Voltage drop and inverter shut off - why???

Offgridgirl

We have been living off grid more or less successfully for two years. I have a fairly tenuous grasp on the solar set up, so please be gentle 😊.
We hadn't been lasting very long without using the generator for awhile and I couldn't figure out why. On Christmas eve, we discovered one of the posts to the batteries had broken!? The next day we took that line of batteries (8 of them) out and hooked everything up to the remaining 8. But we only have power when the generator is running or the sun is shining. The specific gravity on the batteries is great. We've tried turning practically everything off except a few lights but it doesn't matter. The voltage drops until everything shuts down because of low battery.
Our solar installer is stumped. She's going to replace the battery but our batteries have been discontinued so she wants to check with surrette about compatibility. And they are closed until next Monday. She doesn't know what what else could be wrong so probably won't come out till then.

Sorry this is so long but does anybody have a clue what could be wrong?

Thom

Re: Voltage drop and inverter shut off - why???

If u could give some system info it would b a big help. Like below

Thom

706jim

Re: Voltage drop and inverter shut off - why???

Sounds like some sort of bad battery connection.

Which by the way, could be INSIDE one of your batteries.

BB.

Re: Voltage drop and inverter shut off - why???

So you have a reasonable DDM (digital multi meter)?

When under load, you need to measure the voltage across each battery. Across reach cable, and even across each electrical connection. And at the dc input to the inverter.

You are looking for bad connections, corroded cables, bad cells/batteries, etc.

Basically, the inverter should run from 21 to 30+ volts.

And these measurements should be done under load. A good size inverter can take 100 amps or more from the battery bank.

Any bad connection or cell can do the current flow and kill the battery power.

-Bill

Offgridgirl

Re: Voltage drop and inverter shut off - why???

Thanks for the responses.
I do have a digital multimeter, still in the package. I'll crack it open tomorrow and try it out.
There was some corrosion on the connections at then end of the line of batteries we disconnected. So after that I looked over all the connections and cleaned them up if there was anything.
Our system consists of 9 - 250w panels, Magnum Energy inverter, Magnum Energy remote control, 16 - 6 volt Surrette batteries, I'm not sure of the ah, wired to 48 volts, Generac 6kw generator.

Photowhit

Re: Voltage drop and inverter shut off - why???

Offgridgirl wrote: »

..., 16 - 6 volt Surrette batteries,....

Are they the height or a car battery or roughly 2xs the height?

I'd go with a bad connection somewhere along the line, do you get any reading from the inverter when the solar or genny aren't running? Did someone perhaps leave the main breaker flipped while they were disconnecting the string of batteries?

BB.

Re: Voltage drop and inverter shut off - why???

Here is a good starting point for understanding basic electricity:

Electricity for Boaters - BoatSafe.com

At some point, you will probably want a DC Current Clamp meter like this one from Sears (good enough for our needs).

Note that measuring current (AMPs scale)--Be very careful--It is easy to pop a fuse or smoke the meter. That is why I like the DC current Clamp type meter--They are much easier and safer to use (you do not have to break apart electrical connections, cannot "short circuit" with the meter setup wrong, etc.).

-Bill

Offgridgirl

Re: Voltage drop and inverter shut off - why???

The batteries are probably twice the height.
I was a bit hesitant to use the multimeter, now I feel nervous.
I'll be very careful. They only had two at the store, one for $30 and one for $130. Guess which one I bought?
Not the breaker, unfortunately.

BB.

Re: Voltage drop and inverter shut off - why???

As long as the meter is set to voltage scales--You are usually pretty safe. Voltage measures draw virtually zero current, so nothing bad will happen (it is possible to damage/ruin some meters if set to 2 volt scale and you measure 48 volts--But that is just money, not dangerous).

When set to current/AMPs scale--Yea, you really have a need to understand what you are doing around the battery bank/large DC power systems (the meter is, more or less, a dead short).

-Bill

Photowhit

Re: Voltage drop and inverter shut off - why???

Offgridgirl wrote: »

The batteries are probably twice the height.

Might NOT talk with your installer, I would guess you have 700-800Ah of batteries at 48 volts, and your solar array of 9- 250 watt panels can produce about 35 amps at 48 volts on a normal day(per hour)... or about 5% or the capacity. This would be a poor setup for continuous use. 10-13% would be recommended and perhaps more.

