A warning about inverters

[Wil2k]

Hey all..

For anyone using or considering using a 240v inverter in their vehicle, allow me to share a useful tidbit of advice (by experience).

If you're green to inverters & batteries.. take note.

Some inverters have an automatic "Low Voltage Cutout" which the manual usually states is to prevent your vehicles battery from discharging below the voltage needed to start the vehicle.... **BEWARE**

I didn't pay too much attention to the actual voltage that this alarm was set to.. which in my cheapo Jaycar inverter's case was 10.5v.. and just assumed it would save my battery at the correct voltage.

10.5v is a VERY flat battery ladies and gents! In my research it is suggested not to discharge below a 50% state of charge.. which basically means somewhere around 12v. I'm not sure how it all translate to under load / at rest voltages, perhaps someone can summarise good discharge practices.

Sidewinder ARB have this graph accompanying their dual battery monitor:

https://www.aulro.com/afvb/images/imported/2010/10/603.jpg

As you can see.. when I went to start the Canyonero after the low voltage alarm went off... it barely had enough juice to run the dash lights. Quick call to the RACQ and I was back up and running again.

I'd suggest a basic battery monitor be used in conjunction with any Inverters. Although I suspect the top end inverters are a bit smarter about their low voltage warnings. A dual battery rig would be even better as starter batteries don't like constant discharging I hear.

Anyhoo.. just thought I'd share :D

Cheers

Wil

** Ps.. that earth point on your inverter... use it. Stake it and use it! Safety first kids!

[drivesafe]

10.5v is a VERY flat battery ladies and gents! In my research it is suggested not to discharge below a 50% state of charge.. which basically means somewhere around 12v. I'm not sure how it all translate to under load / at rest voltages, perhaps someone can summarise good discharge practices.

Hi Wil2k, the chart below is the correct voltage to State of Charge comparison for batteries in vehicle or RV use.

The chart you have is for open circuit battery voltage which is next to useless when measuring vehicle and RV battery voltages.

Your inverter’s cut-out voltage is actually typical of devices designed to run off the AUXILIARY battery but your warning is still VERY relevant because many fridges also cut-out at 10.5v, which is a flat battery.

A word of warning for you, some vendors are motor mechanics and although they pass themselves off as auto electrical experts, their information may be less than accurate.

As far as cycling batteries to 50%, this too depends on the type of battery and it’s intended use. While taking a cranking battery down to 50%, ( 12.06v ), is a safe level for it when being used as a cranking batteries, there are many batteries that can be safely taken down to 30% ( 11.75v ) including cranking batteries, and even 20% ( 11.58v ), but again it depends on battery type and their intended use.

https://www.aulro.com/afvb/images/imported/2016/06/640.jpg

[Wil2k]

Hi Wil2k, the chart below is the correct voltage to State of Charge comparison for batteries in vehicle or RV use.


Great info! Thanks Drivesafe!

I wasn't actually endorsing the aforementioned snake oil.. I just thought I'd better state where I found that graph! The traxide one was actually the one I was hunting for when I posted that.. but I couldn't remember where I'd seen it! :D

Wil

[drivesafe]

Hi again Wil, and from your post I assumed you were more asking than anything else.

By the way, these 10.5v cut-outs on these devices seem more to be there to protect the device rather than giving any protection to a battery.

[newhue]

Wil2k, I can relate to your experience a bit. I recently used and Aldi brand 300w hand held wisk, in a Aldi 600w inverter. I was amazed how this devices rapped my deep cycle battery for such a shot burst of use. Perhaps I should have had the car running, but user be ware.

ps, I no longer have the Aldi goods in the truck.

[VladTepes]

never mind the "Aldi" but what the hell were you using an electric whisk for in the bush.
Going soft on us?

[newhue]

yeh, now I'm all embarrassed.
Scrambled eggs, the whisk does such a good job, all fluffy like.

[Vern]

now the key to good scrambled eggs is cream, not milk, oh and when cooking, fold the eggs don't 'scamble' them:p

[Bundalene]

Hi again Wil, and from your post I assumed you were more asking than anything else.

By the way, these 10.5v cut-outs on these devices seem more to be there to protect the device rather than giving any protection to a battery.

We use a Trailblazer fridge with a built-in 10.5 volt cut-out. Once the battery drops to 10.5, the fridge shuts down and attempts to re-start after a time delay.

