Even a cheap 3kva would cost more than four more panels, unless you are
committed to purchasing the Rolls Royce of panels. I put budget 160s on my van 12 yrs ago, and they still function just fine. Four of them would cost less than $1000, far less than a 3kva Genset, with enough left over for a larger
amperage regulator.
raymo
My 170W panels were $200 ea and I can get a 3Kva Generator for $500...
You are quite right but I was wanting to know how one goes about actually connecting a generator into such a solar system to charge the batteries while the panels are charging them too..?
If 350 amps is your consumption ...and your batteries at 50% discharge when fully charged can provide 275 amps you clearly have a short fall...on the face of it you need another battery purchase...then you will have 1100 amp hour capacity and a available supply of 550 amp hours giving you a 200 amp hour buffer ..if you need another battery bank you need to buy it now so you start with the intended bank and not adding later.
Being realistic what ever you do you need first a genny and a charger...if I were you I would buy genny, charger and another set of batteries or plan on imaging less hours...namely 11 hours...that is 275 amps worth and 275 amp is all you have to spend...
Have a look at Kings the 4wd folk for a cheap genny..$500 should get you a good one..( they are good to deal with I have found)
AND your charger will need to charge at ,and your batteries able to accept, 25 amps. given that is your usage..30 would be better...I really think the solution may be accepting less capturing time..say 10 hours...you can do that now any more the genny and charger are a must have....anyways more tomorrow..oh it is tomorrow
Alex
Just found these diagrams in the Regulators manual , seems a battery charger via a generator, can be connected to the batteries..? Still cant confirm if this can be run while the panels are also charging the batteries..? I imagine so..?
If 350 amps is your consumption ...and your batteries at 50% discharge when fully charged can provide 275 amps you clearly have a short fall...on the face of it you need another battery purchase...then you will have 1100 amp hour capacity and a available supply of 550 amp hours giving you a 200 amp hour buffer ..if you need another battery bank you need to buy it now so you start with the intended bank and not adding later.
Being realistic what ever you do you need first a genny and a charger...if I were you I would buy genny, charger and another set of batteries or plan on imaging less hours...namely 11 hours...that is 275 amps worth and 275 amp is all you have to spend...
Have a look at Kings the 4wd folk for a cheap genny..$500 should get you a good one..( they are good to deal with I have found)
AND your charger will need to charge at ,and your batteries able to accept, 25 amps. given that is your usage..30 would be better...I really think the solution may be accepting less capturing time..say 10 hours...you can do that now any more the genny and charger are a must have....anyways more tomorrow..oh it is tomorrow
Alex
Yes but that max discharge figure will be quite infrequent, so dropping below 50% DoD (Depth of Discharge) will be infrequent, more often than not the DoD will be much less and probably only around 30% in mid summer....so I was thinking those heavy duty AGM's could handle that for a few years..?
Also see my previous post, there were diagrams and info with my regulator (who would have thought ) referencing generator use...but I'm not clear on what it is telling me exactly..
Hi again Mike. You can charge a battery or a bank of batteries using several
charging methods simultaneously. Solar panels do not allow reverse current,
and battery chargers are protected against reverse current. For example, I
can have my car engine running [ so obviously the alternator is charging the battery]whilst the solar panel is still connected to the battery.
I had forgotten how much cheaper open frame tradesman's style generators
are than the enclosed quieter recreational style ones. I don't know how many amps you are looking at contributing via the generator. Recreational ones all have a 12v charging outlet of 8amps or a little more obviating the need for a separate charger. Any recreational generator will charge at 8 amps, doesn't have to be a heavy, large noisy 3kva unit. My 750w charges 8amps using a minimal amount of fuel.
I note the model in your link doesn't seem to have this feature.
raymo
Last edited by raymo; 21-02-2022 at 01:06 AM.
Reason: more text
Hi again Mike. You can charge a battery or a bank of batteries using several
charging methods simultaneously. Solar panels do not allow reverse current,
and battery chargers are protected against reverse current. For example, I
can have my car engine running [ so obviously the alternator is charging the battery]whilst the solar panel is still connected to the battery.
I had forgotten how much cheaper open frame tradesman's style generators
are than the enclosed quieter recreational style ones. I don't know how many amps you are looking at contributing via the generator. Recreational ones all have a 12v charging outlet of 8amps or a little more. I note the model in
your link doesn't seem to have this feature.
raymo
I imagine I would be using a standard battery charger like this one, operating off the 240V outlet on the generator, I need to confirm that this won't conflict with the regulators "intelligent" charging of the same batteries, using power from the panels..?
