Issues with inverter

samuelpeden

Hi, it's my first post on here but I'm really struggling. We live in Haiti doing voluntary work and are very limited with what is available locally.

We set up a magnum 1512 inverter with 6*6v 225 ah batteries. It's been okay for about 3 weeks but we are having problems charging the batteries. The voltage is fluctuating around 85 but goes as low as 60. We have around 12 hours of power per day. It was continuously clicking in and out of invert mode and not charging. I have set the VAC to the lowest amount at 60. This week we have struggled to charge the batteries because it doesnt seem to put enouycurrent into the charging. I have it set to 10% charge rate and the rc50 tells me it is in bulk charging z but it's at 11.8v and Amps keep on going up and down like it's cycling, it goes from 0a up to about 16 or 20 then back to 0 and repeats every 10 seconds. I have attached a couple of pictures if anyone can help. It was charging all night but when power went off today batteries only lasted about an hour with a total 25 amp load

Oh and it's impossible to get an electrician here that knows anything about this. I am not happy with the wiring but it's 100x better than anything else you see in the country, just got to use what we have here :-)

Estragon

To clarify, are you off or on grid? Do you mean you get 12hrs of grid power per day (using the inverter to charge when grid available, and running on batteries otherwise), or 12hrs of sunlight on a solar system per day (using a charge controller to charge batteries during the day, running on batteries at night)?

Do you have a multimeter?

samuelpeden

Yes, we have approx 12 hrs of grid power per day, sometime more sometimes none, at the moment it is 80v. We don't have solar at all. We have other friends here who have the same system and they manage to charge this way, voltage seems to vary a lot by each neighborhood.

In the remote instructions it says that if VAC in is under 90 it limits charge rate to allow power to appliances. We use all our appliances at less than 90 when grid power is on. When it drops and inverter kicks in it the fans speed up so much we have to turn them down. Is there anyway to drop this down? Or boost the voltage going into the inverter/charger?

We have had power for about 4 hours and voltage has gone up from 11.7 to 11.9. not enough to keep us going tomorrow

mcgivor

Assuming grid input is being referred to, the inverter charger will need to qualify the incoming AC before connection, if the voltage is as low as 60-85V and it actually qualified, as soon as the load, the charger in this case, is connected, it very likely the voltage will sag below the qualification parameters which in turn causes the inverter charger to reject the input, then the cycle repeats itself. One possible  solution is to use a voltage stabilizer to bring the voltage up to reasonable a value, but the fragile grid may have other shortcomings which could prevent even this solution from working.

samuelpeden

Thanks for suggestions. I disconnected the charger/ inverter and took the voltage, then turned charger back on and there was no measurable voltage drop. It stayed between 81-86. We take the power straight from the grid, through the inverter, then to all appliances. We don't have 2 circuits, everything through the inverter except one socket for high loads

mcgivor

Another parameter to qualify is frequency, have you checked that?

samuelpeden

I haven't done that, how can I check frequency? I bought the only multimeter available here, it's 99cents on eBay

samuelpeden

I videos what is happening
https://youtu.be/0y_HhS5El5g

Estragon

@mcgivor - could a grounding issue result in seeing ~60vac input?

mcgivor

The 99cent meter won't have the ability to measure frequency, in the settings set the acceptance frequency as wide as possible....if it is possible naturally, I'm not familiar with Magnum equipment. There may be sags in the voltage the meter cannot capture, which the inverter can, many  quality meters have a max-min capable of doing so. Do you have access to a generator which could be connected temporally to confirm if the problem is with the grid. From all information provided, my guess would be it's a grid issue, can the charging amps be set to a lower value, have you contacted tech support?  Just some random thoughts and ideas.

mcgivor

Estragon said:

@mcgivor - could a grounding issue result in seeing ~60vac input?

Most likely not, it could be a bad crimp connection on the grid side amongst may other possibilities, from what I've seen in Haiti the infrastructure is not what one would call sound and not solely a reference to the grid.

Estragon

Just thinking out loud. I have a vague recollection of seeing ~60v with a floating ground generator system I inherited.

samuelpeden

There is no ground wire anywhere in the country, it's terrifying. Last week someone came to do some work and there was no plug on the circular saw wire, they just push bare wires into the socket. And someone came and did some welding... Just wrapped his cables directly onto the exposed wire that joing the meter and away he went. Currently we have over 60VAC. But apparently the inverter limits charge below 90 so it basically useless. I may be able to try the generator idea, would need a bit of rewiring but would confirm the issue is not with the inverter

Thanks,

Any more ideas keep em coming

BB.

Yea, most charging/AC loads are going to be pretty poorly serviced by less than ~90 VAC (or ~100 VAC, depending on design).

