# Can't charge the leisure battery from the engine **Source:** https://vwcaliforniaclub.com/threads/cant-charge-the-leisure-battery-from-the-engine.60810/ **Posts:** 25 --- ### K — 2026-01-20T17:44:17+0100 (Jan 20, 2026) I've just purchased an ex demo T7 Ocean Diesel and after the 2 hour drive home from the dealers I checked the battery levels and was suprised to see that the leisure battery was on 20%. I was expecting it to be full after such a long drive. I've tried and EHU and it charges fine that way. I then went back to trying to charge it using the engine by starting the engine and checking the display. As the images show below, at first I got the expected behaviour, engine power was providing 30A and the leisure battery recieving 25A. But after a few seconds the engine power dropped to OA and the leisure battery quickly when back to -0.2A (the image shows 0.7A but I was abit quick with the camera!) . It would appear that I am unable to charge the leisure battery from the engine for longer than a few seconds. Any suggestions? I'm new to the vehicle so could I be making a silly mistake somehow? ![1768927082604.png](images\1768927082604-png.143482 "1768927082604.png") ![1768927174141.png](images\1768927174141-png.143483 "1768927174141.png") --- ### — 2026-01-20T17:50:07+0100 (Jan 20, 2026) 13.3 v is fully charged with 25hours of estimated charge remaining! (edit: AGM bat) What does the LB & starter show after 30 minutes with engine fully switch off and no load on the LB , I.e. nothing being used or plugged into 12v sockets --- ### K — 2026-01-20T18:08:19+0100 (Jan 20, 2026) > [Perfectos said:](/goto/post?id=769781) > > 13.3 v is fully charged with 25hours of estimated charge remaining! > > What does the LB & starter show after 30 minutes with engine fully switch off and no load on the LB , I.e. nothing being used or plugged into 12v sockets > > Click to expand... Unfortunately since doing the last test I have had the vehicle on EHU. I'll take it off the EHU, take a picture, then leave for 30m, take another picture and report back! Thanks for the response. --- ### K — 2026-01-20T22:08:03+0100 (Jan 20, 2026) > [Perfectos said:](/goto/post?id=769781) > > 13.3 v is fully charged with 25hours of estimated charge remaining! > > What does the LB & starter show after 30 minutes with engine fully switch off and no load on the LB , I.e. nothing being used or plugged into 12v sockets > > Click to expand... So the following 3 images are with the engine off, no load and no EHU. The first at 5:10pm, the second at 5:52pm and 3rd at 8:34pm. Does this information help explain why I cant charge the leisure battery from the engine? Thanks again for your help! ![1768943053777.png](images\1768943053777-png.143501 "1768943053777.png") ![1768943094110.png](images\1768943094110-png.143502 "1768943094110.png") ![1768943128082.png](images\1768943128082-png.143503 "1768943128082.png") --- ### — 2026-01-20T23:50:50+0100 (Jan 20, 2026) > [kevin1000 said:](/goto/post?id=769799) > > So the following 3 images are with the engine off, no load and no EHU. The first at 5:10pm, the second at 5:52pm and 3rd at 8:34pm. Does this information help explain why I cant charge the leisure battery from the engine? Thanks again for your help! > > > [View attachment 143501](https://vwcaliforniaclub.com/attachments/143501/)[View attachment 143502](https://vwcaliforniaclub.com/attachments/143502/)[View attachment 143503](https://vwcaliforniaclub.com/attachments/143503/) > > Click to expand... Both batteries are fully charged, so when you start the engine the Leisure battery will show an initial charging that rapidly drops to Zero as the electronics determine the Leisure batteries are fully charged. Where did you get this 20% reading you mentioned in your original post? The Hours calculation for the leisure batteries is based on a spot reading of the amps being drawn at that time and can vary a lot. --- ### K — 2026-01-21T08:20:21+0100 (Jan 21, 2026) > [WelshGas said:](/goto/post?id=769809) > > Both batteries are fully charged, so when you start the engine the Leisure battery will show an initial charging that rapidly drops to Zero as the electronics determine the Leisure batteries are fully charged. > > Where did you get this 20% reading you mentioned in your original post? > > The Hours calculation for the leisure batteries is based on a spot reading of the amps being drawn at that time and can vary a lot. > > Click to expand... This is an image of the following day after I got home, you can see the leisure battery looks depleted from the image showing only 5h but I think from the Voltage looks like it’s