Charging with solar panel and cigarette lighter

T

T6surfer

New Member
I was getting the dreaded 2nd battery low alarm on camping trips. I put this down to the opening and closing of the door and other things drawing the battery down. When this happens I have opened the bonnet and measured the battery voltage to be 12.3V or less. I then hook a battery charger to take it back to around 14V.

So I decided to buy of these solar panel trickle charger units. I plugged into cigarette lighter and saw it it connected and watched periodically kick in to charge. Happy days situation resolved, or so I thought.

Whilst camping just now, the dreaded 2nd battery low alarm came back on. The solar panel controller was indicating charged, so this confused me. I then measured the voltage at my cigarette lighters and both reading 13.8v. Checked battery under bonnet reading 12.28v. In case you’re wondering I’m on hook-up

Don't know how to take this forward now, I’m a bit confused. I’ve currently got a normal charger connected to clear the alarm

any ideas ?
 
You need 50w solar plus a solar controller.

For a trickle charge.

What have you got?

Post some pics.
 
I have a 20w charger and controller but that’s not the issue. As there is 13.8v appearing at the cigarette lighter socket, the controller will not activate. Needs to be less than 13v
 
Also which 12v socket are you using and do you have a factory second battery system - I'm wondering if you've accidentally connected your solar to a socket connected to your leisure battery, which would explain the confusing readings.

I think on the factory second battery the 12v socket by the gear leaver is always starter battery.
 
roadtripper said:
Also which 12v socket are you using and do you have a factory second battery system - I'm wondering if you've accidentally connected your solar to a socket connected to your leisure battery, which would explain the confusing readings.

I think on the factory second battery the 12v socket by the gear leaver is always starter battery.
Click to expand...
very true,

factory Leisure battery feed is the top 12v socket.

lower is always the starter battery.
 
I was using the top socket , but the other socket reads the same voltage. They both measure the same voltage as the battery below the passenger seat
 
post pics of the setup,

starter battery,

leisure battery,

chargers,

the solar and PWM controller

etc etc



well see if we can see anything.



both sockets being exactly the same voltage would imply that they are both connected to the same source battery.
 
have a look at adding a couple of battery monitors . . . .


www.t6forum.com

Battery Monitoring -- How I Done It --

Battery Monitoring -- How I Done It -- Part #1 Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends...
www.t6forum.com www.t6forum.com



.
 
what's that cable for ?

that ring terminal is bridging out the vans battery power meter,

it should be connected to chassis, not the battery terminal.


1692376486704.png
 
that panel looks very small. . .

10-15w id guess?


100w panel may get you 6A,

so 10w may get you 0.6A. . . .

(that solar controller says 8A, but you would need 150w worth of panels to get near that)

1692376603787.png


+++++++++++++


i think that panel is way to small to make any difference to you starter or leisure battery



++++++++++++++
 
******************************************************************

SOLAR:

My Panels:




*****************************************************
 
*****************************************************

POWER:



 
That goes to a connector where I attach my battery charGer. there is one on the positive terminal as well.
Nothing is bridged out on that that negative terminal, it’s just under the nut that tightens the terminal
 
thats wrong.

you need to move that ring terminal,

the van "energy management system" is not seeing your charger power,

NO connections must be made to the BATTERY NEG terminal.

no chargers, no jump leads - nothing !

++++++++++++++++


www.t6forum.com

Battery Charging - Main Battery Chassis Point -

Battery Charging - Main Battery Earth Point - so weve all be told NOT to bridge out the battery monitor on the neg side of the battery when charging it. This is so the ECM can correctly gauge the SOC (state of charge) of the starter battery by monitoring the current flow in and out of the...
www.t6forum.com www.t6forum.com



1692377344353.png


+++


this is the vans battery sensor, and you have that cable connected the wrong side of the sensor, you need to move it to the chassis.




1692377437903.png
 
Reading this with interest...does this even mean the the BM2 battery monitor negative must be connected to chassis...reading this i guess so?
 
Ricardo T said:
Reading this with interest...does this even mean the the BM2 battery monitor negative must be connected to chassis...reading this i guess so?
Click to expand...
Yes & No - in regards to a BM2 battery monitor.

the BM2 is ok direct across that battery as its such low power its almost irrelevant, assuming the van is a daily driver.

i run my BM2 direct across that battery for year with no problems.

++++

however i have now moved my BM2 over to a separate fuse box that i fitted onto the starter battery. - just because i could.

+++++



the BIG BUT is - that no CHARGE SOURCES or LOADS must be connected directly to the battery NEG post.

this relates to all T5.1 & T6 & T6.1 - that have the power monitor sensor on the NEG battery connector.

we commonly see converters doing it wrong,

diesel heaters,

trailer electrics etc etc etc . . .

all wrong - those NEG wires need to be connected to the CHASSIS.



+++


you van wont explode or anything - but it will defo mess with the charging and discharging of the vans electrics - most commonly you end up with a low starter battery



.
 
roadtripper said:
Also which 12v socket are you using and do you have a factory second battery system - I'm wondering if you've accidentally connected your solar to a socket connected to your leisure battery, which would explain the confusing readings.

I think on the factory second battery the 12v socket by the gear leaver is always starter battery.
Click to expand...
It would appear not. I’ve just taken delivery of a new campervan based on a LWB 204PS 4Motion Highline PV built on 29 March this year, with a factory fitted second battery installed under the passenger seat. Having measured the voltage at both these sockets at 13.6V when on EHU, whilst the starter battery reads 12.5V, it appears BOTH 12V sockets in the cab are powered by the second battery.

I was hoping to keep the starter battery topped up by connecting a CTEK battery conditioner to the lower socket and fed from the internal mains socket and leave the van hooked up to the mains via the EHU. Unfortunately, in my case this doesn’t look like it’ll work as neither of the 12V sockets appear to be fed from the starter battery and I’ll have to find another feed from the starter battery (probably from under the passenger seat). It seems that VW has changed things.
 
Last edited:
That's intriguing. Possibly the feed may have been moved by the converter, the two family members who have Californias are forever worried about plugging the fridge into the wrong socket despite it being very useful for the sort of charging you mention.
 
You must log in or register to reply here.

Similar threads

H
Solar panel starter battery charger
Replies
7
Views
376
Dellmassive
Dellmassive
Paul Sussex
Sargent alarm
Replies
8
Views
470
Paul Sussex
Paul Sussex
steve-r
Charge a second battery from a cigarette lighter socket
Replies
9
Views
3K
roadtripper
roadtripper
O
LiFePO4 solar charging confusion
Replies
4
Views
359
Orca
O
D
Charging e-bike from leisure battery: blown fuse
2
Replies
20
Views
1K
peter1987t
peter1987t
Back
Top