Leisure Battery Usage - How Long Should It Last

[jo10000_6]

Catching up on a previous thread I may have gone about this in totally the wrong way …..but it seemed correct at the time !

I've had the motorhome a year and have primarily stayed on sites but this year we plan to be on less EHU so I've been carrying out some test to see how long my 1 battery will last and on paper its great.

In practice not so much .


So, my Hymer B544 isn’t power hungry.

I have calculated the following as the primarily power draws :-



TV – 3 Amps

1 Bench Seat Fluorescent Strip – 13W = 1.083 Amp

1 Kitchen Area Fluorescent Strip – 11W = 0.92 Amp

Couple of LED Spots 0.125 Amps x 2

Some Festoons – Not a Lot

Bathroom LEDS – Not a lot and due to intermittent use not concerning.

Water Pump = 5 Amps per Hour – Intermittent use as we know

Truma Vent System – Book seems to suggest 0.2-1.0 Amps Per Hour which seems low when I read about how much other people use but I’m sure I’ve read the book right.

Ariel Amplifier thing – not a lot

Boiler – Not sure TBH



Anyway to get an idea of how long I can last on 1 battery – on paper I calculated I could have the following :-

2.5 Hours TV – 7.5 Amps

4 Hours 2 x Fluorescent Lights – 8 Amps

Water Pump – 10 Mins a Day – 0.835 Amps

Bathroom Lights 10 Mins a Day – 0.14 Amps

Don’t really use the vent system but interested if that’s sounds about right.

Anyway with some festoons and some spot LEDs it came out at approx 17.69 so let’s say 18 Amps a day for the above.

I calculated 2.5 Days and the battery would be at 65% so keeping on the right side of the discharge.

Last week did some experiments TV first then lights.

The figures don’t read well.


I left the TV on for 8 Hours and got to 50% Discharged – so 55 Amps used for what should be 24 – 30 would have been ok but half of the battery - I’m confused.

I left the two strips lights on today for 5 hours and discharged to 60% left – the lights are 2 Amps total per hour – but I’ve used approx. 44 Amps.

Battery 10 months old approx. 12 weekend trips on EHU with a few intelligent charge re-charges as mine is an old charging system and I didn’t want to rely on it for maintaining the battery.

Now I understand perhaps you lose some efficiency in cold weather (10 % mentioned) but this is more than this.

I’m sure I don’t have a drain (no alarm) there’s nothing fancy on the motorhome and all I can think off is battery is duff.

I may have been measuring the battery at the wrong times to get accurate readings but wasn't sure when else to do it and reading a previous thread has brought this to my attention.

Any comments appreciated.

Thanks
Jo

 

[funflair]

It might come down to how good your battery is as they do loose capacity, and some batteries are flooded lead acid and most people don't bother to check them.

Martin

Oops sorry 10 month old battery, but the other comment still applies and what sort of battery is it as they are not all born equal.

 

[JeanLuc]

Several thoughts come to mind.

• What size and type of battery do you have?
• How are you determining the amount of capacity used? You mention % used but are you reading this from a meter or calculating it from the voltage?
• Unless you have a clever battery computer fitted (such as Victron, NASA or Votronic) a battery needs to rest with no load on it before you can get a reliable voltage reading: minimum 1/2 hour but ideally longer.
• You mentioned using a smart charger, presumably overriding the onboard charger. When did you last do this?

 

[Richard n Ann]

Catching up on a previous thread I may have gone about this in totally the wrong way …..but it seemed correct at the time !

I've had the motorhome a year and have primarily stayed on sites but this year we plan to be on less EHU so I've been carrying out some test to see how long my 1 battery will last and on paper its great.

In practice not so much .


So, my Hymer B544 isn’t power hungry.

I have calculated the following as the primarily power draws :-



TV – 3 Amps

1 Bench Seat Fluorescent Strip – 13W = 1.083 Amp

1 Kitchen Area Fluorescent Strip – 11W = 0.92 Amp

Couple of LED Spots 0.125 Amps x 2

Some Festoons – Not a Lot

Bathroom LEDS – Not a lot and due to intermittent use not concerning.

Water Pump = 5 Amps per Hour – Intermittent use as we know

Truma Vent System – Book seems to suggest 0.2-1.0 Amps Per Hour which seems low when I read about how much other people use but I’m sure I’ve read the book right.

Ariel Amplifier thing – not a lot

Boiler – Not sure TBH



Anyway to get an idea of how long I can last on 1 battery – on paper I calculated I could have the following :-

2.5 Hours TV – 7.5 Amps

4 Hours 2 x Fluorescent Lights – 8 Amps

Water Pump – 10 Mins a Day – 0.835 Amps

Bathroom Lights 10 Mins a Day – 0.14 Amps

Don’t really use the vent system but interested if that’s sounds about right.

