Anyone Carry a Spare Battery?

ScottG

So, in theory, does this suggest that a partial charge from a small solar setup does the same damage to a battery? I know there are days when I get some charge, but definitely not a full charge. However, I'm usually starting with a battery that is not down to 50%.

I am working with a bargain basement wet cell. When and if I plunk coin down for one (or two) of those other monsters, I'm pretty sure I won't be talking about moving them either. Hopefully with all the extra juice I won't have to!  :-)

Ratkity

@ScottG,  A good solar controller works even better than your camper's converter. The solar controller works just like a regular 110V battery charger. There's a bulk, absorption and a float stage.

But as you know, there's limitations to solar. The hotter the day is over 77F, the less efficient your panels are. By 95F, your panels efficiency drops significantly. That's solar's dirty little secret. Panels are becoming more and more efficient at a greater temperature ranges these days. I'm hoping one day there won't be that constraint. The best way to circumvent coming up short for your solar needs is to have more solar wattage than you need.

Back to your question. Oscillating within a range of say 60-85% of battery level for weeks and weeks on end.. yes, you will shorten the life of your battery(s). If you do this periodically and then turn off all loads doing a separate full-overnight charge about once a month, I think your battery will live a long time (check water levels if a flooded battery). Deep cycle batteries are designed to go down to 50% repeatedly, but need some TLC and a full charge with an overnight rest with no loads after a monthly charge. 

lightningdon

I carry my original dealer installed battery in the bed of my TV. I cut my fridge 12V electric line and installed male cig lighter plug on the fridge side and female on the trailer side. Couple that with a female to alligator clamp wire, I can unplug the fridge in my T@G, plug into the adapter cable and wire it directly to my spare battery which I sit on a leveler block under the rear of the T@G. When that battery is discharged, I can plug back into the camper lead where it can run off the dual 6V batteries. I do have solar on the T@G. I can go dry camping for an extended time with this setup.

jkjenn

Ratkity said:

@ScottG,  A good solar controller works even better than your camper's converter. The solar controller works just like a regular 110V battery charger. There's a bulk, absorption and a float stage.

But as you know, there's limitations to solar. The hotter the day is over 77F, the less efficient your panels are. By 95F, your panels efficiency drops significantly. That's solar's dirty little secret. Panels are becoming more and more efficient at a greater temperature ranges these days. I'm hoping one day there won't be that constraint. The best way to circumvent coming up short for your solar needs is to have more solar wattage than you need.

Back to your question. Oscillating within a range of say 60-85% of battery level for weeks and weeks on end.. yes, you will shorten the life of your battery(s). If you do this periodically and then turn off all loads doing a separate full-overnight charge about once a month, I think your battery will live a long time (check water levels if a flooded battery). Deep cycle batteries are designed to go down to 50% repeatedly, but need some TLC and a full charge with an overnight rest with no loads after a monthly charge. 

+1....well said @Rat@Ratkity

ScottG

Alas, the real-world verdict on the emergency charge cable will have to wait. With mostly decent weather I kept up just fine for nine days with solar alone. However, I did have to deploy my nearly 40' of cable to get the suitcase into full sun for a few hours each day! I do like my trees, but I can see the advantage of the extra wattage @Ratkity mentioned when conditions are less than optimal.

Moving that extra wattage around, now that's another story...  :-)

ScottG

With some longer dry camping trips planned this summer, I've been revisiting this topic. The current plan is to be able to plug in a portable second battery  and toggle between it and the main battery with a four-way switch. I've been pondering easy and relatively cheap ways to attach my spare battery when needed. 

Can anyone think of a compelling reason why MC4 connectors wouldn't work for this? They accept large gauge wire, the terminals are recessed, they are weatherproof, and they are easy enough to connect and disconnect for the limited number of times I see this arrangement being needed?

CrabTab

MC4 connectors should work. My older hands like SAE or Anderson connectors. I have SAE stuff on my T@B where I frequently disconnect and MC4 where stuff is mostly permanent (up on the roof). It is all 10GA wire. Just started using the Anderson. Bought an SAE to Anderson converter to be able to charge a device from my 'solar array'.

Tabnero

I carry a Goal Zero Yeti 1000 occasionally and just plug the T@b into the AC outlet. Easy and versatile. https://www.goalzero.com/shop/archive-power/goal-zero-yeti-1000-lithium-portable-power-station/

webers3

500Wh portable battery, runs the top-load refrigerator, very convenient at overnight stops since I  don't want to use the car battery, recharged while we drive, and can use as shore power if necessary.

ScottG

I agree the MC4s are a little futzier than other connectors, @CrabTab but I'll probably go with them since I have a supply on hand and I've been using the same all along for connecting my modular solar setup.

I was a little curious why their use seems limited to solar wiring, but that may be more about convention than anything else. The electricity shouldn't care either way, after all. If I end up using this more than just occasionally, I may look more closely at those Anderson connectors.