charged (is that the case? I’m no expert!!!). ![1768980007436.jpeg](images\1768980007436-jpeg.143508 "1768980007436.jpeg") I think the 20% came from the main screen that shows water levels and leisure battery charge, unfortunately I didn’t take a picture. So it seems that the problem could be me relying on this spot calculation and the batteries were actually charged after my journey? Should I only rely on the voltage reading when determining if the batteries are charged? --- ### — 2026-01-21T09:05:15+0100 (Jan 21, 2026) > [kevin1000 said:](/goto/post?id=769823) > > This is an image of the following day after I got home, you can see the leisure battery looks depleted from the image showing only 5h but I think from the Voltage looks like it’s charged (is that the case? I’m no expert!!!). > > [View attachment 143508](https://vwcaliforniaclub.com/attachments/143508/) > I think the 20% came from the main screen that shows water levels and leisure battery charge, unfortunately I didn’t take a picture. > > So it seems that the problem could be me relying on this spot calculation and the batteries were actually charged after my journey? Should I only rely on the voltage reading when determining if the batteries are charged? > > Click to expand... With Lithium batteries , unlike AGM, the voltage is almost maintained during use until it drops quickly as the batteries deplete. When the picture was taken you had a current draw of 10.7 amps so the batteries would last for almost 6 hrs ie: you would draw 60 amps + during that time period if the current draw is maintained, BUT you have plugged in the EHU so you are now charging at 25 amps and using at 10.7 amps. I would expect if you leave things as they are then the Mains charging amps would gradually decrease towards 10.7 amps and the Time remaining should increase as the batteries charge up. Normally switching the Ignition On/Of resets the Hours remaining calibration, but as long as you have a current draw of 10.7 amps I'm not sure if the Remaining Hours will increase that much. I'm not sure how sophisticated the calculation is when charging at the same time. --- ### K — 2026-01-21T09:40:48+0100 (Jan 21, 2026) > [WelshGas said:](/goto/post?id=769827) > > With Lithium batteries , unlike AGM, the voltage is almost maintained during use until it drops quickly as the batteries deplete. > When the picture was taken you had a current draw of 10.7 amps so the batteries would last for almost 6 hrs ie: you would draw 60 amps + during that time period if the current draw is maintained, BUT you have plugged in the EHU so you are now charging at 25 amps and using at 10.7 amps. > I would expect if you leave things as they are then the Mains charging amps would gradually decrease towards 10.7 amps and the Time remaining should increase as the batteries charge up. Normally switching the Ignition On/Of resets the Hours remaining calibration, but as long as you have a current draw of 10.7 amps I'm not sure if the Remaining Hours will increase that much. I'm not sure how sophisticated the calculation is when charging at the same time. > > Click to expand... Thanks, that helps me better understand how things work. I think I need to drain the leisure battery and try again to see if the alternator charges it. I'm hopefully that perhaps there isnt an issue with the vehicle and its more my lack of experience in interpreting the battery display. I'll report back with findings. Thanks again for everyones help so far, much appreciated. --- ### — 2026-01-21T17:43:47+0100 (Jan 21, 2026) > [kevin1000 said:](/goto/post?id=769829) > > Thanks, that helps me better understand how things work. I think I need to drain the leisure battery and try again to see if the alternator charges it. I'm hopefully that perhaps there isnt an issue with the vehicle and its more my lack of experience in interpreting the battery display. I'll report back with findings. Thanks again for everyones help so far, much appreciated. > > Click to expand... If the LB was / is full, before hook up, I would suspect you don't have an issue with alternator charging. As you say , try using the LB to drop the Volts to approx 12.8v then start the vehicle, the LB should start to be charged at anywhere from 12.6v upto 15v (depends on revs) take the vehicle for a drive, you should notice the LB voltage increases to 14.4v (approximately) whilst it is receiving a charge from the alternator? --- ### — 2026-01-21T18:55:16+0100 (Jan 21, 2026) > [kevin1000 said:](/goto/post?id=769829) > > Thanks, that helps me better understand how things work. I think I need to drain the leisure battery and try again