Solar panels are in effect diodes, and as such do not allow any reverse current from any source, be it the battery itself, or any kind of charging system such
as a charger or an alternator. Charging systems are themselves protected from reverse current,so you have no problems. The only current that can go through the regulator is what comes from the solar panels, so no conflict.
raymo
Short answer is you can have two charge controlers paraleled on a single battery bank. As you say, conect a Rectifier to the geny and conect it to the battery in parallel with the MPPT. Make sure the two current supplies don't supply more current than the batteries are designed to charge at.
Solar panels are in effect diodes, and as such do not allow any reverse current from any source, be it the battery itself, or any kind of charging system such
as a charger or an alternator. Charging systems are themselves protected from reverse current,so you have no problems. The only current that can go through the regulator is what comes from the solar panels, so no conflict.
raymo
Quote:
Originally Posted by Joshua Bunn
Hi Mike.
Short answer is you can have two charge controlers paraleled on a single battery bank. As you say, conect a Rectifier to the geny and conect it to the battery in parallel with the MPPT. Make sure the two current supplies don't supply more current than the batteries are designed to charge at.
Thanks guys together that's what I needed to know I think .
So, if I get myself a pure sine inverter generator (eg. the one from Kings) and a good AC to DC charger, say ~30amp, plug it into one of the 240V outlets, then connect it to the battery, as per the regulator is ie. both positives on the same positive terminal on the battery bank and both negatives on the same negative terminal, then, I could switch on the generator at anytime and have it contribute to charging the batteries whether or not the solar panels are pumping current in ...that sound right?
I guess I was concerned that given different chargers/regulators use different sequences/algorithms to charge batteries, I thought having two different ones connected to the batteries might cause conflict in charging..? But seems not so. ?
I assume there would also be no issue with this setup if I was to turn on the generator with charger "during" an imagaing session, should I notice the batteries are getting low..?
Yes, You can start extra charging whilst imaging. As long as the system voltage remains within the stipulated range acceptable to your mount's motors, say 11-15v for example, the motors will just keep motoring along.
raymo
Last edited by raymo; 21-02-2022 at 02:28 AM.
Reason: more text
Yes, You can start extra charging whilst imaging. As long as the system voltage remains within the stipulated range acceptable to your mount's motors, say 11-15v for example, the motors will just keep motoring along.
raymo
Everything will be running off the 12V DC to 240V AC 2000W inverter.
I have spoken to Peter but he cant log in and will catch up with me later.
Here is the charger he recommended and installed for the house system which uses AGM batteries...
More later.
Alex
When we had our solar power station designed for Swan Reach we are advised of a couple of things which I think are pertinent here.
We were advised that the generator should be around 6kva in general to allow for good charging of batteries and this gives you a level of expansion into the future. Our system is pretty large at 79kwh of storage. We opted for a 11kva generator to allow welding and the like on site and for fast charging. The generator also has a autostart system installed so when the batteries get to down to a certain power level (we programme that) it will start up and commence charging the batteries.
Secondly we went with Vitron equipment and an inverter from them. The equipment decides how much power to provide for charging and this then prevents over charging. Generally up to 98% charge of the system it will work in bulk, then it will work in absorption and then finally in float at 99%. Paying for this piece of kit in the system was worth every cent. Our solar charger is a 150/100. The brains of the unit is the Gateway unit and that decides where power is coming from for charging and how much is needed. It can disregard the full solar panel system load.
I think it is worth discussing this with a Vitron Rep and get them to advise you what you actually need. You might actually be covered well now but you might also need more equipment to protect the system.
Our house runs on solar. We have two sets of four panels, both going into their own regulator which are both connected to the batteries along with a 50amp Victron charger than runs from a Yamaha 2400w inverter. The whole lot can be going at once if need be (though that would be a bit much charge for the batteries for any length of time). So we are essentially running the system your thinking of no problems. Each controller/charger looks at the battery volts and adjusts accordingly and I've never noticed any conflict. Batteries are 660ah 2v cells x 12 for a 24v system.
I would wire the panels in series - I find I get better results on cloudy days with the higher voltage/mppt controller setup than running the panels in parallel. (or two parallel sets in series).
