Problem with Solar Generator

lc0338

Hello. I'm new to Forum. Not sure I posted in correct category but have problem with my solar generator and hope someone can pinpoint the problem.
When I plug in my water kettle directly into my solar generator it blew a 200 amp ANL fluse that is installed on the negative side of the battery cable. I had a friend that had a voltmeter clamp on the wire and the fuse blew at 145 amps. The fuse lugs were too hot to touch so basically it melted the plastic surrounding the fuse. The ANL fuse metal ends are very thin. My friend thought that maybe the metal on the ends of the fuse was not heavy enough to carry the current so I ordered a new GO-Power class 4 fuse.
Got the new fuse block installed and without a voltmeter clamp installed I heated some more water and monitored the temperatures with a infrared heat gun. The fuse block did not heat up but I noticed the wire going into my inverter did warm up about 7 degrees increase then all of a sudden the 110 GFCI plug in tripped and shut off the power. On the generator I have a 110 plug on either side. One is GFCI protected and the other one is not. I just happened to have the water kettle plugged into the non GFCI plug in.
My setup:
1) 4ea 6 volt full river 250 ah batteries (DC250-6)
2) Samlex PST-2000-12 Pure Sine Inverter
3) IOTA Battery Charger - 12V 55A
4) Morningstar ts mppt - 45amp mpt charge controller
5) TM-2025-RV Battery Monitor Package

Please note that both the 200 amp fuse and tm-2025 shunt is in the same negative cable between inverter and battery.
Any idea why original anl fuse blew (multiple times) and / or why GFCI is now tripping? Oh, wire size is 2/0

lc0338

Forgot to  mention: The water kettle is 1500 watt

vtmaps

Welcome to the forum,

1500 watts is a lot for a 12 volt system.  1500 watts ÷ 12 volts = 125 amps.  Of course, the inverter is not 100% efficient, so figure 85% efficient:  1500 watts ÷ 85% = 1765 watts.   1765 watts ÷ 12 volts = 147 amps. 

These numbers assume the battery can hold its voltage at 12 volts... but it can't.  As the battery voltage drops, the current increases to maintain constant power.  1765 watts ÷ 11 volts = 160.5 amps.

Also, as the voltage drops, the inverter becomes less efficient, further raising the current.  As the current goes up, there is more voltage loss in the wiring, causing the inverter to see lower voltage and draw still more current. 

A 24 volt system would be appropriate if you need to draw that much wattage.

--vtMaps

Dave Angelini

shunt should be in (-) battery leg. Fuse/breaker in (+) leg. not your problem but...

Did any of this ever work correctly before you tried to heat water?

BB.

Assuming a good quality fuse+fuse holder and the fuse nuts where tight--It does not sound like you did anything wrong:

https://www.bluesea.com/products/5129/ANL_Fuse_-_200_Amp

As Dave says, the shunt should be in the negative battery lead (assuming negative grounded battery bank) and fuses/breakers should be in the positive lead. The typical "worst case" current equation looks like:

• 1,500 Watts * 1/0.85 inverter eff * 1/10.5 battery cutoff voltage = 168 Amps rated fuse/wiring

From the BlueSea link above, you should be able to run 100% of rated current (200 amps) without blowing fuse.

-Bill

lc0338

Dave Angelini said:

shunt should be in (-) battery leg. Fuse/breaker in (+) leg. not your problem but...

Did any of this ever work correctly before you tried to heat water?

Yes, the system has been working. I normally plug the RV into the solar generator. I have used the water kettle directly onto the solar generator before but I may not have had quite as much water in it... so it didn't take quite as long to heat up and kick off.

lc0338

BB. said:

Assuming a good quality fuse+fuse holder and the fuse nuts where tight--It does not sound like you did anything wrong:

https://www.bluesea.com/products/5129/ANL_Fuse_-_200_Amp

As Dave says, the shunt should be in the negative battery lead (assuming negative grounded battery bank) and fuses/breakers should be in the positive lead. The typical "worst case" current equation looks like:

• 1,500 Watts * 1/0.85 inverter eff * 1/10.5 battery cutoff voltage = 168 Amps rated fuse/wiring

From the BlueSea link above, you should be able to run 100% of rated current (200 amps) without blowing fuse.

-Bill

Yes, correct, in that normally fuse is on pos leg. I believe the guy that put my system together put it on the neg leg just because of logistics... the neg cable ran along the back side and it was easy to mount the fuse block onto the plywood back board in my cabinet. Yes, everything was tight as this was one of the reasons I thought it may have blown originally. Here is the fuse block I put in:

http://www.invertersupply.com/index.php?main_page=product_info&cPath=444_447&products_id=2391

this has be a little worried... If I'm boondocking and this can't run a water kettle or microwave for a little bit I spent a lot of money for little gain.

lc0338

Here is a picture of my system. maybe someone can see something out of the ordinary. NOTE: The new fuse block is installed but not mounted to the backboard yet so it looks upside down in the picture.

