Need a 24v charger

[scheek]

I'm about to work on my 6000W/24v inverter. I believe some Mofets are bad. It died. This inverter is about 130 pounds and I don't want to be lugging it around. I'd rather work under ac and test it with a 24v charger inside, then carry it back to the woods. Any idea of how I could come up with something outside of buying batteries. I'm not sure it would have to have a lot of amperage, just enough to see if it worked... But I guess that's why I'm asking you for advice.

Thanks

[Mike90250]

how about 2 automotive jump start packs, wired in series, then paralleled with your 24-28v pwr supply ? That should be enough battery to test load the inverter

Be sure to check the FET drivers, they often blow too.

[scheek]

Hey Mike. Long time no talk to. Cabin build now for 3 years and completely off grid. Now I have an inverter problem within last week. Not sure what I did but anyway I have some FETS out and need to replace all or portion of. That's a good idea you are suggesting. I may have to do that or just carry this sucker back out and re-plug it up. I believe it will take 4 volts to open gates according to specs. I'm not sure I know what that driver looks like. Is that an MOV. I see two of those (little blue blobs) at the end or beginning of the FET rows. Cheers

[opanin17]

The built in charger of the inverter is not adviceable to use for testing.
But you can test with any stable power supply with high current. Another issue is that, if the mosfets fails again, the power supply may also fail since the mosfets will short the output of the power supply during failure.
read more about inverter repairs

http://helpersalone.blogspot.com/2016/08/inverter-repair-1.html

[Mike90250]

the 2 blue blobs are likely a MOV for spike protection
The FET drivers are usually IC's can be any shape, DIP, SMT, trace back the Gate wires of the FET, and you will find the Drivers.

[scheek]

Mike, have you ever heard of two separate solar arrays charging one battery bank.

[Mike90250]

Mike, have you ever heard of two separate solar arrays charging one battery bank.

I HAVE 2 separate arrays charging the same bank via 2 different controllers. took 2 days to tune the 2 controllers to each other, and now they share the load well.

[scheek]

Thanks Mike. Right now my existing panel array (1400w/24v) is about 125' away, using #8 wiring trunk line. If I put another smaller array close by this one, can I use the same trunk line to connect to my new charger, which I will mount next to the older one? Too, would that require a separate fuse box for the new array.

[Logan5]

If you are running 125' you should be running a higher voltage than 24v, Most MPPT controllers can handle in excess of 100v up to 300v on some models. 24 volts running 125 feet even over awg8 is a huge resistor and these long runs heat up during the charging process = a significant loss of power.

[scheek]

You are right. I need to raise voltage to 48. Anyway around this with adding more wire to help, rather than one new bigger wire. My inverter and everything is 24 volt. Can't move panels. Thanks.

[Logan5]

not talking about your inverter or your battery bank voltage, I am talking about your array voltage. your array voltage that runs the 125 feet should be between 100 and 150 volts. not 24 or 48, but 100 plus into your MPPT CC to charge your batteries.

[Mike90250]

Thanks Mike. Right now my existing panel array (1400w/24v) is about 125' away, using #8 wiring trunk line. If I put another smaller array close by this one, can I use the same trunk line to connect to my new charger, which I will mount next to the older one? Too, would that require a separate fuse box for the new array.

If you can get the new array to match the old array voltage within 5%, you need to consider:
1) Combiner Box, one breaker or fuse for each parallel string
2) NO, if you are adding a new charge controller, it needs its own wire to it's own array. Controllers need their own panels, the cannot share panels.
3) as was mentioned earlier - the existing array needs analysis, as to it's efficient layout.

[scheek]

<http://www.wirebarn.com/Wire-Calculator_ep_42.html> Have you seen this done? EG. using two number 6 gauge vs one number 4 gauge. This could help my existing problem.

[scheek]

Thanks.

Right now I see that my existing array gauge wire is not sized correctly. I see on a website (http://www.wirebarn.com/Wire-Calculator_ep_42.html) that I can combine wires to increase the overall size. Have you seen this done. (eg.) Use two #6 vs one #4 from combiner box to charge controller.

[scheek]

If you can get the new array to match the old array voltage within 5%, you need to consider:
1) Combiner Box, one breaker or fuse for each parallel string
2) NO, if you are adding a new charge controller, it needs its own wire to it's own array. Controllers need their own panels, the cannot share panels.
3) as was mentioned earlier - the existing array needs analysis, as to it's efficient layout.

http://www.wirebarn.com/Wire-Calculator_ep_42.html Do you see this done. (eg. using two 6 gauge vs one number 4 gauge) If this works I can beef up what I have now.

[scheek]

If you are running 125' you should be running a higher voltage than 24v, Most MPPT controllers can handle in excess of 100v up to 300v on some models. 24 volts running 125 feet even over awg8 is a huge resistor and these long runs heat up during the charging process = a significant loss of power.

Logan. I have a 24v system. PV panels in 24v series. Pushing about 30 amps total

[Logan5]

You have a lot of learning to do before you spend any more of your money. Study Ohms law and maybe you will understand.

[scheek]

Logan. I have a 24v system. PV panels in 24v series. Pushing about 30 amps total

Agree. I'm doing the best I can. This is the formula page I am using to figure my wire size. http://www.freesunpower.com/wires_cables.php . I will put my amp meter on it later and see what volts it is. Is there a way to tell what your panel voltage is by looking at the labels?