2 batteries

May 15, 2007
471
1
0
Visit site
I have started to stay a lot more on CL sites with no electric . I have a 100w solar panel on the roof and a 110a battery. Question, can i join another battery to the existing one to double its capacity and will the solar panel keep them both charged ?.

Cheers

Graham
 
May 24, 2014
3,687
763
20,935
Visit site
Going off your username, are you in Derby? I am only 5 miles north of Derby. Unless its your surname B)

Firstly they would I believe need to be connected in parallel. In series the two voltages would add making 24v. It would be wise to have identically rated batteries.

This video may help regarding the solar charging
[video]https://www.youtube.com/watch?v=4zAqUHFkIcY[/video]
 

Parksy

Moderator
Nov 12, 2009
11,904
2,399
40,935
Visit site
If you really need two leisure batteries the better option would be to use them in sequence. Unless both batteries are in equally good condition the stronger battery will lose power to the weaker one and this also applies when the solar panel is charging.
A changeover switching system could be useful if you don't want to lift the batteries every time to change them manually.
Edit: p.s. Before somebody else mentions it, you'll need to keep the extra battery in a properly secured battery box ;)
 

JTQ

May 7, 2005
3,356
1,165
20,935
Visit site
I would be concerned about "matching" the batteries, ie getting a second battery of the same technology, and age degredation to parallel with your own. If going this route it is better to buy two new identical batteries from the same batch.
I do use two batteries and with solar but in a particular way that avoids all the above complications. I have a normal caravan battery that serves all the normal duties, it is a 90 Ah gel now 10 years old and still remarkably viable.
Additionally I sometimes take a second 60 Ah wet battery specifically for powering the TV and DVD/radio.
These are both charged by an 85 Watt solar panel via a Morningstar Duo solar controller on a 50/50% split.
Now this is a very clever controller in several ways. First it knows if on that trip it has to deal with one or two batteries and automatically sets itself up. Secondly, you can set it to suit the technology of each battery, so mixing technologies age size etc is side stepped. Finally, whilst set to 50/50 split the available charge, it is smart enough to modify things as one battery becomes fully charged, then biasing the whole to the other.
I have configured my van to power everything from the main battery, or switch specifically the TV & radio/DVD unit to only drasin from the second battery. So, we can be profligate with watching TV, knowing the caravan's power will not be drained by them. The second battery is portable, in a sealled box and left plugged in but tucked under the van out of the way and not affecting the payload.
 
Oct 8, 2006
1,791
555
19,935
Visit site
GrahamDerby said:
I have started to stay a lot more on CL sites with no electric . I have a 100w solar panel on the roof and a 110a battery. Question, can i join another battery to the existing one to double its capacity and will the solar panel keep them both charged ?.

Cheers

Graham

Most solar panel controllers will take and can control two batteries - at least the one in my Bailey U4 Seville can!
 
Nov 16, 2015
10,630
2,943
40,935
Visit site
Welcome back G. I was in St Andrews last week and for the first time we were off EHU. Just for two nights. After a tow from Bamburgh Castle , the 120 amh. Battery was at 12.9 volts at 12.oo pm, and after two night running fridge and heating on gas and just lights on 12 volts at 10 am on the Monday morning the battery was down to 12.4 volts. Not sure how low the battery would have to be before the electronics on the fridge and heater would cut out.
The battery is three years old. Caravan a 2013 Coaachman 560/4.
 
Aug 11, 2018
86
2
580
Visit site
It is an interesting question, use as pair, or use in sequence? On narrow boats they tend to have a battery engine only, and rest all in parallel idea is the less percentage discharge then to quicker to recharge, however not quite that easy.

If the solar panel has fully recharged the battery by night fall, then it is likely a second battery could absorb more charge, however if it has not fully charged one battery, then there will no be any spare power to charge a second.

Unlike the canal boat where engine runs for maybe 6 hours, a solar panel charges for 8 to 16 hours depending on time of year, so in the main it has time to recharge the battery, and time is the key.

Alternating batteries one being used and charged the other one being charged only will likely ensure batteries get fully charged when being charged with an alternator able to deliver 70 amp. However with solar panels we are likely using more than that can deliver anyway so alternating batteries or even doubling up on batteries is unlikely to help.

There are some items that must use electric, water pump can be foot operated but in real terms has to be electric, gas lights have gone, has to be electric, but it can use LED to reduce demand, but cooking has to be gas, and items like Tv's have to be resistricted to a few hours a day.
 

TRENDING THREADS

Latest posts