So I’ve got the usual setup on our 17” OB. We’ve added solar to it, but now want to add a second battery for more storage for free camping.
What’s the best way to add it into the system?
What’s the best way to add it into the system?
17' Series Adding second battery
- Thread starter Brougham
- Start date
Simple, parallel up another batter similar (the same would be preferable) to your original battery + Positive to Positive and - Negative to Negative
If its close or next to the original battery 6mm auto cable will be okay as long as youre not running anything that draws heaps of current like a 2,000 watt inverter
Think of batteries as water tanks, an old battery is like an old water tank with sludge in it and it wont have the capacity of a new tank, same as an old battery
If its close or next to the original battery 6mm auto cable will be okay as long as youre not running anything that draws heaps of current like a 2,000 watt inverter
Think of batteries as water tanks, an old battery is like an old water tank with sludge in it and it wont have the capacity of a new tank, same as an old battery
After I do the + Positive to Positive and - Negative to Negative bit I normally attach the + leads to the + on the 1st battery and the - leads to the - on the 2nd battery.
Here is a good article - https://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel/ which explains the separation of the take off leads.
Here is a good article - https://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel/ which explains the separation of the take off leads.
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It matters little to be honest, if you want you can leave the wiring exactly as is on the original battery and just parallel up a second battery. Some say you must take the negative to the second battery but no one can give me a decent explanation for this. I recently wired up my neighbours van he built, we put 3, 120Ah SLA batteries in and I used 2B&S battery joiners, the battery guy insisted I hook the positive feed to the first battery and the negative feed to the third battery but couldnt tell me why?? (I am actually an auto electrician as well)
Hey @DRW the link that @Glen Bundesen noted gives a pretty plausable reason I thought, though how it goes in real world may be academic like a lot of electrical bench findings.....I wired mine up like that so it must be right...lol lol,lol.
In a perfect world
1. the original battery is probably down on capacity so both batteries should be replaced with identical batteries
2. the joining cables should be large enough to prevent any voltage drop for any type loads, think heavy battery cables
3. the van would have a state of the art multi stage battery charger and multi stage DC to DC charger
4. the solar charger will also have multi stage charging to ensure the batteries are fully charged
Now what we really have
1. a used chinese battery so adding a similar battery will usually double capacity
2. a battery charger that is a trickle charger that it set to an average voltage to charge the battery to an acceptable charge for running what's intended
3. factory wiring (no further comment needed)
4. a van that uses bugger all power in most cases, mabe a TV, a few lights and charges electronics etc possibly a 12V car fridge from time to time (as I said if you are running high current loads the whole thing needs to be re-hashed)
At the end of the day the wiring modifications are usually being performed by a novice (no offence intended) usually in a 17' there is room to fit a battery next to the original battery, the original cables wont always reach the second battery and joining them is less than ideal. Using 6mm auto to connect the battery is using the same cabled Jayco use and with the standard electrical usage there will be nothing in the way of voltage drop.
In my last 2 Jayco's I threw the original charging in the bin, fitted a decent charger, a decent DC to DC charger and had 120W portable solar panel (I often park in the shade) I almost always had my 12V waeco fridge running off the van as well, and in both vans we only had the original battery and all worked fine
But what about the Coffee Machine, they are the must have get back to nature device..........???????/........................(not for me mind I'm too lazy to stuff around and hate coffee with milk).....................I must admit the wiring in the Coromal isn't too bad, batteries of course are chinky but only in the fine print so might be just the label, my cable matches the lugs so they fit nicely and won't melt with the TV and FoxteliQ3 running, Engel runs in Ute and fridge runs on gas and heaps of solar chunt the sun into the battery so the little red gadget keeps showing high 12's...................
and your explanation really does cover it all @DRW , I'm all for real world...how many days till you have a mobile house again..?????????????
and your explanation really does cover it all @DRW , I'm all for real world...how many days till you have a mobile house again..?????????????
Hah thanks everyone. Yep real life is more realistic. My main battery is only 6-8mths old so will just add a second battery the same.
I was wondering whether to run the solar in the same manner (pos to main, earth from second) but probably doesn’t matter
Don’t have an inverter, what doesn’t run on gas or 12v isn’t needed IMO.
I was wondering whether to run the solar in the same manner (pos to main, earth from second) but probably doesn’t matter
Don’t have an inverter, what doesn’t run on gas or 12v isn’t needed IMO.