Inverter low Volt Signal

Submitted: Sunday, Feb 04, 2007 at 21:21
ThreadID: 41982 Views:1775 Replies:7 FollowUps:10
This Thread has been Archived
Hi all
I purchased a 1500w inverter.
I have recently installed it into my car (mid January) and now get a low voltage warning signal at 12.7(sometimes even on 12.9) Volts.
These voltage's are confirmed by my circuit breaker and volt gauge that the fridge is connected to.
The unit is wired directly to my Deep cycle 100amp battery (6mths old) via top quality 2G battery cables with top quality brass connectors both ends(to reduce the possibility of voltage drop). these cables are approx 3m long and allow the inverter to be installed in the rear of my car.

I cannot run ANYTHING from it, due to this problem. I occurs directly after I turn it on and the fan stops.The signal is a beep beep beep continuously until I turn it off, and before I plug anything into it. I cannot use this inverter at all due to this. Any idea what the problem is????

Thanks in advance, as I will be away from my Puter until tomorrow.

On Patrol

Ps: looked at other treads but nothing seems to match my prob.
Back Expand Un-Read 0 Moderator

Reply By: Member - jeff M (SA) - Sunday, Feb 04, 2007 at 22:34

Sunday, Feb 04, 2007 at 22:34
Hello On Patrol ,

I posted the same type of problem a week or so back. As yet I have no answers.
I had been using this inverter for about 6 months on the boat just to run a TV and video for my daughter and one weekend it decided to pack it in.It worked fine the last time we used it,never went out on overload or anything like that now the low voltage light come on as soon as it's switched on.?

The inverter I was using is about 15 years old I would say, it has no fan and weighs about as much as a car battery.So I will try and get someone to look at it soon.Hope it can be fixed because it's on loan from work.

Cheers Jeff M.(SA)
AnswerID: 219775

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 16:25

Monday, Feb 05, 2007 at 16:25
Hey Jeff, are you watching this unfold mate???
FollowupID: 480497

Follow Up By: Member - jeff M (SA) - Monday, Feb 05, 2007 at 22:31

Monday, Feb 05, 2007 at 22:31
Yeh Colin
Watching but nothing new as yet.
I have tried most of the suggestions I reckon, no change.
Mine is a sealed type but pop rivets no screws, so I'll get to them with a drill and take a look inside with the sparky from work tomorrow and will let you know if it was fixable.

Regards Jeff M (SA)
FollowupID: 480609

Reply By: Derek from Affordable Batteries & Radiators - Monday, Feb 05, 2007 at 00:20

Monday, Feb 05, 2007 at 00:20
Hi O.P.

If you back probe the 12V IN on the actual inverter what is the voltage and what does the voltage do as you switch it on ?

What breaker / fuse are you using and have you tried to bypass it to do a quick test ?


AnswerID: 219798

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 09:27

Monday, Feb 05, 2007 at 09:27
Gday Derek

The circuit breaker is on a seperate wiring to the inverter, I just used that guage to compare voltage in the system. As for the fuse, it is inbuilt in the inverter.

The inverter has a digital readout of 12.7-12.9 showing before and after switching on.

I am getting a similar reading at the battery and the input cables, via a multimeter, with just a 0.5 variation at "switch on" of inverter.

Thanks, Colin.
FollowupID: 480409

Reply By: techo2oz - Monday, Feb 05, 2007 at 07:11

Monday, Feb 05, 2007 at 07:11
First test would be to measure the voltage at the inverter end. If it matches that of the battery end, and the connections to the inverter are clean and tight then I would suspect a faulty inverter.

If the voltage under load is less than what you see at the battery end, then I would suspect your circuit breaker has gone high resistance or you have a bad connection somewhere back towards the battery.

It is of course important to measure under load, ie when the inverter is trying to start up. This could also indicate a weak cell internally in the battery. (good volt readings until the load of the inverter kicks in, then it will momentarily drop below the cut-out threshold which then drops off the load.

