Don’t understand battery voltage

Otter Spotter

Otter Spotter

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I have 190amp leisure battery, 160w solar panel, B2B charger,. My indicator regularly say 14.5v. I haven’t been off grid long enough to see the voltage drop below 13v. So question is what should I worry about if I am off grid, is it if the voltage drops below a certain level ? What does it mean? What damage is caused if I continue to use electric in the van whilst the volts go down? I realise these may seem daft questions but I hope to be off grid more and I am not sure what I need to be doing to ensure nothing gets broken!
thanks
 
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Otter Spotter said:
I have 190amp leisure battery, 160w solar panel, B2B charger,. My indicator regularly say 14.5v. I haven’t been off grid long enough to see the voltage drop below 13v. So question is what should I worry about if I am off grid, is it if the voltage drops below a certain level ? What does it mean? What damage is caused if I continue to use electric in the van whilst the volts go down? I realise these may seem daft questions but I hope to be off grid more and I am not sure what I need to be doing to ensure nothing gets broken!
thanks
Click to expand...

If the sun is shining then do not worry... :cool:
 
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This chart may be useful. Habitation batteries designed to be used and discharged, although best not fully however your solar should take care of that. My battery ususally over 13v so not sure where it fits on the chart !
1591520838594.jpeg
 
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Over discharging and damaging your leisure battery may be dependent on your battery technology e.g. wet, Gel, AGM, Lithium and the battery controller/charge equipment you are using.

Our Hymercar has a 95Ah AGM battery and a Schaudt Elektroblock EBL 30 transformer/rectifier which monitors the voltage in the living area battery. If the battery voltage falls below 10.5 V, the battery monitor in the transformer/rectifier switches off all the 12 V appliances.
 
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It's not very useful to try and use a chart because those voltages are for a battery that has been stood with no load for a couple of hours. The best way is to fit a battery monitor like the NASA BM1 👍😎

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Otter Spotter said:
I am in England and will be travelling mainly in West Coast of Scotland, Shetland so Sun doesn’t normally feature much 🌧🌧🌧
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That’s where your B2B will come into its own if you move and travel around often. I abuse my batteries often and without a b2b, knackered my batts as solar and short distances never replaced what I used. B2B soon resolved that issue. But there again, I also have lithium fitted now but still abuse them.
 
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Please be aware that
I. your display is almost certainly showing the voltage going into your battery from the charger or Solar panel and not the true state of your battery.
2. It's almost impossible to measure the state of a battery when there is a load placed on it.
3. Understanding Battery capacity is key to obtaining the maximum life from your leisure battery.
 
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This will also help you calculate your energy usage when off grid.

www.caravansplus.com.au

CaravansPlus: Calculating How Big Your Battery Needs To Be

Ensure you never run out of power again, this guide will help you understand how long your RV battery will last. Determine what size battery you need in your setup by using our easy battery calculator, and some quick tricks to getting the most out of your battery when camping. Article by Peter...
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.

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PhilandMena said:
Please be aware that
I. your display is almost certainly showing the voltage going into your battery from the charger or Solar panel and not the true state of your battery.
2. It's almost impossible to measure the state of a battery when there is a load placed on it.
3. Understanding Battery capacity is key to obtaining the maximum life from your leisure battery.
Click to expand...
Hence my post, I am not sure wha5 to understand even !
 
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Less than 12.06v with everything turned off, no hookup and at night ( no solar charge) is the lowest recommended voltage for a lead acid battery.
Go below that voltage regularly and the battery life will suffer.
 
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The panel controller, left to it's own devices with little or no load on the battery, will charge at 14+ volts to fully charge the battery. Once it's happy that the battery is fully charged the controller will drop its output to 13.5-ish volts to maintain or float the battery. Any load on the battery will drop the voltage and at a voltage pre-set by the controller will cause it to resume at 14+ volts. The only way you can fully know the state of the battery at any given time is to use the table posted above after leaving the battery disconnected for a couple of hours. Hardly convenient so most users keep an eye on the battery voltage whilst it's in use and only worry if it it drops below 12.2v or so when under load. You develop a feel for what's happening to it after you've used it for a while.

As stated above if you want or need better information you need to use an Ah meter which, amongst other things, displays remaining battery capacity as a percentage. The NASA BM1 is such a device. Similar products are available from other sources.
 
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Otter Spotter said:
Hence my post, I am not sure wha5 to understand even !
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Most of us are in this position when first starting out, so that's quite normal and nothing to be concerned about. I have posted a couple of links (posts #8 & #10) that explain the basics and if you read these it will improve your knowledge. There are also lots of information on U-tube and here is a very good clip.



Just take your time and you should be fine. You will see lots of conflicting advice on here with members very quick to tell you what you need to do and what to spend your money on. It may not be right for your particular situation so don't take everything for gospel that is said on here, although all of it will be with good intent and none malicious.
Finaly, RTFM there are just too many members popping up saying how does this work etc, etc, when all the information is at hand in the manuals provided with motor-homes and associated equipment. Surprising the amount off owners who never read them.
 
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Otter Spotter said:
I have 190amp leisure battery, 160w solar panel, B2B charger,. My indicator regularly say 14.5v. I haven’t been off grid long enough to see the voltage drop below 13v. So question is what should I worry about if I am off grid, is it if the voltage drops below a certain level ? What does it mean? What damage is caused if I continue to use electric in the van whilst the volts go down? I realise these may seem daft questions but I hope to be off grid more and I am not sure what I need to be doing to ensure nothing gets broken!
thanks
Click to expand...
There's lots of technically correct responses been given but in the real world are you going to turn everything off and check the battery voltage after an hour?

If you have a monitor which shows the voltage the answer is simple. If it is less than 12 volts turn things off and look for something to charge it. 😀

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Battery charging is a chemical process that depends on the amount of electric charge going into and flowing out of the battery. Charging converts chemicals from one substance to another. Discharging converts them back to their original form. The only reliable way to know the state of charge of a battery is to measure and keep track of the charge going in and out of the battery.

Battery voltage is a reasonable indication of state of charge if the battery has been left unconnected to load or charger for a couple of hours. While it is being charged or while a load is connected, this voltage method is not reliable.

Because mostly you want to know the state of charge while charging from hookup or solar, or while using a load that you don't want to switch off, the best method is to use a battery monitor.

Amps is the flow of electric charge, so a battery monitor measures the amps continuously, and uses a built-in computing chip to add up the charge going in and out of the battery.

When you first connect it, there is a procedure where you type in the Ah capacity of the battery, and then fully charge it, so the monitor knows where it is starting from. From that point, the monitor shows the state of charge in percentage, and is accurate even during charging or discharging.

Popular monitors are the NASA BM1 or the Victron BMV, and there are others. Some EBL panels have them built-in.
 
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