Renogy and Eco Worthy ( as an example ) do substantially smaller LiFePO4 lithium batteries compared to old lead acid based.

Believe me, changing to a lithium leisure battery is a no brainer nowadays. AGM is dead.

One of the best upgrades I have done with my van. 👍

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Hi, I have an old T4 Autosleeper Topaz..i currently have a small 90ah AGM battery under the bonnet with my main battery. I want to upgrade to Lithium without spoending a fortune. Ive been quoted 3k for an upgrade which is way too expensive. With my model im very restricted with physical space unless the bettery is moved to the rear cupboard.

Im not sure what to do..my 90ah agm battery just isnt powerful enough and i really need to upgrade.

Has anyone else been in a similar situation?..ive attached pic of under bonnet current battery.

Thanks View attachment 235358

I have done just that in my Topaz. Found one of my earlier posts below with some pictures that might help ..

https://www.vwt4forum.co.uk/posts/6752309/

 

Clark this is really useful advice thankyou. So just to be clear this is doable then if I also get a DC to DC charger fitted over the current split relay i have..? Can i still have the lithuim battery in place of the Agm in the engine bay?

Whenever i speak to a company everyone is telling me different things..they either want to sell me a £3000 upgrade or they are sdaying it wont work properly...most havent dealt with an old T4 so im not sure thats correct but you seem to have done what i want to do!

 

Yep - you can certainly drop a lithium in place of the existing AGM if the dimensions work. My Fogstar drift 105 was actually a little smaller than the 95aH AGM it replaced. I only moved it as the double battery tray had rotted, and I had created some space under the bench seat by replacing the gas blown air heater with a diesel heater installed under the single seat by the sliding door.

As a minimum you will need to pull the split charge relay out (no need to remove cabling) and add a decent B2B charger. I am a bit a Victron/Fogstar fanboy, as I live off grid and have two large Victron based solar systems with Fogstar battery storage, but Renogy and Ecoworthy are pretty good as well. The original autosleeper cabling is a bit weedy, so I would suggest upgrading that to at least 10mm or 16mm if it will fit.

If you use the electric hook up, then the original mains charger ideally needs upgrading as well - again I have used Victron. Solar is a good addition, but not essential if you're moving on regularly as the B2B will keep things nicely charged. Guess what, I have Victron solar on mine 🙂

I reckon I spent less than £800 including B2B, mains charger, lithium 105aH, smart shunt, and solar using premium kit.

 

This is really helpful thankyou so much. I run a fb group just for the Topz, Trophy, Trident and Talent -(Log into Facebook) we have nearly 3k members now and we have several members that are trying to do this and most are being told by garages that the system wont charge a lithium battery properly - i've been told several times too. My van is older than yours - its a 1995 2.4 Topaz.

To complicate things the small onboard system that i have isnt working properly. I have a 90ah new AGM battery with a new Victron solar controller and a small solar panel on the roof. It runs everything on board fine, but when i plug anything else into it - such as a 12v compressor fridge - it runs it for a short while but then comes up with low voltage error on the fridge - even though the Victron app is saying the voltage is 13v on the battery..so something is wrong somewhere as i believe it should at least power the fridge for a small amount of time. Ive tried it with other things too and its definately my system.

Ive found a decent coversion company in South Wales and they are the only ones that have said this needs to be looked at as something isnt right somewhere - before i spend money on a bigger battery which will mask the problem. So this will be looked at in next 2 weeks and I will show them your message here to help them with putting a new system in my van once my system is sorted.

Youre very welcome to join the grouip if you use FB - im sure i will probably be asking you more questions on here so i hope thats ok!

 

Look at the wiring to the fridge. (And sockets)
I bet it's really thin, as the spec says they take around 3.5 amps when running.
BUT.....they take around 30 amps when the compressor kicks in. (only for a fraction of a second).
This causes a massive voltage drop, the compressor takes huge current and doesn't "spin up" in time, then the circuit trips and says low voltage.
Cable should be at least 6mm (10mm if the cable length is more than 3 metres total).
Afraid it's a common thing when wiring these fridges up.

