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hallamore
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# Posted: 24 Oct 2010 05:54pm
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Hello All,
I need some help. I have a small cabin my family goes to often on the weekend. I had been running the cabin on a EU3000 honda generator (worked fine) but I finally put in a solar system - consisting of a 150 watt array, 8 6volt golf cart batteries wired in series and parallel (to give a 12 volt system) and a 1500 mod sine wave inverter. I took a heavy gague extension cord and cut off the female end and wired it into my breaker box that has a built in transfer switch. I then plug in the male end to the inverter to have power. When the batteries run low, I simply move the transfer switch over to the generator and when its recharged I switch back to solar. I understand there is a way when I am running the generator for cabin electricity that it can also recharge the batteries. My question is how? Do I need a different inverter or some other product? The generator puts out way more power than I ususally use in the cabin. It would be nice to use the extra power to recharge the batteries at the same time.
Thanks for the advice.
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dabones
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# Posted: 24 Oct 2010 07:25pm
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how is the generator connected to your battery bank now? you said through a transfer switch, but that would send 120V back to your inverter, I doubt your inverter is dropping that 120VAC down to 12VDC to then charge your batteries..
I would suspect you need to have teh genny connected to the batteries themselves, ideally via a 12VDC output off the Genny itself...
when you throw the transfer sw on your panel, all that is doing is pulling the INPUT power from teh genny INSTEAD of the batteries, at this point, it's like the batteries are not even there..
so connect a 12V line from your genny to your battery bank and then it should charge when it's running..
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Rob_O
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# Posted: 24 Oct 2010 08:09pm
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Quoting: hallamore Do I need a different inverter or some other product?
Yes, you need an inverter with a built in charger. You can also use a stand-alone charger off the panel when you are on generator power.
With that many batteries, why are you not running a 24V system?
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MtnDon
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# Posted: 25 Oct 2010 03:52pm - Edited by: MtnDon
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Do you have an inverter/charger that does have a built in battery charger? Or do you have a stand alone charger and a stand alone single function inverter.
It sounds to me that you have an inverter/charger. However I am not certain that they all operate the same way.
What is the make of inverter, charger, etc.
With 8 x 6 volt batteries coupled with the fact that you do run the batteries down it sounds as if you could use more PV modules. We never need to run the generator because the batteries are down (we have 12 x 6 volt) , but we do have 624 watts worth of panels and lots of sunshine.
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fasenuff
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# Posted: 25 Oct 2010 05:44pm
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Since you are running a 12v system the simplest thing would be to add a 12v battery charger to your system. An auto type charger would work fine but make sure you get a charger that is designed to cut down the amount of amps it kicks in as the batteries get closer to fully charged. I did not pay attention to what I was getting and fried 2 batteries by using a charger that was a continuious rate and did not reduce the charge amps.
Most chargers are designed so that you could leave it connected and when you run the generator it will be charging the batteries.
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Rob_O
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# Posted: 25 Oct 2010 05:59pm
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Quoting: MtnDon Do you have an inverter/charger that does have a built in battery charger? Or do you have a stand alone charger and a stand alone single function inverter.
The way I read his post, he has 150W of solar panels charging somewhere around 800 AH of battery bank, a cheapie 1500W MSW inverter, and no means of charging the battery bank with the generator
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MtnDon
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# Posted: 25 Oct 2010 08:25pm - Edited by: MtnDon
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Ah! The Honda EU3000 has a 12 VDC output as well as a 120 VAC. Is that somehow involved. ??? More details needed I guess.
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hallamore
Member
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# Posted: 25 Oct 2010 09:41pm
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First of all thanks for all the help. My inverter does not have a charger associated with it. That is the problem. The generator I use to simply power the cabin. It does not power the battery bank. My transfer switch simply transfers the power source from either generator or batteries or vice versa.
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MtnDon
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# Posted: 25 Oct 2010 10:00pm - Edited by: MtnDon
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So, other than the PV panel what exactly charges the batteries? I'm a tad confused by what you are have there? ???
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MtnDon
Member
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# Posted: 25 Oct 2010 10:13pm
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You should have a battery charger that is capable of doing an equalization charge to achieve best battery life in the long run. There are four charging stages: bulk, absorb, float and equalize. Most stand alone chargers do not have that capability. Xantrex makes a stand alone charger with equalization capability. Truecharge series I believe.
A combination inverter/charger will usually have that built in. But they do cost $$.
An excellent charger without the equalization mode is made by Iota Engineering. There are several models so the maximum needed charge rate can be chosen. They also have a smart charge option which helps fast charge and then float charge batteries. Their chargers can be stacked (2 of same model) to increase charge capacity. That requires a small add-on sync controller.
