Inverter powered by 18650s issue?

[m157]

Items I have

Battery pack  Voltage Regulator  Inverter  Status screen  Wire  Charger for battery

So far have tested the whole setup as Battery > Voltage reg > Inverter, use it on a laptop that has no battery (60w) and it ran for ~2 hours

Also the inverter has a .5A drain

 

Is this a normal amount of runtime, or is there alot of leakage?

 

[kb5zue]

18 minutes ago, m157 said:

Items I have

Battery pack  Voltage Regulator  Inverter  Status screen  Wire  Charger for battery

So far have tested the whole setup as Battery > Voltage reg > Inverter, use it on a laptop that has no battery (60w) and it ran for ~2 hours

Also the inverter has a .5A drain

 

Is this a normal amount of runtime, or is there alot of leakage?

 

You don't say what size the battery is, what the output voltage is, etc.  Just looking at what you do have, I'm thinking it is a 12 volt DC battery connected to the voltage regulator to ensure that it is a clean 12 vdc, then connected to the inverter to change the 12vdc to 120vac.  I only say this because I have a very similar setup out in my diesel truck.  I direct connected my regulator to the batteries of the truck then mounted the inverter under the hood.  Ran leads into the cab of the truck from the inverter so now I have a continuous 120vac inside the cab for such things as the shop vac for cleaning out the truck and other things.  But from what you are saying, I wouldn't think the system that you are running would be much of a job but once again, that all depends on the specifics of the equipment used.  Your regulator won't really draw much current but I can't say the same for the inverter.  The status screen won't draw any current to speak of either.  As for  the wire, just make sure that you are using a gauge rated for the total current draw.  If the gauge wire is too small, it will possibly overheat and you definitely don't want that.

[m157]

2 minutes ago, kb5zue said:

You don't say what size the battery is, what the output voltage is, etc.  Just looking at what you do have, I'm thinking it is a 12 volt DC battery connected to the voltage regulator to ensure that it is a clean 12 vdc, then connected to the inverter to change the 12vdc to 120vac.  I only say this because I have a very similar setup out in my diesel truck.  I direct connected my regulator to the batteries of the truck then mounted the inverter under the hood.  Ran leads into the cab of the truck from the inverter so now I have a continuous 120vac inside the cab for such things as the shop vac for cleaning out the truck and other things.  But from what you are saying, I wouldn't think the system that you are running would be much of a job but once again, that all depends on the specifics of the equipment used.  Your regulator won't really draw much current but I can't say the same for the inverter.  The status screen won't draw any current to speak of either.  As for  the wire, just make sure that you are using a gauge rated for the total current draw.  If the gauge wire is too small, it will possibly overheat and you definitely don't want that.

The battery is 36v and the regulator is 36v to 12v 

[Hackentosher]

36v* 4.4Ah = 158.4Wh. So you can draw 158.4 Watts from the battery and kill it in an hour, or draw 1 Watt for 158.4 hours.  Divide that by 60w, and you get 2.64 hours. Sounds alright to me. 

 

You may end up getting a little less than that because the inverter may have some limit, the bms may cut off the battery a little higher, or the cells aren't what they used to be and they may not hold the full 4.4Ah.

[m157]

2 hours ago, Pangea2017 said:

If you have multiple multimeter messure the current and voltage at the battery and the same values after the inverter. This will give you the efficiency. Do the same messurement without anything conected to the output.

32->12->110V is less efficient then 32->110V

if you just want to power a notebook you can go 32->20-12V depending on the notebook model or just build the battery with the right voltage.

I dont trust doing straight to the laptop, its a different one than what we tested with, (20v at 9.2a, 180w) and dont want to fry anything

[Unimportant]

1 hour ago, m157 said:

I dont trust doing straight to the laptop, its a different one than what we tested with, (20v at 9.2a, 180w) and dont want to fry anything

I don't think he means connecting the battery straight to the laptop. I think he means  battery -> voltage regulator with correct output voltage for the laptop -> laptop, which would indeed be the most efficient, with only 1 conversion step instead of 3.

[maleko48]

get yourself a used Nissan Leaf module or two for some serious power.  

[DragonTamer1]

I'm sorry but this is really not an efficient way of doing it, or practical. You are bringing the voltage down to step it back up again to bring it down again. Each one of these changes will result in losses.

 

My suggestion would be ditch the inverter, and monitor if possible. Try and see if you can find a regulator that matches your laptops input voltage and feed right into that. This will be the most efficient way of transferring the power.

[mariushm]

The inverter is designed to accept a wide range of input voltage, from something like 10v all the way up to around 15v (because the alternator of your car charges a lead acid battery at around 13.8v or maybe more).

It's a bit silly to take your 36v battery and convert it down to 12v, because you'll lose a part of your energy in the dc-dc converter.

That DC-DC converter is up to 94% efficient at full load, that's 12v at 20A or around 200 watts. With just a laptop, that probably averages around 40-50 watts, the efficiency of that DC-DC converter will drop to maybe 90% or lower, so you're wasting "juice".

That inverter is designed for up to 750w (but it's most likely wishful thinking, probably up to 500w would be safe to use), so it will probably be most efficient at around 250-300w of power, when it produces just 40-50w of power for your laptop the efficiency will be quite poor. If it had around 85% efficiency at 200-300 watts, it's probably only around 65-70% efficient at 40-50w, so you're losing more power there. 

 

If your laptop adapter isn't one of those fancy ones with a 3rd pin in the DC jack (so laptop would detect what size of charger you plug for example), then you could simply buy a second adapter (or a compatible one), cut the power cable  and use a DC-DC converter to change that 36v to the lower value (18v or 16.5v or whatever).  Converting a higher voltage to a lower voltage is always more efficient than boosting and all that.

You can buy such high efficiency DC-DC converters from good online stores like Digikey for example see : http://goo.gl/iBsLM6 or https://goo.gl/5GY6ZF