Disability hoist drains leisure batteries

[yossarian]

Hopefully the tech guys at factory will have some answers....provided the dealer has asked the right questions.
I had to correct one of their assumptions today as to why they thought the hoist would pull massive amounts of power.
They said a hoist that was lifting a chair and a person sitting in that chair would require something more than the leisure batteries could provide.....
I pointed out that these hoists only ever lift the chair and they cannot ever lift both just by the very nature of the strapping lift attachment ....they are designed for upto 200kg...ours is only around 95kg so well within the capabilities of this particular model.

The hoist is doing a similar job to the hydraulic roof in the ocean.

Back of the envelope calculation:. Lifting 100kg by 0.6m = 588J. Say 50% efficiency and 20s to lift equals 58W for the 20s. A shade under 5A.

Usable battery capacity is about 900Wh and lifting the hoist will use about. 0.32Wh

Physics 2 dealer 0.

 

[ClaudeVanJan]

Also they are widely fitted to numerous new vehicles under the Mobility scheme, without as far as I can see, any voiding of the manufacturers warranty.

In fact, with your system, if it is pulling less than 10 amps then it could have been wired to a 12v socket plug and use the boot 12v socket. I wonder what the Dealership would have said then. Those sockets are fused at 20 amps on the T6.1 so I gather.

I don’t mind paying them but only after they are able to give me a reason or possible reason why these 2 fuses should blow … at least then I would know if we need to change anything to make sure it doesn’t happen again

 

[yossarian]

I don’t mind paying them but only after they are able to give me a reason or possible reason why these 2 fuses should blow … at least then I would know if we need to change anything to make sure it doesn’t happen again

One fuse has blown recently as your front leisure battery has been charging and your other leisure consumers have been working.

The most likely time for the fuse to blow is when someone is repairing the cube fuse. Recall @WelshGas pointed out the need to wrap the disconnected lead in a rubber glove or similar? That's a trap that's easy to fall in to.

The cube fuse is a weak point on this electrical system. I wouldn't get excited about it blowing from time to time. It could be some mistiming with the stop start system, alternator startup or similar.

 

[ClaudeVanJan]

One fuse has blown recently as your front leisure battery has been charging and your other leisure consumers have been working.

The most likely time for the fuse to blow is when someone is repairing the cube fuse. Recall @WelshGas pointed out the need to wrap the disconnected lead in a rubber glove or similar? That's a trap that's easy to fall in to.

The cube fuse is a weak point on this electrical system. I wouldn't get excited about it blowing from time to time. It could be some mistiming with the stop start system, alternator startup or similar.

That makes sense and I can see how it could have occurred… when I took the van back to the converter he disconnected the lead to get to the cube fuse …. He didn’t wrap anything, took off the cube fuse to show me it was blown, reconnected to the battery but left the big red lead sitting ontop of the battery.. on the drive home I did recall the WelshGas point about wrapping so I did that once I was home … but perhaps that was too late

 

[ClaudeVanJan]

Dealer says fusebox part on back order of around 2 weeks but can still drive van until then.
we have a lot of trips back and forth from Newcastle to Edinburgh for the festival over the next 2 weeks so….
I’m assuming then that I’ll now have no leisure batteries charging so will need to monitor and put on battery charger after each trip….
i now also have a new cube fuse but am guessing there is no point fitting it if the main 100a fuse is also gone…
is there anything else I’d need to consider
luckily the van will just be used for transport up, hoist and drop the scooter off and head back home

 

[WelshGas]

Dealer says fusebox part on back order of around 2 weeks but can still drive van until then.
we have a lot of trips back and forth from Newcastle to Edinburgh for the festival over the next 2 weeks so….
I’m assuming then that I’ll now have no leisure batteries charging so will need to monitor and put on battery charger after each trip….
i now also have a new cube fuse but am guessing there is no point fitting it if the main 100a fuse is also gone…
is there anything else I’d need to consider
luckily the van will just be used for transport up, hoist and drop the scooter off and head back home

You should refit the cube fuse as both Leisure batteries will then be charged when on Mains Hookup and the 2 batteries will be balanced.
Without the cube fuse Mains Hookup would only charge the front Leisure battery.