to see if the alternator charges it. I'm hopefully that perhaps there isnt an issue with the vehicle and its more my lack of experience in interpreting the battery display. I'll report back with findings. Thanks again for everyones help so far, much appreciated. > > Click to expand... > [Perfectos said:](/goto/post?id=769881) > > If the LB was / is full, before hook up, I would suspect you don't have an issue with alternator charging. > > As you say , try using the LB to drop the Volts to approx 12.8v then start the vehicle, the LB should start to be charged at anywhere from 12.6v upto 15v (depends on revs) take the vehicle for a drive, you should notice the LB voltage increases to 14.4v (approximately) whilst it is receiving a charge from the alternator? > > Click to expand... This is a chart of Capacity v Voltage of a 12v LiPo4 lithium battery as fitted in the New California. ![IMG_2445.jpeg](images\img_2445-jpeg.143534 "IMG_2445.jpeg") Note the significant voltage change compared with the AGM leisure battery system fitted to the T4/5/5.1/6/6.1 Californias. ![IMG_1532.jpeg](images\img_1532-jpeg.143535 "IMG_1532.jpeg") --- ### — 2026-01-21T19:47:54+0100 (Jan 21, 2026) I would be more concerned at the Amperage - what are you using in the van thats drawing 10.7A. ? What's the 25 amp showing on the hookup that surely isn't what you are drawing? --- ### N — 2026-01-22T17:04:56+0100 (Jan 22, 2026) Hi Kevin I have had the same issue since the beginning of August after having no issues since the van was new in March. 2 trips to my local dealer (who had never seen the new Cali before) and software updates didn't remedy the problem. I took it to the nearest VW Camper Van specialist to me and the fix is a new control module. I've had to wait a couple of months for the part to come in and am booked in on the 17th/18th Feb. Will report back once it's done, hopefully with good news. I'm charging the battery via the EHU every couple of weeks in the mean-time to try and keep the battery healthy. --- ### K — 2026-01-22T18:48:56+0100 (Jan 22, 2026) > [nickyboy83 said:](/goto/post?id=769978) > > Hi Kevin > I have had the same issue since the beginning of August after having no issues since the van was new in March. 2 trips to my local dealer (who had never seen the new Cali before) and software updates didn't remedy the problem. I took it to the nearest VW Camper Van specialist to me and the fix is a new control module. I've had to wait a couple of months for the part to come in and am booked in on the 17th/18th Feb. Will report back once it's done, hopefully with good news. I'm charging the battery via the EHU every couple of weeks in the mean-time to try and keep the battery healthy. > > Click to expand... Thanks for letting me know. I’d be really interested to hear if that resolves your problem, as it sounds very similar to my situation. To be clear, you can charge the vehicle battery with the alternator, just not the leisure battery? I'm currently still doing some testing so I can clearly report the issue to the dealer. --- ### N — 2026-01-22T22:55:32+0100 (Jan 22, 2026) Hi Kevin Yes, main battery charges fine via the alternator but leisure battery doesn’t. The van is my daily driver. Leisure battery charges quickly via EHU but depletes gradually over 2-3 weeks. Good luck with the dealers. I found it a real battle initially for them to understand my issue. Dealer said it was either software or the control module and the software update didn’t fix it so they have ordered the latter. Some of my colleagues have suggested a relay issue but this has fallen on deaf ears with dealer and no doubt the new system is more complicated than previous models. Problem I have found is that it’s difficult to speak to the technicians directly. --- ### — 2026-01-22T23:56:49+0100 (Jan 22, 2026) Sounds like the same issue I had with my T6.1 Ocean - turned out to be a faulty relay in the split charge system. The alternator charging would start for a few seconds then cut out just like yours. Worth checking if your dealer can test the charging relays before going straight to a new control module. --- ### N — 2026-01-23T08:08:05+0100 (Jan 23, 2026) Hi Kevin Yes, main battery charges fine via the alternator but leisure battery doesn’t. The van is my daily driver. Leisure battery charges quickly via EHU but depletes gradually over 2-3 weeks. Good luck with the dealers. I found it a real battle initially for them to understand my issue. Dealer said it was either software or the control module and the software update didn’t fix it so they have ordered the latter. Some of my colleagues have suggested a