400 watt inverter killed my batteries in three days?

softdown · January 2015

Had been using an 800 watt inverter to power security system when I was away. Was pleased to find that my "newish" 400 watt inverter could handle the load. Being away for a few days usually means getting some battery charging in due to lower usage.

Imagine my surprise when I returned after three days and found a battery reading of 10.4 volts. Yes...10.4 volts. It was 12.1 when I left on Thursday. The inverter shut down when I drove up and a security light came on. I expected to find a reading over 12 volts. Instead I was hooking up the genset and battery charger at 9pm.

Perhaps the weather was cloudy down here. Perhaps the alpacas were wandering about and triggering the lights...unlikely. They like to stay in one place and eat hay. Even with both events, I don't think that 4 large batteries would have drained down to 10.4 volts without another influence.

I had thought it was my laptop and router that were draining my batteries at an unusual rate. Only to find that a lowly 400 watt inverter appears to the culprit.

Story on inverter? It had been modified, one outlet had been removed. It was $5 on Ebay so I bought several. 400 watt inverters are perfect for trailer loads. Small inverters tend to be short lived.....maybe 1-3 years of full time useage. Apparently another modification took place.

BB. · January 2015

Re: 400 watt inverter killed my batteries in three days?

Get a DC Current Clamp Meter (this one is "good enough" for our needs) and start measuring. See how much current the inverter does draw.

And "do the math". What is the size of the battery bank, how much power do the security lights use, what is the AH/Voltage of batteries/battery bank, etc...

How much energy was generated by the solar panels (Outback logs) during the time?

Unattended systems with significant loads--Very difficult to automate and protect against various outages/issues.

-Bill

Cariboocoot · January 2015

Re: 400 watt inverter killed my batteries in three days?

Three things:

1). When you left the batteries were already down to nearly 50% SOC (12.1 Volts).
2). Cheap inverters almost always have an LVD that is far too low (10.5) to protect batteries from over-discharge.
3). Buy junk, get junk.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

BB. wrote: »

Get a DC Current Clamp Meter (this one is "good enough" for our needs) and start measuring. See how much current the inverter does draw.

And "do the math". What is the size of the battery bank, how much power do the security lights use, what is the AH/Voltage of batteries/battery bank, etc...

How much energy was generated by the solar panels (Outback logs) during the time?

Unattended systems with significant loads--Very difficult to automate and protect against various outages/issues.

-Bill

Thanks....my meter is on the way here. Still using my old, simple solar set-up that I have used for four years. The security lights don't use hardly any power unless the LED lights come on. I really think I have a messed up inverter. It has been modified. Amateur electronic guys may do more harm than good.

westbranch · January 2015

Re: 400 watt inverter killed my batteries in three days?

What is the size of the battery, it's not in you sig line?

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

Cariboocoot wrote: »

Three things:

1). When you left the batteries were already down to nearly 50% SOC (12.1 Volts).
2). Cheap inverters almost always have an LVD that is far too low (10.5) to protect batteries from over-discharge.
3). Buy junk, get junk.

Agreed...but my away trips have resulted in a restoration of battery voltage in the past. Something unique happened this time. Only change I made was using a much smaller inverter....which should have used less current.

My luck with AIMS inverters had been satisfactory in the past. Last one lasted for 2 1/2 years. I believe it was the modification.

Cariboocoot · January 2015

Re: 400 watt inverter killed my batteries in three days?

softdown wrote: »

Agreed...but my away trips have resulted in a restoration of battery voltage in the past. Something unique happened this time. Only change I made was using a much smaller inverter....which should have used less current.

My luck with AIMS inverters had been satisfactory in the past. Last one lasted for 2 1/2 years. I believe it was the modification.

I didn't even know it was an AIMS, but I am not at all surprised.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

westbranch wrote: »

What is the size of the battery, it's not in you sig line?

I currently use four 125 pound E8Ds. They are a "cheap set" until I am satisfied that I am "battery savvy" That is why I made the thread about forklift batteries. I will probably need to sell a rental unit to buy good batteries. Not too thrilled about that.

