# Is second battery a good idea ?



## jimedmeades (Jun 9, 2013)

Hi everyone,
Can anybody help me please ?
I have a Fiat Ducato Trigano Tribute. It has one 110AH leisure battery, a 100w solar panel, a 800watt inverter.
All is fine and solar panel keeps everything happy.
However in the evenings when using the TV the inverter alarm comes on after a short time which (I think) comes on as soon as the voltage drops a little.
If I have the engine running (not a good idea I know) all is fine.
Does this mean as soon as the battery drops off the "maximum" the inverter alarm will kick in as I suspect ?
Would it be a good idea to add a second battery ?
If so, does it matter what size ? i.e. can I mix the 110AH with say a 125AH?

Thanks in advance for any help.


----------



## Penquin (Oct 15, 2007)

We have a Swift Kontiki which came with one 100ah battery, we suffered from similar problems and decided to fit a second battery which has worked superbly with 2 solar panels....

Our TV though is 12v since running an inverter is a much heavier drain on the battery......

If you think about it - the inverter will take out enough to power an 88w appliance whereas the TV may only be 75w. so the rest is "wasted" but still drained power. That will rapidly deplete the battery.

that might be worth looking at - a different TV to start with as they are power hungry.

If adding a second battery then ideally replace both at once with identical ones since if one is better than the other (and all degrade with time) the poorer one will drag the newer one down rapidly......

The wiring for that needs to be done properly but it is not too difficult - there are some good accounts of what to do with diagrams on here.

Genrally in UK based vans running the engine stops the 12v in the back of the MH


----------



## Sprinta (Sep 15, 2010)

I'm in the more is better camp.

Do you have room for another battery of the same size in the same location, preferably same location for ease of connection. 

If yes then get another battery the same as the existing one to ensure the amperage values balance out.


I've got 2 x 110ah from a 120w panel


----------



## WildThingsKev (Dec 29, 2009)

I suspect that your solar panel is not fully recharging your battery during the course of the day. It may appear to do so because so long as daylight is on the panel the battery voltage will show something above 13v even if only half charged.

Try checking the battery voltage soon after dark with everything turned off, and bear in mind that your control panel battery meter may not be properly calibrated.

Kev


----------



## peribro (Sep 6, 2009)

Something doesn't sound entirely right to me. Whilst another battery is always a good idea, I find it surprising that you are getting a low voltage alarm after watching TV for a short time. Say your TV is consuming 70W, then adding 10% for inverter inefficiency that equates to just under 80W which equals just under 7A per hour. Therefore you should be able to watch TV for some 8 hours (assuming nothing else is drawing from the battery) before the battery is run down to 50% charge remaining. Are you sure it is a low voltage alarm that your inverter is emitting and not an overheat alarm? Is it well ventilated? Alternatively your battery is not fully charging either because the solar panel is not efficient enough or the battery is faulty and needs replacing. Try charging the battery fully off the mains and see what happens.


----------



## jimedmeades (Jun 9, 2013)

Thank you very much everyone for your prompt replies.
A little more information :
The TV is brand new and the battery, solar panel are 6 months old. I don't know how old the inverter is as came with the MH.
I have a MPPT controller (6 months old) which is showing the battery is fully charged this morning at 9am with little sun and the control panel says battery is full.
I am sure the battery is not "low" when the inverter alarm comes on. Do inverters have an adjustment or do they always alarm at a set voltage ?
I need to check it all out more thoroughly when I get home as this was the first trip trying out this set up.


----------



## listerdiesel (Aug 3, 2012)

Inverter low battery alarms are usually around 10.50V or thereabouts, so if the alarm goes, whip out your voltmeter and check the battery volts before the Inverter shuts down.

Peter


----------



## WildThingsKev (Dec 29, 2009)

If you start with the assumption that your battery is low, say12.0v with no load, then putting a charger (any charger) on it will immediately bring the voltage up to over 13v and the control panel will show fully charged. However, this cannot possibly be true because it would take your solar at least 12 hours of full sun to recharge it back to 12.7v off load (and with the "surface charge" removed).

I think your battery is very low and needs a good solid charge, say 2 days full sun, 10hours on mains or an all day drive. 

A second battery will give you a couple more days in the first instance but once you reach your current status will not be of any use. 

Kev


----------



## bigtwin (May 24, 2008)

How and where is your inverter connected?

If it is connected through a 12V 'socket' rather than directly to the battery terminals, you may be suffering from voltage drop along the cable?


----------



## cabby (May 14, 2005)

Is it the way I read this, using an inverter to watch tv, surely the tv should be a 12v so does not need an inverter.

cabby


----------



## jimedmeades (Jun 9, 2013)

Thank you for your replies.
bigtwin - it is through a 12v socket so could be the problem. Before adding another battery (as space is an issue) I will try re-locating the inverter to as close to the battery as possible and connecting it "direct" and see what difference it makes.
Many thanks.


----------



## nicholsong (May 26, 2009)

cabby said:


> Is it the way I read this, using an inverter to watch tv, surely the tv should be a 12v so does not need an inverter.
> 
> cabby


I agree with 'cabby', but the OP did not confirm whether his TV can be operated off 12v - many can accept either 12v or 230v.

I understand that even when operating from 230v TVs drop the voltage back down to something like 12v. for their internal operating.

So it seems the OP is using an inverter, with attendant inefficiencies, to go up to 230v when a TV could be operated on 12v. One would not run the fridge that way.

Something sounds not right.

Geoff


----------



## jimedmeades (Jun 9, 2013)

Thanks for your input.
I am using the "normal" tv and inverter route for a number of reasons :
I was given a brand new tv. The van has an 800watt inverter already.
I will not pay the extortionate price for a 12volt tv in Portugal.

The tv will not operate at 12v.


----------

