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-   -   Generator charging upgrade??? (https://www.irv2.com/forums/f104/generator-charging-upgrade-522636.html)

paul65k 01-25-2021 10:14 AM

Generator charging upgrade???
 
So the question is.............. Would you spend $~750 if you could charge your batteries twice as fast with your generator?

Note: While I have a 24V system I'll use 12V numbers as most have a better point of reference on 12V systems

My current set-up with dual Victron Inverter/chargers will charge my Lithium battery bank at up to 280A (2X140A for each inverter/charger) if I am feeding the inverters with split-phase power (120/240V), for instance, 50A shore power.

Each charging leg uses about 20A to run each charger but if I use the on-board 7500W generator it is only capable of 120V output even though it can deliver as much as 62A it is limited to only one inverter charging as it is not delivering this power in "Split-Phase".

The solution seems to be to use an autotransformer to change the generator output to "Split-Phase (120/240) which will allow both chargers to be in service while using the generator..... a full charge as currently configured can take up to 3 hours, with the autotransformer this is down to 1.5 hours!

My data shows that our cost of generator power is ~$2 per hour all in so the payback is 400 hours and might not make financial sense but the value of not hearing that generator run any longer than necessary is to me...................... Priceless

What do you all think???

Old Scout 01-25-2021 10:50 AM

Not sure I follow--what does phased vs non-phased 120v legs [2] on genset have to do with running separate chargers--you don't need split-phase to run two A/Cs on genset?..I think most of us only have one charger and no Li bats [smile]. So for me, since we don't do a lot of dry camping--its hard to have an opinion....but I do admire your solar/bat set-up.....its top shelf!
Ps--I was pretty happy with my solar upgrade to 600 watts before going to Q-site this year....ran my genset 1 or 2 hours in the morning and maybe 1 hour at night....had between 83-86% SOC [as read on my new Victron battery monitor]on my six 12v L/A bats [some TV, a bit of propane furnace heat and a resid-fridge].....lots of sun shine this year so 600 watts fully recovered bats by early afternoon and kept them at 100% for rest of the day.

paul65k 01-25-2021 12:08 PM

Quote:

Originally Posted by Old Scout (Post 5609540)
Not sure I follow--what does phased vs non-phased 120v legs [2] on genset have to do with running separate chargers--you don't need split-phase to run two A/Cs on genset?..I think most of us only have one charger and no Li bats [smile]. So for me, since we don't do a lot of dry camping--its hard to have an opinion....but I do admire your solar/bat set-up.....its top shelf!
Ps--I was pretty happy with my solar upgrade to 600 watts before going to Q-site this year....ran my genset 1 or 2 hours in the morning and maybe 1 hour at night....had between 83-86% SOC [as read on my new Victron battery monitor]on my six 12v L/A bats [some TV, a bit of propane furnace heat and a resid-fridge].....lots of sunshine this year so 600 watts fully recovered bats by early afternoon and kept them at 100% for rest of the day.

Very cool....happy that is working out for you!!

In our case, the 2 inverter/chargers that we now have installed are set-up in split-phase (120/240) which requires the power in to be 180* out of phase just like a 50A shore power cord will do. this is our case as we plan to upgrade the rooftop AC to a mini-split with 2 zones, which require a 120/240 connection just like at home and we can now do this.

When the generator was installed at the factory it was set-up to feed both sides of the 50A panel but there was no need for split-phase or "220" as none of the circuits needed the split-phase wiring. In our case, we still get good charging from the generator but it could actually be DOUBLE for $~750.....This is the dilemma:angel:

Brianna 02-04-2021 03:13 AM

Paul,
Sounds like a solution looking for a problem, in my opinion.
Imagine how much wine/beer you could buy for $750.

��

paul65k 02-04-2021 03:36 PM

Quote:

Originally Posted by Brianna (Post 5622440)
Paul,
Sounds like a solution looking for a problem, in my opinion.
Imagine how much wine/beer you could buy for $750.

��

I think of it a little more like the guy who just spent $15K on a new more powerful engine for his hot rod and his transmission won't let him take it out of 3rd gear ;)........for $700 more he can now use 4th, 5th, and 6th gear and get the full potential out of that new motor...... Right?? :cool:

Freqz 02-04-2021 03:44 PM

Sure. Itís only money, right? Not listening to the genset drone on for an extra hour/day has to be worth something, right?