How often and how do you equalize your batteries?

Photowhit

Re: Voltage drop and inverter shut off - why???

How often and how do you equalize your batteries?

I guess I should explain, batteries can, and will have reduced capacity over time, The SG can be fine and just have diminished capacity. The low ratio of charging current, might indicate chronic under charging, which can sulfated cells, equalizing can help regain some of this lost capacity. There have been threads here about long equalizing trying to recover Rolls battery banks...

waynefromnscanada

Re: Voltage drop and inverter shut off - why???

Photowhit wrote: »

I guess I should explain, batteries can, and will have reduced capacity over time, The SG can be fine and just have diminished capacity.

And that's exactly what happened to my 12 year old bank a couple of years ago. SG was still good, they just had no useful capacity left.

Offgridgirl

Re: Voltage drop and inverter shut off - why???

Good morning
I measured the voltage across each battery and it was about 7 on each.
I'm not sure what else I can measure, very easily anyways.
I equalize when the sg gets low. More often in the winter. I use the generator to equalize.
This has come on pretty sudden. Sort of not working right for maybe a week and then the broken battery and now nothing.
Everything looks fine if the power is shut off to the house and there's no sun and the generator isn't running. As soon as we turn the power on, the voltage drops and the inverter shuts off. It will cycle on and off and the voltage will go up and down.
Thank you very much for the responses.

Aguarancher

Re: Voltage drop and inverter shut off - why???

“She doesn't know what else could be wrong so probably won't come out till then”

If I was in your situation and my installer wouldn’t come out to try and help get me back up, I’d be looking for a new service person. It would be different if you had grid back up. Just my opinion.
Sounds like you may have either a wiring or a hardware settings issue. Good Luck

BB.

Re: Voltage drop and inverter shut off - why???

With the meter on the DC input to the inverter and problems with it turning on and off, exactly what are the voltages you are reading when you attempt to load the system with no charging current?

A battery can read 7.0 volts (which should mean that you are charging the battery bank--equivalent to ~14.0 volts for a 12 volt bank, or 28.0 volts for a 24 volt bank) and still be "bad" when you try to load it down (no solar charging, no generator charging).

Note that we need to know the "exact" meter readings... 12.7 volts is a fully charge battery, 11.7 volts is a near dead battery (battery resting voltage, no charging/discharging current for ~3+ hours) or ~15.4 volts and 22.4 volts for your 24 volt battery bank.

-Bill

jtdiesel65

Re: Voltage drop and inverter shut off - why???

Offgridgirl wrote: »

Good morning
I measured the voltage across each battery and it was about 7 on each.
I'm not sure what else I can measure, very easily anyways.
I equalize when the sg gets low. More often in the winter. I use the generator to equalize.
This has come on pretty sudden. Sort of not working right for maybe a week and then the broken battery and now nothing.
Everything looks fine if the power is shut off to the house and there's no sun and the generator isn't running. As soon as we turn the power on, the voltage drops and the inverter shuts off. It will cycle on and off and the voltage will go up and down.
Thank you very much for the responses.

What kinda breakage on the battery? What do you mean "as soon as we turn on the power"? Like that very second, in a few minutes?

Four things come to mind:

- Electrolyte dropped below plates, so batteries are toast.
- Battery broke internally and somehow discharged the other batteries down to zero, so now batteries are toast
- Chronic undercharging. But I would expect it not to be so sudden...but also perhaps it would be hard to notice if you weren't constantly hovering over your system. What does the electrolyte look like? Cloudy or with some dark junk in it=not good.
- Huge load on the system (short?). So you turn on the power and instantly your voltage drops to the low voltage cut out. Is the inverter loaded as soon as you turn on the power? Maybe toggle off all the breakers in the house then turn on the power. See what happens. Then turn half the breakers back on, turn on power. Observe result. Then turn those breakers off and turn the other half on. Turn on power and observe result.

oil pan 4

Re: Voltage drop and inverter shut off - why???

BB. wrote: »

With the meter on the DC input to the inverter and problems with it turning on and off, exactly what are the voltages you are reading when you attempt to load the system with no charging current?