I need to change my sig line to reflect that is the system that I am slowly installing.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

Looks like my batteries are now effectively shot. Keep charging them. They keep draining at truly miraculous rate. Who in the world thought of a 10.4 volt shut down point? I'd vote for 11.5 volts.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

Where can I get a small inverter with reasonable shut down parameters? Like 11.4 volts or something?

I am hauling my recently shot batteries back to Denver for a period of de-sulfidization. Can't hurt. I have two 8 amp de-sulfidization chargers.

Currently getting by with one good battery outperforming four destroyed batteries.

Cariboocoot · January 2015

Re: 400 watt inverter killed my batteries in three days?

softdown wrote: »

Where can I get a small inverter with reasonable shut down parameters? Like 11.4 volts or something?

I am hauling my recently shot batteries back to Denver for a period of de-sulfidization. Can't hurt. I have two 8 amp de-sulfidization chargers.

Currently getting by with one good battery outperforming four destroyed batteries.

You have two choices: spend the big bucks or innovate.
An Outback FX2012T has programmable LVD just like the others in their line.
Or you rig up your own with a Voltage controlled switch operating the inverter's on/off.
Either will let you choose the cut-off point. 12 Volts (minus heavy load allowance if needed) is usually a good place to turn off as it insures the batteries will not be below 50% SOC.

That 10.5 Volt setting is leftover from the days when batteries were cheap and most 12 Volt inverters were installed in vehicles; the issue rarely came up.

BB. · January 2015

Re: 400 watt inverter killed my batteries in three days?

Is this for your Outback system? Looking at the programming manual, it appears you can set it:

http://www.outbackpower.com/downloads/documents/fx_vfx_series/fx_series_programing_manual.pdf

on Page 11 to between 9 and 12 volts (36 and 48 volts for 48 volt system) with a 5 minute delay to prevent false shutdowns (Mate required?).

-Bill

BB. · January 2015

Re: 400 watt inverter killed my batteries in three days?

And the MornningStar 300 watt TSW 12 volt inverter can be set to 10.5 or 11.5 volts (switch setting).

http://www.solar-electric.com/lib/wind-sun/SureSine.pdf

Also has a remote on/off wire that you could connect to a LVD detection circuit.

-Bill

Vic · January 2015

Re: 400 watt inverter killed my batteries in three days?

AND, the FM CC has an Aux output (which would not require the Mate) that should be configurable as an LVD to control a Relay/contactor on the 12 V inverter input ... perhaps. Believe that many relay.

BB Bill, did not know that that the SureSine had selectable LVD, very nice. FWIW, Vic

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

These are all awesome responses, this board continues to amaze me. An internet anomaly to be sure.

I'll have my new Outback system operational by years end. Maybe better with luck. Solar has got to be the most complex set of knowledge and skills that I could imagine.

For now...I just need a little inverter to run internet and security system when I am away. So the $300 PSW Morningstar is likely more than I need.

Decided that the alpacas that I got last month have been triggering the security lights and killing the batteries. I think that all I really need is an 11.5 volt shut off point. Also need some big, new batteries apparently.

Cariboocoot · January 2015

Re: 400 watt inverter killed my batteries in three days?

Vic wrote: »

AND, the FM CC has an Aux output (which would not require the Mate) that should be configurable as an LVD to control a Relay/contactor on the 12 V inverter input ... perhaps. Believe that many relay.

Yes, but it is somewhat unreliable to use the CC AUX as an LVD because it doesn't check Voltage at the battery but rather at the controller. As such the V-drop under low Voltage & high current conditions can be wrong; the controller 'thinks' the Voltage is higher than it really is. This can cause problems such as rapid cycling or even just plain wrong shut-off point.

Vic · January 2015

Re: 400 watt inverter killed my batteries in three days?

