adding another leisure battery wire up. Have I ballsed up

[Monty don]

So got the leads made to put neg to neg on both batteries and pos to pos linking them in a bank

Then left the two original pos and neg on original battery as they were

Right?

 

[Sandancers]

I think the advice is to wire the two batteries together in parallel, using nice thick wire. Then the positive connection goes from the positive of battery A and the negative connection goes from the negative of battery B.

 

[Monty don]

yes Iv seen that but what difference does it make surly you have a bank and it will charge the way Iv done it

 

[Mikeco]

That’s okay the way you have done it.

 

[Monty don]

ohh good

2 jobs done today also had no charge from solar panel into control unit under seat

It was one of the boot lace conectors

Im now getting a charge through

It was reading about 5 v or is that amps on the main control unit no sun out

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[Lenny HB]

yes Iv seen that but what difference does it make surly you have a bank and it will charge the way Iv done it

If the batteries are next to each other and only two batteries its OK the way you have done it as the difference in charging and power distribution will be negligible. If adding more batteries it is better to do it the correct way then the load sharing is equal between the batteries.

 

[Neil S]

My 2x100 amp are wired this way

 

[thebriars]

The above wiring does not match the standard fitment wiring for my motorhome. Battery A has both +ve and -ve take off to habitation, the second battery is simply linked to the first, though through a fuse.

 

[Neil S]

As opposed to

 

[Lenny HB]

The above wiring does not match the standard fitment wiring for my motorhome. Battery A has both +ve and -ve take off to habitation, the second battery is simply linked to the first, though through a fuse.

As said it is OK for two batteries providing they are next to each other and you don't need a fuse when they are close.

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[thebriars]

As said it is OK for two batteries providing they are next to each other and you don't need a fuse when they are close.

I think I'd trust the manufacturer.

 

[Lenny HB]

I think I'd trust the manufacturer.

As long as it's not Brit built with under size wiring you will be OK.

 

[tonyidle]

I think I'd trust the manufacturer.

I can't imagine why having seen caravan and motorhome wiring over the years.

 

[Neil S]

was told that wiring two leisure battery’s this way meant that they both discharge and recharge equally

 

[autorouter]

yes Iv seen that but what difference does it make surly you have a bank and it will charge the way Iv done it

Yes you are right, both batteries will charge. Many second batteries are wires like this. The method that Neil S describes is very slightly better, in that the small voltage drops in the cables are equalised between the batteries. They therefore are charged and discharged identically.

The way you have wired them, there will be a slight voltage difference while charging and discharging. In the long term this can lead to one battery working harder than the other, so its life will be reduced. But if the wires are short and thick, and the terminals are solidly connected, the effect is small, so it matters less.

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[thebriars]

View attachment 416496 was told that wiring two leisure battery’s this way meant that they both discharge and recharge equally

Negligible difference when they are next to each other. Charging current is certainly not that high and unless you are using an inverter there are no high current discharge currents either in a modern van. Also consider that even the same makes of battery will have different internal resistances, so there will be an imbalance in charge discharge current as a result of that.

 

[Sandancers]

I think I'd trust the manufacturer.

That's what they said on the Titanic !

 

[Ringy]

Hi, I’ve just joined the group having bought our first Mhome last week. There’s an inverter with alligator clips not attached to anything which sits beside a spare leisure battery which is not attached to anything. So I connected the clips to that battery, plugged the TV into the inverter and it all worked. Question one is, what’s the best way to keep this spare battery charged, and how do I test how charged it is. Secondly the main leisure battery (connected to the van battery and solar power) is only a couple of feet away, under the same sofa - any thoughts on why that would not have been parallel connected to the ‘spare’ one to create a ‘bigger’ leisure battery? Thanks in advance!

 

[autorouter]

I know all batteries look much the same, but you're a motorhomer now, and a funster to boot, so we'd better sort that out ASAP. What type of battery are the leisure and spare batteries?

The obvious explanation is that the previous owner never got round to connecting them. Or they may be different types, with different charging profile requirements. Also there is a case for running an inverter from a separate battery bank, because it's easy to run batteries flat with an inverter, leaving you without lights, water pump and fridge.

You can tell approximately what is the battery state of charge by measuring its voltage when it is 'rested', ie no charger or load connected for at least one hour. Just measuring voltage while it is charging or under load will not give an accurate indication. There are charts on the internet to tell you state of charge from the resting voltage. The exact voltages depend on which type of battery (Wet,Flooded, VRLA, AGM, Gel etc.). Do you have a multimeter?

This chart is for standard wet lead-acid batteries.

 

[Ringy]

autorouter - thanks so much for this. I’d need to check for sure what types they are, but on reflection I do like the idea of running the inverter from an isolated spare, which seems to be what this is. Will need to buy a multimeter (assume that’s something to check the charge level) ....and also a charger.....any recommendations in that regard?

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[autorouter]

For measuring voltage, resistance and continuity (broken wire, bad connection, blown fuse etc) any cheap multimeter will be OK. You can get one from Screwfix or Toolstation for less than a tenner.

Charging is a bit more complex. It depends on what you are charging it from. I'd get a multistage intelligent charger for charging from the mains, at home or from a campsite hookup. They charge up quickly, then go into float mode automatically, which keeps it topped up without overcharging.

You mention solar power. You can upgrade your solar controller to a 'dual' controller which will charge two batteries. It's normally used to trickle charge the starter battery, but could equally be used for two separate leisure batteries.

Charging from the engine alternator is another possibility. You could add another 'split charge relay', which is an electrical switch that connects the alternator/starter battery to the leisure battery when the engine is running, and disconnects when stopped. There are plenty of other options, including battery-to-battery (B2B) chargers if you want to get complicated.

 

[Jaws]

I think I'd trust the manufacturer.

The wiring in every Autotrail I have seen ( inc my own ) is woefully undersized.. About the same cross section as is normally found on a headlight ( so spec'd for maybe 4-6a or so ! )

 

[thebriars]

The wiring in every Autotrail I have seen ( inc my own ) is woefully undersized.. About the same cross section as is normally found on a headlight ( so spec'd for maybe 4-6a or so ! )

The wiring on mine is fine, good sized conductors, fused, and decent battery connectors with shrouds.

 

[Jaws]

The wiring on mine is fine, good sized conductors, fused, and decent battery connectors with shrouds.

What year and model ?

 

[thebriars]

Benimar 2019.

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[Ringy]

autorouter - cheers! Will give it some thought, but will probably keep it simple (relatively!) and go for The multi stage intelligent charger for now.