# Leisure batteries and Inverters



## SineadandTony (Jul 22, 2009)

We only purchased our MH in November and have not really got much use from it yet. Just purchased and fitted a 1000watt inverter running from 2 110 AH Leisure Batteries. Today I fully charged the Leisure Batteries to check out how long they would last with the inverter. I put up my 12v satellite dish then turned on my 15inch TV and Sky Box. I also ran one light. Nothing else in the MH was running and I got a low "Low Battery Pre Alarm" after less than 5 hours.....
Is this normal and is this as much as I can expect from my leisure batteries if using a 1000watt inverter?

Also wondered if the Leisure Batteries will be charged from the engine while driving or while the engine is running?


----------



## trevorf (May 16, 2005)

I would have expected more than that from 2X 110AH batteries.
How old are the batteries? Have you had them tested on a load tester? How did you charge them?

Yes they should be charged whilst the engine is running.


Trevor


----------



## SineadandTony (Jul 22, 2009)

The batteries are the same age as the MH. . .july 2008. I charged the batteries on EHU but dont have a load tester to check them. The display in the MH showed them at 13.4v before I switched on the inverter.
I did think myself that I should have got much longer from them.
Any idea what sort of time I should get considering the load is so small?


----------



## wakk44 (Jun 15, 2006)

There are several factors to consider when working out the expected life of leisure batteries with your example.

1/

You don't want to discharge the batteries to below 50% to avoid shortening the life of the batteries.So with 220 A/H of battery power you have approx.110 A/H at your disposal.

2/

The current consumption of each appliance must be worked out.A 15''TV typically is around 40 watts = 3.5A @ 12volts.

The sky box will in my experience use slightly less current,mine takes 2A @ 12volts.(through an inverter) 

A standard halogen bulb uses approx.0.3A.

I assume you have a 12volt automatic dish,which should lock on in less than 30 seconds,so a very small amount of current used.

All these examples are typical,check your appliances to find out the exact current they take.


So you have a total of of approx. 6A being drawn from the batteries every hour.With 110A/H available it is 110 divided by 6 which is nearly 19 hours.

Then take into account the inverter is 80%-90% efficient and I would have expected at least around 16 hours of continuous use from 2 fully charged leisure batteries.


----------



## TheBoombas (Aug 23, 2006)

They will only charge with the engine running if the control panel switch is selected to charge the habbitation area!

Was that the battery reading whilst still connected to hookup?
You should take the reading at least 1/2 hr after disconecting from the mains.
Also you may have other appliances running of the batteries, like Radio, Alarm. Pump. On som of the Autotrials the rear camera is on all the time (No Switch) and some like mine need to be switch off.


----------



## SineadandTony (Jul 22, 2009)

There were no other appliances working....fridge off...pump, water heater off.....charger off so that the inverter was not charging the leisure batteries. As I said earlier the display showed 13.4 volts when I disconnected the EHU but dropped to 12.8 when I switched on the inverter.

About 5 hours later I got the Low Battery Pre Alarm with the display showing9.8 volts

My reversing camera only comes on when I put the MH into reverse so dont know anything more about switching it on/off


----------



## wakk44 (Jun 15, 2006)

If you are confident that both your leisure batteries are ok then it is possible that there could be some 12 volt leakage on the system dragging them down.

The way to check this is to switch off all 12 volt appliances,remove the negative terminal on the primary leisure battery and connect an ammeter in series between the negative cable and battery post.

A more expensive option would be to fit a battery conditioning monitor similar to >>>THIS<<< which would also tell you how much current each 12 volt appliance was taking,as well as other useful functions at the push of a button.


----------



## TheBoombas (Aug 23, 2006)

SineadandTony said:


> My reversing camera only comes on when I put the MH into reverse so dont know anything more about switching it on/off


I now the actual rev cam only work when you select reverse, but on some the actual camera is powered either straight off the batteries or via a switch. to check this is simple... Just have a look at the rear camera at night.. If the Led's are glowing then you know it's getting power from somewhere like my one does!
I don't think it's much of a drain mind. and unless your invertor is taking too much out of the batteries or there is some other leakage like was sugested earlier. On the other hand it could well be that the batteries are not up to scratch?


----------



## pieterv (Feb 3, 2009)

As Steve mentioned, you don't want to discharge below 50%. If your battery monitor shows a voltage of 9.8V you are deeply discharged, which will not do your batteries any good at all.

