UKH

My camper is parked in the shade all day and the leisure battery is slowly draining. Im wanting to connect a mains charger to it, but am a bit worried about damaging the solar controller. Should i disconnect this first, or am i worrying about nothing? 

Similarly i am thinking about having a switch (or vsr) to connect the leisure battery to the van battery when driving to do the same. Would this be a problem?

Its an epever mppt beast, but it doesn't say owt in the instructions about connecting an external charger. It does say i need to disconnect the solar before disconnecting the battery which would be a pain, so would rather not.

In reply to markalmack: should be no problem leaving the solar charger connected when you have the mains charger connected. Similarly no problem if you have a voltage sensitive relay to connect the two batteries. Reason for disconnecting the solar panel (if it has no proper solar charge controller along with the panel) is that without a proper controller the voltage from the panel could go up to 30V - which could damage other components.

In reply to markalmack:

I have an ePever MPPT controller. It's no problem charging the battery with it still connected, it's designed to cope. A standard van setup will have a VSR that connects the leisure battery to the alternator when the engine is running, so I am effectively putting the leisure battery on charge every time I start the engine.

I've never worried about disconnecting the solar panel before the battery, but not a bad idea. But if you disconnect the solar, always cover the panel first so that it is not generating.

In reply to markalmack:

I’m no expert and don’t know your setup but In winter I just hookup van via normal 240v for 24hours once a month. Have a friend who keeps her van permanently hooked up when at home. CC club have various tech sheets online that may be of help?

In reply to Hooo:

I've never worried about covering the panel before disconnecting, just make sure the cable ends are insulated before I put them down.

I never use to bother about disconnecting the panel before the battery either - never seemed to do any harm to my old controller or anything running off it, however when I updated my system recently to LiFePO4, I had a fit of sensibility and installed a DC circuit breaker - no excuse for being lazy that way 🙂

In reply to markalmack:

Anyone know if it’s ok to have two separate solar panels rigged to two separate charge controllers plugged in to the same 12v battery? I assume it’s like when you’re alternator is on; so it’s absolutely fine?

(It would be useful if you had a fixed panel on the roof and a portable panel that you get out when you’re parked up).  

In reply to George_Surf:

No problem doing that. If you have a smart solar controller that does multi stage charging it might get confused. All this would mean is that you battery might only charge to 95% or so, it won't do any damage.

In reply to Ciro:

It's more the re-connecting I worry about. Fiddling around in a little cupboard trying to get a 6mm2 cable into a small terminal is a bit worrying when said cable could deliver 8A or so.

Although, as you say it's no problem if you're careful. I once reconnected it all and got out of the van only to see that the cover had blown away and the panel was in full sun

In reply to Hooo:

It might be capable of delivering 8A, but unless you've got multiple panels in series, the max voltage will be about 40 - 50v... 48V DC is the upper limit of what's considered safe for DC. You'd get a nasty shock if you stuck them in your mouth, but through dry skin you'd be lucky to feel a tingle.

The only real danger would be if you connected it next to the vent of a charging lead acid battery and managed to blow it up with the spark - but that could just add easily happen when disconnecting first. Best avoided by not having your LB & charge controller in a dodgy configuration.