Leisure batteries wired wrongly/differently

Effectively you now have 3 leisure batteries therefore approximately 3 times storage of electricity. A fully charged battery should have an output of nearly 14 volts ( better quality battery has a higher max volts ie 13.9 volts, poorly made ones ie 13.2 volts ) . Most MH gears stops working effectively when the volts drops to 12. Your idea is something that I am considering to do in our MH but there one issue that I need to research.
My concern is now you have 3 batteries to recharge with a system that has been designed for charging 1 battery. Will the charging demand be too much from the alternator on the engine and destroy it? Your local auto electrician who repairs starter motor and alternator should be able clarify this. Best of luck.
Ps, the same point might be an issue for the mains charger (240 volts)

It may be putting out the correct voltage, but how many amps is it putting out, as far as I remember the recommended thing is to not have the total amp Hr of the batteries greater than 10X the charger, so you have 1@110 and 2@135 = 380a/Hr so you need a charger putting out 38amps. This isnt taking into account the charging of the engine battery if its linked in.

A good bit of info here.
The 12volt Side of Life (Part 1).
AND.
The 12 volt Side of Life Part 2.

Cheers Davy, but I am not trying to keep the starter battery charged, Motorhome is used often so no real need.

My idea is to keep one main leisure battery charged by using two higher AHR leisure batteries, so far it has worked great after one weekend.

As above, not got a clue if it will be successful long term or even whether it is doing what I think it is doing and is just basically 3 x leisure.

Not great in theory, grand in practice, if all batteries are holding charge independently and using decent cables.
Did it often wit 2 different batteries. No probs!

I don't think there is a need for a North- South Electricity Inter-connector that causing all the planning shytte down here.

Just Ring Douz and he'll power up to the whole island for a week with that of power kit!

was considering an isolator switch, I'll fit one now.

Nearly sure there is a fuse from alternator, in fact there is, it was blown on a jump start before we purchased it. Which seems to be a regular occurence for Motorhomers if they need to jump start the engine battery.

P.S. The Yankee has gone, back in our Itineo now, long story

You just answered a question I have been asking for a few years, what is the benefit of a B2B when it seems a split charge relay is doing the same thing.

An answer at last

Is there a way too lets say........ use the first leisure and only have it topped up by two or more leisures when needed? by fitting a relay or some sort of switch or would that not work? or absolutely no point?

Sort of like how a solar panel works only having the obvious differences.

Not really practical, see my later post.

Don't see the point.

The three batteries connected together gives you way over 300AH, the system works automatically by charging and discharging through your existing wiring, you do not need to measure anything, or switch anything

OK lost me somewhere
If you are looking at a 12v mains charger when it is charging it shows anywhere between 20 to 30v output which are needed to put the amps into the lesser 12v battery. The alternator also operates above at somewhere 14 to 15 but with bigger amp output
If you connect batteries they will discharge at the same rate i.e. 3 120amp batteries will last roughly 3 times longer than 1 120amp battery. Batteries of different amp rating discharge at different rate hence the reason they always say when you connect batteries together that should be the same amp or
as near as possible, also a similar age as a older battery will drain a newer battery without taking a charge itself and in time will reduce the capacity of the more powerful battery to the lesser one even in good ordeer
So if you have three batteries wired with suitable cable why not just use them as i cannot see any advantage in not.

Dont know if any of this makes sense as i said i am confused with many of the points I jiust dont see how a 12v leisure battery can be used to charge another

Will some please explain in simple words
David

Not sure, but it's jump start leads so thought it should be heavy enough.

Very well explained.

Must add........ when I put the volt meter on my three, they all read the same.

If they are the diameter of your small finger they'll be OK

" No idea on the technical electrics 'know how' but the idea was, the two 135ahr will feed the 110ahr and keep it charged, sort of like a power reserve and working similar to a Solar Panel. "

You should not mix up mix old and new or different amp /hr battery s ,because the will work at the lower rate ( which is rather like what you said above ), in stead of having a total of 380ahr you will be closer to 310ahr .
Two things to consider.
1st--This only a problem if you were aiming for the larger capacity, you still have a sizeable chunk of power
2nd-- Logic would be the 110 will die first hopefully after a long time, leaving you with two battery's that will now only work at the lower level because that's all they ever did ,then your back to square one.
Helpful or not ?

If your charger is showing those volts its a old timer ,modern smart 5 stage & float chargers show nowt until connected to a load and will step volts/current up or down depending on whats required.

Most of the new ones will as they pulse charge batterys that have been deep discharged,all depends on make and model.

Heavier output alternators are available as some vans come with them fitted as standard.

I am just back from my local auto electrician and got a good education. Our base vechicle is a 2010 ford transit and over the last 6 months I have felt it was a bit lazy starting and the leisure battery was not lasting for two nights. Both batteries were reading approximately the right voltage with a meter.
This morning the alternator was tested first and paased with an output of 14.5 volts and a maximum power of 150 amps per hour, ( typical model found on most vans).
The engine battery was tested using a duty cycle load tester and found that it is only storing 60% of its capacity. The leisure was marginal better at 75%.
When we purchased the MH 18 months ago two new batteries had been fitted and we have only done about 6000 miles since.
Here is the explanation as how this has happened.
Modern diesel engines as designed to run every day and there is various things that drawing power 24/7, such as imobilisers, radio, etc. I our case the engine battery is becoming partly discharged after a couple weeks idle , so when the engine is started the alternator is sending most of it output to the engine battery to recharge it and this cycle of surging power has killed the battery.
The solution is now fit an insolation switch on the engine battery whenever parked up for a couple of weeks.
My leisure battery is located under the floor in the garage and it been exposed to outside temperatures, we are going to warp its box with some foil insulation to protect it from the cold.
We have space under the drivers seat to fit a second leisure battery which about 6 meters from the existing leisure battery which can be done.
Link both batteries with some heavy cables, say 50mm square, size of baby finger, change the existing earth cable on main leisure battery to similar size as above but route it to the main earth point on the engine instead. This allows a better flow of electricity with less risk of power surges.
The mains charger has an output of 16 amps per hour and will not be affected by two batteries to charge except it will take twice as long.
It will be a month or so before I will any of this work but I will post the results. Cheers

you'll be able to sell it on as a contribution to the grid soon

Ally

See links below for another explanation

http://www.12voltplanet.co.uk/split-charging.html

http://www.12voltplanet.co.uk/…rgers.html