Pieter


----------



## Wizzo (Dec 3, 2007)

SineadandTony said:


> As I said earlier the display showed 13.4 volts when I disconnected the EHU but dropped to 12.8 when I switched on the inverter.


I would suspect that one or both of your batteries is/are duff. The voltage shown when on EHU is the charging voltage and nothing to do with the actual voltage of the battery. 12.8 is probably nearer the true voltage but I suspect may still be carrying some of the surface charge from the EHU. I too would expect a lot longer than 5 hours.

JohnW


----------



## TheBoombas (Aug 23, 2006)

I also don't like the idea of running eveything off an invertor in the first place, when most items will work direct from 12volts and use less power as they are not having to use reducing transformers.

IMHO Id think it could be the batteries that are at fault, the panel voltage reading is a false guide and just shows the current voltage not the actual condition of the batteries, I'd get them checked out first.

brian


----------



## Antonia (Apr 27, 2008)

*Cable*

Hi

How long is your cable run, battery to invertor?, 12v high current flow to invertor will cause a massive voltage drop in cables over a certain maximum length. Also, using a cable that is too thin will cause massive loss due to heating.
Measure the voltage across the battery terminal and across the input to the invertor any voltage drop is a worry. Also 'feel' the input cable after it has been on a short while to see if its hot.

Regards

Antonia


----------



## SineadandTony (Jul 22, 2009)

Thanks to everybody who has given me advice so far.....I left the MH on EHU all night so now my batteries should be fully charged. When I disconnected the panel showed 13.3 volts. I have everything turned off at the moment so will check the batteries in about an hour and see what the voltage is then......Will report back later


----------



## SineadandTony (Jul 22, 2009)

Ok. . . . So its now nearly 3 hours since I disconnected the EHU and the panel is showing the Leisure Batteries as 13.0v. This would lead me to believe that there is no extra draw on the batteries as they have only dropped 0.3 v in three hours.

This in turn would lead me to believe that the Leisure Batteries might actually be kaput.....

Anyone agree or have an alternative opinion


----------



## erneboy (Feb 8, 2007)

!3 v seems high after having been disconnected for three hours, so I would be a bit suspicious of your on board read out.

Lets assume it is a little optimistic but more less correct. What you can do now is put a known load on the batteries, say your television. Work out the power consumption and run it till your batteries show 12 volts, that will indicate that you have used half the capacity but all the power you can safely use without risking discharging your batteries too far. You can do this running several appliances as long as you know their power consumption. You want the answer in amp hours or amps used per hour. Do you need help with that calculation.

Given the size of your battery bank I would expect you should reach 12v after consuming around 80 amp hours of power through your inverter as you cannot count on it being much better than 80% efficient, Alan.


----------



## Jezport (Jun 19, 2008)

If you are using a 240v TV through the inverter take a look at the label on the back of the TV, as some LCD TVs can use 80W where the most modern 12v LCD TVs can use under 20W


----------



## SineadandTony (Jul 22, 2009)

Have not had an opportunity to do anything since yesterday but just checked the display panel and put a volt meter across the terminals of the Leisure Batteries.....Both showing 12.7 Volts. The EHU has been disconnected since 3pm yesterday with o load 

Just about the batteries, they are
NUMAX XV27 MF
1000 MCA
160 min RC
Maintenance free
All double dutch to me. . . . . :? 

So maybe i was incorrect in my assumption that they are 110 AH batteries


----------



## CliveMott (Mar 10, 2008)

A few pointers :-

A typical halogen downlighter has a 10 watt bulb and will consume just under 1 amp (0.85 ish)

The battery selector switch on some systems must be set to the habitation battery for the EHU to charge it.

A 3 hour charge will not get close to fully charging one battery, let alone two. The biggest Sargent charger (from memory) charges at 16 amps. (Sorry, I am sat in a hotel room at Newquay using a notebook) So if one battery is fully discharged it will take a minimum of nearly 7 hours, double for two batteries. But the charge rate reduces as the battery voltage rises so it takes longer.

The end of charge voltage should be around 14 volts or marginly under. If its on charge and indicating 13.4 volts then you have many more hours of charging to go!. Or its not charging on EHU??

So to prolong battery life.
1 Make sure the charger is working correctly.
2 Only use an inverter for things that will not run directly off 12 volts
3 Change any halgen lighting to LED replacements.
4 Use gas for anything that requires heat.
C.


----------

