MSPAE4440 Magnum 48V inverter faults under small load

Thanks zoneblue for the Links.  Helps add some perspective.

Sorry Jogotta,  did not mean to demean your efforts or battery bank size,  when saying that it was "bordering on tiny".

Hope that you can accept that everyone here has spent quite a lot of their time in trying to   H E L P   you.

You have gotten a lot done.   As zoneblue mentioned,  battery systems are Energy Hazards,  so SAFETY  is very important,  and as was noted,  making mobile systems safe requires additional steps.

Good Luck,  and please DO let all of us know how you are progressing.    Vic

zoneblue said:

From the youtubes:
https://www.youtube.com/watch?v=xexCorX0jpE
https://www.youtube.com/watch?v=bmdRs-iHyBY

Youve got reasonable sunlight and yet the controller is in bulk at 56.2V at only 0.5A. That shows that while the SOC is up there, its charging real real slow.

The second video more clearly shows the disco and battery interconnects. It shows that youve got some work to do. In the spirit of totally trying to help:
- the use of double cables from battery to disco. Its best not to do this in case you get a slight manufacturing defect in one of the cables and it starts a cascade failure trying to take more and more of the load.
- one or more battery take offs to either your DC side, and/or a second inverter. Doing this will result in the batterys becoming out of balance. When individual batterys are low the low cells will reverse polarise destroying the cell. During absorb, the high cells will boil  and boil waiting for the low cells to catch up.
- unprotected wires hither and thither. Esp the unfused ones. Use conduit and secure them down.
- battery venting might need some attention, cant see.
- big batterys are a bit like a bomb. Ideally we like concrete sheds and minimising the use of flamable materials nearby. In RVs thats not possible obviously, so best practice wiring and circuit protection is and must... and do you have a fire extinguisher nearby?
- big baby and 100A carling panel mount. Not sure this is the right solution. You want a high AIC rated breaker there, and a full sized disco makes a good place to safely house all the unfused stuff.
- array combiner needed, not the 4 into 1 mc4s. This is to prevent array fires in the event of a panel short.
- breakers unmounted dangling in the left corner, i guess youre getting to that. But you need to finish the install before powering it up regardless of ones enthusiasm

If you cant ramp up the batterry, then your 4400W inverter is overspecced, its an easy mistake to make, bigger is better etc. With inverters, the opposite applies, small is beautiful.), At peak load thats: 4400W/0.85/44V=  118A. Thus you want this breaker:
http://www.solar-electric.com/mnedc125.html or maybe the next size up, seems like someone said the manual went with the 175.

Can you exchange the inverter for a 2kW model at all? That will be better suited to your overall setup.

Reconfiguring your array into 4S brings the need for additional caution for both shock and fire safety. If your going this route, all the high voltage array cabling needs to be conduited, all the way to the disco and controller.  Chassis  bonding should all be really tight.

Do you have an electrician friend or an contractor that can lend some hand? Id hate to see something bad happen here.

I tracked down her Facebook page TRusty bucket bus page and conveyed a bit of information. I guess she's a bit gunshy and has had issues. I think she sort of started out without much guidance and has had some poor guidance, including some guys are a Facebook RV Solar site most of which were good, but some bad, using a AC breaker for DC (she has changed that) She has asked Magnum about the configuration of her array. I guess she doesn't trust my/our interpretation.

Some at the Solar RV have "washed their hands of her", Their words. Guess there was a blowup there, she's no longer a member of that group, after she wanted to have a single anchor and pivot her panels on the roof, attaching the sides by ropes. She actually has additional support under the edges of the panels, but I don't know if she plans to anchor one side down for travel.

As to the inverter, I'd say keep it, it could be used during the day with some things that would be hard to start without the extra room, but plan to keep loads below 2000 watts, I personally use a 1/20th of capacity for my desired continuous loads when operating off batteries, so 22 amps at 48 volts or around 1000 watts max for anything running longer than 20-30 minutes.

I don't like the idea of higher voltage on an RV, Would have preferred a system more in line with what Zoneblue has just suggested. But she has working material, the only configuration that would work by the Magnums guide lines is strings of 4, magnum allows up to a high enough voltage that they would work, but the higher voltage would also come with more care needed, particularly in a dynamic situation, all pass throughs would need to be well buffered.

I encouraged her to return and work with the good (great!) people here, I don't think it will happen, but perhaps.

Well a little update. She must have gotten word back from Magnum. She posted;

• So, I rewired my panels today .. instead of having 4 sets of two wired in parallel I've got 2 sets of 4 wired in parallel ... the panels weren't providing enough power to fully charge the batteries... after I did that ... the amperage started cranking into the batteries and after a few minutes the controller started to fault because the batteries were over heating. I had to modify the settings in the controller to basically cripple the panels to keep them from blowing up the... batteries. In a nutshell ... I've ordered 4 more 12v 225ah batteries to add a second string.. this will up my amp hours to 450 and make all things solar power possible.

Of course if anyone's remembering, she will now have mismatched batteries... Guess she might have asked about the charging current, Though I'm a bit surprised, 2300 watt array should only produce about 35-36 Amps charging at 48 volts, during the heat of the day. @15% of 225 Ah battery bank. I thought Trojans would go to 15%. Then again, maybe she doesn't understand that the charge controller will limit the voltage or perhaps she doesn't have a BTS for the P-100 (though I think it comes with one)

Magnum asked her about her neutral to ground bond. Wondering if "the forum had told her about neutral to ground switching with shore power. I almost feel like I should tell Magnum, we were just trying to help her solve some problems that already existed. This can be easily handled at an E-Panel as I recall.

Well even though she figured it out, sort of, she did delete all my interaction. So I won't pursue helping her. It would be nice if people would ask leading questions, start ahead before jumping in, and have a desire to learn.

I certainly learn from this forum! and thank you to all who have helped me over the years. I'm about 22 years into the experience.

Her face book Blog is called "The TRusty Bucket - A Conversion School Bus" if anyone would care to check it out.

zoneblue said:

 Its not Magnum's job to design anyone's system.