 

Thanks for this - i had those long cheap Amazon 12v extension things plugged in - i unlugged all of them, plugged the fridge straight into the direct 12v socket and it works fine!..so my system is ok - its those cheap thin wire extensions ive got plugged in thats dropping the voltage too much. I am going to upgrade my battery but at least this means I dont have to get the conversion company to test the system to see whats wrong

 

I would recommend you do not install a lifepo4 in the engine bay. I would recommend you move the installation inside with a battery box vented instead, and use appropriate sized cabling to accommodate the length to ensure no voltage drop, which is vital for DC2DC chargers to operate optimally.
The main reason for lifepo4 not being installed in the engine bay is due to the potential of high temperatures that will ultimately shorten the life and capacity of the battery, as lifepo4 does not like charging in extremes, be it + or - temps. This isn't just my personal opinion and is fact, there have been some big court cases around manufacturers claiming to have engine bay lifepo4 batteries and being proven otherwise. One example documented on YouTube with DCS.

 

I would recommend you do not install a lifepo4 in the engine bay. I would recommend you move the installation inside with a battery box vented instead, and use appropriate sized cabling to accommodate the length to ensure no voltage drop, which is vital for DC2DC chargers to operate optimally.
The main reason for lifepo4 not being installed in the engine bay is due to the potential of high temperatures that will ultimately shorten the life and capacity of the battery, as lifepo4 does not like charging in extremes, be it + or - temps. This isn't just my personal opinion and is fact, there have been some big court cases around manufacturers claiming to have engine bay lifepo4 batteries and being proven otherwise. One example documented on YouTube with DCS.

thankyou - yes a few people have said this - im going to see a garage in few weeks time to discuss upgrade. Changing subject have you had your 2.4d turbo upgraded??

 

I'd highly recommend the Renogy 50A DC to DC charge controller. I have one on my T3 syncro and another on my T4 syncro high top. If nobody has explained why you need to toss your existing relay and use the DC to DC controller, it is because the LiPo battery runs different voltages than your main lead acid (start) battery.
I also put in a Renogy 10A charger and hooked it direct to the LiPo battery. I tried running it through the solar input and that was incompatible. Instead I put in a switch so when on shore power I can turn it on if needed. My T4 came with a roof mounted solar panel and it runs through the charge controller.
The beauty of the Renogy is that when hooked to a solar panel it prioritizes the house battery for charging but when that is full it will direct the charge to the start battery.

Anybody in need of a stock German 240 volt battery charger? My T4 had the 240 set up and it's been converted for 120 here in the US.

 

Hey, i did this to my pop top cockburn.

Any questions, please @ me or if you're at lattitude come find our Manx flag and share a wine.

Renogy dc to dc with mppt.
200w panel (all i could fit on roof)
2 big wires from van battery to the renogy + & -
You have to do some calculation for the awg size depending on distance.
Ring terminals on amazon
Termination crimp on amazon
Wire strippers
Heat shrink for tidying
Fuses off amazon, again fuse for your wire not your load! You want the fuse to pop before the wire goes up in flames.
A few of those resettable trip switches to make working on system or turning it off easy.
Bus bars for termination of + and -
Mini fuse box for lighter loads like fridge, i bought a 16 slot one, in hindsight a 6 will do nicely for what we need in the older vans.
Maybe some 30a leisure relays (i put my fridge on one) and kept the original cockburn control panel.

TIME + PLANNING and also a basic knowledge of DC circuits, paper to draw stuff out, ruler or string to measure wire.
You'll need knee pads and some zip ties to keep stuff tidy.

I traced the circuits using a multi meter and cut the fused wiring for fridge (which was by the main battery) and pulled it through, reused most of it for the relay trigger and put new, more modern and bigger wire in for the fridge which i also upgraded to compressor (5 days with no sun on 100ah LifeP04).

I have the settings dialed in for the cheap lifep04 12.8v battery, you just need to watch it doesn't drop passed 12.8v as thats pushing towards 10% remaining and that renogy dc hates low voltage meaning you'll need to unhook and charge with a special lifep04 charger, £30 on ebay.

Ramble over - i promised a writeup when i did this last year but I've been making changes and stuff since + had some real world use.
Will do one when back from festival where everyone seems to be running their engines and I'm not because this is the way!

 

Don't forget that LiPo also doesn't like cold temperatures. Doing a lot of winter camping then you might need a battery heater, heated battery, or locate it to a warm area in the van. They will discharge at cold temps but will not charge below a set temperature. I think my BMS cuts off at around 32F.

 

I've used mine all winter, albeit it was a warm one but the temperature where i put it was always above 8 degrees, even when it was -2 outside at night partly because the dc-dc and all wiring stuffed into a small space so residual heat just ticked it over nicely.
You could just grab some slinky ducting and put your heater vent towards where the battery is for 5 minutes and that would resolve charging problems.