Verna

My first Zamp solar panel, an 80 watt model, had Anderson connectors, and they were a very good and tight connection. They connected either to a set of alligator clips or to a “Zamp” plug.  

ScottG

I finally got around to my back-up battery project this week. My original plan had been to install a four-position battery selector (and associated wiring) near the main battery, but as I started planning things out I realized this would create more impedimenta in the already crowded tub than I was interested in having.

I finally decided to replace my existing 2-position switch (installed near the converter) with the 4-way switch, and to run new wiring from under the driver's side bench directly back out to the tub.

I'm pretty happy with the simplicity and functionality of this set-up. I don't expect to need it very often, but it should provide a bit of insurance for those times when my single battery and solar may not be able to keep up. The relative portability of the auxiliary battery also allows for flexible charging options (e.g, moving it into the sun with a solar suitcase, charging it with the tow vehicle, or even bringing it somewhere where it can be plugged into an electric charger.)   

Here's the new 4-way selector switch which allows uninterrupted switching between batteries.



Here's the wiring behind the switch showing the attachment points for the new battery lines. (I used black wires but labelled them with red and white tape to differentiate them.) The new wiring follows the existing harness and ends in an MC4 pigtail in the tub.



And here is the auxiliary battery with it's own MC4 pigtail hooked up to the other end of the new cable. (When not in use the cable is secured to a plastic clip inside the tub.)



The worst part--and probably a deal breaker for doing this mod on most 320s--was running the new wires from the tub to the converter. Following the path of the existing wiring harness was no small task given the (almost) completely inaccessible space beneath and behind the toilet. I my post about that experience in a separate discussion.  :-/ 
   

digitaldean

My second battery solution is as follows. I bought an identical grp31 AGM as my spare battery, and put it in an ArkPak battery box (pic attached). It normally stays in the truck (SUV) when camping hooked up to buffer my second Dometic portable fridge/freezer (Norcold backup and much more fridge space). I can swap batteries with the trailer one, but I can simply wire this direct to the trailer battery too. 2 batteries in the trailer box adds to tongue weight and takes away precious space, this way does not and has many other uses. I use it for my electric fishing motor on my boat, for charging devices or grinding coffee (it has a 350W inverter built in), I can jump start the SUV with it if that battery get low, and more. This portable charges by 120v, has a solar direct 12v charging input from a portable panel, and comes with a 12v charging cable that I can connect to the trailer solar system if charging is needed. It displays charging status, has a 7 stage charger built in for keeping an expensive AGM healthy, and it's easy to swap in any battery into this box with simply setup. They're not cheap ($500cdn), but they're very versatile and handy. They work for regular lead acid, AGM, and Lithium batteries. Not that I'm selling these things, but it's really made my life easier and provided insurance for more than just the trailer battery.
Dean

 

VictoriaP

@digitaldean That ArkPak is nice! I have a Goal Zero Yeti, but being able to easily change the battery when it reaches the end of its useful life is a definite plus with your setup. Thanks for recommending!

msmith

Power everything, other than the AC, with a small 12 volt portable power station from inside the T@B.

First I tested my Bluetti AC50S power station (500 watt hour, 300 watt) energizing the whole T@B by plugging directly into the shore power receptacle. That worked but found it was drawing 29 watts even with everything turned off because the inverter in the power station and the converter in the T@B use power! So a fellow camper Patrick Bowdish and I came up with a way to tap into the 12 volt wire coming from the house battery so I can use the power station from inside the T@B and also bypass the inverter/converter saving 29 watts. 

I tapped into the house battery wire (red wire) on the back of the converter with a 10 gauge wire (+) and an SAE connector. Other wire (–) goes to the grounding bus. SAE connector mounted to the wall next to the LP/CO detector. Used a cigarette port connector to SAE connector wire to connect to power station’s regulated 12V 10amp cigarette port. 

I found that starting up the power station threw an error code E27 (overload). After trial and error testing we found a workaround: power up with house battery first - turn on power station - then turn off house battery. The converter must be getting a power surge on startup that’s too much for power station’s electronic protection system. But once the converter has 12V power the power station can be energized and allowed to flow power into the converter and house battery. But when the house battery is turned off the power station continues to power the whole camper. 

Bottom line - when boondocking we can now power the fridge all night without running down the house battery or power the T@B on rainy days when we have no solar power + save 29 watts of power wasted on the inverter/converter.

Viajero

Depending on your budget consider something lite a Yeti or Jackery that uses Lithium battery’s. Much lighter to haul around. Then just select a quick connect that can handle 20 or 30 amps and fuse accordingly. 