Wow, you're drawing 25 amps / 300w continuously from your setup? That's a goodly amount of juice! One of those little 2kva Honda generators would do the trick and be easy to cart around and would power a little 20amp 12v charger no problems. They have a pretty good rep in the caravanning groups. I'd put some big fuses on the battery too. I'm also a big fan of the Victron brand of gear too - chargers/mppt's/inverters etc - very good gear.
Here are some pointers from my assistant.
He would have posted under his handle but is having problems logging in.... So he has emailed me and I now pass it on.
Alex.
Sounds like you are pushing the batteries with a discharge of 350 amp hours every day. A lead acid battery generally is designed for a cycle of not more than 10%, of the 20 hour rating if daily. So a 550 amp hour battery shouldn't be discharged more than 55 amp hours, over the period the rating applies for, usually 100 hours, or 5.5 amps continuous. Taking the 20 hour, or 1 day rate, the battery capacity of a 550 amp cell is probably around 350 amp hours, so this means a daily discharge cycle of no more than 35 amp hours, so you are pushing them and they will fail prematurely. Neglecting to account for the daily discharge rating of the battery, and using the published, usually 100 hour rating, results in many failed battery's after a few years.
As for the charge current, a decent battery should accept charge at the 10 hour rate, at least until the voltage rises, then you must back off the charge as the battery, sealed types, must not be allowed to gas under any circumstances. Hence the recommendation for a regulated charger, or keep a close eye on the voltage and back off the charge when approaching the gassing voltage, which should be published in the manufacturers data.
Example, our main house battery's are rated at 2,700 amp hours, 48 volts, and that's a 24 hour rating. The 100 hour rating is well over 3,000 amp hours, and the main charger from the generator, is 500 amps, yes, 25 kw of battery charging, but they can absorb that easily and I have a voltage sensitive relay that disconnects the charger at about 56 volts, to prevent gassing. (Its actually a submarine battery and weights 4.5 tons). We also have over 20 kw of solar connected,
Also, if you are drawing around 30 amps from the battery's, to charge the battery's, you will obviously need more than 30 amps going in.
A little about efficiency is called for here.
Power (losses), is proportional to the amps squared. So, at 12 volts, we can say its efficiency is 1, at 24 volts, the current is 1/2 that of 12 v, so the efficiency is 4 X better, or 1/4 the losses at 12 v (amps squared, remember ?), and at 48 volts, the losses are 1/16 those of 12 volts. Ah ha, you now say, that's why we transmit power at high voltages, yup, you got it in one.
The currents you are seeing are quite heavy for 12 volts, and it may be useful to go to 24 volts, and use a Victron inverter/charger (which will automatically regulate the charge rate and switch over to run the gear off the generator if its operating), giving max power into the battery's. This is how most professional systems operate. To operate the scopes electrics, 24 to 12 volt converters are available from Jaycar, and the efficiency of such a system will be much better.
As for auxiliary charging whilst the solar is connected, as long as you don't exceed the gassing voltage for your sealed battery's, it will be OK. Although, too much current can cause the battery's to reach gassing voltage before they are fully charged, so its a bit of a two edged sword. Any decent solar regulator will sense the increased battery voltage and probably switch itself off. Also, be aware that the inverter will have over and under voltage sensing and may react to boost charging by switching itself off, hence the advantages in a combined inverter/charger.
In a previous life, I owned a company that designed and installed solar, hydro, wind and grid systems, and still am an accredited design and installer.
On another note, I operated a homemade 10 foot radio telescope dish at our other farm, and if I can find the traces, may publish them if enough are interested.
........
Me again.
There is a other email but I will do another post..in a minute or two.
Alex
Contents of second email....
Add this in as well please.
Temperature also affects the charge acceptance. The colder it is, the less battery capacity you have available. Also, the colder the battery's, the less efficient they are. Generally you need to put about 10 % more back in than taken out, for lead acid types, but this gets worse as the battery ages and also varies with discharge rates, high discharge means less efficiency and more losses and more energy needed to go back in, not unsubstantial with a battery our size.
If I have a 3000 watt continuous, pure sine inverter generator with a 15amp 240V outlet, what size (amps) 240V to 12V battery charger can it safely run?
, seems a battery charger via a generator, can be connected to the batteries..? Still cant confirm if this can be run while the panels are also charging the batteries..? I imagine so..?
.
