Adding a house Battery

Christopher Thwaites · 09-15-2008, 05:57 PM

I want to add a 3rd battery to my Van. It has the factory stock dual battery system, one under the hood,one under the pass. side door. The system does not isolate one battery. All aux. plugs and systems run off both batteries.
They both run down equally when I run my 12v fridge. It's a National Luna 50 Twin.

I am wired for solar but have not installed a panel yet.
I want to wire the 3rd battery directly to the solar system and put a switch between the 3rd battery and the other 2 so that I can manually choose to seperate the 3rd battery from the other 2.
My questions are.....
1. Will this compromise my existing system in any way?
2. Do the batteries all need to match?
3. Will my alternator charge all 3 if I need it to.
4. What size solar panel would be good if all I'm running is the refer that draws 1.53 to 2.6 amp/hours on average.

I'd appreciate any input.

Ford_6L_E350 · 09-15-2008, 06:59 PM

First, go to this website and print the brochure:

http://www.surepower.com/separator.html

I believe SMB installed a 1315 in our van and it works to keep the camper loads from running down the starting batteries. And it will allow either system (camper or starting) to charge the other batteries. When one system reaches the spillover voltage (13.2V) it automatically starts to charge the other system.

We have the large (4cf?) Norcold refrig and a 125W solar panel. The refrig draws ~2 amps and runs about 50% of the time. The panel is big enough for even cloudy days. However, we have two camper batteries. We tend to camp in fall with shorter days and still have plenty of charging to park for a full week or more without starting the van.

Mike

SMBReno · 09-15-2008, 08:31 PM

I, too went through this when all batteries died. The previous owner had installed a marine battery switch, but couldn't remember the connections and hadn't done a schematic or labels. I don't have solar, but added a new 4D AGM, swapped the old (02) isolater for a 1315 battery separator, and finally a new linkpro battery monitor. I highly recommend this last item if you are concerned about your batteries and charge state. It is a fairly simple install, and with this and a digital voltmeter you can troubleshoot and monitor everything. You can download the Linkpro info online. Quite sophisticated. I installed the guage into an ABS electronic box with a tether rather than placing in a bulkhead so it is easily read. The key to AGM life is keeping them charged (as opposed to the "deep cycle" nomenclature).

Christopher Thwaites · 09-16-2008, 10:41 AM

Mike/SMBReno,
Thanks. This sounds like a better approach than a manual switch. My fridge has a built in battery monitor with a simple display.
I haven't installed a solar panel yet but SMB prewired the system when my top was installed. Will I still need an additional monitor?
The battery shop I go to recommends a wet deep cycle battery over the AGM since the battery location is outside. Seems like there is no concensus from forum members on prior posts regarding AGM vs wet. Although AGMs seem to prevail for some reason.
I have no other needs for power other than the fridge.
Sounds like a 125watt panel will give me plenty of juice for my needs.

Ford_6L_E350 · 09-16-2008, 11:04 AM

Quote:

Originally Posted by Christopher Thwaites

My fridge has a built in battery monitor with a simple display.
I haven't installed a solar panel yet but SMB prewired the system when my top was installed. Will I still need an additional monitor?

My SMB was prewired and I installed the solar panel. The solar controller SMB installed is adequate for monitoring the electrical system. I'm sure there are better systems out there, but ours is adquate.

Mike

SMBReno · 09-16-2008, 12:32 PM

The Badgertrek forum has an extensive discussion on this topic - really depends on use - we use our SMB for 1-2 weeks then plug into shore power. I moved the 4D inside (EB50 design) behind water tank and adjacent to the inverter for access and avoiding lifting with a floor jack (not fun). Personally, I feel that either an accurate digital voltmeter or a battery monitor (or a generator/solar - neither of which do we have) is useful if like us you are 100 mile away from any service in a remote location and are concerned about starting. The Linkpro also monitors battery usage in real time - basically a gas gauge for the battery and can trigger a generator/alarm. I suppose you could use it to trigger solar charging to the battery if necessary. Just my thoughts having what some might characterize as paranoia about dead starting batteries. Finally although I have one, I would trust a battery switch more than separator as mechanical only. Separators do fail.

**daveb** · 09-18-2008, 08:49 PM

Quote:

Originally Posted by Christopher Thwaites

Mike/SMBReno,
Thanks. This sounds like a better approach than a manual switch. My fridge has a built in battery monitor with a simple display.
I haven't installed a solar panel yet but SMB prewired the system when my top was installed. Will I still need an additional monitor?
The battery shop I go to recommends a wet deep cycle battery over the AGM since the battery location is outside. Seems like there is no concensus from forum members on prior posts regarding AGM vs wet. Although AGMs seem to prevail for some reason.
I have no other needs for power other than the fridge.
Sounds like a 125watt panel will give me plenty of juice for my needs.

I'm sure there is a discussion on battery types (with links) somewhere on this site.
Wet cell batteries take longer to charge, need to be monitored to keep the water up, and suffer from off gassing during high amp charges. Heat affects them more.

AGM's can be more expensive, generally weigh more, and are subject to failure if the voltage drops below 10.2 volts. I think Optima batteries weigh a little more than a wet cell counter part.

I plan to install a bypass switch ASAP just incase the battery separator fails as it has in the past. I still prefer the battery separator for normal operation.

Depending on your load, a small extra battery might not suit your needs. I find 2 4-D's work for me but the single 4-D was at the limit. Your mileage might vary. So research the archives here and on the owners group.
Good luck on your quest.
Dave

Christopher Thwaites · 09-19-2008, 11:04 AM

Good points Dave,
It will take some thought to sort out the pros and cons of battery types since I'm sort of outside of the usual SMB conversion.
I'll get back to the forum battery discussions and hope for a revelation.
I have already decided to have a manual battery switch in addition to the electronic isolator.
Thanks