Our backup battery will be the 82 KWh battery in the Tesla tow vehicle. 😊

GatorEgg

Just bundgy an extra battery in your tub.  It’ll fit.  Or if you want a little project there is a dual battery tray made for the T@b tub.
https://www.enhancedperformancesystems.com/product-page/t-b-dual-battery-conversion-kit

pthomas745

Can we look at this one more time?  An owner on the FB page has an extra 80 amp hour battery. Wants to be able to use it somehow, instead of the time and expense and install or swaps of lithiums/dual 6V, etc. My brain isn't working quickly enough to sort this out today!

If you the DIY battery 7 pin connector, going directly from the "spare" battery into the trailer's 7 pin plug and the battery switch was on: it would simply charge the trailer's battery from the spare, and that extra power would be used to run the fridge, for example?

If the trailer battery disconnect switch was off, and the spare was plugged directly into the trailer's 7 pin...all the power from the spare battery would be used to power the trailer?    The installed solar would then be able to charge the trailer's battery without the trailer battery being "in use"?

Sharon_is_SAM

pthomas745 said:

Can we look at this one more time?  An owner on the FB page has an extra 80 amp hour battery. Wants to be able to use it somehow, instead of the time and expense and install or swaps of lithiums/dual 6V, etc. My brain isn't working quickly enough to sort this out today!

If you the DIY battery 7 pin connector, going directly from the "spare" battery into the trailer's 7 pin plug and the battery switch was on: it would simply charge the trailer's battery from the spare, and that extra power would be used to run the fridge, for example?

If the trailer battery disconnect switch was off, and the spare was plugged directly into the trailer's 7 pin...all the power from the spare battery would be used to power the trailer?    The installed solar would then be able to charge the trailer's battery without the trailer battery being "in use"?

@pthomas745 -
if you connect the second battery via the 7 pin with the battery switch on, they both supply current to the junction box and I think you are basically running the batteries in parallel and they will equalize out their charges, but, yes, you can power the TaB.  But the second scenario, the battery switch only applies to the primary battery.   The extra battery will supply current to the TaB via the junction box + and - terminals.  The installed solar will continue to charge the primary battery.

rcarlson1957

msmith, love my AC50S Bluetti. Since I have a 3 way frig and on propane if not shore power, I use it in the back of my TV in pass thru mode to power my ICECO GO20 frig when we stop and turn off TV. Have two 120v portable Bluetti panels. Use one for the T@B thru a Victron Solar Controller in the tub and the other connected to the AC50S to power the ICECO if not on shore power. Like your unique use for your Bluetti. 

pthomas745

I finally got around to fiddling with the 7 pin spare battery adapter, and it works like a charm. Just like everyone said it would!

Bought the inexpensive 7 pin vehicle adapter.  Learned how to take the plug apart, stripped out all the extra wires leaving the black wire (12V positive) and white wire (ground, or negative).  If you take the plug apart: make a mark or pay very close attention to how the plug goes back together.  The plug has to go back together with the wiring in the correct orientation.

Crimped in a 30 amp battery fuse holder.  My wiring skill is getting less disastrous, but still not very pretty. I'm going to wrap this up with a wire loom.  I used the battery clamps because I had this pair just waiting for a project.

Battery switch off, plugged in to the trailer, and it works just fine.

arunakalu

Thank You, got this Error and was checking on web and found your workaround. Now I am powering our camper too with the AC650s from a cigarettle light port I installed to Control Center.

msmith said:

Power everything, other than the AC, with a small 12 volt portable power station from inside the T@B.

First I tested my Bluetti AC50S power station (500 watt hour, 300 watt) energizing the whole T@B by plugging directly into the shore power receptacle. That worked but found it was drawing 29 watts even with everything turned off because the inverter in the power station and the converter in the T@B use power! So a fellow camper Patrick Bowdish and I came up with a way to tap into the 12 volt wire coming from the house battery so I can use the power station from inside the T@B and also bypass the inverter/converter saving 29 watts. 

I tapped into the house battery wire (red wire) on the back of the converter with a 10 gauge wire (+) and an SAE connector. Other wire (–) goes to the grounding bus. SAE connector mounted to the wall next to the LP/CO detector. Used a cigarette port connector to SAE connector wire to connect to power station’s regulated 12V 10amp cigarette port. 

I found that starting up the power station threw an error code E27 (overload). After trial and error testing we found a workaround: power up with house battery first - turn on power station - then turn off house battery. The converter must be getting a power surge on startup that’s too much for power station’s electronic protection system. But once the converter has 12V power the power station can be energized and allowed to flow power into the converter and house battery. But when the house battery is turned off the power station continues to power the whole camper. 

Bottom line - when boondocking we can now power the fridge all night without running down the house battery or power the T@B on rainy days when we have no solar power + save 29 watts of power wasted on the inverter/converter.

Denny16

The AC/DC two-way fridge runs directly from DC when not on shore power, and does not require the use of the inverter.  
cheers