Sanity Check & Comments Requested for 24V System Build

[Bill Taylor]

That is what I was thinking Bill. What battery charger were you thinking about for $300?

I will dispense my advice and opinions at my own peril. I don't want to start a pissing match about which charger is the best. But since you asked me....
I like the Xantrex 458 2000w inverter/chargers. They can be found used for about 300 bucks. You get the 2000 watt continuous duty inverter, 30 amp transfer switch, and 100 amp charger in one box. Yes, they are modified sine wave. (I would be happy to have a "modified sine vs pure sine" discussion with anyone). And yes, they are dated technology. But, their giant Transformer allows for a massive surge and they are built to last. Every year I see at least 50 or 60 systems with those being used 24/7. Very seldom do they fail. And when they do, anyone with basic electronic skills can repair them. They have several charge profiles to choose from and temperature compensated charging. I haven't noticed a lot of people talking about temperature compensation. If your batteries ever get outside of the 60 - 80 degree range, temp sensor is a must. (Except lithiums.) I will not use a battery charger that does not have a temperature sensor on it. They will even work fairly well with lithium, better than the Magnum's. It would be really easy to hook the air conditioners up on the inverter output and put a lamp timer on a line cord for the AC input. Just have the lamp timer shut the input power off between 3 and 8. The battery is charged off-peak, you're running everything off the batteries for a zero draw on peak.
Progressive Dynamics makes a really great multi-stage charger for under $300 new.

I have seen a lot of pretty impressive looking Chinese chargers and inverters on the market. And I have tested a few of them out. I have not tried them all, but so far, I am not too impressed. Again, just my opinion

 

[Bill Taylor]

Bill - what plan do you have? I just switched to Save Choice Max and will pay .0523 Off Peak and .087 On Peak (as long as the 1 hour of most usage is not "On Peak" - then I get a $17 penalty for that day).

I pay several different APS bills on different properties. My house has had Premier Choice until just recently. So I can avoid that on-peak demand charge. I've had three days already this summer with over 4kw hourly peak. But I just put it in a couple of mini splits. I will be trying those out for the next month or so and I may change over to the saver Choice Max if it works like I think it's going to.

 

[Bill Taylor]

APS is making it easier and easier for all of us with APS to get off the grid. I so much miss SRP.

No kidding. I am a CR-11 contractor and I have been trying to get transformer information so I can do fault current calculations for a permit. 5 emails to engineering in the last 3 weeks. No response. Not to mention at least a dozen conflicting requirements from different pages in their distributed generation section. It's pretty obvious they're not too keen on customer owned solar.

 

[mafemm5109]

I will dispense my advice and opinions at my own peril. I don't want to start a pissing match about which charger is the best. But since you asked me....
I like the Xantrex 458 2000w inverter/chargers. They can be found used for about 300 bucks. You get the 2000 watt continuous duty inverter, 30 amp transfer switch, and 100 amp charger in one box. Yes, they are modified sine wave. (I would be happy to have a "modified sine vs pure sine" discussion with anyone). And yes, they are dated technology. But, their giant Transformer allows for a massive surge and they are built to last. Every year I see at least 50 or 60 systems with those being used 24/7. Very seldom do they fail. And when they do, anyone with basic electronic skills can repair them. They have several charge profiles to choose from and temperature compensated charging. I haven't noticed a lot of people talking about temperature compensation. If your batteries ever get outside of the 60 - 80 degree range, temp sensor is a must. (Except lithiums.) I will not use a battery charger that does not have a temperature sensor on it. They will even work fairly well with lithium, better than the Magnum's. It would be really easy to hook the air conditioners up on the inverter output and put a lamp timer on a line cord for the AC input. Just have the lamp timer shut the input power off between 3 and 8. The battery is charged off-peak, you're running everything off the batteries for a zero draw on peak.
Progressive Dynamics makes a really great multi-stage charger for under $300 new.

