Alternator Upgrade

[Rabbit]

Hi
My TSI Highline has a 180 amp (I think) alternator, but due to my planned audio upgrade I'm thinking it might be wise to increase it to a 250 amp one. How straightforward is this? Where can I get one etc?

The standard alternator is already powering two 4 channel amps that give 970 RMS watts which the van is handling fine (volts drop to around 13.2v), however, I plan to add a sub with another amp that will increase the load by 800 RMS watts at times, so worse case it will be 1770 RMS watts, and that isn't even allowing for what is lost in heat. The current 2 amps are class A/B so will be pulling around 1500 watts at times, the sub amp is class D, so probably 2500 watts total (192 amps at 13 volts) the alternator needs to supply plus all the regular stuff, so a 250 amp alternator should just do it.

 

[Ed Webb]

Wow, that's one way to confuse a human.

 

[andys]

Interesting, not heard of anyone upgrading the alternator on a T6 and didn't even realise it was an option.

 

[Dellmassive]

Good question this. and one ill be interested in. I have a big ICE setup but not installed in the van yet, but we do have mains inverters that will draw over 200amps, hense the interest.

I think 180amp was the max size available from OEM.

but as these vans are euro6 stop/start etc the alternator is smart and its output is ECU controlled on/off/high/low as the ECU determines..

then add the braking Regen into the mix and it starts to get tricky....


so your current setup of amps etc . . . . im assuming your still using the battery current monitor on the negative pole of the battery?

if you are, then im going to assume that the van will "see" the additional current your ICE is drawing and compensate for the volt drop by requesting additional demand fron the alternator (up to a max of 180A)


long story short, we ended up leaving the existing 180amp alternator and smart charging and swapping out the OEM split-charge relay solution for a 60amp DC-DC (from travelvolts) charger that charges a second "battery bank"

we then run out inverters from there, so far 120amp max draw.


so i suppose one option for you is to build a battery bank of red or yellow top batteries in the back, add a big CAP across it. then use a 60amp DC-DC charger to keep the battery bank topped up. The run all your amps from that battery bank. not sure how much run time your get before the battery bank drops down.

only other option i can think of is modify the van to bin-off the euro6 stuff and go OLD SKOOL with an old non ecu controlled alternator that just uses an internal regulator to minitor the volt drop and output accordingly.

ill be interested to see other peoples options.

 

[Rabbit]

Fair enough
I think I need a larger 250 amp alternator to ensure that the amps get enough juice. Can it be done?

Been reading about smart alternators which I assume the t6 has, so would I maybe be better looking at higher AH battery’s instead?

 

[Deaky]

I wouldn't think it would be an issue unless you're going to be running all the amps on full tilt all the time.

 

[Rabbit]

Good question this. and one ill be interested in. I have a big ICE setup but not installed in the van yet, but we do have mains inverters that will draw over 200amps, hense the interest.

I think 180amp was the max size available from OEM.

but as these vans are euro6 stop/start etc the alternator is smart and its output is ECU controlled on/off/high/low as the ECU determines..

then add the braking Regen into the mix and it starts to get tricky....

I came across the 250 amp alternator being the max size for a T4, which probably explain why I'm struggling to find one for the T6. Having one custom made seems to be an option (though I haven't found anyone yet who can), the trouble is the darn smart feature

so your current setup of amps etc . . . . im assuming your still using the battery current monitor on the negative pole of the battery?

if you are, then im going to assume that the van will "see" the additional current your ICE is drawing and compensate for the volt drop by requesting additional demand fron the alternator (up to a max of 180A)

As far as I am aware yes, i'm getting the voltage readings via the Alpine head unit which is getting it from the CAN system. The amps are drawing enough power now that the start stop system rarely kicks in anyhow so its not all bad

long story short, we ended up leaving the existing 180amp alternator and smart charging and swapping out the OEM split-charge relay solution for a 60amp DC-DC (from travelvolts) charger that charges a second "battery bank"

we then run out inverters from there, so far 120amp max draw.


so i suppose one option for you is to build a battery bank of red or yellow top batteries in the back, add a big CAP across it. then use a 60amp DC-DC charger to keep the battery bank topped up. The run all your amps from that battery bank. not sure how much run time your get before the battery bank drops down.

only other option i can think of is modify the van to bin-off the euro6 stuff and go OLD SKOOL with an old non ecu controlled alternator that just uses an internal regulator to minitor the volt drop and output accordingly.

ill be interested to see other peoples options.