Cariboocoot wrote: »

Yes, but it is somewhat unreliable to use the CC AUX as an LVD because it doesn't check Voltage at the battery but rather at the controller. As such the V-drop under low Voltage & high current conditions can be wrong; the controller 'thinks' the Voltage is higher than it really is. This can cause problems such as rapid cycling or even just plain wrong shut-off point.

Well, using the Inverter LVD (setting this probably requires the Mate) may well have similar issues with not having remote battery V sense leads.

Seemed to me that we were speaking of a fairly temporary situation with the SureSine (which has a fixed but selectable LVD).

The FM CCs do have a settable LVD -- resolution to 0.1 V, IIRC). In the FM Aux menus, there are settings for LVD, ReConnect voltage, and seconds of delay (ages 38 - 39) in the FM CC Manual that I have.

This should address at least some of your concerns about disconnect/reconnect. Any battery-connected device, which could have significant current flowing in its battery leads (and no Kelvin connections) may well have errors in LVD/Reconnect voltages. But, often they are much better than nothing, or a fixed and too low LVD ... IMCO, just to split some more hairs.

FWIW, Vic

Cariboocoot · January 2015

Re: 400 watt inverter killed my batteries in three days?

Yes, I know that stuff ... being somewhat familiar with Outback equipment.

But the LVD in an inverter is subject only to the Voltage sense on the input; there is no power coming at that point from another direction as there is with the FM output terminals where it is trying to judge Voltage from battery with possibly varying load as the inverter turns on/off and power coming in from the PV to the same point.

I'm not saying it can't or wouldn't work, just that it isn't as reliable as inverter LVD or a separate detection system.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

http://www.theinverterstore.com/600-watt-pure-sine-inverter-charger.html#

For $339....this one can be set to battery priority mode.....11.5 volts

600 watts with pure sine wave for future reference

newl · January 2015

Re: 400 watt inverter killed my batteries in three days?

softdown wrote: »

Decided that the alpacas that I got last month have been triggering the security lights and killing the batteries. I think that all I really need is an 11.5 volt shut off point. Also need some big, new batteries apparently.

Tossing an alternative idea out here, have you considered solar powered security lights? The ones that I use on my property have adjustable sensitivity and timing settings and they work quite well and are fully self contained and were reasonably priced at around $30AUD each.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

newl wrote: »

Tossing an alternative idea out here, have you considered solar powered security lights? The ones that I use on my property have adjustable sensitivity and timing settings and they work quite well and are fully self contained and were reasonably priced at around $30AUD each.

I bought a few, have yet to install. My shop is very large, it would take oodles of them.

My security lights track motion and record it. I can also set them to bark like a dog. But the alpacas like to approach the building and get their treats from me. This triggers the lights and kills the batteries when the sun isn't working. Lazy sun this winter. It is almost surreal to keep waking up to dense fog and cloudy days. This is supposed to be a semi-arid climate.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

Is there a switch that will disconnect power when voltage drops to a certain level? Even cheap inverters have such a device inside of them. The problem is.....10.5 volts = real battery damage after a certain period of time.

It will be interesting to see if desulfating helps to rejuvenate them much. Desulfating looks good on paper but a lot of experienced people doubt that it can usually do much.

jimindenver · January 2015

Re: 400 watt inverter killed my batteries in three days?

Sorry to hear about the 8-Ds, those are pricy to replace and a pain to move. You are right though, for this being called Sunny Colorado, we sure see a lot of clouds.

I second the solar security lights. I've installed them for people and they love them. When they kick on they light up quite a area.

Where in Denver if you don't mind. I'm out east in Green valley ranch where the brown cloud doesn't effect my solar as much.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

jimindenver wrote: »

Sorry to hear about the 8-Ds, those are pricy to replace and a pain to move. You are right though, for this being called Sunny Colorado, we sure see a lot of clouds.

I second the solar security lights. I've installed them for people and they love them. When they kick on they light up quite a area.

Where in Denver if you don't mind. I'm out east in Green valley ranch where the brown cloud doesn't effect my solar as much.

