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Small Cabin Forum / Off-Grid Living / inverter not reading watts
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bc thunder
Member
# Posted: 22 Oct 2021 09:17
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my mpp all in one inverter seems to have some quirks this morning... It shows only 10 watts being used, but is closer to 200 watts. Plugged in the honda and it shows the 2oo watts. swichted back and nothing again?
It is starting to get cold here last two mornings(-5c outside, +5c inside) Too cold??? batteries outside in battery box too cold???
Any thoughts???

Brettny
Member
# Posted: 22 Oct 2021 09:41
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Is the LCD screen outside in the cold?

bc thunder
Member
# Posted: 22 Oct 2021 09:51
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no everythings inside and not showing any coads.
It is against an outside wall.
If it's the cold, should I turn it off at night, then in morning after a good heat from the fire, turn back on?
I have call in to the dealer but no repley yet.
My confidence is rocked and I.m starting to project bad thinks one after another lol.
Thanks for the imput!

bc thunder
Member
# Posted: 22 Oct 2021 11:06
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It seems to be back to normal now, I think.....
I have put a piece of reflective styrofoam insulation behind it, against the wall, but it's going to get way colder than this. Fingers crossed....

Steve_S
Member
# Posted: 22 Oct 2021 12:18
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Temperatures should have no effect whatsoever... I could see it if it was say -30 and there was a hairline crack in the PCB or so (not common). Battery Temps also somewhat moot as Voltage & Amps are still there.

First things first, you cannot do much internally to the AIO and you wouldn't want to unless directed to do so by Growatt. Check all of your wiring connections to make sure they are tight and that nothing (crimps included) is compromised.

Lead/AGM Batteries do not care about temps unless really into extremes and low state of charge.

Lithium Based does care and depending on chemistry the thresholds vary as to when they must cutoff. LFP/LiFePO4 for example will not take a charge below 0C/32F BUT can safely discharge till -20C/-4F. LFP can take a REDUCED charge from 0C/32F-8C/46F. * Excluding Yttrium Doped LFP.

A "Typical" BMS with Cold Temp sensors will cutoff discharge or charge when temps are out of range. IF this is indeed the case, the AIO would not see the battery as connected.

bc thunder
Member
# Posted: 22 Oct 2021 15:55
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Thanks Steve, everything looks ok.
It was completly normal, except the usage watts. It showed the fridg at 165w instead of 65, and didn't show the internets 80w at all. 1 or 2 hrs later it was fine again. The manual does say use between 0c and 50c, but no codes were tripped......
I'll see what happens tomorrow morning

Brettny
Member
# Posted: 24 Oct 2021 06:53
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Temp will have an effect on the LcD screen. Some dont work when cold as there is a liquid in them.

bc thunder
Member
# Posted: 24 Oct 2021 08:11
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It happened again around 8:00 last night and seems to be areg. thing now.
Funny thing is it works fine right now on solar, but when I charge with the honda it does'nt read all wattage being used. Seems fine in every other way, but if one reading is on the blink, might not be long before a full on catastrophic hydraulic failure....
The after sales support on these are a little lacking to say the least!

bc thunder
Member
# Posted: 3 Nov 2021 09:10 - Edited by: bc thunder
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test #403 trouble posting
seven batteries read6.1 or 6.2
but one reads 6.08
Is this a big problem to cause troble for the inverter?

Brettny
Member
# Posted: 3 Nov 2021 09:18
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Here is a spec sheet for volts/SOC from Trojans website. 6.08v is about 50% or dead. Can you re work the bank to remove that one and see if the problem still exists?
Screenshot_20200323.png
Screenshot_20200323.png


bc thunder
Member
# Posted: 3 Nov 2021 09:20
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Its 24 volt system, so id need to remove 4 altoghter I think. So no

bc thunder
Member
# Posted: 3 Nov 2021 09:31
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Charge with the honda and 10 minutes later they are at 6.5

gcrank1
Member
# Posted: 3 Nov 2021 12:17 - Edited by: gcrank1
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When I had issues with my 12v system bat-bank I reduced it down to the best 'extra' battery I had then started charging each of the others on the smart charger for 3 full cycles. As one charged I checked the prev charged several times over 24hrs and had one that did not hold to the end. 2 others seemed to sortof recover. By then I discovered a friend had an old school load tester, boy, did that sort it out quickly. One of those two had no beans.
I put the other one back into service with the oddball bat I had left running and have been running on them since late spring?
Thing is, you have to get the 'bad' bats out of the system, they pull the others down and weaken the whole bank.