A battery can read 7.0 volts (which should mean that you are charging the battery bank--equivalent to ~14.0 volts for a 12 volt bank, or 28.0 volts for a 24 volt bank) and still be "bad" when you try to load it down (no solar charging, no generator charging).

Note that we need to know the "exact" meter readings... 12.7 volts is a fully charge battery, 11.7 volts is a near dead battery (battery resting voltage, no charging/discharging current for ~3+ hours) or ~15.4 volts and 22.4 volts for your 24 volt battery bank.

-Bill

And that's why you don't use a DMM to test if your batteries are good or not. Finding a bad battery is a job for an actual battery tester.
The battery load tester wont tell you what your amp capacity is but if you have a bad cell in one battery that is causing your entire bank to fault out when a load is applied it will identify the offending battery.

waynefromnscanada

Re: Voltage drop and inverter shut off - why???

Offgridgirl wrote: »

I equalize when the SG gets low. More often in the winter. I use the generator to equalize.

OUCH! This statement raises red flags! When the SG gets low, it means the batteries need to be CHARGED.
EQ is required when the SG is different between battery cells, some high, some low. (True, but exaggerated somewhat to get the point across)
Sounds like they were being put through an EQ cycle when they were in need of being charged. This could well have damaged the batteries, shortening their life.

gww1

Re: Voltage drop and inverter shut off - why???

I am finding with my battery, If I want to get the sg up during winter I have to use eq voltage if I want to get it done with a 6 hour or less absorb time. My battery is not temp compensated. I have been fighting low sg for over a year and this is the only way I can raise them every 3 to 5 days. At my very high absorb voltage of 61.4 volts the batteries only get to about 1.260. The eq voltage for the last 2 to three hours that would normally be absorb time gets them to close to 1.280 or above. I eq till sg quits raising once a month. The batterys never get above 70 degrees f except for the monthy eq. The sg would raise at the normal absorb voltage better during hot weather. My eq voltage is 63.2. I have fork truck battery and only write this cause of the comment of damageing a battery when charging with eq voltage. I have worked hard and this is the only thing that is giving me any kind of consistant result. Ten hours of just absorb may accomplish the same thing but it is hard enough to get 5 or 6 hours.

gww

waynefromnscanada

Re: Voltage drop and inverter shut off - why???

gww1 wrote: »

I am finding with my battery, If I want to get the sg up during winter I have to use eq voltage if I want to get it done with a 6 hour or less absorb time. My battery is not temp compensated. I have been fighting low sg for over a year and this is the only way I can raise them every 3 to 5 days. At my very high absorb voltage of 61.4 volts the batteries only get to about 1.260. The eq voltage for the last 2 to three hours that would normally be absorb time gets them to close to 1.280 or above. I eq till sg quits raising once a month. The batteries never get above 70 degrees f except for the monthy eq. The sg would raise at the normal absorb voltage better during hot weather. My eq voltage is 63.2. I have fork truck battery and only write this cause of the comment of damaging a battery when charging with eq voltage. I have worked hard and this is the only thing that is giving me any kind of consistent result. Ten hours of just absorb may accomplish the same thing but it is hard enough to get 5 or 6 hours.

gww

In your case, possibly, or partly because of no temperature compensation, your absorb voltage appears to be too low, and your compensating by using EQ. The absorb voltage is adjustable on the controllers you have listed in your signature. You should be able to bring it up so it will properly charge without having to use EQ to finish it off. BUT, you'd have to adjust it back down for Summer. Battery temperature sensors feeding the controllers may well solve your problem without having to manually boost the voltage in cold weather.

gww1

Re: Voltage drop and inverter shut off - why???

Wayns....
Thanks. I acually had temp comp but differrent age equipt. Outback tech thought I would have better luck running with out the temp comp. In the end I really try to watch sg alot. I am retired and I do know this doesn't make for nearly a very seamless operation. I have actually found reading what might be the truth of what is trully going on with the battery to be very hard. I have tried many ways to make it run more seamless without having to buy more equiptment. If I switched out the mx60 for an fm80 I could probly get by with out as many manual adjustments but am not sure of that. That is just what I am doing now as it is seeming to work better since it cooled down then what I was doing before. January has been the worst I have ever seen for any sunlight so I am using the grid alot and didn;t do that earlier. If anyone ever reads my tactics, I hope they take it with a grain of salt as I am still Having a hard time of getting it right or knowing which is which.
Thanks
gww

softdown

Re: Voltage drop and inverter shut off - why???