I have seen a lot of pretty impressive looking Chinese chargers and inverters on the market. And I have tested a few of them out. I have not tried them all, but so far, I am not too impressed. Again, just my opinion

Hi Bill

I just acquired an RV with the Xantrex 458 installed, 2000W / 20A. I am wondering how I can install solar panels and LiFePo4 batteries to update the current set-up of (2) lead-acid batteries, insufficient for off grid. Can't seem to find literature in the manual as to the use of solar or LiFePo4. Your expertise with this system would be greatly appreciated.

I would like to install ~1300 W solar panels (2S2P) and 200Ah batteries. I understand this system is 12V. I suppose I could purchase a separate PV charge controller to charge the batteries directly, but was trying to keep the current system as simplified as possible. That would still leave the question for the DoD schedule of the batteries using the Xantrex and using shorepower would charge using the Xantrex.

Cheers

 

[Bill Taylor]

Hi Bill

I just acquired an RV with the Xantrex 458 installed, 2000W / 20A. I am wondering how I can install solar panels and LiFePo4 batteries to update the current set-up of (2) lead-acid batteries, insufficient for off grid. Can't seem to find literature in the manual as to the use of solar or LiFePo4. Your expertise with this system would be greatly appreciated.

I would like to install ~1300 W solar panels (2S2P) and 200Ah batteries. I understand this system is 12V. I suppose I could purchase a separate PV charge controller to charge the batteries directly, but was trying to keep the current system as simplified as possible. That would still leave the question for the DoD schedule of the batteries using the Xantrex and using shorepower would charge using the Xantrex.

Cheers

You won't find anything in the 458 manual about lifepo4 batteries. That inverter was on the market before those were even invented. You are going to be spending some money, take your time and learn about this stuff. I see people all the time that buy the wrong parts. What works for the guy on YouTube may not work for your particular situation. You are going to need a charge controller for those solar panels, I would go with an MPPT unit. I'm assuming by your numbers you are looking at 325 watt panels. Those are 60-cell grid-tie panels. You're going to need a controller that will handle the voltage from those. Don't go cheap, get a good one, do some homework. A crappy controller will rob you every day. Avoid Chinese, IMO.
Lithium batteries, well, I've been playing with some of the cheap ones. I'm pretty surprised at the capacity and quality of the lower-cost units. They are testing out almost as good as the expensive ones. Battle born is not bad, just wayyyyyy over-rated. Again, just my opinion.
A 200 ah battery bank sounds pretty small, it depends what you are planning on running. You can ballpark 1.5 kwh for 200 ah of lifepo4. You may also have some problem starting an AC because of the surge. It's possible for the inverter to require a large inrush of current, more than the BMS can handle. Multiple small batteries usually beats one large one. It spreads the surge out over multiple BMS units.
Is this system going to stay in the RV? Or is it coming out and being installed in your house?

 

[mafemm5109]

Thank you Bill. You confirmed my suspicions. Originally I was going to install (4) Trina solar 400W panels, but after measuring the real estate on the roof, I will only be able to install (a) (3) 400 W panels (b) (2) 400W + (2) 310.....still deciding. I am in the NW and larger arrays will be needed during winter time to harvest as much sun as possible. My max daily consumption will only be ~ 1200Wh, and 200Ah should be sufficient @ 1920 Wh (12*200*0.8).
Since the 12V system will have limitations with the size of the solar array, probably the best thing to do is to upgrade to a 24V system.
The MPPT charger I have in mind is an EPever BN tracer 4215 (145 Voc, 40A, 1040W, 24V) per set of (2) panels in series, but have not decided on the Inverter.
The other option is a Growatt all-in-one (24V, 3KW, 2000W/145 Voc max input), with a (2S2P) Solar configuration. Although not sure which configuration would be best, 2-400W in series and parallel with 2-310W in series or 400W-310W series (2) in parallel
On the battery, I haven't chosen, but have been looking at either the Bigbattery powerblock or a prepackaged battery from Fortune cells from Electric car part company. If I upgrade to the 24V system, I will probably probably get (2), to avoid the heavier weight of a single unit, and as you mention, multiple BMS.

Will need a step down converter, fuses......

System will be in the RV only

Any recommendations are welcome