

 

[highdesertranger]

your best bet is to follow wrcsixeight's advice.&nbsp; 8 amps isn't much.&nbsp; not really even worth running the gen unless it's an emergency.&nbsp; &nbsp;highdesertranger

 

[wandering mike]

I agree with the others, but wonder why you would run a generator rather than just idle the engine? &nbsp;I know there will be some talk about how it hurts an engine to idle, but when you look at not just semi's, but police cars, taxis and all kinds of other idling vehicles, it causes you to wonder what kind of damage it will do from a "real world" perspective. &nbsp;I suppose you can argue that the alternator will go out sooner, but then you are "using up" the Honda too. &nbsp;<br><br>I know in my Chevy 3500 chassis, I have a 105 amp alternator that charges the house batteries pretty quick and the big engine uses about 1/2 gallon an hour at idle. &nbsp;Don't know how that would compare with a Honda generator, but from the manual for my Onan 4000, it is about the same consumption for a lot more amps. &nbsp;I will usually charge with the engine rather than the Onan if I am out someplace. &nbsp;

 

[Noah]

Great advice, and I thank you indeed.<BR><BR>"I agree with the others, but wonder why you would run a generator rather than just idle the engine?"<BR><BR><BR>&nbsp;&nbsp; A very good point and I realize I should have been more specific in my original post...&nbsp; The reason for the Gen in the first place is to run a small window unit air conditioner. I work nights and am hoping to get a wink of sleep in the afternoons but it's heating up fast here in nor-Cal.<BR><BR>&nbsp;&nbsp; I figured if the Generator is going to be running for a few hours anyway, I might as well top off the battery while it's going. I normally rely on solar to charge, but the shade is just much more comfortable when it's a hundred degrees or more.&nbsp; Though, I'm starting to wonder whether I can even use the 120 volt outlet and the 12v receptacle at the same time...&nbsp; Either way, no biggie, I don't run my house battery down below 85% anyway. I'll just make sure to get some sun at some point or idle the engine as you suggested.<BR><BR>&nbsp;&nbsp; It is nice to have so many options.<BR><BR>Thanks again for the responses.<BR><BR>-Noah

 

[wandering mike]

Noah, yes, that now makes sense. &nbsp;I assume the window unit will be 1500 watts probably at best. &nbsp;So conceptually, you have 500 watts left. &nbsp;I think others can comment on start up demand for the A/C, but what I think I might try in your situation is to get a small battery charger and plug it into the generator and connect it to the battery. &nbsp;Then you are just trickling away.<br><br>One thing about this though, I have blown a couple small battery chargers by plugging them into cheaper inverters. &nbsp; One was the charger in one of those "jumper" battery devices and the other was the charger for the battery for a portable drill. &nbsp;Probably it is an issue for modified sine vs full sine wave chargers or something. &nbsp;Maybe the Honda has good clean power. &nbsp;I would read the warnings or just get a cheap charger to give it a try.

 

[Zil]

It would be much less expensive to charge with the honda. If you are using lead acid batteries you dont have to worry about overcharging as the honda doesn't put out over&nbsp; 14 . something volts. and the LA will be fine. Keep the water level up in your batteries.

 

[wrcsixeight]

The Honda's sine wave is clean and smooth.<br><br>Idle speed alternator amperage on many vehicles is pathetic. &nbsp;The alternator can only output its rated output in a lab, at high rpm, when cold, with devices capable of asking for that much current, over cabling that can pass that much current.<br><br>The Max rating never occurs in a vehicle, especially not at idle, and certainly not with batteries in the 85% range, where idling to recharge is truly an ineffective waste of gas.<br><br>Idling the engine can contribute to carbon build up on the valves and also thins the oil as it can get thinned by fuel dilution.<br><br>Most people after driving, judge their battery state of charge by surface charge voltage. &nbsp;I can have batteries at 50%, drive for a half hour then they are at perhaps 60%, yet surface charge will have them holding 13+ volts for hours afterwards, but they are only at 60%. &nbsp;The person without an amp hour counter sees this surface charge voltage and thinks the batteries are full charged, when they are far from.<br><br>A good alternator can bring the batteries upto 80% relatively quickly, but that last 20% takes forever whatever the charging source. &nbsp;Most people with larger RV's do 50'%s to 80'%s with their generator and a high powered converter to return them to 80% as fast as possible, and use as little fuel in the generator to do so as possible &nbsp;Getting to 100% from 80% will take longer than 50% to 80%, regardless of charging source, yet getting back upto a true 100% weekly is important for retaining battery capacity. &nbsp;Some might use the generator to do 50 to 90's if out for longer than a week.<br><br>That is the nature of lead acid battery recharging and the best alternator in the world is not going to change that

 

[wandering mike]

Thanks for the insight on alternator charging. &nbsp;I certainly don't use an idling approach to get that final 20%. &nbsp;But for the 50% to 80% I find that idling is quicker than the generator. &nbsp;But then again I only have a 30 amp converter in my rig and I am sure it is not efficient, so that might be why what I do works for me. &nbsp;The alternator would only have to run at less than 30% of full output to be a quicker charge. &nbsp;<br><br>Glad to hear about the Honda's good clean power. &nbsp;I have toyed with getting one or two of those when the Onan dies.