Anyway with some festoons and some spot LEDs it came out at approx 17.69 so let’s say 18 Amps a day for the above.

I calculated 2.5 Days and the battery would be at 65% so keeping on the right side of the discharge.

Last week did some experiments TV first then lights.

The figures don’t read well.


I left the TV on for 8 Hours and got to 50% Discharged – so 55 Amps used for what should be 24 – 30 would have been ok but half of the battery - I’m confused.

I left the two strips lights on today for 5 hours and discharged to 60% left – the lights are 2 Amps total per hour – but I’ve used approx. 44 Amps.

Battery 10 months old approx. 12 weekend trips on EHU with a few intelligent charge re-charges as mine is an old charging system and I didn’t want to rely on it for maintaining the battery.

Now I understand perhaps you lose some efficiency in cold weather (10 % mentioned) but this is more than this.

I’m sure I don’t have a drain (no alarm) there’s nothing fancy on the motorhome and all I can think off is battery is duff.

I may have been measuring the battery at the wrong times to get accurate readings but wasn't sure when else to do it and reading a previous thread has brought this to my attention.

Any comments appreciated.

Thanks
Jo

If you're that interested to know, probably the best thing to estimate it for you is a NASA BM1 (orBM2) battery monitor. Or similar.
Best 100 quid I've ever spent

Warning: it does feed your obsession

 

[pappajohn]

Change the Fluorescent lights to LED strips.
You don't need to change the lamp body, just buy an LED strip and remove the tube and wiring from the switch then wire the LED to the switch.
Fluorescent strips have a crude inbuilt inverter as they run on 230v.

My RV had 9 x twin 13watt lamps.... 234 watts... 19.5amps plus poor loses due to crude inverters, maybe 25amps total
Changed the tubes to 4watt LED strips.... Similar light output..... 72watts...6amps

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[Reallyretired]

I assume that you are basing the battery state of charge on voltage. You do need to measure it after leaving it at least an hour with nothing charging or discharging it before measuring. If you measure while there is still something using power or soon after switching it off the battery voltage will still be lower, making your battery appear flatter than it really is.
Do also bear in mind that different types of battery have different voltages at similar levels of discharge eg flooded LA or gel.

 

[Viennese]

Don't see the point of all that calculation - unless it never gets a regular charge. If you are planning to go without EHU, then put a solar panel and and/or give it a regular run??

 

[Madcaravanner]

Don't see the point of all that calculation - unless it never gets a regular charge. If you are planning to go without EHU, then put a solar panel and and/or give it a regular run??

Whilst I would do the calculations
BUT
I would change ALL lights to LED
Fit more than one battery (we have 3 )
We have a Solar panel

We do not have to worry too much we have lasted weeks without 240v this way

 

[Sundowners]

You didn't mention phones or computer devices------ if you charge these, don't underestimate the power they draw!!

 

[jo10000_6]

Several thoughts come to mind.

• What size and type of battery do you have?
• How are you determining the amount of capacity used? You mention % used but are you reading this from a meter or calculating it from the voltage?
• Unless you have a clever battery computer fitted (such as Victron, NASA or Votronic) a battery needs to rest with no load on it before you can get a reliable voltage reading: minimum 1/2 hour but ideally longer.
• You mentioned using a smart charger, presumably overriding the onboard charger. When did you last do this?

Hi Jean-Luc

Its an Exide Dual ER550 - 110 Amp.

Martin (Funflair) has perhaps highlighted in another thread that perceptive power can be wrong.

To be honest all I did was take a voltage meter reading at the end of the test (perhaps should have let it rest) - looked at my chart for an approx. discharged number then used the % to get to amps used.

I'm leaning towards the battery monitor - you guys have quoted a few as options - its not buying it its getting it fitted correctly as reading the instructions it has to be installed and lets say slightly calibrated to get accurate results..

I've removed the battery a few times for charging with a better charger - a few weeks ago probably then yesterday.

To add to the discussion when I removed it yesterday and popped it on charge it took my 7.2 Amp smart charger 3 hours 50 mins to go to 100% - so 28 Amps back in - again just as an approx.

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[jo10000_6]

If you're that interested to know, probably the best thing to estimate it for you is a NASA BM1 (orBM2) battery monitor. Or similar.
Best 100 quid I've ever spent

Warning: it does feed your obsession

View attachment 281514

I looked at the BSM1 this morning and whilst obviously an older one now the price reflected this and didn't seem that bad - fittings a different matter.

