Balance Cable for topping up Starter Battery.

[campandfly]

Thought I would create a dedicated thread for those thinking of how to top up their starter battery and possibly using a balance cable.

Disclaimer:- This is definitely a Hack, I am not an electrician. You need to be very careful. Different vehicles may have various electrical setups. VW do not recommend charging batteries via the 12v cigarette lighter sockets.(at least in my user manual)

The purpose of making a balance cable was for topping up the starter battery and not letting it get low if you are parked up, eg. not on hookup and are not driving or running the engine.
Yesterday was a beautiful sunny day so I decided to test my DIY Solar setup and balance cable.
I deliberately ran my starter battery down by playing the radio and leaving the headlights on. I don't recommend doing this. It was done purely to test both systems.

Our Cali has the original batteries and is 5 years old.
The leisure batteries were at 13.4volts ~full (I can get them up to 13.7v if on hookup)
The Starter battery after running down was at 12volts ~50%
The Cali was NOT on hookup.
It was a full sun day and the 100watt solar panel was chucking out ~20v 5amps. My Solar controller charges the leisure batteries to 13.4volts.
The overhead control panel was showing the leisure battery level starting at 13.4v and 0.0 A amperage draw below it.
For the test I turned everything off in the leisure area including all lights,fridge and unplugged any accessories.
The overhead Amp reading should be 0.0 A occasionaly it will be 0.2 A as the control panel I think uses a bit.
The balance cable has
2 male cigarette lighter plugs fused at 10amps and with LED lights built in.
It also has an inline switch rated at 240v and 30amps.
The inline switch is really important otherwise you will have sparks flying when trying to plug in the 2nd plug.
I first made sure the inline switch for safety was in the OFF position.
Plugged one end into the kitchen cabinet 12v outlet and made sure the led comes on.
Plugged the other end into one of the dash 12v sockets and made sure the led comes on.
Then turned the online switch to ON.

After plugging in the Balance Cable the Voltage display started to come down. It showed the Amperage drain which on this test was about 3.4 A and reducing. The starter battery voltage started to increase. I quick tested the starter battery voltage via the other dash cigarette lighter socket.
After less than 2 hours with Solar going into the Leisure batteries the starter battery was up to 12.8volts and the draw had reduced to <1.5A at which point I decided to unplug the balance cable.
At the end of the test the Starter battery finished at 12.8volts and the Leisure batteries were at 13.1volts and still charging via solar and was soon back up to 13.4v.
So it worked fine.

It is not something I would do on a regular basis, only if really needed
I have read somewhere that balancing batteries with large differences in voltage produces a fast charge which is not beneficial to the long term health of the receiving battery.
I would not leave this cable attached unattended.
My vehicle is out of warranty so it is probably not a good idea to do it if you are still under warranty.
I would make sure the cable was not used if I were on hook up.
I would not turn on the ignition or start the vehicle while the cable is connected.
I would also turn off all items that run off the leisure batteries as a precaution.
There is no reason this would not work without the solar panel connected although performance would be reduced.
As I stated at the beginning I am not an electrician so any constructive comments are appreciated.

 

[andyinluton]

The only thing I would suggest is putting a fuse in the cable at a lower amperage than the fuses on the feeds to the lighter sockets. That way if something blows it will be a fuse that you can see and get at easily.

 

[campandfly]

The only thing I would suggest is putting a fuse in the cable at a lower amperage than the fuses on the feeds to the lighter sockets. That way if something blows it will be a fuse that you can see and get at easily.

Yes I am not certain what amperage the socket fuses are.

 

[Nick.C]

Feels like someone could make a few quid knocking these up and selling them on to those of us that are less electrically minded

 

[WelshGas]

Yes I am not certain what amperage the socket fuses are.

The 12v sockets are fused at 15 amps although the socket plastic cover says 20 amps.

 

[campandfly]

Thanks @WelshGas
The balance cable has 10amp fuses so should be ok.

 

[marchugo]

In my T5.1 the 12 V cigaret lighters on the dashboard and in the kitchen block are laid out for max. 15 Amps, and fused accordingly. So if you install a 10 A fuse in your balancing cable, you're on the safe side.

Regards from Amsterdam,

Marc.