As my 5 week old van has broken down a 2nd time (power steering pump) I'm very keen to alter the euro6 stuff. Caps and dc-dc charger I will look into thanks.
Just been told my van will be out of action to the 5th, so I'll ask VW about my options now as they have sorted out a courtesy vehicle.

 

[Rabbit]

Well according to vw it can’t be done or rather it’s not recommended. I do have the 180 alternator and whilst upgrading a smaller alternator to the 180 is doable, going above that would mean altering the engine management to outside of its design so would void the warranty.

Will have to look at other options instead.
Ps how do you diesel owners live with the noise need to cover up the mpg screen though

 

[Dellmassive]

Yeh thought VW would say that.

Looks like your going to have to go down the DC-DC charger, battery bank, cap, route.

Travelvolts does a 60amp recarc charger. But I'm sure I've seen a 100amp one somewhere.....sterling maybe?


I'd be interested to see what your pulling already with your setup now? Amps wise that is.

Have you got a current clamp meter to get any current flow readings?

Also got any pictures of your setup?

 

[Rabbit]

Even better i've got my own thread
Its All About The Sound!
These are the amps though fed by 0 gauge wire (the tape was added by me for marking/securing), black box on the bottom is a Rainbow DSP
Don't have a current clamp meter, but then I don't have my van at the moment...
However, they don't cost much so I'll sort one out as I'm curious too and as soon as I get the van back I'll take a reading and post back.

Gives me time anyhow to google dc-dc chargers and battery banks, caps I already understand which will help with the planned sub install (would love a 15 inch!).

 

[Rabbit]

Yeh thought VW would say that.

Looks like your going to have to go down the DC-DC charger, battery bank, cap, route.

Got my head around battery to battery (dc-dc) chargers now, so thanks for the heads up

A 15 inch sub is a pipe dream, but a 10 or 12 inch needs around 800 watts which a 60 amp dc to dc could just cover at 13 volts. So running the sub amp off a separate battery with a capacitor to handle the big pulls charged up by a dc to dc seems like a solution that will work. The largest I have found so far is a sterling 120 amp, which would cover the current but not the added sub amp, so see little point in forking out the extra for that, would cover a 15 inch...

Now just got to figure out where the sub could go

Worth it in the end, but boy is car audio a pain to install

 

[t0mb0]

Surely, your amps will never pull anything like the rated power continuously. I can’t imagine you will have a problem with the standard alternator.

 

[Rabbit]

Surely, your amps will never pull anything like the rated power continuously. I can’t imagine you will have a problem with the standard alternator.

Trouble is that the current amps are class A/B, which means they sound wonderful but aren't very efficient. If my amps are supplying 500 watts to the speakers another 250 to 375 watts is heating the back of the van, so 500 wats output means 750 to 875 watts being drawn from the battery, working on 13 volts that's 57.69 to 67.3 at times, when it's playing a load and heavy track then its going to be more like 700 watts out 1225 in (or more) = 94.23 amps draw. I'm going to get a current clamp to check 1st before I do anything, but I would be surprised if there was enough left over for a sub amp when the lights, wipers, air con etc are all running. If I'm lucky my figures a way of which would be great, hope for the best plan for the worst.

 

[Dellmassive]

I've got a few of these in my testers kit.

https://www.amazon.co.uk/UNI-T-UT21...lamp+meter&dpPl=1&dpID=41sD0XebR4L&ref=plSrch

Whatever you choose just make sure they meter DC current say up to 100amps. Because the cheaper ones only do AC current or very low DC current.

I use a few of them as you can watch where the power is going.

Ie:
Alternator output.
Amps fuse block input
Van fuse box feed.
Battery charge /discharge.
Etc etc Etc.

Also have a look at my thred on here about stop/start/Regan and the Aux battery charging. I've got some detailed charts and graphs showing the voltage swings of the alternator output and the 15v regen charge your amps will see when braking.

 

[Rabbit]

Can you give a link to the thread? Start/stop seems to come up loads

Thanks for the tester, i'll order that one

 

[Dellmassive]

Can you give a link to the thread? Start/stop seems to come up loads

Thanks for the tester, i'll order that one

heres the link with the stop/start/regen charts >>>>>

Stop/start...regen...smart Alternator... Dc-dc Charger For Leisure Battery Or Not?