Just a quick search for transformer based voltage stabilizers have an input range of ~85-130 VAC:

https://www.amazon.com/ELC-TR-2000-Voltage-Regulator-Transformer/dp/B00MCWSYWA

This one simply adds or subtracts 20% based on input voltage:

https://www.amazon.com/APC-LE1200-Automatic-Voltage-Regulator

Depending on how high your line voltage goes (do you ever get 120 VAC?), you could install a step up transformer and then use a voltage stablizer to limit high voltage... This guys has a pretty high input voltage limit of ~147 VAC:

https://www.amazon.com/Tripp-Lite-LC1200-Conditioner-Outlet/dp/B0000512LA

-Bill

samuelpeden

Thanks, that looks promising if we could add 20% to the voltage. Can I wire it in straight between the circuit breaker and the inverter? How big of a wattage would we need? The electrics through the whole house go through it, biggest wattage is probably hairdryer. We can't use that on the inverter but we use it through the sockets the inverter powers when connected to the grid. Would we need a 5000 watt or something? If it's charging batteries at 35 amps how does that correspond to AC in wattage?

Thanks for your help

We went to the electricity company today but the machine that fixes things wasnt there so they will come another day when they find it...

BB.

With AC, it does sort of get complicated very quickly... Watts is the rate of power usage... But when we look at wire/breaker/transformer ratings, we need to look at VA (volts*amps). One of the "real" equations used for calculating power is:

• Power (Watts) = Volts * Amps (VA) * Power Factor

Power Factor is a number that ranges from 0.00-1.00 and depends on your loads. A heater/filament lamp has PF~1.0  and an induction motor has PF ranging from 0.6 to 0.8 or so... LED and CFL (twisty florescent) lamps can have a PF from 0.5 to ~0.95 (cheap ones are typically closer to 0.5-0.6). An AC battery charger can have a PF from 0.6 to 0.95 (Power Factor corrected electronics should have PF ~0.95).

What does this all mean... You need heavier wiring/breakers/transformers/generators/inverters if you have "poor" PF loads. The typical home has a PF of around 0.80 or so...

Your Well pump, probably not a great power factor (maybe ~0.67). Your AC inverter-charger, probably >0.80

You would take the Wattage load for a home and multiply it by (very roughly) 1/0.80 (1.25x) to figure out the VA rating.

Obviously, having your power company fix the problem would be ideal... But you are probably in a place that is far from ideal and you have to work with what you have.

An example of how the calculation for a battery charger would be made (using both nominal and "very good" charger numbers). Note that I use an 80% (1/0.80) derating for your genset/AC inverter/voltage stabilizer. In general, most "residencial" power systems are designed to run at ~80% of nameplate capacity for hours at a time--100% is for short term 10-20 minute or so maximum loads--Battery chargers can run at rated current for hours at a time):

• 35 amps * 14.75 volts = 516.25 Watts "into battery bank"
• 35 amps * 14.75 volts charging * 1/0.85 charger eff * 1/0.80 charger PF * 1/0.80 derating for AC power system = 949 VA rated branch wiring/transformer/etc. minimum recommended rating
• 35 amps * 14.75 volts charging * 1/0.95 charger eff * 1/0.95 charger PF * 1/0.80 derating for AC power system = 715 VA for "pretty nice" AC charger

Note that with all of the deratings for a "typical" AC battery charger, you require a system capable of almost 2x the Battery Charging Watts in VA (volts*amps).

Note that when your load is, for example, 1,200 Watts at 120 VAC and a voltage stabilizer (assuming 60 VAC low input voltage):

• Current at 120 VAC = 1,200 Watts / 120 VAC = 10 Amps
• Current at 60 VAC (using stabilizer) >~ 1,200 Watts / 60 amps = 20 Amps (input to voltage stabilizer, ignoring losses)

Solar power (and battery backed/voltage stabilizing) is not cheap... Installing a "smaller" system for your critical loads and "something else" for non-critical loads may be required (battery backed AC inverter--LED lighting, refrigerator, emergency water pump, computers, etc.). A voltage stabilizer only for hair dryers, non-electronic washing machine, etc.... Anything you can do for efficiency/splitting off critical loads can save you money and keep the "expensive" power usage to a minimum size needed.

Here is a nice write-up on supplying your own power and the issues behind PF/etc.:

http://www.screenlightandgrip.com/html/emailnewsletter_generators.html

-Bill

samuelpeden

Okay that's helpful thanks. Thank you for taking the time to write all that, I think I mostly understand. All we run in our small house is: small loads- lights, chargers, wifi
Medium loads- fridge 800w/24hr and chest freezer almost the same, max 2 fans
Large loads- washing machine 600w
Never through inverter = if we ever use power tools, hairdryer, straighteners run on a separate circuit

That's everything we have. From what you said a 5000 watt regulator should be plenty, right? Could I wire this before the inverter so except for one separate socket everything would run through it all the time?

https://www.amazon.com/Simran-AR-5000-5000-Watt-Stabilizer-Transformer/dp/B00526JQ4S?keywords=voltage+regulator+stabilizer+5000+watt&qid=1532108983&sr=8-3&ref=mp_s_a_1_3