 

[marchugo]

Ok, WG beat me. He has the amperage
info in his head, I had to look it up in the manual (it's in the Cali appendix of the manual).

 

[AlanC]

Do make sure the dash sockets are connected to the engine battery before you do this, not all are.

My 2010 van only has a cup holder socket as standard and this is fed from the leisure batteries and not the engine battery confirmed by Breeze in Poole who had to go on the VW website to find out.

Alan

 

[campandfly]

Feels like someone could make a few quid knocking these up and selling them on to those of us that are less electrically minded

They are easy to make and not expensive. I would not feel happy selling one as they could easily be misused and cause problems.

 

[AlanC]

They are easy to make and not expensive. I would not feel happy selling one as they could easily be misused and cause problems.

I would agree, the worst-case scenario is a full short circuit of both leisure batteries and a van on fire.
As has already been said, if the fusing is right then that will blow before anything worse happens,

Unless you are a confident electrician/electronics engineer, then I would not recommend this route.

Alan

 

[Loz]

I made one and the plugs both have 10A fuses and the sockets that are rated for 20a are fused at 15A.

 

[Amarillo]

My vehicle is out of warranty so it is probably not a good idea to do it if you are still under warranty.

I'd have thought the opposite is true. If something goes wrong you could then return the vehicle to your dealer with a perplexed look on your face, remembering first to remove and conceal the balancing cable.

 

[drbios]

Thought I would create a dedicated thread for those thinking of how to top up their starter battery and possibly using a balance cable.

Disclaimer:- This is definitely a Hack, I am not an electrician. You need to be very careful. Different vehicles may have various electrical setups. VW do not recommend charging batteries via the 12v cigarette lighter sockets.(at least in my user manual)

The purpose of making a balance cable was for topping up the starter battery and not letting it get low if you are parked up, eg. not on hookup and are not driving or running the engine.
Yesterday was a beautiful sunny day so I decided to test my DIY Solar setup and balance cable.
I deliberately ran my starter battery down by playing the radio and leaving the headlights on. I don't recommend doing this. It was done purely to test both systems.

Our Cali has the original batteries and is 5 years old.
The leisure batteries were at 13.4volts ~full (I can get them up to 13.7v if on hookup)View attachment 57235View attachment 57236
The Starter battery after running down was at 12volts ~50%
The Cali was NOT on hookup.
It was a full sun day and the 100watt solar panel was chucking out ~20v 5amps. My Solar controller charges the leisure batteries to 13.4volts.
The overhead control panel was showing the leisure battery level starting at 13.4v and 0.0 A amperage draw below it.
For the test I turned everything off in the leisure area including all lights,fridge and unplugged any accessories.
The overhead Amp reading should be 0.0 A occasionaly it will be 0.2 A as the control panel I think uses a bit.
The balance cable has
2 male cigarette lighter plugs fused at 10amps and with LED lights built in.
It also has an inline switch rated at 240v and 30amps.
The inline switch is really important otherwise you will have sparks flying when trying to plug in the 2nd plug.
I first made sure the inline switch for safety was in the OFF position.
Plugged one end into the kitchen cabinet 12v outlet and made sure the led comes on.
Plugged the other end into one of the dash 12v sockets and made sure the led comes on.
Then turned the online switch to ON.

After plugging in the Balance Cable the Voltage display started to come down. It showed the Amperage drain which on this test was about 3.4 A and reducing. The starter battery voltage started to increase. I quick tested the starter battery voltage via the other dash cigarette lighter socket.
After less than 2 hours with Solar going into the Leisure batteries the starter battery was up to 12.8volts and the draw had reduced to <1.5A at which point I decided to unplug the balance cable.
At the end of the test the Starter battery finished at 12.8volts and the Leisure batteries were at 13.1volts and still charging via solar and was soon back up to 13.4v.
So it worked fine.

View attachment 57237 It is not something I would do on a regular basis, only if really needed
I have read somewhere that balancing batteries with large differences in voltage produces a fast charge which is not beneficial to the long term health of the receiving battery.
I would not leave this cable attached unattended.
My vehicle is out of warranty so it is probably not a good idea to do it if you are still under warranty.
I would make sure the cable was not used if I were on hook up.
I would not turn on the ignition or start the vehicle while the cable is connected.
I would also turn off all items that run off the leisure batteries as a precaution.
There is no reason this would not work without the solar panel connected although performance would be reduced.
As I stated at the beginning I am not an electrician so any constructive comments are appreciated.