relay issue but this has fallen on deaf ears with dealer and no doubt the new system is more complicated than previous models. Problem I have found is that it’s difficult to soak to the technicians directly --- ### K — 2026-01-23T17:07:14+0100 (Jan 23, 2026) > [nickyboy83 said:](/goto/post?id=770011) > > Hi Kevin > Yes, main battery charges fine via the alternator but leisure battery doesn’t. The van is my daily driver. Leisure battery charges quickly via EHU but depletes gradually over 2-3 weeks. Good luck with the dealers. I found it a real battle initially for them to understand my issue. Dealer said it was either software or the control module and the software update didn’t fix it so they have ordered the latter. Some of my colleagues have suggested a relay issue but this has fallen on deaf ears with dealer and no doubt the new system is more complicated than previous models. Problem I have found is that it’s difficult to soak to the technicians directly > > Click to expand... Thanks, think I'm now convinced the van has an issue and I'm going to head to the dealers. PLease let me know how you get on and if the dealers resolve the issue for you! Below is my latest testing of the problem. I'm posting so people can tell me I've tested it wrong or if I have it correct, so people can recognise the issue in their van. The images below show the issue. **Image 1**: Indicates the state of the batteries before attempting to charge them. Note, leisure battery on 20% **Image 2**: Engine started, both batteries seem to be charging. Energy from the engine is ACTIVE. **Image 3**: Within 60 seconds, energy from the engine switches to READY, leisure battery no longer charging but the vehicle battery continues to charge. ![1769183895864.png](images\1769183895864-png.143562 "1769183895864.png") ![1769183921615.png](images\1769183921615-png.143563 "1769183921615.png") ![1769183984464.png](images\1769183984464-png.143564 "1769183984464.png") --- ### — 2026-01-23T17:11:35+0100 (Jan 23, 2026) > [kevin1000 said:](/goto/post?id=770037) > > Thanks, think I'm now convinced the van has an issue and I'm going to head to the dealers. PLease let me know how you get on and if the dealers resolve the issue for you! > > Below is my latest testing of the problem. I'm posting so people can tell me I've tested it wrong or if I have it correct, so people can recognise the issue in their van. > > The images below show the issue. > > **Image 1**: Indicates the state of the batteries before attempting to charge them. Note, leisure battery on 20% > **Image 2**: Engine started, both batteries seem to be charging. Energy from the engine is ACTIVE. > **Image 3**: Within 60 seconds, energy from the engine switches to READY, leisure battery no longer charging but the vehicle battery continues to charge. > > > [View attachment 143562](https://vwcaliforniaclub.com/attachments/143562/)[View attachment 143563](https://vwcaliforniaclub.com/attachments/143563/)[View attachment 143564](https://vwcaliforniaclub.com/attachments/143564/) > > Click to expand... I can’t imagine a T7 is much different to the 6.1 in using a basic relay switch when running to feed alternator power to the starter and leisure at the same time. It ready does look like this is not working properly to my untrained eyes. --- ### J — 2026-01-26T08:34:20+0100 (Jan 26, 2026) > [kevin1000 said:](/goto/post?id=769779) > > I've just purchased an ex demo T7 Ocean Diesel and after the 2 hour drive home from the dealers I checked the battery levels and was suprised to see that the leisure battery was on 20%. I was expecting it to be full after such a long drive. > > I've tried and EHU and it charges fine that way. I then went back to trying to charge it using the engine by starting the engine and checking the display. As the images show below, at first I got the expected behaviour, engine power was providing 30A and the leisure battery recieving 25A. But after a few seconds the engine power dropped to OA and the leisure battery quickly when back to -0.2A (the image shows 0.7A but I was abit quick with the camera!) . It would appear that I am unable to charge the leisure battery from the engine for longer than a few seconds. > > Any suggestions? I'm new to the vehicle so could I be making a silly mistake somehow? > > [View attachment 143482](https://vwcaliforniaclub.com/attachments/143482/) > [View attachment 143483](https://vwcaliforniaclub.com/attachments/143483/) > > Click to expand... Mine happened the same; No clue at the dealer; always saying that was a software problem; every 14 days i nee d to EHU; I finally had to tell them what the problem