Quoting: MtnDon My transfer switch simply transfers the power source from either generator or batteries or vice versa.
I take to mean the transfer switch has one power input from generator and another from the inverter and the one output to the cabin.
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Rob_O
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# Posted: 25 Oct 2010 10:22pm
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Ok, that's what I thought. You need a charger of some sort.
Don has an integrated inverter/charger. Good stuff if you can afford it
Lower budget solution would be a battery charger you can turn on when the generator is running. Get a multistage one that won't fry your batteries like fasenuff did
Either way you get the job done
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hallamore
Member
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# Posted: 25 Oct 2010 10:35pm
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Don,
Can you recommend a combined charger/inverter then?
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hallamore
Member
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# Posted: 25 Oct 2010 10:36pm
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Don, one more thing....you are correct about how the power feeds supply the cabin....one input from the generator, one input from solar and one output to the cabin
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Rob_O
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# Posted: 25 Oct 2010 10:44pm
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I type too slowly, Don has already elaborated on my simple explanation. Here is a link with details on his PV system
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MtnDon
Member
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# Posted: 25 Oct 2010 11:06pm
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1 thing I should have asked; you do use flooded cell lead acid batteries, like golf cart or something? If you had AGM batteries they do not ever get equalized, that will damage them.
Regarding an inverter/charger combination unit, what all do you run on the AC? Just lights? Or do you run things with motors in them or a microwave? Generally speaking those items, as well as desk top computers (not laptops) run better, cooler and quieter, on Pure Sine Wave power. That means motors last longer. Because less power is wated as heat in the motor the battery capacity also lasts longer.
Outback and Xantrex make excellent equipment. Magnum Energy is also very good. Xantrex and Magnum make both Pure Sine wave and Square Wave. (most folks refer to square wave as modified sine wave as it sounds better, but on an oscilloscope it it obvious the wave is square)
Because we run a microwave, a vacuum, air compressor and assorted tools and doo-dads I decided on a 3500 watt Outback inverter/charger. It's a lot of money compared to most of the off name square wave inverters; I did a deal on a clear out on mine though. But it is fully programmable and if we should ever go power mad, two or more can be stacked for more output, even 240 VAC.
I had great experiences buying from Affordable Solar, The Solar.Biz, Northern AZ Wind/Sun, and their pricing is fair in my opinion. For odds n ends solarseller.com has been very good to deal with.
All have info pages/sections.
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hallamore
Member
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# Posted: 25 Oct 2010 11:16pm
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Don,
Yes they are flooded lead acid golf cart batteries. We typically run lights, tv, coffee pot. Occassionally we will run the microwave for a couple of minutes. We don't run motors. Based on your opinion I looked at Xantrex web site. Their combo inverter/charger I see has GFI AC outlets. Can I take a heavy duty extension cord and cut the female end off wire another male end (so both ends have a male end on it) and simply plug the entension cord into the generator and inverter/charger to charge the battery bank?
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MtnDon
Member
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# Posted: 25 Oct 2010 11:43pm
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No.
The Xantrex has AC outlets as you noted. That is the AC power output only, the AC the unit makes from being connected to the batteries through a separate set of DC cables.
You didn't note what model you looked at, but both the DC and AC inputs are usually hard wired. There are terminals to bolt the power input leads to. In the case of the DC connections they are also used to put power into the batteries in charge mode. But the AC input into the inverter/charger is a separate connection from the outlets.
You could have a cord connected to these AC input terminals and plug that into the generator output.
These combination inverter/chargers usually switch automatically when the generator power is supplied by either connecting the gen plug or starting the generator. Some inverter/chargers are more user programmable than others. For example, I can set a delay of my choosing so when the generator power is seen by the inverter/charger, there is a delay to permit the generator to warm up before being asked to work.
Then the inverter/charger takes the AC input and starts charging the batteries. It also automatically stops taking DC battery power to make AC power. AC power from the generator is passed through the inverter/charger to fulfill the cabin needs while the batteries are charged.
Xantrex makes a lot of inverter/chargers. Not all have equalization capabilities in charging mode. check the specs. You can usually download all the data sheets and owners manuals so you can read all the details.
BTW, making double male ended cords for any purpose is very unsafe. You never know when an unknowing person, or a forgetful self, will pickup the wrong end at the wrong time.
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hallamore
Member
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# Posted: 26 Oct 2010 08:35pm
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Quoting: MtnDon You could have a cord connected to these AC input terminals and plug that into the generator output.
Don, This just might work perfectly. One more question. If I hard wire into the inverter/charger and leave the other end as a male end on an extension cord and plug that into the AC output on the generator. Does the inverter/charge have a charge controller built into it so the batteries don't overcharge?
