Author Options:

Can I power a large inverter with many of those external solar batteries for phones? Answered

I'm looking for cheap solar + batteries to run the air conditioning and other electronics on a boat. If i order those external 4600mah solar battery packs that are meant to power your phone while hiking, I can get them for fairly cheap from China. 

I'm looking at an inverter online that outputs 1000w, it takes 12v input. Assuming standard usb output of 1.5 volts, does this mean i wire 8 in series as a set which would draw 100amps/hour, so for each 8 battery set it would last ~150 minutes(1.5A output per battery, 4.6amps capacity) at load?

How feasible is this as a long term solution (multiple charges and discharges)?

4 Replies

mpilchfamily (author)2014-02-01

The batteries don't output 1.5A. What you are looking at is a rating of power for the batteries. It's not 1.5A it's 1.5Ah (amp hours). Meaning the batteries will last about 20 hours under a 1.5A load. The inverter will be drawing way more than 1.5A to produce 1000W AC. At 120VAC the inverter can handle up to 8A output. The Inverter needs a lot more amperage from the batteries than 8A to boost the 12VDC input up to 120VAC. Well more amperage than those little cell phone chargers can safely offer. They may only last a couple of minutes tops. Assuming they don't overheat due to the current draw and blow up on you.

Use the Boat's batteries and let the engines charge them. Assuming the boat has a bank of batteries. If it doesn't you'll want more than 2 wired in parallel to offer anough power to the inverter to last a good amount of time. If you can't run the engine enough to keep the batteries charged than you'll need to invest in a set of solar panels that can supply more than enough power on there own to keep the inverter running. This way you have power overnight from the battery banks and there is enough extra power coming from the panels during the day that they can charge the batteries while running the inverter. You'll need several full sized roof top panels for this and a good place to mount them.

Select as Best AnswerUndo Best Answer

tsukasa1105 (author)mpilchfamily2014-02-02

They are rated at 4600mah = 4.6amp hours. They discharge (charge a phone) via usb, which protocol maxes out at 1.5amps. Not sure where you got the 20 number from, I could be wrong here but drawing 1.5amps from 4.6 amp hours should be 3 hours per batter right?

I can wire as many batteries in series or in parallel as is necessary, i'm just trying to get my head around the math to see what makes sense. I know Google uses the strategy of a whole bunch of common but shitty servers being more economical than buying enterprise servers, I am trying to determine if the same is true with batteries.

Select as Best AnswerUndo Best Answer


i have those chinese power banks with and without solar cells mounted on them. i have to tell you that their circuit is delicate and cant handle more than a few amps(barely enough to charge tablets and phones. solar panel itself is not enough to recharge these things but helps battery topped if you leave them for a long time next to your window.

1000w inverter means 1000/120V=8.3A or 1000w/230V=4.3A output. you will need 1000w/12V=83A input but since nothing is 100% efficient... lets say you will need to draw 90-100A from battery on max load. you are right on amps/hour but USB isn't 1.5V, usb standard uses 5VDC. that 1.5 means max current you can draw from that port. it means you can charge phones up to 1.5A on that port but a tablet will probably heat or blow up the circuit. if you connect these power banks in and out in series you will only burn them because parts inside are these things usually not rated over 16V(capacitors for example) and no way they can handle 5amps, let alone 100 amps..

however you can take out the batteries and wire them in series but you cant recharge them with their small circuits anymore... they are all 3.7V li-ion or li-po batteries (4.2topped, 3V flat), seldom uses ni-mh. still you need 150 of them, to draw 2A from each 50 in parallel for 100amps 3 in serial for 12.6-9V or 200 of them for 16.8-12V. you may want to draw 3A(100-132 of them) but they tend to heat up.... in the other hand wires would be mess.
that is why it wont work.

you can build a pretty neat solar system with cheap PWM charger and lead-acid batteries two 70amps car batteries in parallel would run for about 70-80 minutes at best and max load.

Select as Best AnswerUndo Best Answer

iceng (author)2014-02-01