I still have a modest home in the Englewood/Sheridan area. My solar project is in the San Luis Valley. Small cabin in the Sangre de Cristo mountains and a big shop in the flats. Would have been a pain to flatten out a big patch in the mountains. Superb area for solar... until this past month. Sun is shining today though.

softdown · January 2015

Re: 400 watt inverter killed my batteries in three days?

http://www.ebay.com/itm/12-volt-battery-low-voltage-cut-out-cutout-cutoff-cut-off-disconnect-dis-connect-/321416391361?pt=LH_DefaultDomain_0&hash=item4ad5e8eac1

Default: 11.5 disconnect 12.7 reconnect
This unit looks ideal for the needs of small solar applications. Think I will get two.

softdown · February 2015

I rec'd this unit and hooked it up today. Seems to be made reasonably well. If you have a spare set of small inverter cables (with battery clamps), you can make this unit work within minutes. My cables appeared to be 10 AWG and slid right in. Not sure if 8 AWG would easily fit. So I don't think this unit is made for large loads.

It can be adapted for higher loads with an external solenoid/relay.

softdown wrote: »

Re: 400 watt inverter killed my batteries in three days?

http://www.ebay.com/itm/12-volt-battery-low-voltage-cut-out-cutout-cutoff-cut-off-disconnect-dis-connect-/321416391361?pt=LH_DefaultDomain_0&hash=item4ad5e8eac1

Default: 11.5 disconnect 12.7 reconnect
This unit looks ideal for the needs of small solar applications. Think I will get two.

waynefromnscanada · February 2015

softdown wrote: »

. If you have a spare set of small inverter cables (with battery clamps), you can make this unit work within minutes.

If you mean the spring loaded kind like used on booster cables, expect the inverter to shut down on low voltage due to relatively high resistance at the battery terminal connections.

animatt · February 2015

that low voltage disconnect is rated fairly low. MAX 30 amps. That should limit the inverter you put on it. Looks cheap. Not sure what would happen if you drew over the rated 30 amps.

I would recommend the morningstar inverter it has very low power consumption. along with a reasonable LVD.

The inverterstore inverter has to use more power all the time. It(600w inverter) looks to have a large El transfomer in it. While the morningstar has a nice torodial transformer.

animatt · February 2015

the 600w inverter states "optional 25w power save mode"

the morningstar if i remember correctly uses 6w in normal mode. And sub 1w in standby mode.

The 600w inverter should (while still functioning) power larger loads. Morningstar has a great reputation. Those generic Low frequency inverters not so much. I do have a pair of generic ones. They do have their place. I just do not think their place is unattended. or for 24/7 powering. more for on demand or in conjuction with a generated to take advantage of its built in charger

softdown · February 2015

Believe I said that it is for smaller loads unless you wire an additional solenoid/relay. The additional material is supposed to go up to 300 amps. The morningstar is over $300. My unit costs $26.

I'm just saving several hundred dollars worth of batteries until I get my real system operational.

"Looks cheap"? Bloody hell...it costs $26. I own it and gave my review. So you trump this upon viewing a photograph? Questionable form to do "trump reviews" with that amount of knowledge.

animatt wrote: »

that low voltage disconnect is rated fairly low. MAX 30 amps. That should limit the inverter you put on it. Looks cheap. Not sure what would happen if you drew over the rated 30 amps.

I would recommend the morningstar inverter it has very low power consumption. along with a reasonable LVD.

The inverterstore inverter has to use more power all the time. It(600w inverter) looks to have a large El transfomer in it. While the morningstar has a nice torodial transformer.

mike95490 · February 2015

softdown wrote: »

............... The morningstar is over $300. My unit costs $26.

I'm just saving several hundred dollars worth of batteries until I get my real system operational.

"Looks cheap"? Bloody hell...it costs $26. I own it and gave my review. So you trump this upon viewing a photograph? Questionable form to do "trump reviews" with that amount of knowledge

Don't ask the question if you can't handle the answers. Cheap $30 inverters that destroy a $400 battery bank, aren't cheap anymore.

400 watt inverter killed my batteries in three days?

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