Simple solution

[Mikevet]

I am looking for a plug and play option. I don’t want mppt or other.

I have a 12 v 200 amp lithium on my sailboat. It’s way over kill for my system. I currently have 110 volt charger on it. I want to start storing my boat an hour away. I need a way to solar trickle charge my battery when I am away.

On a weekend, I might use 1/3 to half my batteries energy. I may use it again 10-30 days later. So it has to sit and charge.

What is the smallest recommended charger? Is there one I can just alligator clip to terminals? I don’t want a permanent mount solution. I plan on just securing to the roof when I’m not there. Will it discharge my battery at night?

 

[seneysolar]

Victron 75/10 mppt and almost any single solar panel over 50W would work.

I dont recommend alligator clips but you could install a plug in pigtail on the battery for easy disconnect.

 

[Mikevet]

There’s no way to do this without a mppt or the like? I just want to trickle charge the battery no a/c input etc. can I buy a small 2x2 panel on exam and do a pigtail plug?

 

[efficientPV]

My LiTime battery manual says you can just clip a solar panel onto the battery. Add a diode for a little extra safety. The BMS will automatically shut off when charged. A little added step would be to add a $5 buck converter to limit the upper voltage. should any shipboard electronics be active.

 

[seneysolar]

There’s no way to do this without a mppt or the like? I just want to trickle charge the battery no a/c input etc. can I buy a small 2x2 panel on exam and do a pigtail plug?

You need something to keep from over charging.

They sell solar battery tenders but they are very low wattage and have a crappy controller built in.

Putting an uncontrolled panel on a lithium battery and leaving it unattended is just asking for problems.

 

[wpns]

Yes, you _can_ use the BMS for overcharge protection, it'll (probably?) disconnect when the battery is overcharged, and your battery (probably?) won't explode and destroy your boat. But really, you shouldn't.

If you want to recharge half of 2400WH in 10 days and you get 5 peak hours you need about a 50 watt panel. As @seneysolar said, any low-power SCC should work, but the Victron 75/10 is $45 on Amazon, connect that permanently to your battery and have a disconnect for the solar panel(s) and you're done.

 

[Mikevet]

That sounds simple. Thanks. The 75/10 will disconnect when fully charged? Can I connect the a/c charger through that as well?

 

[wpns]

That sounds simple. Thanks. The 75/10 will disconnect when fully charged? Can I connect the a/c charger through that as well?

Well, not disconnect, but stop charging the battery, yes.
Put the AC charger in parallel with it, they shouldn't fight, but I also can't imagine you'd run both at the same time.