Solar only charges 2nd leisure battery

[hansel]

Hi!

I've bought a 100w kit from Roger at Solar Camper Solutions, I have thought that everything has worked well since I installed the solar cell 1 month ago. But during our last trip, I discovered that the battery life was shorter than it used to be before I bought the solar cell. One morning, after the heater had been on all night, I measured the current from the batteries. The first leisure battery (under the seat) then had 12.25v while the second leisure battery had 13.05v. I could also see in victron's bluetooth app that it was in float mode for most of yesterday so it seems that the solar cell only charges the second leisure battery, but not the first and it also seems that the car only uses the first battery while powering the heater and the fridge.

I have noticed that the leisure battery under the seat is charged from EHU and when driving. Does anyone have any idea why the leisure battery under the seat is not charged from the solar panel? And why the car isn't utilizing the 2nd battery?
I have been wondering if a fuse could have blown, but then the batteries should not be charged from EHU or while driving?

Thanks,
Roland

 

[Wesel]

A cable connects the + terminals of the 2 batteries. In this connection there is a fuse. This one is definitely burnt. It is a special 50 or 75 amp fuse, a small cube located on the + of the rear battery, where you connected the solar panel.
Be careful during work , it is at this moment that there is a risk of blowing this fuse.

 

[yossarian]

https://vwcaliforniaclub.com/search/336193/?searchform=1&q=cube+fuse&o=relevance

Replacing the fuse without charging the front battery could quite likely blow the fuse again.

If you are stuck on site a temporary kludge would be to move the solar charger +ve to the top of the cube fuse. You would be running off one battery but at least receiving solar charge.

 

[KGCali]

Just check the cube fuse on the rear battery using a multimeter, the voltage on top and below the fuse should be the same, if different the cube fuse is blown. You can buy the 75A Cube fuse from here... https://www.12voltplanet.co.uk/battery-terminal-cube-fuses-50-300a.html

 

[hansel]

thanks for your answers! I checked the cube fuse with a multimeter and it was OK. I also tried moving the solar charger + ve to the top of the cube fuse according to yossarian's suggestion but it made no difference.
When the car is driven or connected to EHU, both batteries are charged (I have checked this with a multimeter). When the car is stationary and gets charged from the solar cells, only the rear leisure battery is charged. Is there possibly a fuse for the front leisure battery as well? But if it were blown, shouldn't the battery be charged from the generator or EHU? Or maybe there are two separate fuses. By the way, I have a T6.1, forgot to mention it in my original post

 

[markab]

Where have you connected the -neg terminal from the solar charger, direct to the leisure battery or to a chassis ground bolt?

 

[Steve1]

thanks for your answers! I checked the cube fuse with a multimeter and it was OK. I also tried moving the solar charger + ve to the top of the cube fuse according to yossarian's suggestion but it made no difference.
When the car is driven or connected to EHU, both batteries are charged (I have checked this with a multimeter). When the car is stationary and gets charged from the solar cells, only the rear leisure battery is charged. Is there possibly a fuse for the front leisure battery as well? But if it were blown, shouldn't the battery be charged from the generator or EHU? Or maybe there are two separate fuses. By the way, I have a T6.1, forgot to mention it in my original post

Hi, when charged from the engine or mains do both the battery under the seat and the rear battery have exactly the same voltage readings. Also when the solar is charging does the front battery increase at all even a little i.e. solar panel covered Vs uncovered any change in front battery at all ?

 

[hansel]

At first I connected it directly to the leisurebattery, but later, after a week or so, I connected it to the groundbolt that holds the battery in place

 

[hansel]

Hi, when charged from the engine or mains do both the battery under the seat and the rear battery have exactly the same voltage readings. Also when the solar is charging does the front battery increase at all even a little i.e. solar panel covered Vs uncovered any change in front battery at all

when driving, they do not have the same voltage reading. The rear always has the highest value. I guess it's because it gets extra power from the solar cell? I have not had the opportunity to connect the car to EHU yet during this troubleshooting, so I do not know what voltage readings look like then. When the solar cells provide electricity, the voltage increases sharply in the rear battery, but in the front there is no increase at all

 

[Steve1]

when driving, they do not have the same voltage reading. The rear always has the highest value. I guess it's because it gets extra power from the solar cell? I have not had the opportunity to connect the car to EHU yet during this troubleshooting, so I do not know what voltage readings look like then. When the solar cells provide electricity, the voltage increases sharply in the rear battery, but in the front there is no increase at all

Thats odd, perhaps the back is still not being charged by the engine when driving maybe only solar ? Can you see a big voltage increase on the rear when the engine is started or not ?

 

[Steve1]

when driving, they do not have the same voltage reading. The rear always has the highest value. I guess it's because it gets extra power from the solar cell? I have not had the opportunity to connect the car to EHU yet during this troubleshooting, so I do not know what voltage readings look like then. When the solar cells provide electricity, the voltage increases sharply in the rear battery, but in the front there is no increase at all

I think to test properly you might need to temporarily disconnect the solar and carefully isolate it's connection. Once disconnected both sides of the cube fuse should measure the same voltage, and the under seat battery should measure the same voltage also. If the engine is started that voltage should go up to a much higher voltage at least 13.4 usually on both batteries probably higher. But they should both be the same, and both sides of the cube fuse the same also. If they are not the same that suggests a problem with the fuse or a bad connection in the cable.

 

[hansel]

Thats odd, perhaps the back is still not being charged by the engine when driving maybe only solar ? Can you see a big voltage increase on the rear when the engine is started or not ?

You are right, it seems like the battery in the back is only charged by solar. I just went to the garage for some more troubleshooting and when I started the engine the battery in the front went up to 14.6v and the one in the back was stuck at 12.99v (which is the same level as before the engine was started). Before I did this I disconnected the solar from the battery in the back.