Dave Angelini

When you finish the wiring I would suggest you figure a better way to protect the battery terminals.  This looks dangerous to me!
Look at it in failure mode, the fuse melts or bolts loosen and short. Fire starts and you come back to pools of melted aluminum and scrap metal.

jonr

If you measure current in the two center jumpers with a clamp meter, how well matched are the amps?

vtmaps

You should connect to the batteries diagonally.  The inverter should connect to the terminal where the iota and the midnite controller connect.

And as Dave points out, it looks very dangerous.

--vtMaps

jonr

> connect to the batteries diagonally.

If they are well matched.  If they aren't, you may do better leaving the wiring as is and putting the series pair with higher resistance towards the back.

lc0338

Hey guy's was out for a day. Had to haul 200 square bales hay. August in Oklahoma. It was a little warm.

Anyway, thanks for the replies since I posted the picture of my unit.

Any ideas on ways to protect battery terminals?

My electrical friend is coming back to help do some voltage checks. As I mentioned earlier, after I installed the new go-power fuse everything seemed to work ok.... it was 95 degrees  when I did the test. The fuse lugs heated up maybe 2 degrees max but the 2/0 cable going into the inverter heated up to about 102 degrees (7 degree increase). I don't think that was too much considering the water kettle is 1500 watts and it was almost full (1 3/4 quarts). As mentioned in previous post before the kettle heated completely the inverter fan kicked on (again probably no issue) then the GFI plug in tripped.
This morning I thought I would try the water kettle trial again. My electrical friend still has not come over... but plans to when he gets caught up... anyway, without anything plugged into the generator as soon as I turn on the inverter the overload light comes on and it starts howling. There is nothing plugged in..
What is going on? Sounds like an inverter problem maybe?

lc0338

vtmaps said:

You should connect to the batteries diagonally.  The inverter should connect to the terminal where the iota and the midnite controller connect.

And as Dave points out, it looks very dangerous.

--vtMaps

Can you send me a napkin drawing of how it should be changed? Also, any recommendations of what to use to make less dangerous.

lc0338

jonr said:

If you measure current in the two center jumpers with a clamp meter, how well matched are the amps?

two center jumpers??? help me see where you are talking?

lc0338

jonr said:

> connect to the batteries diagonally.

If they are well matched.  If they aren't, you may do better leaving the wiring as is and putting the series pair with higher resistance towards the back.

All 4 batteries were new and installed at same time. Have asked vtmaps or anyone to send me a napkin sketch of how best to connect batteries.

jonr

> two center jumpers???

The two heavy black wires with red on the end.    Test each with a DC clamp ammeter ($40) while there is some load on the system.  Doesn't necessarily matter if the batteries were installed at the same time - especially now that you have been operating with unbalanced wiring for some time.  There is a good chance that "fixing" the wiring without measurements will make things worse.

vtmaps

lc0338 said:
Can you send me a napkin drawing of how it should be changed? Also, any recommendations of what to use to make less dangerous.

here's a picture

The way to making the batteries safer is to put them in a box.  The cables from the batteries run through conduit to the electrical box.  Those battery cables may be unfused... thus the requirement for conduit.  The box may need to be vented to the outside. 

  --vtMaps

BB.

I believe the danger concern is that you have metal straps across the top of the battery--A shifting strap, can ground one or short the terminals.

Also--Some sort of cover over the top of the battery connections to protect against tools (while you are working in the area) shorting the terminals.

-Bill

lc0338

vtmaps said:

lc0338 said:
Can you send me a napkin drawing of how it should be changed? Also, any recommendations of what to use to make less dangerous.

here's a picture

The way to making the batteries safer is to put them in a box.  The cables from the batteries run through conduit to the electrical box.  Those battery cables may be unfused... thus the requirement for conduit.  The box may need to be vented to the outside. 

  --vtMaps

Thanks for the picture. Understand. I am having another problem now. The inverter overload light come on when I turn it on (even though there is nothing hooked up). I wanted to test the two center jumpers like jonr mentioned before I switched the wire where it should be but have to figure out the Inverter overload issue first.

lc0338

jonr said:

> two center jumpers???

The two heavy black wires with red on the end.    Test each with a DC clamp ammeter ($40) while there is some load on the system.  Doesn't necessarily matter if the batteries were installed at the same time - especially now that you have been operating with unbalanced wiring for some time.  There is a good chance that "fixing" the wiring without measurements will make things worse.

Ok, gotcha. Will have to figure out why inverter overload light comes on (and screams) first before I can put any load on it. I may have already screwed up the battery the inverter is connected to. I bought the inverter from Best Converters and have sent Randy an email asking if he has any ideas what is going on with inverter.

lc0338

BB. said:

I believe the danger concern is that you have metal straps across the top of the battery--A shifting strap, can ground one or short the terminals.

Also--Some sort of cover over the top of the battery connections to protect against tools (while you are working in the area) shorting the terminals.

