My goal is to run my desktop PC during loadshedding (essentially a DIY UPS)

I measured 300-400W load running various software

 

Could I get some advice on the below config?

battery (1.5 kWh) - https://www.sustainable.co.za/collections/lithium-batteries/products/hubble-s120-120ah-1-5kwh-12v-lithium-battery

Inverter / Charger (1000W) - https://www.sustainable.co.za/collections/hybrid-inverters/products/rct-axpert-vm1-1k12-1kva-1kw-12v-hybrid-inverter

 

Is this inverter/charger compatible with the chosen battery?

Is this inverter/charger overkill for my goal? should I rather get an inverter and separate charger?

Can I, in the future, drop in a second S120 battery in parallel to get 3kWh with this inverter?

 

This UPS seems to be a cheaper option: https://www.geewiz.co.za/mecer-inverters/104647-mecer-1200va-720w-inverter-battery-charger-ups-intelligent-fan.html

 

 

Appreciate any advice.

The mecer inverter would be fine if you just want a backup for your PC. It is very popular and works fine with the hubble battery.

It's also probably quieter than the Axpert. The fan noise can be an issue.

Have a look for the mecer inverter thread on mybroadband, it's discussed in detail.

If you want to expand the system later, or connect to a DB, or connect solar, then the Axpert would be a better option.

So I on the other hand tend to prefer the Axperts, but I repair and work with them daily...

At the end of the day, the Hubble batteries are good and will work fine as long as you setup the charge voltages etc. In the settings, set the battery type to user defined and you will then be able to setup the float, bulk and cutoff specifications. You can then later on just add another battery in parallel to get double the capacity, the built-in BMS should take care of the rest like battery balancing etc.

Otherwise, overkill is a subjective thing. So if you plan on using a maximum of 500W, a 1kW should be fine. Once you exceed 50% of your inverter capacity your efficiency drops through the ground, so staying under the 50% is the best way to make sure you're getting the most out of your system. However, at that price you could probably find a VM II 2,5kW from MCE Electric.

On 2022/10/26 at 11:55 AM, Brendonvdh said:

The mecer inverter would be fine if you just want a backup for your PC. It is very popular and works fine with the hubble battery.

It's also probably quieter than the Axpert. The fan noise can be an issue.

Have a look for the mecer inverter thread on mybroadband, it's discussed in detail.

If you want to expand the system later, or connect to a DB, or connect solar, then the Axpert would be a better option.

Thanks,

Not too stressed about noise since I always wear headphones when my PC is on

One thing I see about these Mecer inverters are that they are modified sine wave which might damage my PC over time? 

 

On 2022/10/26 at 12:13 PM, Psy said:

So I on the other hand tend to prefer the Axperts, but I repair and work with them daily...

At the end of the day, the Hubble batteries are good and will work fine as long as you setup the charge voltages etc. In the settings, set the battery type to user defined and you will then be able to setup the float, bulk and cutoff specifications. You can then later on just add another battery in parallel to get double the capacity, the built-in BMS should take care of the rest like battery balancing etc.

Otherwise, overkill is a subjective thing. So if you plan on using a maximum of 500W, a 1kW should be fine. Once you exceed 50% of your inverter capacity your efficiency drops through the ground, so staying under the 50% is the best way to make sure you're getting the most out of your system. However, at that price you could probably find a VM II 2,5kW from MCE Electric.

Thanks solid advice I didn't know about the efficiency drop-off with inverters.

Could you advise which cable type/thickness I need to use to connect the S-120 to the VM1 Axpert?

Since you work with these are you able to say if the charging settings can be configured to match the S-120? and can you set charge/discharge limits at 10% -> 90% to extend the overall lifespan?

Edited October 27, 20223 yr by jeddles

50 minutes ago, jeddles said:

Could you advise which cable type/thickness I need to use to connect the S-120 to the VM1 Axpert?

Ok there are 2 factors that come into play with cable:

1. The longer the cable the thicker it needs to be to reduce losses

2. Thin multi-strand cable (Like welding cable) works much better than a cable with fewer thicker strands (Like house cable)

If you are looking to run like a meter of cable, I usually recommend 35mm welding cable. Your losses are minimal and the cable is designed for higher current uses. You could look into like 50mm cable if you want it longer but it'll be overkill and you'll struggle to get it into the VM DC connections.

50 minutes ago, jeddles said:

Since you work with these are you able to say if the charging settings can be configured to match the S-120? and can you set charge/discharge limits at 10% -> 90% to extend the overall lifespan?

So I haven't played with a VM I since I found the VM II at a cheaper price. However, the setting should be more or less the same across the range.

Setting 2: charging current (The 40A default is usually fine but you can go higher if charges take too long)

Setting 5: Battery Type (Please use "User-defined", just trust me.)

Then, make sure that 26, 27 and 29 are set accordingly to your batteries specifications. Se the cutoff voltage to 11V, it will help keep the battery healthy where the default is 10,5V which isn't too great for these Hubble's. Just make sure that you stay under the 14,4V limit of your battery, you can read more about the limits in the Hubble spec sheet (https://cdn.shopify.com/s/files/1/0601/7623/6737/files/hubble_lithium_s-120_sus_edit.pdf?v=1646310826).

 

At the end of they day, my best advice is to take a moment to go through the inverter manual. I know it can be a tough read sometimes but 99% of the info you need for these things can be found in there, I'm here to help if any of it confuses you or if you have a question that falls into that 1% that isn't in the manual xD

Edited October 27, 20223 yr by Psy

53 minutes ago, jeddles said:

One thing I see about these Mecer inverters are that they are modified sine wave which might damage my PC over time? 

Yes and no, modified waves are a little debated... it very much depends on how the inverter is generating the wave. Look I have a modified sine wave inverter just to run my TV and WIFI, those haven't been blown by the modified nature of the inverter but my LED light was completely fried...

A PC can run on DC, since the first thing it does is rectify the incoming AC. Some (older/cheaper) power supplies with power factor correction don't like the modified sine . Since most UPSs designed for PCs are modified sine, you have a very good chance of it being fine.