I think you can tell I already have the obsession ! Feed me feed me now

 

[jo10000_6]

Change the Fluorescent lights to LED strips.
You don't need to change the lamp body, just buy an LED strip and remove the tube and wiring from the switch then wire the LED to the switch.
Fluorescent strips have a crude inbuilt inverter as they run on 230v.

My RV had 9 x twin 13watt lamps.... 234 watts... 19.5amps plus poor loses due to crude inverters, maybe 25amps total
Changed the tubes to 4watt LED strips.... Similar light output..... 72watts...6amps

I'm going to get to this Papa John - but for the purpose of the exercise I still wanted to see what my battery will give - but its on list and I will get there. Thanks, Jo

 

[jo10000_6]

I assume that you are basing the battery state of charge on voltage. You do need to measure it after leaving it at least an hour with nothing charging or discharging it before measuring. If you measure while there is still something using power or soon after switching it off the battery voltage will still be lower, making your battery appear flatter than it really is.
Do also bear in mind that different types of battery have different voltages at similar levels of discharge eg flooded LA or gel.

Thanks for this - I will re-visit - hadn't really done that.

 

[jo10000_6]

Don't see the point of all that calculation - unless it never gets a regular charge. If you are planning to go without EHU, then put a solar panel and and/or give it a regular run??

There's no proper split charge on my vehicle - there's a crude system but the auto electrician said be wary of connecting it.
Whilst I would love solar - based on my off the grid time 2 batteries should do it hence the exercise Im doing.
My roof is a busy little area as well - Im not sure Id get enough solar on there to make it worth while.

 

[jo10000_6]

Whilst I would do the calculations
BUT
I would change ALL lights to LED
Fit more than one battery (we have 3 )
We have a Solar panel

We do not have to worry too much we have lasted weeks without 240v this way

I suppose that's an option - I have to weigh up what I put on the motorhome when I know at some point I will upgrade - although not for a couple of years - I fairly sure I will do just that in the future. Best wishes Jo

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[jo10000_6]

You didn't mention phones or computer devices------ if you charge these, don't underestimate the power they draw!!

I agree but I tried to make the exercise simpler by just powering a known consumption. It didn't turn out simple though !

 

[JeanLuc]

It might help responders to give useful advice if you can let us know what charging system your van has. Hymer have fitted Schaudt units for many years but yours may be an early model. There are lots of old Hymer owners and I’m sure most of them get on perfectly well with the standard charger.

p.s. that should read ‘owners of old Hymers’ not ‘old Hymer owners’!

 

[jo10000_6]

Its a Elektromatic LA110 Charger.

I've had good information from both @scotjimland and @autorouter previously on the capabilities of the charger - I know the charger is lacking.

Sorry don't know how to pull from an old posts and Im not sure Ive put there names in correctly either

I think Jean-Luc this is a matter of adding the charger to my ever growing want list. Some one has just shown one they have just purchased in "what I bought this week" and it makes me think I should do the same.

Thanks for your input - very appreciated.

 

[jo10000_6]

Update on the battery situation :

So I purchased a battery monitor (shunt type) - fitted it - played around with a few things. Had to comprehend that really this is an amps counter as whilst on charge on discharging the figures are still not accurate - I getting better at not being black and white as much !

Now you guys would have had the battery monitor in no time but these things take me a bit of time as I factor my motorhome time into all my boring life stuff ! Also because some most of its new to me it just takes me time as I probably go about thing in the wrong way around as I don't have the vision to see an easier way.

Anyways - I discharged 40 Amps and once the battery had settled it was at 12.2V - so approx. 60%. This isn't too bad a reflection of my 110 amp battery.

@pappajohn - I

Change the Fluorescent lights to LED strips.
You don't need to change the lamp body, just buy an LED strip and remove the tube and wiring from the switch then wire the LED to the switch.
Fluorescent strips have a crude inbuilt inverter as they run on 230v.

My RV had 9 x twin 13watt lamps.... 234 watts... 19.5amps plus poor loses due to crude inverters, maybe 25amps total
Changed the tubes to 4watt LED strips.... Similar light output..... 72watts...6amps

Thanks PappaJohn - eventually worked up the nerve just to take it all out over the kitchen - 30 minutes ago had my LED strip connected - very pleased with myself - need dark to see how good or if I need another strip.

Conclusion - I will be OK for 3 days without hook up now I have changed the tubes and now have the ability to see amps going out.

Tempted to buy a portable solar panel ….just because I want one !

Thanks for your previous input.

Jo