6 Volt Batteries and Solar Charging

[martinandanne]

I have one of these NOCO 5 Watt Solar Battery maintainers. Assuming I have two 6 volt batteries in series to product 12 volts, am I correct that I would still use a 6 volt controller despite the fact the output from the batteries is 12 volts?

Thinking of switching to 6 volt batteries because going to 2 12-volt batteries may require more space than I have available. But this has led me to a whole lot more questions!

Thanks!

Martin

[Lwiddis]

Sam, I agree and will!

[Sam_Spade]

Lwiddis wrote:
My 10 watt solar panel IS keeping the two Trojans at 12.7 as the WindyNation system sleeps under the RV cover.

While I am NOT a fan of testing the specific gravity of cells all the time (because in most circumstance it isn't really necessary), in this case I think that you need to check the SG at least once when you think it is fully charged just to get that voltage reading in perspective.
12.7 may or may not indicate a full charge.

[the_happiestcam]

I use a 5 watt panel to run a fan - it keeps airflow in the box my charge controller is in, in case the sun is shining on it clicky

[Lwiddis]

My 10 watt solar panel IS keeping the two Trojans at 12.7 as the WindyNation system sleeps under the RV cover.

[Searching_Ut]

As mentioned, no controller would be needed with that small of a solar panel. The batteries would hold the voltage down and you couldn't push enough current to be an issue. The problem, depending on battery, temperature and a few other variables the self discharge on 2 deep cycle batteries could be as high as 1 percent. That could be a couple amp hours a day on two golf cart batteries. You'll be unlikely to get 2ah a day out of that panel on many days, so you'll very likely be not keeping up with the slow self discharge of your batteries when your rig is parked. If you don't have a shut off switch to turn everything off on your trailer they will run down a lot faster.

[Sam_Spade]

martinandanne wrote:
I have one of these NOCO 5 Watt Solar Battery maintainers.

To restate what has already been said a little differently:

Notice that it is NOT called a charger.....because it doesn't have enough capacity to charge up a dead battery in most conditions.

It is intended ONLY to maintain a full charge over long periods.....and on small batteries.

It will be virtually worthless for the batteries you describe.

[scrubjaysnest]

I use a 5 watt panel connected directly to a battery in a boat as a maintainer after the battery is fully charged. Works great with a diode to prevent reverse current to the panel. For the car we leave at home while we travel I use a 35 watt with a charge controller, again after making sure the battery is fully charged.
For the RV I use one 100 watt portable panel through the charge controller to maintain the house and cranking batteries.

[RoyB]

My 10WATT small Solar Panel ZAMP-SOLAR Model ZS-M-10 0.56A MAX DC current that comes with the Torklift Battery box does not do well charging a 12VDC battery...


Google Image

I will say it does help a little bit as a trickle charger to keep the batteries up after they have been charged already... It will raise my 50% depleted charge state Battery DC voltage up to around 12.3-4 VDC sitting in the high sun during the long day with the battery still connected to the truck system with its parasitic drains still functioning.

It does not keep up very well with a couple of my DC Chargers plugged into the Truck 12VDC sockets keeping my cell phone and tablet peak charged for long periods of time listening to my Police Scanner frequencies during the same charging period. Keep in mind my 12VDC battery is all but dead as it is and started loosing its stay charged performance a year or so ago. It needs replaced big time hehe... But with the trickle charge it gets when sitting in my yard I can still get started each day to use the truck...

I sit it in the windshield dash area of my truck plugged into a 12VDC socket inside the truck.

These small wattage panels are worthless to me and I would not buy one to use except to trickle charge a battery setup after it has already been charged and just sitting there with no parasitic drains being pulled from it...

Just my thoughts here...
Roy Ken

[SoundGuy]

KD4UPL wrote:
That panel is likely only good for about .3 amps Imp at most. That's not enough to overcharge those batteries.

NOCO claims "up to 410 ma" ... why in the world would anyone spend $63.95 for such an insignificant amount of charging? :h

[KD4UPL]

2 6 volt batteries in series become 1 12 volt battery and should be treated as such. I wouldn't bother with a charge controller on a 5 watt panel. That panel is likely only good for about .3 amps Imp at most. That's not enough to overcharge those batteries. The general rule of thumb is that you don't need a charge controller for charge current 1 percent or less of the battery AH capacity. 2 6v golf cart batteries would be around 220 Ah. 1 percent of that is 2.2 amps or 7 times the capacity of your panel.

[SoundGuy]

martinandanne wrote:
I have one of these NOCO 5 Watt Solar Battery maintainers. Assuming I have two 6 volt batteries in series to product 12 volts, am I correct that I would still use a 6 volt controller despite the fact the output from the batteries is 12 volts?

If you already have that solar panel you've linked to you don't need anything more - just hook it to the two 6 volt batteries which are connected in series and are in effect a single 12 volt battery. Question is - why bother with such a tiny panel which outputs so little as to be almost meaningless. :h

[time2roll]

5 watts is generally too small for two batteries even for storage.
Need to fully charge first and disconnect everything else.

[mike-s]

No. Two 6 volts in series is no different electrically than a single 12 V. You want a charger made for a 12 V battery.