The problem is that the cubefuse seems OK according to the multimeter, I even bought a new fuse today which I replaced just in case but it made no difference. So if it isn't the cubefuse that's blown, what else could it be? Maybe it's time to book an appointment at VW instead, I was just hoping that there was a more simple solution to this like a blown fuse

 

[Steve1]

You are right, it seems like the battery in the back is only charged by solar. I just went to the garage for some more troubleshooting and when I started the engine the battery in the front went up to 14.6v and the one in the back was stuck at 12.99v (which is the same level as before the engine was started). Before I did this I disconnected the solar from the battery in the back.

The problem is that the cubefuse seems OK according to the multimeter, I even bought a new fuse today which I replaced just in case but it made no difference. So if it isn't the cubefuse that's blown, what else could it be? Maybe it's time to book an appointment at VW instead, I was just hoping that there was a more simple solution to this like a blown fuse

If you have proved it's not the fuse ( I assume both sides of the cube fuse were at 12.99 in your test) then that only really leaves a broken wire or disconnected terminal. Probably on he positive wire between the two batteries although the negative would have odd effect too. You can probably check the negatives by using your meter to do a resistance check between the negative terminal of a battery and a chassis bolt. You should expect an ohm or less. Repeat on the other battery. Readings should be similar and low on the ohms setting. If this works out ok which from your description I would expect it will that only really leaves a broken wire or terminal between the front and rear batteries I think.

 

[Wesel]

Do you have the same voltage above the fuse and below the fuse with respect to ground?

 

[hansel]

Do you have the same voltage above the fuse and below the fuse with respect to ground?

Yes, the reading was 12.99v on both sides of the fuse. It was mentioned in another thread that the T6.1 has a fuse on the front leisurebattery aswell but I havn’t been able to locate it it if it exists (it is not a cube fuse)

 

[Wesel]

So you own a t6.1 ?
It would be a good thing to modify your avatar where it always says "looking to by"

 

[yossarian]

S339 on diagram 75-3 is your cube fuse.
J1116 (the IBS sensor) is, on all versions that I've seen, actually wired to the positive of A24 (the rear battery) not as depicted on the diagram.

On the positive side there is not much to fail on the way to B562. Possibly a crimp connector or something like that. The fuses in fuse holder G are not in play as far as a positive interconnect fault between the batteries goes.

It might be worth checking the negative paths through the two IBS sensors J934 and J1116.

If it's not S339 it's probably something silly to do with the solar installation. I would carefully check all the paths between the two battery positives and between each battery and chassis ground.

 

[hansel]

So you own a t6.1 ?
It would be a good thing to modify your avatar where it always says "looking to by"

Thanks for the reminder! I forgot to change my status when i finally bought a California

 

[hansel]

S339 on diagram 75-3 is your cube fuse.
J1116 (the IBS sensor) is, on all versions that I've seen, actually wired to the positive of A24 (the rear battery) not as depicted on the diagram.

On the positive side there is not much to fail on the way to B562. Possibly a crimp connector or something like that. The fuses in fuse holder G are not in play as far as a positive interconnect fault between the batteries goes.

It might be worth checking the negative paths through the two IBS sensors J934 and J1116.

If it's not S339 it's probably something silly to do with the solar installation. I would carefully check all the paths between the two batteries and chassis ground.

View attachment 94499

View attachment 94500

Thank you so much! I will continue the troubleshooting tomorrow

 

[flying banana]

The batteries are connected or should be connected in parallel. So if your cube fuse is good what goes into one battery will go into the other . This must be a warranty issue

 

[hansel]

If you have proved it's not the fuse ( I assume both sides of the cube fuse were at 12.99 in your test) then that only really leaves a broken wire or disconnected terminal. Probably on he positive wire between the two batteries although the negative would have odd effect too. You can probably check the negatives by using your meter to do a resistance check between the negative terminal of a battery and a chassis bolt. You should expect an ohm or less. Repeat on the other battery. Readings should be similar and low on the ohms setting. If this works out ok which from your description I would expect it will that only really leaves a broken wire or terminal between the front and rear batteries I think.

I did a restistance check between the negative terminal and the chassisbolt that holds the batteri in the back, and it was close to 0ohm so I guess that means it's OK. However i wasn't able to find a similar bolt close to the battery in the front. Do you know where I might find a suitable bolt in the front?

 

[hansel]

It might be worth checking the negative paths through the two IBS sensors J934 and J1116.

May I kindly ask how I would do this with a multimeter? As per steve1 suggestion I checked the negatives between the negative terminal and the chassis bolt that holds the battery.

 

[yossarian]

May I kindly ask how I would do this with a multimeter? As per steve1 suggestion I checked the negatives between the negative terminal and the chassis bolt that holds the battery.

Switch your meter to ohms or continuity. Each ibs sensor on the negative pole of each battery should be close to zero ohms from the negative side to the battery pole.

All the paths on the current flow diagram should be close to zero ohms.

 

[yossarian]

You can narrow the fault down to the paths between the two batteries since they are at different voltages and that can't occur if they are connected in parallel.

If you find the problem or it's intermittent s339 could blow if the batteries have a large voltage difference.

Rechecking s339 from time to time might be worthwhile

 

[Steve1]

I did a restistance check between the negative terminal and the chassisbolt that holds the batteri in the back, and it was close to 0ohm so I guess that means it's OK. However i wasn't able to find a similar bolt close to the battery in the front. Do you know where I might find a suitable bolt in the front?

The front battery under the seat has a similar clamp holding it down, on my van you can pull off the plastic panel on the rear of the seat box to reveal the battery clamp. Not sure if this stayed the same on the later vans though.