bc thunder
Member
# Posted: 3 Nov 2021 17:06
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Ya, I'm going to try to get a load tester myself. Your the second person today to mention it. I know I'm not getting a good long charge on them. Little sun this week, and I've been tring to use the generator as little as I could. Add in colder temps and I THINK that's my problem.
I may also try Brettny's idea with the timer. Turn the fridge off at midnight till 4am.
The inverter dealer thinks I should buy more panels and batteries, but that"s a bit spendy right now.
Thanks everyone for your thoughts and ideas......

gcrank1
Member
# Posted: 3 Nov 2021 18:15
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When we were running a fridge it wasnt opened late in the eve and the rest of the night so the cold wasnt 'running out of it'; Id just unplug it until morning.
I tested the temp at the unplug time and in the morning and it hadnt really risen enough temp to worry about. Sure saved Watt-Hrs!

bc thunder
Member
# Posted: 3 Nov 2021 18:26
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To be honest G, I was thinking about that too......
I'm also thinking I might just turn off the Inverter, as the fridge is the only draw not turned off with a power bar. Tomorrow calling for full sun

ICC
Member
# Posted: 3 Nov 2021 20:23
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Quoting: bc thunder
test #403 trouble posting
seven batteries read6.1 or 6.2
but one reads 6.08



I don't have any real contribution to the meter problem, but there was a comment posted about cold weather being a moot point. That is a misleading statement.

First, am I correct to assume these are lead acid batteries? Are they flooded batteries or AGM? If they are flooded do you have a hydrometer? A hydrometer can help by finding a cell or cells that are low or bad.

How old are the batteries? All the same age, same mfg batch?

Cold weather does affect the available capacity of any lead acid battery. When the temperature drops to about feezing a lead acid battery actually loses about 25% of its rated capacity. FYI, lead acid battery capacity is rated at 77 degrees F. At 0 F a lead acid battery is only going to have abouthalf of its rating available even if fully charged according to the hydrometer or voltage.

One good thing is that a fully charged lead acid battery will not freeze until it drops to below -80 F. (I forget the exact number... something like -92 F I think).

The bad thing is if you use up much of the capacity the batteries may freeze if it drops below zero.

This link has a graph and table of temperatures and capacities. It does not matter on the brand or anything other than the temperature as all lead acid batteries use the same chemistry.

ICC
Member
# Posted: 3 Nov 2021 20:26
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.... and if you do use a hydrometer the readings have to be adjusted for the temperature of the electrolyte. As a rule of thumb, subtract four points (.004) from your hydrometer reading for every 10 degrees below 80 °F. There are some hydrometers that do automatically correct for temperature. Most simple float types do not have that ability.

bc thunder
Member
# Posted: 3 Nov 2021 21:25
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Hey ICC ya, fla, all the same, 8 weeks or so old.
I was told today about the load tester, and hydrometer. Going to see if I can get one.
It may be a perfect storm:no sun, not long enough on the generator, colder weather.
Thanks for the info, will help for sure.......

ICC
Member
# Posted: 3 Nov 2021 21:45
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This is probably the best one

https://www.solar-electric.com/midnite-solar-battery-hydrometer.html?gclid=Cj0KCQjw5o iMBhDtARIsAJi0qk0O-DcfNE-ii5zOIyH8PCIdMtQ7u0-xvGkuPT6k3Gk1ALjgnV7rKZkaAr0NEALw_wcB

ICC
Member
# Posted: 3 Nov 2021 21:46
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No matter what one you use rinse after use with distilled water

gcrank1
Member
# Posted: 3 Nov 2021 23:00
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If they are only 8wks old do you Know, for Sure and Certain, that they were Completely Fully Charged before putting in service?

Brettny
Member
# Posted: 4 Nov 2021 06:02
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New batteries, not much sun and now showing signs of a dead battery...I'm betting on they just need a really good charge.

Do you have a 30a+ charger you can run off your generator? I would highly recommend one. This time of year the days are only getting shorter. You could also move your fridge outside and it may never run overnight.

bc thunder
Member
# Posted: 4 Nov 2021 06:43
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ICC: one thing I'm not sure about; do I need to isolate each battery I test, or can I leave them in series while I test each???

Gman:I don' know much now, I new way less then lol.
I do know I ran the generator from 3pm till it ran out of gas (sickly older dog, can't take the heat), most nights for two weeks right after I bought them. That's on top of good sun in late Aug.

