choosing a 24v >=5000w inverter

[frostyllama]

Any suggestions?

Looking mostly at the 24 5000 victron quattro but open to alternatives. Schneider electric looks like it has some good gear. Shore charging is important.

Run various appliances through a killawatt and done an energy audit with the spreadsheet in snoobler's signature https://diysolarforum.com/resources/system-energy-audit-and-sizing-spread-sheet.12/ My current pack will get me about 2 days of backup at estimated use which is fine for me.

This puts me little above 5000 watts continuous suggested by the spreadsheet. I think this is overkill for my actual usage at peak, I'll watch what I run at the same time. It's nice to have a safety margin though.

Despite the benefits of a 48v system, really would like to stick to 24v. The battery pack is already purchased. Have 14.4KWH of 16 cells of EVE 280 and 2 overkill solar 24v 100 amp cont BMS'. Don't think there's more room to shove 16 more of these cells into the project and the redundancy of 2 8 cell packs seems a lot better than 1 48v battery if one of the cells fails.

 

[snoobler]

The Quattro is a 4kW inverter with a 5kW overload for 30 minutes and a 10kW overload for 20 seconds.

The Quattro has a 30W idle draw. That's another 0.72kWh/day if you didn't factor that into your audit. That's 10% of your capacity in those two days.

Maintaining redundancy with 2X 24V batteries is a good argument.

 

[frostyllama]

The Quattro is a 4kW inverter with a 5kW overload for 30 minutes and a 10kW overload for 20 seconds.

The Quattro has a 30W idle draw. That's another 0.72kWh/day if you didn't factor that into your audit. That's 10% of your capacity in those two days.

Maintaining redundancy with 2X 24V batteries is a good argument.

Thanks snoob, you've been very helpful. 4000 watts should be ok with a mindful eye and close management.

Wondering if 2x multiplus or switching to Schneider or another manufacturer would be a better option.

 

[snoobler]

As Victron's hogtied submissive b*tch, I can't imagine Schneider would be a better option.

The existing 24V 2400/3000 multis are about $1100 each, and they're almost identical to the Quattros. The Quattros can be connected to two AC inputs, but it can only use one at a time... basically a built-in ATS for AC in. It will favor one over the other if both are active.

Note that the Multiplus-II is slated for release in North America/120V Real Soon Now(tm).

 

[frostyllama]

1100 is a steal, where are you finding them for that price? The cheapest I've found is $1284 pre tax and ship on the 24/3000 120

 

[snoobler]

Erm... sorry. Going off memory. I haven't looked in awhile.

If you call the VAR I have listed in my signature, they might be able to beat their Amazon price. I recently bought a 250/100 MPPT from them, and they saved me $100 over any other price I could find online.

 

[frostyllama]

Alright, pulled the trigger on 2 multiplus 24/3000 120vac units. If you've got the space this seems like a better choice than 1 quattro because it gives you a higher peak wattage with redundancy. So far, I'm happy with the decision.

For anyone looking I was able to find them on ebay through all_marine_electronics . They are offering a 100 bonus coupon with buy it now towards other victron gear in their shop with a multiplus purchase. Put in an offer for $1180 per unit and it was instantly accepted. free shipping, total was $2531 with tax in california. Best price I could find.

 

[mattleonard]

@frostyllama - I'm looking at a similar plan as you - though for a portable off-grid system. I eventually want ~5-6kw of power - but often only need less than half that, so planning to go with (2) Multiplus 24v/3000kVa units that can allow me for modularity, and redundancy - combined when I need the power, and otherwise can be half the weight/size, or allow me to have 2 rigs out in different places at the same time.

I just ordered my first Multiplus (along with a SmartSolar MPPT, and still debating my configuration around BMV, smart shunt, Cerbo, Venus etc). I've already got ~5500kWh usable of LifeP04 battery.

Where in CA are you? I'm in Oakland.

 

[frostyllama]

Hey there, I'm between Sacramento and Tahoe. Town called Pollock Pines. around 2 hours on a good day from Oakland.

If you haven't already run an audit, snoobler has a great spreadsheet in his sig. It'll help manage the needs and expectations of your system.

Sizing the inverter is all about peek loads. Like you, I'll be running loads well under peak in most conditions. If you don't need to run multiple things at once you can save a lot of money with a single inverter. Two multiplus' will give you a lot more flexibility if you find that one is not enough. there are multiple stacking configurations for them as well, if you need 240v for example.

The vendor I purchased it through, Ryan with Marine Technical Supply, gave me a call and upsold me on a cerbo with a smart shunt and gx touch 50. Gave me a good deal.

The smart shunt works well with the cerbo. The cerbo networks all the devices and lets them talk to eachother. In my opinion this is one of the biggest selling points for victron. With those two units you can use VRM victron's cloud service to monitor the system from your phone or computer. The touchscreen is a nice accessory to view the system on, that said, you can use a tablet or any other device to monitor it. You'll likely need an MK3 programmer as well, I'm uncertain if you can program without it. My biggest complaint with victron, all the accessories aren't cheap haha.

I've yet to purchase the panels or charge controllers. Still sizing out that part of the system on the short bus.