The Odyssey battery we use are still able to start our TD5 Defender once the fridge has been shut down due to the low voltage cut out.

Erich.

[drivesafe]

Hi Bundalene, this is a common situation, particularly with high energy batteries like Odyssey, Optima and Orbital.

These spiral wound type AGMs can also be taken much lower than other batteries and not seriously harm them.

BUT, you still shorten any battery’s life span when taking them down to these low voltages. Best to avoid if you can.


I recently used and Aldi brand 300w hand held wisk, in a Aldi 600w inverter. I was amazed how this devices rapped my deep cycle battery for such a shot burst of use. Perhaps I should have had the car running, but user be ware.

Hi newhue, this is actually very good advice. Where there is likely to be heavy load for a short time, run your motor and protect your batteries.

A good rule of thumb for power usage from batteries, is to try to keep your long term current draw to no more than 5 amp per every 100 Ah of battery capacity and no more than 10 amps per 100 Ah of battery capacity for short time current loads.

In other words, if your using one of my SC80 isolators and you have a 75 Ah cranking battery and a 100 Ah auxiliary battery, try not to apply loads of more than 7.5 amps and you will actually get more power from your batteries between charges.

Newhue, in your case, even running your set up for a short period, you should have had at least 400 Ah of battery capacity to make sure you didn’t do any harm to your batteries.

And VLAD, no you can not take your microwave oven with you!

[slug_burner]

Hey all..

Anyhoo.. just thought I'd share :D

Cheers

Wil

** Ps.. that earth point on your inverter... use it. Stake it and use it! Safety first kids!

I think that an inverter is a bit like a double insulated device and does not need an earth.

We need a real sparkie to pipe in here but my understanding is that and earth is a means by which to ensure your ELCB works or prevents metal chassis from staying live as they blow the fuse or circuit braker before anyone can get hurt. Otherwise an earth is just an extra connection to which you can hook yourself up to when you are holding an active in your hand (knowingly or not.)

[shining]

An old sparkie....just an ember now! Apologies to the others with newer knowledge for the simplified explanation.
Normal earthing relies on a low resistance to draw a high current and blow the fuse.
ELCB - Earth leakage cicuit breaker measures the current going to earth. If it rises above a certain level (30mA?? grey matter failing) it trips out.
RCD -Residual current device. Compares the current going in and out (active and neutral) and earth. If more current is going in than going out it must be going somewhere and again trips out.
This is why some resistive or capacitive loads like motors or fridge compressors or large banks of fluro lights would trip these devices out.

EDIT: ELCB and RCD trip out very fast typically 10mS, a full alternating current cycle (sine wave) takes ~16mS. So the electricity is disconnected much faster than a heartbeat so you don't go into defib.

[drivesafe]

Hi shining, while off subject but this may interest you.

In some set ups, both inverters and generators will not trip a standard RCD, BUT, an Australian invention is just coming on to the market that over comes this problem ( and many others ).

The device is called a Universal RCD and is the worlds safest RCD.

I’m NOT an electrician so I won’t go into the specifics but I hope to be marketing these URCDs in my motor home and caravan AC panels in the next week or so.

It’s great to see an Australian invention leading the world.

[wardy1]

This thread was always going to be about scrambled eggs!:twisted:
Milk works, cream works...... try ORANGE JUICE!
The whole thing is you need something to curdle the eggs and then you FOLD them with a spoon or gently with a fork......NEVER a whisk as it puts too much air into the eggs....save the whisk for omelettes (but that is in another thread lol).
Orange juice doesn't effect the flavour (surprisingly)and makes for the best colour you have ever seen in scrambled eggs! Best part is, you don't tend to get the water deparation usually associated with the use of dairy), 2nd best part is, it is easier to keep than fresh milk/cream when travelling. BTW, UHT, or Longlife milk doesn't work that well in scrambled eggs.... some may/will argue but it doesn't imho

[shining]

Hi Drivesafe,

Google is my friend. Yes they look fast and sensitive. Very Good.

[d2dave]

yeh, now I'm all embarrassed.
Scrambled eggs, the whisk does such a good job, all fluffy like.

An easier way is to put your fridge in the rear of a series landie with the eggs in it.

Dave.

[Wil2k]

An easier way is to put your fridge in the rear of a series landie with the eggs in it.

