Should battery voltage drop by so much when off EHU ?

[Geoff57]

Hi, I am hoping someone with battery knowledge can answer my query.
I have a 2018 AutoSleeper Broadway that has been on EHU for the last 4/5 weeks. We have had a few days away using EHU and returned last night.
The readings when on site were above 13.0v for both batteries.
I have just been into the van which is currently not on EHU and the readings for both batteries is 12.4v !
This seems rather low to me as I thought they would drop to around 12.9v and then slowly fall over the next week or so.
The other thing which may not be relevant is that the app. for the tracker shows a reading of 13.0v for the vehicle battery.
I was wondering if the readings on the control panel in the van are inaccurate and may need resetting ?

Any thoughts would be greatly appreciated.

Geoff

 

[Spriddler]

The panel readings may not be accurate. Best way is to put a multimeter on the terminals of the batteries.
12.6v is fully charged.

 

[pappajohn]

13.9v/14v is the charger voltage, it would show that even without a battery.
Fully charged and just off charge is 12.9v
An hour or so off charge would show 12.6v/12.7v.
As a battery ages it loses capacity to hold a charge so your battery may be showing its age

 

[Geoff57]

Many thanks Spriddler and Pappajohn for your very quick responses.
I think I wrongly assumed that 12.9v was the normal reading...not realising that it would drop to 12.6v/12.7v after an hour or so.
I will try and take a reading with a multimeter but it may be time to look at replacing the battery.
Regarding a new battery, I think mine is a 105AH. Would there be a problem replacing it with a slightly larger one, say 110AH ?

 

[nicholsong]

Is it a 'wet' battery and have you checked the electrolyte level?

Our panel reading is always lower than the multimeter direct onto the terminals and since batteries were new has never shown over 12.5v. As you said next is to check with multimeter.

Even if the battery is showing its age at 12.4v it is not completely finished - it may have another one or two year's use.

My last engine battery was 11 years in my possession plus whatever it had done before, so could even have been original, so 17 years-old, but they don't make them like that any more!

Geoff

^{_{Subscribers  do not see these advertisements}}

 

[ManTheVan]

A new 110Ah battery won’t make much of a difference, unless your original is on its last legs. However, a cheap replacement may not last long either. Generally, the heavier, the better, as they contain more lead.
….or you might opt for 100Ah LiFePO4 which would effectively double your capacity, but would probably involve some extra cost and time installing B2B and a different EHU charger if your existing one doesn’t have the correct profile.

 

[Geoff57]

Thanks nicholsong....you may have set my mind at rest.
I'm not technical at all...battery from memory is sealed with a clear plastic tube coming from it for venting.
I suppose the daft question now is when will I know to replace the battery ?

 

[Spriddler]

Many thanks Spriddler and Pappajohn for your very quick responses.
I think I wrongly assumed that 12.9v was the normal reading...not realising that it would drop to 12.6v/12.7v after an hour or so.
I will try and take a reading with a multimeter but it may be time to look at replacing the battery.
Regarding a new battery, I think mine is a 105AH. Would there be a problem replacing it with a slightly larger one, say 110AH ?

No prob at all just as long as its type is compatible with your charger and fits the space available.

TBH Since you do very little off-grid camping I would just maintain your charging regime for the one you have and see how it goes. After all, if it starts to dwindle or dies completely whilst away a replacement won't be difficult to obtain within an hour or so.

 

[Geoff57]

Thanks ManTheVan.
I don't think I'll go down the lithium route as firstly I do very little wild camping and my vehicle has smart chargers which I would not want to mess about with knowing my very limited electrical knowledge !

 

[Geoff57]

13.9v/14v is the charger voltage, it would show that even without a battery.
Fully charged and just off charge is 12.9v
An hour or so off charge would show 12.6v/12.7v.
As a battery ages it loses capacity to hold a charge so your battery may be showing its age

Just thinking about your comment re charger voltage. Does this mean that on a site with EHU even if the battery is in a poor state you can still have electric in the van ?

^{_{Subscribers  do not see these advertisements}}

 

[Spriddler]

Thanks ManTheVan.
I don't think I'll go down the lithium route as firstly I do very little wild camping and my vehicle has smart chargers which I would not want to mess about with knowing my very limited electrical knowledge !

When on EHU the 12v system in your m/h is (in effect) being powered by the charger rather than the battery so a weak battery won't prevent the 12v equipment from working.

 

[Spriddler]

Just thinking about your comment re charger voltage. Does this mean that on a site with EHU even if the battery is in a poor state you can still have electric in the van ?

Yes, as in my post above which crossed with yours.

 

[Geoff57]

I would like to thank you all for your replies to my initial query.
Did not expect such quick responses.
It shows me what a great forum this is.

Geoff