I'm a solar newbie by board standards. But I like to attack the cheap and simple solutions and possibilities first. "Some corrosion" is not conclusive but it leaves me wondering how much of an issue unseen corrosion might be. Are your battery connectors clad in zinc (silver in color)? Is there rubber shrink wrap, or other solution, over any possibly exposed battery connection cable? I have seen battery cables that didn't look too scary but they literally disentegrated when force was applied. i.e. - there was almost nothing left of the copper wires at the connection.

I'm not saying this may well solve your current issue. But I will say that battery cable corrosion must be eliminated and prevented. I hope your battery cables are at least #4 AWG in size with larger (#2 AWG or bigger) being better.

But like I said, most of the guys here have forgotten more than I know. Solar electricity is the most formidable subject that I have encountered.

Offgridgirl wrote: »

Thanks for the responses.
I do have a digital multimeter, still in the package. I'll crack it open tomorrow and try it out.
There was some corrosion on the connections at then end of the line of batteries we disconnected. So after that I looked over all the connections and cleaned them up if there was anything.
Our system consists of 9 - 250w panels, Magnum Energy inverter, Magnum Energy remote control, 16 - 6 volt Surrette batteries, I'm not sure of the ah, wired to 48 volts, Generac 6kw generator.

waynefromnscanada

Re: Voltage drop and inverter shut off - why???

Just re-reading your info about having an absorb voltage of 61.4, that is indeed pretty high, but you are using fork truck batteries - - do you know for sure what the SG should read with those batteries, or what the required charge voltage is for them? What the manufacturer recommends? And the voltage you read across the batteries, is that being read right on the actual battery terminals, thus bypassing any battery cable end/corrosion problems mentioned by softdown?
Point of interest, Every year, once a year, I give each battery terminal/cable end etc a quick spray of Rust Check anti-corrosion and after 15 years all my cables, cable ends, nuts, bolts etc all look exactly as they did when brand new.
http://www.rustcheck.ca/index.php?page=shop.product_details&flypage=shop.flypage&product_id=52&category_id=6&manufacturer_id=0&option=com_virtuemart&Itemid=321&vmcchk=1&Itemid=321

gww1

Re: Voltage drop and inverter shut off - why???

Waynes..........

Just re-reading your info about having an absorb voltage of 61.4, that is indeed pretty high, but you are using fork truck batteries - - do you know for sure what the SG should read with those batteries, or what the required charge voltage is for them? What the manufacturer recommends? And the voltage you read across the batteries, is that being read right on the actual battery terminals, thus bypassing any battery cable end/corrosion problems mentioned by softdown?

If you are referring to my post? I have been on the phone with the battery maker many times. Those voltages are the only way to get the sg to the 1.285 through 1.295 that the battery makers state is full. One cell still misses or bairly makes that. I did go for 3-6 months at 57.2 volts absorb and some times 20 hour eq at 62 volts and could not get the sg up prior to contacting the manufactuer. I did this based on the sales rep. I am having a bit better luck with sg now using the higher voltage but wonder about capasity. Battery maker thinks my plates are still not formed after about a year and a half. I have checked voltage at the battery including individual cells and all match to .1 to .3 volts per componant. I set each componant to compensate for these differances. The componants have been calabrated and this is as close as I can get them to each other.

You had mentioned that eq voltages were damageing to batteries when used during charging and I just wrote my experience based on the battery makers recomendations which may change as the battery forms/ages. This was not my thread to take over and I don't expect anyone to take what I am doing as advice but more of a report of what I am having to do to get my sg up.

I am all ears if you have suggestions and if it is not out of line, this being someone elses thread.
Thanks for your previous thoughts on this matter.
Cheers
gww

waynefromnscanada

Re: Voltage drop and inverter shut off - why???

Sorry about that, getting old and confused. Hahahaha