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Rob_O
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# Posted: 26 Oct 2010 08:46pm
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You will still need a charge controller
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MtnDon
Member
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# Posted: 26 Oct 2010 09:38pm
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An inverter/charger is equipped with it's own control circuits. If the inverter/charger in question has a three stage charger it will start in bulk charge mode, switch to absorption mode and end in float when the batteries are full. There is no worry about overcharging the batteries from running the generator and charging with the inverter/charger. If the unit has four changes the fourth stage is the equalization charge and that is selected manually, although some units like my Outback can be programmed to do an equalization on a schedule.
The charge controller you have for the solar PV module is only used for the module power.
Some of the Xantrex inverter/chargers that have built in GFI outlets can also be hard wired to the cabin instead of using the plugin.
Which one are you considering?
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hallamore
Member
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# Posted: 13 Nov 2010 08:49am
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Don,
In doing some research I am thinking of purchasing the Xantrex Freedom HF (1800 watt model). Do you have any knowledge about this one? Namely I am most concerned if it will equalize the batteries as well as have the 4 stages for chaging the batteries. If you don't think this will do for my setup, any suggestions?
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MtnDon
Member
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# Posted: 13 Nov 2010 11:36am - Edited by: MtnDon
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The spec sheet on that one states N/A for equalization voltage. I found the same thing on the HW series. The GS does manual equalization; it's marketed for RV use but it will work for you. I use an Outback that was designed for RV use. And the SW and ProSine series have equalization ability.
inverter/charger
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larryh
Member
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# Posted: 13 Nov 2010 04:59pm
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As to the original question. I have a Honda 2000 generator. If I hook via the 12V charging cord to my battery I see no reason I can't be using the battery for lights or radio, ect. while it being charged by the generator. I need to get out my manual, we talked about this before and I still haven't gotten around to reading again how the charger acts as it fills the battery.
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MtnDon
Member
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# Posted: 13 Nov 2010 08:04pm
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Running a load off the batteries is fine when the generator is charging the batteries. The manual URL states the DC output to be 8 amps, so the the load will be subtracted from what the generator can supply and the balance used for charging. That will make the time to charge longer. The manual makes no mention of there being any regulation of charge so it probably does not have regulation. Hard to say for sure, but that's what I think.
8 amps at 12 volts DC (96 watts) is not much output for the run time. You could get much less generator run time by using the AC power from the generator to power a good charger, 30+ amps . But that would be an extra piece of equipment, extra costs. But would cut down on generator run time and fossil fuel use.
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larryh
Member
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# Posted: 13 Nov 2010 08:27pm
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Don,
You know so far I have used mostly the electric battery charger on my battery, but when I used the honda 12v output it did it way faster?
Larry
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MtnDon
Member
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# Posted: 13 Nov 2010 08:59pm
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That's odd, unless the AC powered charger has a taper off as the battery charge nears full. I have an auto charger like that. It's better for the battery but as long as you watch the fluid level and the temperature of the battery you can charge at quite high a rate.
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larryh
Member
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# Posted: 13 Nov 2010 09:41pm
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I finally checked the specs on line an it does not have a taper charge so one has to watch when the battery level is nearly full, but it seems to do a good job other wise. I notice it says "automotive" type battery, I am using a RV battery for a back up system in my home, but so far its seems to charge it fine. The electric ones I used do have a taper down setting so it stops charging when it reaches the full point.
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hallamore
Member
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# Posted: 13 Nov 2010 11:02pm
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Don,
Ok I don't think I can afford a $1000 plus charger/inverter so I think you told me Iota makes a pretty good charge. See the attached link
http://www.iotaengineering.com/dls90.htm
If I purchased this, can I simply plug it into my honda e2000 generator (13.3 A) AC and charge the battery bank?????
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MtnDon
Member
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# Posted: 14 Nov 2010 12:31am
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I thought you had the Honda 3000 
The 2000 with 13.3 amps available would be better used with the Iota DLS55. A Honda 3000 can power the Iota DLS90
If the charger can demand more power than what the generator can supply you may find the generator being overloaded.
I have the DLS55 for our RV. It's a great choice for a charger that does NOT have the equalization feature. URL
I have the IQ option that provides automatic 3 stage charging (bulk, absorb, float) Bulk supplies the full rated output of the charger.
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hallamore
Member
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# Posted: 14 Nov 2010 08:47am
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Don,
Thanks for the info. I actually have both a 2000 & 3000 Honda at my cabin. I think I will get the DSL90. For equalization I will have to use the C35 Charge controller. As always your help is much appreciated. If you are ever interested in in vacation here in Southern Iowa (about 2 hours from KC) you and your family are more than welcome to use my cabin. Great hiking, fishing and smack dab in the middle of Amish country in Iowa.
Regards,
Hallamore
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