*falls about laughing!* :D

[miky]

I have an inverter, but only use it while motor running, usually to charge things as I am moving.
Alarm set at 10.5V but shuts off at 10V.

As has been said, I reckon it is to protect the inverter rather than my battery.

.

[Wil2k]

I got a bit creative and built a battery voltage monitor (Jaycar kit) and added a buzzer to it. I can set the monitor to raise the alarm at a preset voltage, and when it drops below that I get a red LED status light and a small buzzer going off.

I've built the circuit into the space above the cargo are accessory socket and used the blank panel that the rear seat headphones / remotes would occupy in a posher edition. Two small holes, cables directly down to socket. Piggy backed off the existing connectors. easymode!

I looked at a bunch of pre-made options from jaycar and auto suppliers, but this suited me better. LED is easily visible from outside the car, and at the rear (where most camping takes place in my case). Also (in my case) most longer usage of accessories when stationary (eg for camping) tends to be via this socket.

Tested it out, ran my laptop off the inverter for well over an hour before it triggered at a smidge below 12v. Crank battery had no dramas starting again. I'd like to set it more precisely that the trimpot allows though, so i may replace it with a finer range one OR fixed resistors.

Will post pics if anyone is interested. Cost under $15.

[Signal1]

Little OT but last blackout we had, my wife was in the middle of placing a business order online required within a 30min deadline. She's screaming, cursing anything and everyone. I ran a lead out to the inverter in the Disco and powered up the modem, router and notebook. She queried where I was getting power? "From that thing in the Disco you think is a waste of money!" I replied.

It's nice to be validated sometimes.

[Hoges]

;):twisted::p:wasntme:

[maggsie]

I got a bit creative and built a battery voltage monitor (Jaycar kit) and added a buzzer to it. I can set the monitor to raise the alarm at a preset voltage, and when it drops below that I get a red LED status light and a small buzzer going off.

I've built the circuit into the space above the cargo are accessory socket and used the blank panel that the rear seat headphones / remotes would occupy in a posher edition. Two small holes, cables directly down to socket. Piggy backed off the existing connectors. easymode!

I looked at a bunch of pre-made options from jaycar and auto suppliers, but this suited me better. LED is easily visible from outside the car, and at the rear (where most camping takes place in my case). Also (in my case) most longer usage of accessories when stationary (eg for camping) tends to be via this socket.

Tested it out, ran my laptop off the inverter for well over an hour before it triggered at a smidge below 12v. Crank battery had no dramas starting again. I'd like to set it more precisely that the trimpot allows though, so i may replace it with a finer range one OR fixed resistors.

Will post pics if anyone is interested. Cost under $15.
G'day Wil2k,
I would be interested in a few pics.

Regards
Maggsie

[Wil2k]

G'day Wil2k,
I would be interested in a few pics.

Hey Maggsie,

Here are the blurry poorly lit pics I took on my iPhone ;)
One note.. when I added the buzzer, I took the +lead to it from the other side of the resistor in sieries with the LED so that it had enough voltage to operate. Also, in the second hole (for the buzzer to buzz through) I have put a thin piece of cotton cloth between the buzzer and the plastic (a small circle) held in place by the glued buzzer. This is to keep the dirt out of the buzzer, but it also mutes it a little. I may try it without it.

Here's the Kit I used: LED Battery Voltage Indicator Kit - Jaycar Electronics (http://www.jaycar.com.au/productView.asp?ID=KA1778&CATID=25&form=CAT&SUBCATID=347)

http://www.staticfarm.com/gallery/landrover/battery_alarm_1.jpg

http://www.staticfarm.com/gallery/landrover/battery_alarm_2.jpg

http://www.staticfarm.com/gallery/landrover/battery_alarm_3.jpg

http://www.staticfarm.com/gallery/landrover/battery_alarm_4.jpg

http://www.staticfarm.com/gallery/landrover/battery_alarm_5.jpg

http://www.staticfarm.com/gallery/landrover/battery_alarm_6.jpg

[austastar]

I ran a lead out to the inverter in the Disco and powered up the modem, router and notebook. She queried where I was getting power? "From that thing in the Disco you think is a waste of money!" I replied.

It's nice to be validated sometimes.

Nice!

cheers

[squizzyhunter]

Nice work! Think Ill try this one out :-)