-Bill

The straps are to hold down the batteries; to keep them in place. The batteries are sitting in foam to keep them from shifting side to side. I do agree with you probably need something over the bare battery terminals. Thanks!

BB.

Wrap the straps in tough tape or use nylon straps?

Also look for what is above in the battery box--Drove an old 1953 GMC delivery pick up truck where the battery hatch spring fell right on top of the battery (a single battery--not 4 like yours). Fortunately, only needed a new battery (not much plastic in those old trucks).

-Bill

lc0338

BB. said:

Wrap the straps in tough tape or use nylon straps?

Also look for what is above in the battery box--Drove an old 1953 GMC delivery pick up truck where the battery hatch spring fell right on top of the battery (a single battery--not 4 like yours). Fortunately, only needed a new battery (not much plastic in those old trucks).

-Bill

Good idea. Thanks!

BB.

I have used this pipe wrap tape before on various projects... Relatively tough stuff (for tape):

http://www.homedepot.com/p/2-in-x-50-ft-20-Mil-Pipe-Wrap-Tape-53550/100179778

-Bill

Johann

lc0338 said:

jonr said:

> two center jumpers???

The two heavy black wires with red on the end.    Test each with a DC clamp ammeter ($40) while there is some load on the system.  Doesn't necessarily matter if the batteries were installed at the same time - especially now that you have been operating with unbalanced wiring for some time.  There is a good chance that "fixing" the wiring without measurements will make things worse.

Ok, gotcha. Will have to figure out why inverter overload light comes on (and screams) first before I can put any load on it. I may have already screwed up the battery the inverter is connected to. I bought the inverter from Best Converters and have sent Randy an email asking if he has any ideas what is going on with inverter.

Check the DC voltage with an DC volt meter at the inverter input/12 volt and battery, it may be to low.

Marc Kurth

As Johann said: Read your battery voltages.
Read them standing idle, under a light load and with a heavy load. This can really help to understand what is happening.

lc0338

Thanks all for the replies. For now the generator is down. The inverter overload light is on which indicated an upper burn according to samlex tech support. They say the max temp rating is 40 deg C (104 f). I would think they would have some overheat cutoff safety rather than crash and burn. Oh well. I bought the inverter in 2013 but did not get it into operation until April 2015 so it is about 3 years old and out of 2 year warranty. So, I will not be doing anything until I get another inverter. 

lc0338

Since I am at a decision point... which new inverter to order, any recommendations of one's with higher heat capacity or at least will shut down to protect itself?

Also, for my current system what would be involved to change it over to 24 volt instead of 12 volt. I understand that would help provide larger load with lower temps. 

DRickey

The charge controller should be able to handle 24v unchanged (might autodetect, might need to have a setting changed). You'd need a new inverter, but you're buying one anyway so this is the time to make that change (the most expensive single piece). You'd also need a new 'shore power' charger but those are comparatively cheap. If you can stand the pain, a Xantrex/Schneider Electric Freedom SW 2024 ($1600, 2000 Watts) or 3024 ($1900, 3000 Watts) will fill both functions (inverter and shore/generator power battery charger) while being considerably more heat tolerant.

Other than that, it's just switching the batteries to series rather than series-parallel. It will mean half the amps for the same Watts, so less battery drop and conductor waste. It means not being able to use the battery voltage straight for LED lighting, but you can get cheap converters to bring the 24v down to 12v for that. And you do need to cover those batteries with something, even if it is just a sheet of heavy plastic. Dead shorts across the posts at 24v can melt steel.

lc0338

DRickey said:

The charge controller should be able to handle 24v unchanged (might autodetect, might need to have a setting changed). You'd need a new inverter, but you're buying one anyway so this is the time to make that change (the most expensive single piece). You'd also need a new 'shore power' charger but those are comparatively cheap. If you can stand the pain, a Xantrex/Schneider Electric Freedom SW 2024 ($1600, 2000 Watts) or 3024 ($1900, 3000 Watts) will fill both functions (inverter and shore/generator power battery charger) while being considerably more heat tolerant.

Other than that, it's just switching the batteries to series rather than series-parallel. It will mean half the amps for the same Watts, so less battery drop and conductor waste. It means not being able to use the battery voltage straight for LED lighting, but you can get cheap converters to bring the 24v down to 12v for that. And you do need to cover those batteries with something, even if it is just a sheet of heavy plastic. Dead shorts across the posts at 24v can melt steel.

Thanks for the reply. Since this unit is used as a generator I don't see much problem not having 12 volt directly from batteries. If ever a need, as you mention, there are 24 to 12v converters. That is a pretty good chuck of change though for the inverter/charger... although just another samlex like I had will cost $600 plus and with no over heat self protection... not going that route again for sure. Since this unit is intended to sit in the sun I need to minimize temperatures as much as possible so it seems like converting from 12 to 24v is the best direction. Hope I can get more replies from others as well.