Added benefit is running your 240V loads off 30, 20, or 15A shore power with less stress on the batteries.

paul65k 02-04-2021 08:20 PM

Quote:

Originally Posted by Freqz (Post 5623269)
Sure. It’s only money, right? Not listening to the genset drone on for an extra hour/day has to be worth something, right?

Added benefit is running your 240V loads off 30, 20, or 15A shore power with less stress on the batteries.

Actually The system will already run 240V loads from the existing inverters on batteries alone or with any of the 30/20/15A inputs including the generator input as the dual inverters are set-up as split-phase......the Autotransformer will allow the generator to drive both chargers vs just one when charging the batteries from the generator:D

Freqz 02-04-2021 09:02 PM

Quote:

Originally Posted by paul65k (Post 5623635)
Actually The system will already run 240V loads from the existing inverters on batteries alone or with any of the 30/20/15A inputs including the generator input as the dual inverters are set-up as split-phase......the Autotransformer will allow the generator to drive both chargers vs just one when charging the batteries from the generator:D


Yes, but the second inverter is 100% battery powered right now in that scenario, no? The auto transformer would allow you to run both on AC with zero DC draw which is *small* benefitó saves losses on AC-DC-AC conversion (negligible, probably) and micro cycles on the batteries. :). Batteries are expensive enough that treating them with baby gloves is a plus, IMO.

But really, dumping 2X the current into the batteries from the gen is worth $700 or so in my world.

paul65k 02-04-2021 09:10 PM

Quote:

Originally Posted by Freqz (Post 5623673)
Yes, but the second inverter is 100% battery powered right now in that scenario, no? The auto transformer would allow you to run both on AC with zero DC draw which is *small* benefit— saves losses on AC-DC-AC conversion (negligible, probably) and micro cycles on the batteries. :). Batteries are expensive enough that treating them with baby gloves is a plus, IMO.

But really, dumping 2X the current into the batteries from the gen is worth $700 or so in my world.

I agree, you're absolutely correct!......I'm still trying to figure out how to wire it in so that it will convert both the generator and 120V shore power without needing 2 of them:confused:

Freqz 02-05-2021 06:33 AM

Generator charging upgrade???
 
1 Attachment(s)
Quote:

Originally Posted by paul65k (Post 5623678)
I agree, you're absolutely correct!......I'm still trying to figure out how to wire it in so that it will convert both the generator and 120V shore power without needing 2 of them:confused:


Transfer switch...

Iíve been (very roughly) sorting this out for my FW build.

Attachment 317126

Brianna 02-05-2021 08:08 AM

I hope, some day to get a tour of the paul65k coach.
Everything written about it is so beyond, beyond, amazing.

paul65k 02-05-2021 10:07 AM

Quote:

Originally Posted by Freqz (Post 5623935)
Transfer switch...

Iíve been (very roughly) sorting this out for my FW build.

Attachment 317126

Thank you I'm still trying to figure out the way to wire after the transfer switch to the inverter(s).....dual Multiplus 3000s in my case.

Why would you need the AT on the output side of the Quattro......doesn't it already have 240V output capability?

If not you could use dual multiplus 3000s (about the same price as a single Quattro) and set them up for split-phase output, which would actually give you a bit more overall wattage???:confused:

paul65k 02-05-2021 10:08 AM

Quote:

Originally Posted by Brianna (Post 5624053)
I hope, some day to get a tour of the paul65k coach.
Everything written about it is so beyond, beyond, amazing.

Thanks but, she's just an "Old Beater"....but we love her:cool:

Freqz 02-05-2021 11:31 AM

Quote:

Originally Posted by paul65k (Post 5624255)
Thank you I'm still trying to figure out the way to wire after the transfer switch to the inverter(s).....dual Multiplus 3000s in my case.

Why would you need the AT on the output side of the Quattro......doesn't it already have 240V output capability?

If not you could use dual multiplus 3000s (about the same price as a single Quattro) and set them up for split-phase output, which would actually give you a bit more overall wattage???:confused:


It my case, it would be a 240V inverter so you need the auto transformer to provide split phase 120V. (I donít necessarily need split phase but I do need a neutral)

Iím building this around a 8k Quattro to support a mini split and induction cooktopó 6kVA seems a little light for my use. Your way gets more charging current and cost a bit less. Several ways to skin this particular cat!


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