 

[stevensknk]

<P>Kind of seems like an ideal way of charging your battery would be to charge it quickly to 80% with a generator or alternator, say in the morning, then let a solar system get it from 80-100% throughout the day. Sounds like doing this would allow you to get away with a much smaller (cheaper) solar system. Anyone doing this &amp; how small of solar panel can you get by with?</P>

 

[WheelEstate USA]

Mike mentioned cop cars idling for hours. These vehicles have better cooling systems and something like 120 amp alternators. We have the 120 alternator on our motorhome and it makes a big difference in charging time when compared to the ford van we used to have. I'm not sure whether it would pay to idle a 454 engine or fire up the Onan genny, which burns a half gallon an hour. That's why we conserve and have solar panels.

 

[squirbel]

To the OP - read this article!

http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

 

[WheelEstate USA]

Handy Bob has some good info on his blog, especially since he has lived it for a number of years.

 

[MK7]

Idling the car for a long time, ie. 30-60 minutes or more is bad for the catalytic convert(s). The motor oil will get dirty faster too, and that can lead to other problems. Engine bay is going to be hotter and parts will start heating up more, this can't be good for the computer circuit boards.<br><br>Cops, taxi, etc. usually don't drive their own vehicles. These are owned by their organizations so they don't care. They also have better cooling systems and auxiliary coolers usually to the tranny or even the motor oil. And their perspective organizations have their own motor pool that repairs and maintains their fleet. <br><br>Then there's the waste of fuel and extra pollution as at idle, it's running very rich....lots of building inside your intake and motor now. Big truckers are about the same, as it may not be their trucks and/or their fuel that they're burning so they don't care. Independent truckers are less likely to idle for long periods. <br><br>And charging a battery with high amps will charge a good battery to 70-80% real quick, but it's not the best for the battery as it heats up the cells too much, that's why the last 20% takes forever or may not even be recharged. This is why when I charge my batteries with a quick charger (1hour), it never lasts as long as when I charge with a slow one (5hour). But if you're in a jam, then OK.

 

[Guest]

You are wasting money not hooking a generator up to a charger like mine 100 amp w 3 auto charging modes for long battery bank life. 8 amps unregulated is a waste and can hurt your bank. you should also know a fully charged battery is 12.7 volts or 2.2v per cell and 11.9 volts is the lowest you should go and any lower will hurt the flooded battery's.

 

[cygvan]

aside from vehicle charging options...<br><br>using a portable generator, either inverter or non-inverter type to charge batteries is best, im my opinion, coupled to a dedicated charger.<br><br>i recommed Iota brand sold by Arizona Wind &amp; Sun. get the version with it IQ4 module to make it a "smart charger".<br><br>then, your generators capabilities are mostly irrelevant. assuming it can run what the charger needs amp wise.<br><br>i have an Iota 45 amp IQ4 charger. it has a 3 prong plug to plug into any A/C source.<br><br>it will properly charge ALL types of batteries. i use it for my AGMs.<br><br>this model uses a max of 11 amps A/C to produce 45 amps D/C.&nbsp; so it can be plugged into any outlet rated for 15 amps or more. it will not draw more amps than what is needed to perform the charge state needed by the battery bank.<br><br>mine is plugged into the A/C system of my van and is energized when i park and plug in for the night.<br><br>i have plugged into honda 2000 to top off battery while on vaca.

 

[Jasoncbus1]

I agree with the others, but wonder why you would run a generator rather than just idle the engine? &nbsp;I know there will be some talk about how it hurts an engine to idle, but when you look at not just semi's, but police cars, taxis and all kinds of other idling vehicles, it causes you to wonder what kind of damage it will do from a "real world" perspective. &nbsp;I suppose you can argue that the alternator will go out sooner, but then you are "using up" the Honda too. &nbsp;<br><br>I know in my Chevy 3500 chassis, I have a 105 amp alternator that charges the house batteries pretty quick and the big engine uses about 1/2 gallon an hour at idle. &nbsp;Don't know how that would compare with a Honda generator, but from the manual for my Onan 4000, it is about the same consumption for a lot more amps. &nbsp;I will usually charge with the engine rather than the Onan if I am out someplace. &nbsp;

Hey Wandering Mike, I just found this post looking for ideas. I've heard of people hooking house batteries to their vehicle alternator. My question is how? Is there somewhere I can go where they do this? I can't, wouldn't even know where to begin. Maybe a mechanic shop? Any help will help Thanks

 

[mayble]

Hey Wandering Mike, I just found this post looking for ideas. I've heard of people hooking house batteries to their vehicle alternator. My question is how? Is there somewhere I can go where they do this? I can't, wouldn't even know where to begin. Maybe a mechanic shop? Any help will help Thanks

Jason, check out Bob's very helpful post on this here: http://www.cheaprvliving.com/electrical/electricity/

 

[highdesertranger]

while hooking your house battery up to charge while driving is certainly a great idea. using a car engine as your primary generator is not. running your vehicle everyday to charge your battery is very, very inefficient. highdesertranger

 

[bcbullet]

The best plan (at least in regards to using only a generator for charging) as everyone has said is to get a 3 stage smart charger and run it off the generator AC. When buying a charger, keep in mind that their power factor (actual output efficiency) is likely in the 60% range, so with 1600 running watts available on the Honda, the best you can reliably expect to plug into it will be a 70 amp charger and you will be at full load.