Solar car Battery Charging Connections

[gavinwibrow]

I have a small solar panel that I use to trickle charge the batteries in the D4, but the following question also applies to the RRC with TD5. Both cars have dual battery systems (newish Traxide in the D4 and a simple Redarc system in the Softdash).

The red clamp goes onto the primary battery +ve post, and I connect the -ve clamp to the second battery -ve post.

However, I think I recall that in some situations/cars it is recommended to connect the -ve clamp to a body earth, NOT to the battery.

Comments?

[AK83]

I have a small solar panel that I use to trickle charge the batteries in the D4, but the following question also applies to the RRC with TD5. Both cars have dual battery systems (newish Traxide in the D4 and a simple Redarc system in the Softdash).

The red clamp goes onto the primary battery +ve post, and I connect the -ve clamp to the second battery -ve post.

However, I think I recall that in some situations/cars it is recommended to connect the -ve clamp to a body earth, NOT to the battery.

Comments?

I can't comment re the traxide, but with the redarc VSR if you just connect to the main battery, it can cause the VSR to cycle on and off in some situations.
Once it's charged a bit, and the VSR kicks in and the aux is at a low state of charge and needs some charge, it pulls the main battery down, and switches off the VSR again .. thus not charging the aux battery.
This will cycle until the main batt does eventually get a sufficient charge to hold the VSR stable so it doesn't cycle.

So sometimes I start the charge on both ... connect red to main +ve, and black to aux -ve and use the manual over ride to keep it connected till they get some charge.

redarc set the cutoff too low at 12.7v so it does this cycling .. kind'a annoying.
I guess the traxide will not do this if you just connect to the main, as my understanding is that it holds them connected down to 11.9v.

If the solar is connected up immediately after shutdown .. ie. at least before any battery drain on either and they have a decent surface charge on them .. then I'd say just go to the main, and let the DBS system do the rest of it for 'ya.

I'm looking for a semi decent little panel myself now, as I switch between D2 and D1 for a couple of weeks .. so the other sits for a longish period, self discharging.

[Tins]

It used to be good practice to connect -ve clamps to a vehicle earth rather than the battery, as vented batteries can emit gas that can explode due to an arc spark. Connecting to a vehicle earth away from the batt mitigates this.. Not so common these days but I still do it.