Thought I would create a dedicated thread for those thinking of how to top up their starter battery and possibly using a balance cable.

Disclaimer:- This is definitely a Hack, I am not an electrician. You need to be very careful. Different vehicles may have various electrical setups. VW do not recommend charging batteries via the 12v cigarette lighter sockets.(at least in my user manual)

The purpose of making a balance cable was for topping up the starter battery and not letting it get low if you are parked up, eg. not on hookup and are not driving or running the engine.
Yesterday was a beautiful sunny day so I decided to test my DIY Solar setup and balance cable.
I deliberately ran my starter battery down by playing the radio and leaving the headlights on. I don't recommend doing this. It was done purely to test both systems.

Our Cali has the original batteries and is 5 years old.
The leisure batteries were at 13.4volts ~full (I can get them up to 13.7v if on hookup)View attachment 57235View attachment 57236
The Starter battery after running down was at 12volts ~50%
The Cali was NOT on hookup.
It was a full sun day and the 100watt solar panel was chucking out ~20v 5amps. My Solar controller charges the leisure batteries to 13.4volts.
The overhead control panel was showing the leisure battery level starting at 13.4v and 0.0 A amperage draw below it.
For the test I turned everything off in the leisure area including all lights,fridge and unplugged any accessories.
The overhead Amp reading should be 0.0 A occasionaly it will be 0.2 A as the control panel I think uses a bit.
The balance cable has
2 male cigarette lighter plugs fused at 10amps and with LED lights built in.
It also has an inline switch rated at 240v and 30amps.
The inline switch is really important otherwise you will have sparks flying when trying to plug in the 2nd plug.
I first made sure the inline switch for safety was in the OFF position.
Plugged one end into the kitchen cabinet 12v outlet and made sure the led comes on.
Plugged the other end into one of the dash 12v sockets and made sure the led comes on.
Then turned the online switch to ON.

After plugging in the Balance Cable the Voltage display started to come down. It showed the Amperage drain which on this test was about 3.4 A and reducing. The starter battery voltage started to increase. I quick tested the starter battery voltage via the other dash cigarette lighter socket.
After less than 2 hours with Solar going into the Leisure batteries the starter battery was up to 12.8volts and the draw had reduced to <1.5A at which point I decided to unplug the balance cable.
At the end of the test the Starter battery finished at 12.8volts and the Leisure batteries were at 13.1volts and still charging via solar and was soon back up to 13.4v.
So it worked fine.

View attachment 57237 It is not something I would do on a regular basis, only if really needed
I have read somewhere that balancing batteries with large differences in voltage produces a fast charge which is not beneficial to the long term health of the receiving battery.
I would not leave this cable attached unattended.
My vehicle is out of warranty so it is probably not a good idea to do it if you are still under warranty.
I would make sure the cable was not used if I were on hook up.
I would not turn on the ignition or start the vehicle while the cable is connected.
I would also turn off all items that run off the leisure batteries as a precaution.
There is no reason this would not work without the solar panel connected although performance would be reduced.
As I stated at the beginning I am not an electrician so any constructive comments are appreciated.

This is very bad practice. Batteries must NEVER be placed in parallel? No 2 batteries are the same. The strongest will charge the weakest. The cycle will oscillate. Parallel charging must be done via isolating circuitry and the minimum of resistors. Then you have the problem of heat dissipation.

Good luck!

 

[Loz]

This is very bad practice. Batteries must NEVER be placed in parallel? No 2 batteries are the same. The strongest will charge the weakest. The cycle will oscillate. Parallel charging must be done via isolating circuitry and the minimum of resistors. Then you have the problem of heat dissipation.

Good luck!

Apart from the fact that the ocean has 2 in parallel and all 3 are exactly the same type due to the relay they still insist on using.
I tested mine and it is working just fine.

 

[WelshGas]

This is very bad practice. Batteries must NEVER be placed in parallel? No 2 batteries are the same. The strongest will charge the weakest. The cycle will oscillate. Parallel charging must be done via isolating circuitry and the minimum of resistors. Then you have the problem of heat dissipation.

