Basic Testing of a 3000W 24V Inverter

[OnGrid]

I found a used Reliable 3000W converter that I might be purchasing and I want to test it.

I have two flooded 12V Starting 1000CCA batteries on my boat that I want to put in series for the test. I think they are about 80Ah.

My question is can I just connect them in series and turn on inverter and test a load? Do the batteries need to be connected in series for 24 hours first?

I just want to verify the inverter works and put a load on it for about 15 minutes or so.

 

[Samsonite801]

My question is can I just connect them in series and turn on inverter and test a load? Do the batteries need to be connected in series for 24 hours first?

Yeah, just connect the batteries in series, and turn it on for your test. Some people temporarily use a resistor in series between to let the capacitors in the inverter charge up at a slower rate for a few seconds, then plug the cable all the way on once the current has equalized...

I never really worry too much about the spark anymore. I look at that as a good test, if they make an inverter that could blow something when you touch the battery cable on it, then maybe it's not very well built to withstand it, since it is known that most users will just connect the battery right up in order to run the inverter, so usually these days I just plug it in and watch the spark and think how cool it looks, and then move on with my day.

If I happen to have a resistor or a test light around, I might use it to charge the caps (used to do it all the time with car audio amps or 12v capacitors in car audio back in the day), it has always been controversial on whether it matters or not, it's up to you.

I might use the resistor to charge the caps on a customer install, or on someone else's inverter to be safer against any liability of potential failure, but it doesn't really matter to me as much on my own equipment...

 

[MichaelK]

How will the batteries stay charged? If you are putting a load on them to test the inverter, what happens to the batteries after you finish your testing?

I suppose you can select items to power on a sliding log-linear scale, that is alternatively plug in something that needs 10W, 20W, 50W, 100W, 200W, 500W, ect. and see how high you can go. You are not likely to power anything close to 3000W with such a small battery for any length of time. Keep in mind that the inverter all by itself will be consuming some of the power just by being turned on.

Assume that the battery is going to be drained fast, and starting batteries don't like sitting drained long. How will you get those batteries recharged after testing is concluded.

 

[DThames]

Not the test that "you" want but do this test also. Turn it on with no load except a light. Try an LED light and also an incandescent light. I have one similar to what you describe and it causes lighting to flicker until it is loaded up to about 1/3 of its full rating. Not good for house lighting at all.

You might need to do a short test, recharge, and then test again. If you only have 80ah battery, don't expect to load it much before you trip under voltage on the inverter. Anything more than about 1000w and you might see the battery drop off pretty quickly.

 

[OnGrid]

How will the batteries stay charged? If you are putting a load on them to test the inverter, what happens to the batteries after you finish your testing?

I suppose you can select items to power on a sliding log-linear scale, that is alternatively plug in something that needs 10W, 20W, 50W, 100W, 200W, 500W, ect. and see how high you can go. You are not likely to power anything close to 3000W with such a small battery for any length of time. Keep in mind that the inverter all by itself will be consuming some of the power just by being turned on.

Assume that the battery is going to be drained fast, and starting batteries don't like sitting drained long. How will you get those batteries recharged after testing is concluded.

It amazes me on this forum, that so many people don't answer the question. It's just for a test. I'm not worried how the batteries will stay charged.

 

[OnGrid]

Not the test that "you" want but do this test also. Turn it on with no load except a light. Try an LED light and also an incandescent light. I have one similar to what you describe and it causes lighting to flicker until it is loaded up to about 1/3 of its full rating. Not good for house lighting at all.

You might need to do a short test, recharge, and then test again. If you only have 80ah battery, don't expect to load it much before you trip under voltage on the inverter. Anything more than about 1000w and you might see the battery drop off pretty quickly.

Thanks

 

[MichaelK]

It amazes me on this forum, that so many people don't answer the question. It's just for a test. I'm not worried how the batteries will stay charged.

It appeared to me that Samsonite adequately answered your original question. I didn't see the need to regurgitate a second answer. My concern though that lead-acid batteries are quickly ruined when left in an uncharged state.

Don't worry though, from this point forward, I won't show any concern whatsoever for your success or well-being.

 

[12VoltInstalls]

never really worry too much about the spark anymore. I look at that as a good test

It’s not. The spark reshapes the terminals at the arc making for a possible poor connection. It’s just too easy to precharge rather that zap it.
Can also displace metal which is a potential hazard, too.

 

[Samsonite801]

It’s not. The spark reshapes the terminals at the arc making for a possible poor connection. It’s just too easy to precharge rather that zap it.
Can also displace metal which is a potential hazard, too.

Like I said, it is controversial topic, if I have a resistor with me I probably use it if possible, but for example I carry around a 1000w inverter in my truck I connect with alligator clips to my main truck battery sometimes to run a tool or something, I don't worry about the spark as I just don't have time to fuss with it.

On my Prius, I have an APC SURT6000XLT UPS in the trunk, I always unplug the 215 VDC input cable (at the Anderson connector input on inverter) which feeds it from the car hybrid battery whenever I'm not using it, then later when I need to use it for gen power, I just plug it back in, and then cold-start the UPS, it isn't really feasible to put a resistor in there first, it is a Anderson connector, I just plug it in and go, been doing that for a couple years now and the inverter still works fine.



People are certainly free to adopt whatever strategy they like, I do opt more for safety when I'm dealing with other people's equipment, but for my own stuff, I really don't care, I have bigger fish to fry, if it blows I'll just go buy another one, not too worried... So far I haven't had a problem with anything getting damaged... I haven't noticed any reshaping of terminals on my stuff, it's not a lot of amperage to melt anything (like a welder would be or anything)...