 

[Rabbit]

heres the link with the stop/start/regen charts >>>>>

Stop/start...regen...smart Alternator... Dc-dc Charger For Leisure Battery Or Not?

Interesting read Though I'm still trying to get my head around it all.
As far as I can tell to preserve my warranty I need to get VW to fit the leisure battery system (but specify an AGM battery), then upgrade the relay switch to a dc to dc myself.

 

[Dellmassive]

I think your find they wont do it, or if they will it will cost the earth.

your warranty will cover your "as fitted" kit . . . so if you haven't already got the leisure battery setup you can always add it yourself and shouldn't effect the warranty providing you done it right..

you will be better off just fitting your own DC-DC charger and battery bank.

the main bits will be . . . . . .

- run new feed from the main starter battery to feed your new DC-DC charger.

- install a new switch feed from the BCM (for switching the charger on/off during restarts), or just connect a feed wire direct to a ignition switched feed (middle dash fusebox center line of fuses)

- fit new battery bank

- use the correct gauge cables and fuse everything correctly

- use proper ground connection/cable gauge.



the factory kit uses a 80amp supply fuse with a 100amp split charge relay (controlled via the BCM). (I've binned this off in the passed and just run in my own thicker cables)



If you go for a DC-DC charger then you can use any battery and will not need the AGM versions.

Travelvolts has some kit available and advice, have a look at his split charge section in the link below. . . . . .


Electrics | Travelvolts

https://docs.wixstatic.com/ugd/d959f6_bce9d79e040b4c72a73cb9e883b45929.pdf

 

[Rabbit]

My concern is just in regards the alterations needed to the engine management software so as it knows about the extra battery. I have a vcds device already, but I don’t know what boxes to tick/untick.

Thanks I will take a look at the link

 

[Dellmassive]

Good question, im sure the BCM must a feedback circuit from the leisure battery to monitor its voltage ( . . . maybee . . . . )


one odd thing i did notice was that the OEM leisure battery had a second cable connected.

it worked out to be a feed wire via a fuse under the passenger bench that supplied the additional 12v outlet socket on the top of the dash.

when i was installing USB charger sockets (posted in another thread on here) i noticed that the 12v sock on the top of the dash has TWO cables connected to the center pin?

one was obviously the feed wire from the fuse,

but i never sussed out what the second wire done? . . . .

i just assumed it was a feedback wire to the BCM for monitoring the leisure battery voltage .?



anyway all that said . . . . . you wont need to adjust the BCM settings if you fit a DC-DC charger. you just take a feed from an ignition switched live (plus main supply from the battery) and connect it all up.

the DC-DC charger will just draw current from the alternator/starter battery as your amps do now.

the BCM will monitor the extra current draw via the sensor on the negative battery post and adjust the charging characteristics as required to keep up the supply demands.

the cleaver bit is the DC-DC charger will use Boost/Buck converters internally combined with a 4-7 stage battery charger circuit to charge your battery bank as required.

and it will only supply up to its max rated current draw from the VAN, so the redarc 1240 will supply a max of 40amps into your battery bank.


when your running you amp under load they will take say 40amps from the redarc and the rest from your battery bank, up to the max you can draw at which point you voltage will sag,

a cap will help sag on the heavy bass drops but wont help with volt drop due to drawing to much power.

if when your hitting it hard you get too much volt drop, then you need more batteries..... but were talking serious wattage now.



this is why you need a current meter to see what amps your pulling . . . .



have a quick look here >>>>

and here >>

just remember ohm law I=V/R and power equation W=VxI

so a 1000w amplifier draw at 13vdc is (1000 / 13 = 76.9amps draw) (W/V=I)

so you need to make sure your battery bank can deal with a 80amp draw for 1000watts (160amps for 2000W) of power. (but for how long will you be hitting it hard, 10 seconds. 2mins?. 10mins? 1hour? 4hrs?)


i remember i was driving to Bristol one time and was playing it loud, for about and hour (1000wats) and killed the alternator... took it to a garage for repair and the mechanic said it was totally roasted all blue and burned-out/meted......!!!!

turned out it was only 65amp alternator and i was drawing the max from it, over the 1-2hrs it just melted itself...... but that was a one off.


think i got all that right, but im sure ill be corrected on any slip ups.