Good luck!

You’ll have to take this up with VW. As @Loz stated, VW have been doing this with the California Leisure Batteries since at least 2003 and the introduction of the T5 California. I’m not sure about it’s predecessor the T4 California.

 

[drbios]

Doesn't make it technically correct. VW have got the Cali charging of leisure batteries wrong anyway so I would not hold them up as an example.

As I say, good luck. There is no way I am putting a bit of 10A wire between two 100Ah energy stores. Have fun.

 

[Blk33]

You could try a diode in series with the positive cable (say 10 - 20A diode).
The diode would drop about 0.6 volt so the starter battery would charge to about 12.4 volts.
The diode would prevent 'oscillation' with the starter battery discharging back through the leisure battery.
A fuse and switch would be a good addition also.

 

[Kenny Marsh]

Interesting, I ski for long periods in the alps (or did ) and now have 220w solar camper solutions set up so don't worry about my leisure batts. However, I still worry about my starter battery even though it's not been a problem. My camper is a shuttle with a California interior and roof, I'm not sure how much is California and how much is aftermarket parts e.g. Seats are aftermarket. It has a split charger or voltage sensing relay but only works one way but now with solar I have spare energy at times to also charge the starter battery. My next job is to compare relays and consider swapping mine for a dual sensing relay to achieve this. Do full Californias have split charge relays, if so could it be an option instead? Alternatively, I was looking at installing a lead to the starter battery side that I could manually change or a changeover switch, in place of the leisure battery charge lead from my victron controller for emergencies so my solar would instead charge the starter battery.

 

[Stuart]

Great thread as I just been wondering about this question myself. Presumably one of these car to car cables would also work for this?

Streetwize Charge and Go-Car to Car Starter | Euro Car Parts

Streetwize Charge and Go-Car to Car Starter at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

 

[Blk33]

Great thread as I just been wondering about this question myself. Presumably one of these car to car cables would also work for this?

Streetwize Charge and Go-Car to Car Starter | Euro Car Parts

Streetwize Charge and Go-Car to Car Starter at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

Looks like it would work nicely.
I haven't seen these in Aus.

https://www.streetwizeaccessories.com/files//85150602-97e8-408f-89b9-a7bb00f5afc6/SWCG%20Manual.pdf

Check out the manual for operation.

 

[OGII]

Looks like it would work nicely.
Check out the manual for operation.

I've something similar, though not used it for a few years. In theory I could connect my standalone leisure battery (solar charged) to the van's leisure battery via the wall socket to transfer from one to the other.

From the pdf for the product listed they suggest 45 mins max. Could be as that's just long enough to top up an undercharged starter battery? The thin/low rated cable suggests it can't be transferring much current/amps in that time?

If you were to leave longer than 45 mins is it doing any longer term damage? My knowledge of looking after batteries properly is nonexistent. Can't help but think the jump start accessories such as these are just a quick fix for folk needed to get a car started on a cold morning and not something you should do too often?

Anyone got knowledge?

Thanks

 

[Blk33]

I've something similar, though not used it for a few years. In theory I could connect my standalone leisure battery (solar charged) to the van's leisure battery via the wall socket to transfer from one to the other.

From the pdf for the product listed they suggest 45 mins max. Could be as that's just long enough to top up an undercharged starter battery? The thin/low rated cable suggests it can't be transferring much current/amps in that time?

If you were to leave longer than 45 mins is it doing any longer term damage? My knowledge of looking after batteries properly is nonexistent. Can't help but think the jump start accessories such as these are just a quick fix for folk needed to get a car started on a cold morning and not something you should do too often?

Anyone got knowledge?

Thanks

I'm not sure the reason for the 45 minute limit - maybe overheating???
Basically if a battery to be charged has a capacity of say 100 AH, and is fully discharged, you charge the battery at 100 amps for one hour, or 1 amp for 100 hours. Higher the current, more heat so this is approximate.
So if your plug in charger charges at 10 A and you only charge for 45 minutes, then you approx charge the the battery 7AH - which is a long way from 100 AH.
I think you would have to leave the charger in for a number of hours to have any effect.