is (got from a wassap chat) and on wednesday they will fix it, It is the "disyuntor" = circuit breaker; hope it is the end to a very long story!!! --- ### J — 2026-01-26T09:26:45+0100 (Jan 26, 2026) Following this thread as we are having the same issue on a t7 ocean cali diesel. Will try the circuit breaker --- ### — 2026-01-26T09:33:22+0100 (Jan 26, 2026) > [kevin1000 said:](/goto/post?id=769779) > > I've just purchased an ex demo T7 Ocean Diesel and after the 2 hour drive home from the dealers I checked the battery levels and was suprised to see that the leisure battery was on 20%. I was expecting it to be full after such a long drive. > > I've tried and EHU and it charges fine that way. I then went back to trying to charge it using the engine by starting the engine and checking the display. As the images show below, at first I got the expected behaviour, engine power was providing 30A and the leisure battery recieving 25A. But after a few seconds the engine power dropped to OA and the leisure battery quickly when back to -0.2A (the image shows 0.7A but I was abit quick with the camera!) . It would appear that I am unable to charge the leisure battery from the engine for longer than a few seconds. > > Any suggestions? I'm new to the vehicle so could I be making a silly mistake somehow? > > [View attachment 143482](https://vwcaliforniaclub.com/attachments/143482/) > [View attachment 143483](https://vwcaliforniaclub.com/attachments/143483/) > > Click to expand... Hi It’s a side note to your problem. I leave my fridge turned On 24/7 as I’m concerned about the leisure battery being constantly fully charged during the winter months. I do daily my T7 Coast, but it can sit for 24hrs without moving so the battery can drop down to 50% sometimes. It doesn’t help your problem, but that is definitely wrong what’s happening to your van --- ### K — 2026-01-26T11:47:21+0100 (Jan 26, 2026) > [Juliet Staines said:](/goto/post?id=770182) > > Following this thread as we are having the same issue on a t7 ocean cali diesel. Will try the circuit breaker > > Click to expand... Sorry to hear so many others are having the same issue. I’d be interested to hear if anyone has actually managed to get it fixed through their dealer. How was the experience and how long did it take? I reported the issue to my dealer within the first week of ownership, so I believe I still have the option to reject the vehicle under the Consumer Rights Act. I really don’t want to send it back, I like the van and I’d like to give them the opportunity to fix it. That said, I definitely don’t want six months of going back and forth to the dealers!! --- ### J — 2026-01-26T12:24:49+0100 (Jan 26, 2026) > [kevin1000 said:](/goto/post?id=770222) > > Sorry to hear so many others are having the same issue. I’d be interested to hear if anyone has actually managed to get it fixed through their dealer. How was the experience and how long did it take? > > I reported the issue to my dealer within the first week of ownership, so I believe I still have the option to reject the vehicle under the Consumer Rights Act. I really don’t want to send it back, I like the van and I’d like to give them the opportunity to fix it. That said, I definitely don’t want six months of going back and forth to the dealers!! > > Click to expand... We've had the van since last year and hadnt noticed the battery drain until now feels as if the button at the front to charge whilst driving has stopped working. I watched a YouTube Video from cali Chris where you can download a free app to the dash computer so its easier to check the battery charge it basically turns the screen into the same one as in the back better to keep an eye on the percentage. Good luck too! --- ### B — 2026-01-26T15:15:09+0100 (Jan 26, 2026) I haven't seen anywhere in this thread mentions of the Max Power button. That's what makes T7 charge leisure battery during driving. I always use it since it makes StartStop system go away ![:)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 "Smile :)") --- ### J — 2026-01-26T16:00:08+0100 (Jan 26, 2026) > [blind\_oracle said:](/goto/post?id=770260) > > I haven't seen anywhere in this thread mentions of the Max Power button. That's what makes T7 charge leisure battery during driving. I always use it since it makes StartStop system go away ![:)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 "Smile :)") > > Click to expand... Didn't know what it is called but ours has stopped charging the leisure battery no idea why on our T7 ![☹️](https://cdn.jsdelivr.net/gh/twitter/twemoji@14.0.2/assets/72x72/2639.png "Frowning face :frowning2:") ---