Solar Battery Questions

• 

  ESEMCE on 16/08/2018 - 15:42

  +1

  Your photos show two 12 Volt batteries connected in series maybe? This would doubls the Voltage of the storage system, 12V+12V to make a 24V battery.

  The panels are likely directly feeding the batteries to float charge them.

  The inverter looks like an automotive step up Inverter to convert the 24 Volts from the batteries up to 240V in order to run regular appliances. It doesn't look like a solar inverter to step down the voltage from panels to charge the batteries.
  Anything that is 24V only will happily chug along from a direct connection to the batteries whether the Inverter is on or off. Guessing that this is what you're seeing?

  The photo of the black box, looks like a simple fuse holder to me, with 2 glass fuses.

• 

  aarn on 16/08/2018 - 16:12

  +1

  I think the batts. are connected in parallel. Anyway, the OP could tell us if any 12V lights are still used in the van. Looks like the solar panels feed in from the white powerlead, from which red + black leads capped with alligator clips attach to terminals on one battery. Looks like the heavy wrinkled red lead connects the two battery positive poles, a smooth black lead connects the two negative poles. Assume the power inverter is actually hooked up, and OP can get 240V (AC) power at the flick of a switch.

  Can't see any evidence of a regulator. OP will have to be careful that on long, sunny days the batteries don't overcharge. You will hear a lot of bubbling if this is occurring. Better still, buy a cheap (~$10) multimeter. 'Good'/new 12V batteries should show ~ 13.5V when fully charged. When charging, they will show up to ~ 14.8V maximum - anything above this indicates damage has been done, and is being done, to the batteries.

  Battery health - rock them back/forward daily, if the van is stationary. Otherwise lead sulphate will settle out of solution, reducing battery life. Also, check fluid level of each cell (12V battery has 6 x 2v cells) every, say, every two weeks - top up each cell with distilled water (don't use rainwater unless you are sure it is pure).

  I had 12V then 240V solar battery systems in a stationary van for ~ 20 years. The killer - apart from the odd rat-bite of a lead - was leaving the batteries stationary. So rock 'em regularly! Will try to upload article published ~ 2001 in 'Grass Roots'. Cheers

  • not wanting to nanny-state your set-up, but overcharging batteries results in production of hydrogen (inflammable) and oxygen (explosive!) so you might consider putting a reulator between solar panels and batts.
  • 

    ESEMCE on 16/08/2018 - 16:23

    +1

    Could be right about being wired in Parallel… nice spotting on the smooth versus ribbed cabling.
    I got fooled by the ribbed cabling going between one Positive and the next Negative terminal.. but looking closer that tangles it's way possibly through the fuse box, not between batteries.

    Either way, I think we're agreed that the Inverter is a step up and the batteries are likely being directly charged with no controller. (unless that's hidden somewhere else)

• 

  Euphemistic on 16/08/2018 - 16:21

  +1

  I'm not sure of them being in series. The cable between the two batteries wouldn't normally have one red one black in that case. Most caravans are set up for 12v, not 24 so it would likely be in parallel. If they are in series, the cable between the two batteries should go straight from the positive terminal to the negative terminal between the two batteries and nowhere in between. If the cable does not loop straight from one to the other then assume parallel.

  Trace the cables if it goes van-pos1 and neg1-pos2 and neg2-van it is series. If it goes Neg1-van and Neg2-van and also Pos1-van and Pos2-van then it is parallel. I've abreviated negative terminal on battery one to neg1, postive on battery 2 to pos2 etc, and -van to indicate the circuit goes to the van, not another battery.

  Most caravans will be set to run on 12v for lights etc and the inverter used to power the 240v sockets. That inverter looks quite small, so I wouldn't be running too much off it.

  There might be a switch somewhere to switch between 240v source (plugged into the grid) or 12v to run solely on the batteries.

  The solar panels should have a regulator between them and the batteries, but it doesn't show in the pics.

  Black box does look like a fuse block.

• 

  aarn on 16/08/2018 - 17:06

  I suspect this setup has 12V constantly available, but there is a master-switch to engage the 240V system (as inverters just suck power from the batt.s even when there is no load ie. nothing using 240V is switched on). Maybe OP could confirm…

  Sorry, unable to find my 'Grass Roots' article from ~ 2001. But OP will get good advice on youtube. AA

• 

  Tasmaniac on 16/08/2018 - 17:43

  Thanks guys and yes, the panels run through a regulator to the batteries and theres wires forming a 24v system. I just discovered also that the red battery terminal wire runs straight to the fuse box. The weird thing is theres three wires from the negative. One goes to the inverter and the other two just disappear off through the caravan. From the inverter theres just one cable that runs to the fuse box. Anyway I also dont think theres any kind of switch to swap from solar either, I could be wrong though if its wired somewhere else. Anyway thanks again.

  • 

    Euphemistic on 17/08/2018 - 06:38

    Have you tested it as 24v? It would be unusual to run 24v system in a caravan that hooks up to a 12v car. Unless the van was previously towed by a truck with a 24v setup.

    It definitely looks like a home made setup. The wires could be anywhere, to anything. Do some more investigations.

  • 

    ESEMCE on 17/08/2018 - 07:49

    I suspect the socket next to the Inverter is the only 240V battery powered outlet…
    Any other 240V outlet in the caravan is likely only externally powered, therefore no switch required to toggle between battery power and 240V.

    Batteries in Parallel means that the two Positive and two negative terminals are essentially the same terminal, so don't let that confuse you. The wires heading into the fuse box (one from the LHS -ve and the other from the RHS +ve terminal remember it's irrelevant what battery the terminals are connected to) are 12V only.

    The skinny wires connected by alligator clips aren't going to carry much current (especially not at only 12V), and the Voltage drop across them will be significant if they're longer than a couple of metres.
    If there are 12V outlets in the vicinity, I'm guessing these wires are feeding them looks to me as though there might be two 12 V outlets only

    The extra wires coming into the Fuse Box, must be the feed wires from the Solar Controller.
    I'm guessing the wire coming in are positive (at the top left of the photo) and Negative (in the middle) with the bottom cable carrying both positive and negative wires) going to the Inverter. Unless I am mistaken, it looks like there's a Black negative wire from the Inverter cable wired into the middle Solar input wire?

• 

  TheBilly on 18/08/2018 - 19:35

  Your van will have one of these combos

  Solar Panels > Regulator > Batteries

  Solar Panels > DC Charger > Batteries

  If you charge direct from panel to battery the batteries will fry. So you definitely have something in between - a regulator is just used for solar panels - a dc charger has the ability to regulate solar panels and also charge batteries via other means like - from car battery while driving, or plugging into a powerpoint.

  To take it a step further, your caravan may also have the following near your tow ball.

  Anderson Connector

  This will allow your batteries to charge from your vehicle as you tow, but your vehicle will also need a point to connect back to your vehicles battery. Also if you chatge from your vehicle you need a DC charger or isolator so it doesnt keep sucking power from your car and inly sucks power when it is running.