 

[frostyllama]

@frostyllama - I'm looking at a similar plan as you - though for a portable off-grid system. I eventually want ~5-6kw of power - but often only need less than half that, so planning to go with (2) Multiplus 24v/3000kVa units that can allow me for modularity, and redundancy - combined when I need the power, and otherwise can be half the weight/size, or allow me to have 2 rigs out in different places at the same time.

I just ordered my first Multiplus (along with a SmartSolar MPPT, and still debating my configuration around BMV, smart shunt, Cerbo, Venus etc). I've already got ~5500kWh usable of LifeP04 battery.

Where in CA are you? I'm in Oakland.

Let me know how that portable pack goes. I played around with the idea of using a milwaukee packout as a battery box and storage for the inverters. Easier to wheel around and work on.

 

[OzSolar]

The Quattro is a 4kW inverter with a 5kW overload for 30 minutes and a 10kW overload for 20 seconds.

The Quattro has a 30W idle draw. That's another 0.72kWh/day if you didn't factor that into your audit. That's 10% of your capacity in those two days.

Maintaining redundancy with 2X 24V batteries is a good argument.

Assuming 5000w @ 25v I plug 200 amps into the BlueSeas Wizard and it spits out 2AWG (105C) cable. However the manual says 2 x 50mm2 cables which converts to 2 x 1AWG. I'm having a hard time tracking down the radical discrepancy. Can you please elaborate or point me towards a thread that might help me understand what I'm missing?

Thank you

 

[John Frum]

Assuming 5000w @ 25v I plug 200 amps into the BlueSeas Wizard and it spits out 4AWG (105C) cable. However the manual says 2 x 50mm2 cables which converts to 2 x 1AWG. I'm having a hard time tracking down the radical discrepancy. Can you please elaborate or point me towards a thread that might help me understand what I'm missing?

Thank you

5000 ac watts / .85 conversion factor / 24 volts low cutoff = 245 service amps
245 service amps / .8 fuse headroom = 306.37254902 fault amps.
That means 2/0 awg pure copper cable with insulation rated for 105C and a 300 amp fuse.
That is a minimum assuming that the cable runs are short enough that voltage drop is not an issue.

If Bluesea says its ok to run 200 amps over 4 awg cable then I think they are mistaken.

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

Victron wants big cables on their units probably because they have significant surge capacity.

 

[OzSolar]

5000 ac watts / .85 conversion factor / 24 volts low cutoff = 245 service amps
245 service amps / .8 fuse headroom = 306.37254902 fault amps.
That means 2/0 awg pure copper cable with insulation rated for 105C.
That is a minimum assuming that the cable runs are short enough that voltage drop is not an issue.

If Bluesea says its ok to run 200 amps over 4 awg cable then I think they are mistaken.

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

Victron wants big cables on their units probably because they have significant surge capacity.

Thank you smoothJoey. Yes very short cable runs, less than a meter for sure.

That 4AWG was a typo on my part left over from trying different scenarios to see if I could see what were the major deciding factors in the BlueSeas wizard. It actually spits out 2AWG which, of course, is still a long ways away from 2/0.

I've not seen "fuse headroom" mentioned before. What is that about? The adjustable low volt cut out on this Victron is ~20v (from memory) so that adds a few more amps. Yikes.

.

 

[John Frum]

I've not seen "fuse headroom" mentioned before. What is that about?

To size the wire we determine the max current for the circuit then we multiply by 1.25 so that we don't blow the fuse under normal operating conditions.
Multiplying by 1.25 is the same as dividing by .8.
The fuses job is to protect the wire and higher rated fuses have lower resistance so I fuse near the capacity of the wire.

The adjustable low volt cut out on this Victron is ~20v (from memory) so that adds a few more amps. Yikes.

Using LFP batteries you should not discharge with any significant amount of current to a point where any one cell nose dives into the low knee.
20 volts is dead empty and its likely the bms will disconnect before the inverter/charger does which is a "bad idea"TM.

 

[OzSolar]

To size the wire we determine the max current for the circuit then we multiply by 1.25 so that we don't blow the fuse under normal operating conditions.
Multiplying by 1.25 is the same as dividing by .8.
The fuses job is to protect the wire and higher rated fuses have lower resistance so I fuse near the capacity of the wire.

Using LFP batteries you should not discharge with any significant amount of current to a point where any one cell nose dives into the low knee.
20 volts is dead empty and its likely the bms will disconnect before the inverter/charger does which is a "bad idea"T

So you add 1.25 without any detailed analysis of the system or whether or not the loads are constant or intermittent?

I agree that voltage is a terrible way to attempt to determine the SOC of any battery chemistry. Since my first off grid system in 1992 I've always used shunts to count the AH in and out.

 

[John Frum]

So you add 1.25 without any detailed analysis of the system or whether or not the loads are constant or intermittent?

Not addition, multiply the max load by 1.25 or divide by .8.
I think I forgot to mention voltage drop.

I agree that voltage is a terrible way to attempt to determine the SOC of any battery chemistry.

I don't know who you are agreeing with.

Since my first off grid system in 1992 I've always used shunts to count the AH in and out.

I can see that you are very experienced and awesome.

 

[OzSolar]

Not addition, multiply the max load by 1.25 or divide by .8.
I think I forgot to mention voltage drop.

I don't know who you are agreeing with.

I can see that you are very experienced and awesome.

No, I'm not awesome at all. Just a person trying to learn. Thanks for turning my attempt to grow into a chance for you to make fun of me.