DC to AC inverter

[john.b]

Hi, I've been running a small 1400w pressure washer off my system for a while now but last year the washer gave up so i bought a new one, the new one is a little bigger at 1700w, the inverter is a chinese 3000w with 6000w surge Modified sine wave but won't run the new washer, i was thinking i may need to up grade my system to a 24v and started to look into this when i found a few reviews on this 12v inverter

https://www.amazon.com/Reliable-Efficiency-Inverter-Converter-Display/dp/B0154C5F3A

So decided to give one a try, however it's the same and just won't start the pressure washer although it does try unlike the other one i have.

I'm i expecting to much from my 12v system or is there an answer to my problem ?

My battery bank is 430 AH and was 90% charged at the time of testing all leads are heavy although the leads that come with the inverter were on the thin side but there was two for each terminal.

Just in case it makes a difference i'm in the UK so it's 240v AC, the pressure washer gets used every day for around 20-25min, the washer is not plugged into the inverter direct it's through an extension cord approx 45ft

Any help would be great.

Thanks you
john

[bcroe]

There are IC engine powered washers. If your wiring is short, you might consider putting a big
(car starter class) DC motor to battery on the pressure washer. Bruce Roe

[Yet another Yeti]

Battery bank?

MODERATOR: He/She has been warned previously about running amok at the keyboard without any clue as to the accuracy of the output.

All postings by Yeti are suspect as to safety and accuracy.

Two or three 12 V , 115 Ah in parallel ?

Might be that there are some of your batteries not
being in good state .

Parallel tends to disguise the health of batteries , since voltages
are shown as average ( U₁ + U₂ + U₃ ) / 3 .

[john.b]

Battery bank?

Two or three 12 V , 115 Ah in parallel ?

Might be that there are some of your batteries not
being in good state .

Parallel tends to disguise the health of batteries , since voltages
are shown as average ( U₁ + U₂ + U₃ ) / 3 .

Hi, my bank is made up of three batteries in parallel, one 230ah and two 100ah, the 230 is new but the two 100s are old although they seem to be in good condition, i understand what your saying about the health being disguised and have been going to buy another 230ah the same so will give that a try.

Thanks you for your help
john

[jflorey2]

Parallel tends to disguise the health of batteries , since voltages
are shown as average ( U₁ + U₂ + U₃ ) / 3 .

Not really. It's more like U1=U2=U3. Parallel connection doesn't average voltages; it forces all voltages to be the same. On battery systems where voltage effectively sets charge level (like lithium chemistries) this means all cells paralleled are at approximately the same state of charge. On battery systems where charge current is required to complete a charge (like lead acid) they can drift apart in terms of SOC (not voltage.) Which is one reason paralleling lots of lead acid batteries is usually a bad idea.

[john.b]

Just a quick update, i bought a new 230ah battery but still no further forward the 1700w pressure washer just won't run, i tried the two 230ah batteries together and then all four but nothing, it has to have something to do with the start up surge as i can boil a 3000w kettle no problem, i guess my only answer is to drop back to a 1400w pressure washer.

[Sunking]

Just a quick update, i bought a new 230ah battery but still no further forward the 1700w pressure washer just won't run, .

So what is the problem? You have a 12 volt toy trying to do real work of a 2 hp engine. Not going to work. In order to run 1700 watt son 12 volts requires 150 amps. At 150 amps on a 12 volt battery requires a 1500 AH battery. It is doing exactly what you planned for it to do. FAIL. 12 volts should be no higher than 100 amps using wire the size of your wrist.

[john.b]

So what is the problem? You have a 12 volt toy trying to do real work of a 2 hp engine. Not going to work. In order to run 1700 watt son 12 volts requires 150 amps. At 150 amps on a 12 volt battery requires a 1500 AH battery. It is doing exactly what you planned for it to do. FAIL. 12 volts should be no higher than 100 amps using wire the size of your wrist.

Mmm i think somewhere in that lot we may have some kind of answer, 10 out of 10 for being a tool about it though.

[Mike90250]

Mmm i think somewhere in that lot we may have some kind of answer, 10 out of 10 for being a tool about it though.

Sunking is the best tool around for a neophyte, he cuts right to the end, and gives the news straight up. Sadly, it's nearly always bad, but most importantly he's nearly always right.

In your case, the batteries are not able to supply the power (their voltage sags under heavy load) and the inverter screams about low voltage.
Larger (thicker) cables could help

1700 running watts needs at least 3x that for the starting surge. 5100watts
at 12V that's going to be
141a and 425a

Additionally, a mod sine inverter will cause a motor to consume at least 20% more power, so your starting surge just went to 510A

So you need to select cable that can carry 500A without causing much voltage drop. Keep cables short, and connections snug (don't strip a bolt getting things too tight)

[Sunking]

Mmm i think somewhere in that lot we may have some kind of answer, 10 out of 10 for being a tool about it though.

Nothing like an Attitude Adjust Upside the Head with a 2 x 4. Cuts right to the chase and gets the point across with no misunderstanding.

John plain and simple, your system cannot do what you want it to do. At least not for long. You are well beyond 12 volt toy territory. Why do you thing EV's and utilities use high voltage instead of 12 volt toys?

[john.b]

Mike and Sunking, thank you both for getting back, all your points are understood and very welcome thank you, i had a feeling i was pushing my 12v system to hard which is why i asked this in my original post, don't get me wrong i'd rather someone was straight with me than blow smoke up my backside, my problem is you see so many people with a bad attitude these days and it grinds me down as it can put people off wanting to do things right, i know i don't need to tell you that this subject is and can be very dangerous so the way i look at it is if someone walks away from advice because of the attitude it could end very bad for them, however in the future i will try to be a little more thick skinned.

Can i ask if upgrading my system to 24v would work or is this still pushing things ?

Take care
john

[Mike90250]

adding more batteries and moving to 24v would work. Simply reconnfiguring the existing batteries to 24v won't help, they will still be asked to do the same amount of work

The mod sine inverter is part of the problem, you could reduce your power draw by 20% by changing to a pure sine inverter

[john.b]

adding more batteries and moving to 24v would work. Simply reconnfiguring the existing batteries to 24v won't help, they will still be asked to do the same amount of work

The mod sine inverter is part of the problem, you could reduce your power draw by 20% by changing to a pure sine inverter

Thanks Mike, i'll think that all over and go from there, to be honest i'm starting to think it may be getting a little to much just to be able to run this washer for the amount it gets used and the overall cost is going to be greater than what it's worth.

Take care
john