BNY: My best charger I have is my honda 2200, and the batteries do hold there SOC way longer after 2 or 3 hours on it. Today is going to be full sun, but tomorrow I can run them on the honda for a full tank of gas (7hrs?) and see if that helps.
The fridge manual says not to use it at less than 10c (50f I think), was almost -10c (13f ?) last night. Pretty soon I could put freezer contents in a cooler outside, and fridge contents in a window box. I just hate spending thousands on a solar system, only to use prehistoric caveman tecnologies lol. It is a little frustrating....
Thanks Guys

bc thunder
Member
# Posted: 4 Nov 2021 07:01
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Last night, at 12:00, the inverter led display showed 25.1
So I turned off the out going power bar, shuting down power to everything but the inverter itself. At 530am, it showed the SOC at 24.5 The volt meter showed the batteries at 6.05
So in about 5 or 6 hrs, @ say -6c, they went from 80%ish to about 50% with no real draw of power, other than the inverter itself. Could that be due to weather ect... Or does that raise a red flag for anyone???
Think I'll shut my brain off today, the batteries aren't the only thing completely drained around here

ICC
Member
# Posted: 4 Nov 2021 08:56
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Quoting: bc thunder
The fridge manual says not to use it at less than 10c (50f I think)


That means the temperature of the room the fridge is in should be no colder. It does not matter what the outside temperature is as the fridge is not outside.

ICC
Member
# Posted: 4 Nov 2021 09:08
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Quoting: bc thunder
one thing I'm not sure about; do I need to isolate each battery I test, or can I leave them in series while I test each???


A hydrometer measures each cell individually.

If using a voltage meter the batteries should have been sitting with no charge or discharging for a couple of hours ideally. Or at least under very low load such as a DC led light, no big loads. Some inverters have a rather large idle/standby load.

Quoting: bc thunder
So in about 5 or 6 hrs, @ say -6c, they went from 80%ish to about 50% with no real draw of power, other than the inverter itself.

That should not be happening. That sounds like the inverter has a huge standby draw.

I have left batteries disconnected from all incoming charge and with all loads turned completely off for weeks with very little drop in charge. With 8 batteries in a 24 volt configuration, you should not have more than a couple of percentage points drop of capacity overnight if the loads are off. Even with the inverter left in standby, if it is a decent inverter.

ICC
Member
# Posted: 4 Nov 2021 09:11 - Edited by: ICC
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Quoting: bc thunder
My best charger I have is my honda 2200, and the batteries do hold there SOC way longer after 2 or 3 hours on it.


If you mean that you are using the DC output of the Honda to charge the batteries that is part of your charging problem right there. I believe the maximum 12 volt DC amps output is about 8 amps; 1 amp per battery in your case. That is more like a float charge than a re-charge of capacity. To charge 8 batteries you should have a charger that plugs into the 120 VAC socket and charges the batteries at up at least a 25 amp rate. I pick that because I do have a small cabin system of 8 GC-2 batteries that works fine for me and is charged at a maximum of about 24 amps.

Those are 6 volt golf cart batteries; two series strings of four???

Brettny
Member
# Posted: 4 Nov 2021 11:18
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8amps is what I remember seeing on the DC output on those hondas too. For the amount of fuel being used that's prety poor. Theres a calculation for battery bank size vs charger size, 8amps is way to small. There also not very accurate with charge rates/voltage.

I use a 12v@30a charger with a 900w inverter. I would look for a 50a+ charger paired with your 2kw honda. More amp output means less generator run time.

With a 120v charger on a cloudy day you can boost charge in the morning and let it float out the rest of the day on solar. The most fuel/input watts.

gcrank1
Member
# Posted: 4 Nov 2021 11:35 - Edited by: gcrank1
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+1 on Not using the 12vdc tap to charge a battery bank! Use a 120vac charger, a 'big' one and pref a new-generation 'smart' charger.
Imo you should be checking the charge, if using a voltmeter, individually. Only one post needs to be disconnected from each battery but that does discon the bank from the SCC/array too.
Note that pretty much all SCC instructions say to discon the array 1st before discon the bats. Then recon the bats to the SCC is done 1st to tell the SCC what it is connected to for voltage. The re-con to the array is last.
Dont linger on this, lead-acid batteries do not not like to sit in a state of discharge, it compromises and/or kills them.
There is a website, Battery University, that you may want to visit, your batteries will thank you for it.

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