Overload inverter bypass.

[daromer]

Average joe uses it as inverter ONLY. No grid hooked up since thats not possible to control.

And I agree. UPS is either a UPS or standalone dumb inverter

[OffGridInTheCity]

I have used APC UPSs for the last 15yrs. In one case I tried to use a APC UPS 1500 for a large HP printer - and it would overload everytime the printer 'fired up'. After (maybe) 50 overloads it blew the APC. Based on this, I wouldn't design a system that had regular/ongoing overloads.

I love APC UPSs - I have 2 of the 3000 models with my own 7p7s 18650 battery packs in them. I use them to smooth the twice daily Inverter On/Off +automatic-transfer-switch cycles of my off-grid system. Their output wired to subpanels to parallel 120v plugs thru the house to various electronics (computers, TV, even the K-Cup coffee maker because it has a clock/auto-turn-on) and as mentioned, they have internet cards where they can monitored/managed at a central computer area.

One of the downsides is that they burn 40watts/hr, 24/7, just turned on sitting there. In my case, with 2 of them, that's 1.920kwh per 24hr day - or about 5% 'loss' of my PV power per day in summer - so not very efficient.

[daromer]

40w is nothing... Mpp is 60-80w per phase... So for me thats 240w Idle Lost hehe

[dragonfly]

Well I now have my hand on the UPS, its an APC SUA2200 (230v model) off approx 2005 vintage, so no LCD screen, just a few LEDs on the front.

I've pulled the batteries, and diagnosed that one of the 4 batteries, is bulged, and self discharging. So technically I could fix it for about £40 but that would only give me approx 2-3hrs runtime on my anticipated load. However I i replace the batteries with 4x 100ah batteries, I should get nearer the 24hrs I'm looking for ideally. Next issue is according to the manual the originally batteries were recharged in 4hrs, so I guess this would be also like 24hrs to recharge with the new batteries. I need to get this down to a maximum of 6hrs (i.e. well within the overnight cheap electric). I haven't looked up whether the batteries are wired at 24v or 48v yet, but I know they are in 24v packs. So to charge a 100ah battery pack, that is 50% discharged, to full in 6hrs, will take atleast a 20a battery charger (preferably multi stage), either 1 x 48v or 2 x 24v depending on the wiring. Can these be run in tandem with the APC charger or will they interfere with each other?

[OffGridInTheCity]

Well I now have my hand on the UPS, its an APC SUA2200 (230v model) off approx 2005 vintage, so no LCD screen, just a few LEDs on the front.

I've pulled the batteries, and diagnosed that one of the 4 batteries, is bulged, and self discharging. So technically I could fix it for about £40 but that would only give me approx 2-3hrs runtime on my anticipated load. However I i replace the batteries with 4x 100ah batteries, I should get nearer the 24hrs I'm looking for ideally. Next issue is according to the manual the originally batteries were recharged in 4hrs, so I guess this would be also like 24hrs to recharge with the new batteries. I need to get this down to a maximum of 6hrs (i.e. well within the overnight cheap electric). I haven't looked up whether the batteries are wired at 24v or 48v yet, but I know they are in 24v packs. So to charge a 100ah battery pack, that is 50% discharged, to full in 6hrs, will take atleast a 20a battery charger (preferably multi stage), either 1 x 48v or 2 x 24v depending on the wiring. Can these be run in tandem with the APC charger or will they interfere with each other?

You can charge the batteries from more than 1 source.   The additional sources can be grid -> dc or solar etc.   But you don't want to overcharge or the APC will sound alarm - so you need to find a compatible charging system.      I'm not up on all the options but for example a cheap mpt-7210a  (like this https://www.amazon.com/dp/B01HCL7LEW/ ) is settable so you can choose a good output (max) charging voltage and can do up to ~ 10a @ 24v...   maybe 2 of them to get you to 20a.   You can power it from a 120v -> DC powersupply (grid) or from solar panels.

[dragonfly]

Thanks, I think whatever I use, has to be cheap, if charging costs much more than £100, then I might as well bite the bullet and just get an mpp inverter, I probably only need something like 300w output, and they do something like PIP1012MSE for under 200USD just they take your eyes out with the postage on top.

[OffGridInTheCity]

Thanks, I think whatever I use, has to be cheap, if charging costs much more than £100, then I might as well bite the bullet and just get an mpp inverter, I probably only need something like 300w output, and they do something like PIP1012MSE for under 200USD just they take your eyes out with the postage on top.

The mpt-7210a are cheap and are a buck boost - e.g. dc input can be lower than battery charging output voltage (unlike most charge controllers) - and fully customize-able/settable.    
There are a many youtubes on setup/operation - so you can see before you buy.   Some downsides are the fan is noisy/cheap and they are not MPPT  (not as efficient when hooked to a solar PV input).

I use one in my custom yeti - and it works great on both Renology Solar Panels and a constant DC power supply... so my yeti can power up from sun or 120v plug!