Second Battery

[VanBlanc]

Found out today that the OE second battery is, as I feared, only 85Ah which is no real use. So I am faced with 2 choices;

a) butcher around under the passenger seat and put a 110Ah in their instead - has to lay on its side.

or

b) put another 85Ah under the drivers seat with but will it fit?

 

[chriscroft]

With all the amazing progress that has been made in battery technology over the last few years tesla cars; iwatches etc etc the leisure battery market is still in the dark ages.
I know the batteries in electric cars are expensive about £100/kwh = £10k for a decent sized car. I think a leisure battery at 85ah X 12v = about 1kwh X 50% (leisure batteries only usually give up 1/2 their steady power (max) because of voltage drop) = 0.5kwh, and a decent one costs over £100. So come on Tesla we aren't far off, lets have a 5kwh battery for £500+. I would defiantly have one, and electric car batteries last for many many many cycles.

 

[VanBlanc]

Martyn at Travelvolts tells me;

"You won't need another split charge set up. Get the same battery from VW and do it straight away before the fitted battery gets any use. Join the batteries together using 16 mm cable and a 100 amp fuse at each end on the + cable. Easy enough to get cables from one seat to the other as there is a channel in the floor with some existing wiring in it."

So;

• how much space do I have under the drivers seat - is it the same as the passenger seat?
• can i get the second battery tray and fitting from VW and fit them there?

Pics or workshop diagrams would be great.

BTW I have suggested to him the he joins up but in the meantime here is a really useful post he has made about the Smart Alternator.

 

[VanBlanc]

I was talking to a T6 Kombi owner on Monday who told me his second battery was 85Ah (as was the one on my T5 Kombi). However today I have looked at a T6 panel delivered yesterday and it only has a 68Ah!!

I am certainly not going to just add another one of those - I might as well mod the seat base and go for a single 110Ah.

So have to wait for a chassis number then we can find out what it is but now I'm tempted to consider 2 x low profile 110Ah

 

[chriscroft]

I was talking to a T6 Kombi owner on Monday who told me his second battery was 85Ah (as was the one on my T5 Kombi). However today I have looked at a T6 panel delivered yesterday and it only has a 68Ah!!

I am certainly not going to just add another one of those - I might as well mod the seat base and go for a single 110Ah.

So have to wait for a chassis number then we can find out what it is but now I'm tempted to consider 2 x low profile 110Ah

I hope that smart alternator/split charger puts 100% of juice into it; if its the same as the main battery with stop/start technology holding back capacity; it's all becoming a bit rubbish.

 

[VanBlanc]

Talking to Martin @travelvolts as far as he is aware ATM the ECU sorts out the difference between charging the vehicle battery up to 80% and the leisure up to 100%.

Time will tell but at least if I go for plenty of Ah the fridge will last a while off grid

 

[chriscroft]

Talking to Martin @travelvolts as far as he is aware ATM the ECU sorts out the difference between charging the vehicle battery up to 80% and the leisure up to 100%.

Time will tell but at least if I go for plenty of Ah the fridge will last a while off grid

Hope he is correct

 

[travelvolts]

You have misunderstood about the start battery being at 80%. The alternator doesn't charge it more than 80% unless under regenerative braking. The latter is used to complete the charge process. On the subject of batteries, I would expect the 85 ah fitted by VW is equal to any low case 110 that may be on offer. Especially if it's an AGM.

 

[chriscroft]

You have misunderstood about the start battery being at 80%. The alternator doesn't charge it more than 80% unless under regenerative braking. The latter is used to complete the charge process. On the subject of batteries, I would expect the 85 ah fitted by VW is equal to any low case 110 that may be on offer. Especially if it's an AGM.

But if the alternator only charges to 80%, to allow capacity for the regeneration from braking, it must be possible to park the vehicle up with only 80% capacity in it. i.e if you have been drawing current on a dark cold night, and not using the brakes enough to create a surplus charge, over the actual current draw. At the point you turn the van off, it will only have 80% in the battery. Alternatively on a day when current demand is low, and you have been driving enthusiastically using the brakes, you will be parking up with 100% capacity. I think

 

[travelvolts]

During the regen phase (engine overrun and braking) the output from the alternator is very high to allow rapid charging. I believe it is 15 volts plus.

 

[jonnyboy]

I was talking to a T6 Kombi owner on Monday who told me his second battery was 85Ah

That was me. Nice to meet you. Ended up spending far too much in Absolute Audio

 

[VanBlanc]

That was me. Nice to meet you. Ended up spending far too much in Absolute Audio

I looked at a brand new van on Thursday and it only had a 68Ah AGM second battery - almost good enough for a torch

Going to have to wait until I get a chassis number in a few weeks to find out what is going on with them

 

[jonnyboy]

I run twin Optima PC 1500's in my Land Rover 90 which are 68Ah (one for cranking, one for leisure) and I get about 4 days out of the leisure battery without starting the engine. That's running the fridge continually and charging phones and GPS's overnight. So I was chuffed with 85Ah in the T6. But then we don't usually run lights/anything else in the T6/LR as we're usually camping out.