AnswerID: 219805

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 09:28

Monday, Feb 05, 2007 at 09:28
see my reply above.
Thank You
FollowupID: 480410

Reply By: Robin - Monday, Feb 05, 2007 at 09:44

Monday, Feb 05, 2007 at 09:44
Hi On Patrol

There is also a less likely type of issue that can cause units like this to fail when run from long leads that is not related to volts drop.

A test I would do would be to run it off a seperate battery and cables and see that it works.

I have a 1500w ebay unit and it will work very well off a small 18AH gell cell using much thinner 8G cable , or course it won't put out full power like this but this should give you an indication that under normal circumstances it should work in a very uncritical installation.

What brand is yours ?

Robin Miller
AnswerID: 219824

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 16:22

Monday, Feb 05, 2007 at 16:22
Same as yours Robin, it was your post that made me decide on that unit. All the best advice I had was that I should run as good a cable as possible for such draw, hence 2g cable, the inverter is mounted on my cargo barrier for many reasons (high up away from water ingress, out of sight from prying eyes, ease of access etc..)

So Robin, what is the other possible issue?????
FollowupID: 480494

Follow Up By: Robin - Monday, Feb 05, 2007 at 19:39

Monday, Feb 05, 2007 at 19:39
Hi Colin

The other outside possibility , other than faulty unit is lead inductance.

I have just checked mine and simulated low volts by running it off 2 thin wires of 2mm copper each 3m long, and plugging in a 150w lamp as a load.

My unit ran without issue at 11.4v

I also put it on an almost dead battery 12V and it ran ok without load , and cut out with 150w lamp showing 10.5v

Its seems mine is quite uncritical and reasonable that yours should be the same.

It is easy to open up by taking off the black base plate via 4 screws. There are 7 I think internal fuses and also visible are two trim pots. Might be worth alook round for anything loose.
However don't know if your into electricity and there are dangerous volts inside and as the unit is new its probably better not to touch.

I would still go with my original suggestion of running the unit off a seperate battery via completey different leads (even thins ones).

If it still fails then its probably better to return it.

If I can do anything else let me know

Robin Miller

FollowupID: 480555

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 21:38

Monday, Feb 05, 2007 at 21:38
Hi Robin,
Thanks for your help.
I just got an E-mail from watersidetradingco to ask me to post the unit back to them for replacement. They claimed two other units have had the same issue.
I must admit that their response was. They supplied me with a free post address for return and a new unit will be sent by return mail from them.
FollowupID: 480593

Follow Up By: Bonz (Vic) - Monday, Feb 05, 2007 at 22:01

Monday, Feb 05, 2007 at 22:01
Was just about to say to return the unit and get one that works correctly.
Time is an illusion produced by the passage of history

Lifetime Member
My Profile  My Blog  My Position  Send Message

FollowupID: 480597

Reply By: Nav 8 - Monday, Feb 05, 2007 at 10:55

Monday, Feb 05, 2007 at 10:55
Sounds more like a volt drop problem to me. I would first charge the battery with a separate battery charger for a few hours, then test each cell with a hydrometer. This will give you a true reading of your batteries condition and you have to be certain of this before you look any further. Nav
AnswerID: 219833

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 16:23

Monday, Feb 05, 2007 at 16:23
Done all that Nav. thanks, Colin.
FollowupID: 480496

Reply By: rolande- Monday, Feb 05, 2007 at 18:26

Monday, Feb 05, 2007 at 18:26
G'Day Colin,

Have you tried turning on with the engine running, and then again with the engine switched off?

I had an inverter which recommended turning on while engine running.

Just a thought

AnswerID: 219955

Follow Up By: On Patrol - Monday, Feb 05, 2007 at 18:37

Monday, Feb 05, 2007 at 18:37
Nice thought Rolande , Yeah I've tried that one.
No difference mate, Colin.
FollowupID: 480535

Reply By: Member - jeff M (SA) - Tuesday, Feb 06, 2007 at 18:28

Tuesday, Feb 06, 2007 at 18:28
I drilled out the pop rivets in the inverter today and had a look inside the inverter.

We found a few transisters blown , all up there is 25 transister so we are fitting new ones .Ordered them today.

Cheers Jeff M (SA)
AnswerID: 220218

Sponsored Links

Popular Products (11)