 

[yossarian]

You should refit the cube fuse as both Leisure batteries will then be charged when on Mains Hookup and the 2 batteries will be balanced.
Without the cube fuse Mains Hookup would only charge the front Leisure battery.

As usual just check you don't have a large voltage differential before replacing. One of the battery manufacturers suggests you should see a 12.4V before any hookups.

Is your dealer waiting for a 100A fuse? I can give you a Chinese version when you are in Edinburgh

 

[ClaudeVanJan]

You should refit the cube fuse as both Leisure batteries will then be charged when on Mains Hookup and the 2 batteries will be balanced.
Without the cube fuse Mains Hookup would only charge the front Leisure battery.

when I pick van up I’ll check if cube fuse has been replaced … if not I’ll replace with the one I have

 

[ClaudeVanJan]

As usual just check you don't have a large voltage differential before replacing. One of the battery manufacturers suggests you should see a 12.4V before any hookups.

Is your dealer waiting for a 100A fuse? I can give you a Chinese version when you are in Edinburgh

I’ll ask for details of exactly what it is that is on back order then let you know .
also I’ll double check for any voltage differential …. Assuming if none then ok to hook up but if there is large difference then use charger to bring lower battery back in line
ill let you know about the 100a fuse but either way it would be nice to put a face to an avatar and say thanks

 

[ClaudeVanJan]

The saga continues ....the dealer charged me £337 to replace the master fuse block (their description) which apparently sits next to the front leisure battery...they argued it wasn't a warranty issue as it was possible during the hoist fitting (18mths ago) that the positive terminal had accidentally touched the chassis...I couldn't argue any different so paid it.
So in their words everything is now working as it should......only it isn't ...
Van recently returned from trip to Ipswich and I then put it on hook up for 14 hours...
Console display still shows 0hrs
Display shows 12.70v
rear meter reading was 12.72v
front was 12.81v

Incidentally the technical question the dealer was going to pose to VW didn't actually happen...they dont really care do they ??

So I'm going to bypass the dealer and try to engage with VW Customer care at central office to see if I can find a solution

 

[yossarian]

Ping back if you want to start troubleshooting again.

 

[ClaudeVanJan]

Ping back if you want to start troubleshooting again.

thanks ...that would be good now that the 2 blown fuses have been replaced.
I won't have much access to the van til Thursday as Lee is using it this week so I can troubleshoot then...cheers

 

[yossarian]

Console display still shows 0hrs
Display shows 12.70v
rear meter reading was 12.72v

Rear leisure battery on multimeter?

front was 12.81v

Front leisure battery or starter battery?

 

[ClaudeVanJan]

Yes rear was multimeter below the cube fuse
Front was leisure battery.

 

[yossarian]

Yes rear was multimeter below the cube fuse
Front was leisure battery.

Voltage difference front to back

0.1 V difference suggests the cube fuse is blown (again). One could use Ohms law to work out what current you need over a low resistance connection to produce 0.1V difference but the bottom line is the fuse is probably blown or there's some resistance in the path between the two batteries. If you look at the linked photo this is a good way to prove the fuse.

https://vwcaliforniaclub.com/attachments/9e5792f0-b064-4755-aacb-65b05019b414-jpeg.99737/

Here we see 0.77V across the fuse whis is basically impossible if the fuse is intact. Most modern meters can do a continuity test with the probes as pictured without getting confused by the batteries.

So I would confirm if you really have a 0.1V difference front to back. If so you probably need a new fuse. VW appears to be fitting a 100A fuse to the latest MY23 vans. Consider uprating the fuse to this value if your fuse issue is not related to poor fitting.

0 hours on the display

The hours display on the unit is flakey at best. It does suggest a low state of charge or low state of health on the sensors. One sensor is miswired to obtain its voltage from the wrong battery (a VW mistake). Once everything is working a reset of both sensors will probably get this metric displaying normal VW (inaccurate) numbers.

Control panel shows rear battery voltage

This is pretty weird to be honest. I can't see how this could be miswired. I'd double check the reading. If accurate then something weird has happened most likely related to the new fuse holder or whatever was replaced.

Previous recommendations which I'm not sure if you've had sorted:

• Move hoist positive above cube fuse to attach it to the main leisure bus.
• Consider rewiring the rear sensor to match current model years.