Thread: A warning about inverters

Originally Posted by Wil2k

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.

Originally Posted by drivesafe

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!

Wil

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.

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.

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

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

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

Originally Posted by 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.

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.