12 volt system help required.

[mibosa]

Hopefully I have completed the Photobucket transfer properly and you are able to see the photograph of my 12 volt battery system. 

I have a 130 AH deep cycle battery which I have installed to power a 9 x 12 volt LED spot lights, two LED strip lights and some 12 power sockets.  As the photo shows, I have used B&S 6 wire from the battery terminals to fuse boxes.  In the photograph you will see that I have placed fuse boxes in the top row for both + and - leads to address lighting issues and the lower row is for addressing power sockets.

When the battery has been fully charged using an appropriate charger (with no other leads attached) the reading is 14.08 volts.  Upon attaching the + and - leads to the battery it then drops to 13.48 and after almost two hours it drops further to 12.90 volts.  And that is with no 12 volt lights on or any appliances drawing on the 12 volt power sockets. What am I doing wrong or is all this normal??  What is causing the voltage drop??

[Observatory]

Hi Mibosa, my 12volt knowledge is pretty basic but to me your battery seems to be operating normally.

I've used a similar size battery off-grid for my own van for 3 years. Like yours, when charging it goes to a bit around 14.2 volts. When sitting with out charging: 13.4 volts. When under load 12.6.

One thing to note is that DC is very inefficient over greater distances ie voltage drop with longer wiring. Maybe try detaching some of your wires to see if there is any variance in your voltage drop??

Cheers
Pete

[mibosa]

Thanks Pete. When you say detaching some of my wires, are you referring to the wires from the fuse holders to the individual lights and power sockets or the red and black B & S 6 wires from the battery terminals to the fuse holders? Just checking the meter now, almost 5 hours after I connected them all up it is down to 12.79. The battery seems to be getting slowly lower as the night goes on and at this rate by morning it would be down to the danger/urgent recharging level. Why am I loosing battery charge at this rate when I am not using the lights etc do you think? I might have to go onto one of the 4WD sites where they specialize and trouble shoot these 12 volt system problems. Regards, Bob

[gregh]

Hi Mibosa,

What you are experiencing is perfectly normal. All batteries require a higher than set voltage (in your case 12v) to effect a full 100% charge. When the charger is removed, the voltage will drop rapidly to 12.6v - 13v depending on battery type and condition. If your battery is holding 12.9v after initial voltage drop, I'd say you have a pretty good battery.

Question; are your batteries connected to a solar panel??

Cheers
Greg

[mibosa]

Hi Greg. No, there are no solar panels connected. I am in the process of doing up a 1966 Viscount Ambassador and thought I would do all the 12 volt electrics, which includes running the lighting and power socket cables through the roof space whilst I have the ceiling out and before putting the new one in. As per my last post/thread where it dropped down to 12.79, I disconnected the red and black main battery cables and the meter then told me the battery was at 12.93v. The idea will be that I will set up an Anderson plug underneath the van to connect to a solar panel to charge it when possible or charge it using the smart charger whilst near 240v. I just could/can't work out why the battery voltage was dropping when there was nothing drawing on it. Thanks Greg, Bob.

[Observatory]

Hi Mibosa,

What Greg said - you are experiencing normality

Yes disconnecting the lights wires; as even though they are off, current still travels to the switches creating a small load on your battery.

Pete

[DC3Td]

Sounds good to me too Mibosa & you`ve built a real neat battery system.

[mibosa]

Thanks DC3Td, I seem to be reassured by the the feedback that what I thought may have been faulty is in fact the norm. Thank you for your compliment about my battery set-up. I haven't seen any other 12 volt set-ups so I am just trying to use a bit of initiative with space management, in this case the weight being almost over the axle and enough room to add a second battery if required, with fuses easily accessible for any maintenance etc. Regards, Bob.