Advice on best battery/inverter/solar solution for boondocking

[rossdn]

My wife and I are getting ready to go on the road in our 2018 16’ Bambi Sport; we are planning to primarily boondock. We don’t have huge electrical needs but definitely want to make sure we have the electricity we do need while boondocking.

My strength isn’t electricity so I’m hoping some of you much wiser individuals can provide some recommendations for our setup. Currently we have two basic flooded cell batteries, which need to be replaced, and a xxx portable solar panel.

As we will be boondocking we are looking for some quality, low maintenance batteries and we’d like to install an inverter to get our electrical outlets working to support charging of phones / electrical devices. I have read that golf cart batteries and Lithium batteries are the best options for batteries.

Do any of you have some suggestions for me and/or recommendations on someone in the central California area who is a good source for RV/Trailer electrical advice and service?

We would be open to adding a rooftop solar panel as well if that would be useful.

[dznf0g]

Originally Posted by rossdn

My wife and I are getting ready to go on the road in our 2018 16’ Bambi Sport; we are planning to primarily boondock. We don’t have huge electrical needs but definitely want to make sure we have the electricity we do need while boondocking.

My strength isn’t electricity so I’m hoping some of you much wiser individuals can provide some recommendations for our setup. Currently we have two basic flooded cell batteries, which need to be replaced, and a xxx portable solar panel.

As we will be boondocking we are looking for some quality, low maintenance batteries and we’d like to install an inverter to get our electrical outlets working to support charging of phones / electrical devices. I have read that golf cart batteries and Lithium batteries are the best options for batteries.

Do any of you have some suggestions for me and/or recommendations on someone in the central California area who is a good source for RV/Trailer electrical advice and service?

We would be open to adding a rooftop solar panel as well if that would be useful.

Well, best =$$$$$. You have covered about a $6k (or more) spread in your question.

I, for one, am at a point where two group 29 lead acid batteries, 200Watts of panels on the roof, and a 160 watt suitcase works quite amply for me. Then, when necessary, I have a set of Honda 2000ei for backup.

Did all the work on the solar myself and have far south of $2k in it, including the suitcase. Batteries were there anyway, solar or not.

[DKB_SATX]

One recommendation is to avoid using an inverter to charge your phones. It's inefficient... you should be able to get 12V adapters or if the Sport line is like the Flying Cloud line you already have USB power outlets to charge your phones. If you're talking about a laptop, there may be a 12v option for charging your laptop as well.

Lithium ion systems are very nice in terms of amp-hrs available, weight and location options but they are still quite expensive relative to AGM options. For our trailer, I'll go AGM when I have an excuse to replace the original Group24s and maybe when the AGMs get tired the lithium options will be a better value proposition.

[SilverHouseDreams]

As others mentioned, the "Best" boon docking setup is one that does NOT use an inverter...unless you have a way to carry far more battery capacity than you can fit into a Bambi. The first step is to find out how much energy you actually use so you can determine how much you "need".

The cheapest path is to reduce how much energy you consume, as adding capacity is always far more costly (and complicated). So efficiency first, which means anything that uses USB to charge should charge from a 12V port. Anything that is truly DC powered should also run directly off of 12V (e.g. your laptop). To help you along your path you may as well invest in an actual battery monitor now, such as the Victron BMV-712...its relatively easy to install, plenty of us on the forums have done so and you will find references. It just connects between the 12V negative line from the battery and your trailer.

Once you have a battery monitor you can truly see how much net energy you consume, you can also correlate to how much energy different items use (e.g. your fan on high vs low, or all lights on vs just enough). If you have any lighting that is not LED, swap those bulbs out now.

With a Bambi you are constrained on space and weight capacity, and while lithium definitely packs more power per pound or volume...you do have to determine if it is worth the upgrade. You will need a new converter (120V to 12V) to charge it. If you already have solar, you will need a new solar controller...and if you don't, just make sure anything you buy can also work with lithium (programmable voltage, or specific settings for lithium). You will also need to modify the charge line from your tow vehicle to the trailer for lithium.

The sensible place to start is with a battery monitor, and then add a portable solar panel setup (with a charge controller that is lithium ready, just in case). These both will work for your existing battery setup and carry forward to any other upgrades you make. A good option for portable solar is a Renogy suitcase (from their eBay store), should find a 200W setup for less than $400 without the charge controller.

You mention your batteries need to be replaced...on a 2018 trailer? Why? Perhaps just get them replaced under warranty if they truly need to be replaced, and then start small and figure out what you actually need. Otherwise you can just go skies the limit, buy 2 100Ah lithium batteries, new converter, battery monitor, solar panels, solar charge controller...and be about at the limit of what you can probably do on a 16' Bambi...

Cold weather won't be great with your lithium batteries outside, so then you'd have to find a way to move them inside. It might be a new can of worms to move them inside, which comes at the cost of the very limited storage space a 16' has. You'd have to find a home for them under the dinette benches, or the 12V wiring becomes even a bigger can of worms to try to find a place toward the back of the trailer.

Of course you should weigh your "unplugged" capacity against your water and black+gray tank capacity, as you might find you exhaust those before you would run out of battery. YMMV obviously. A Sport 16 is always going to be more restricted than what you read about on the forums, as is the 22' that I have...we won't be easily adding 400W of solar to the roof nor 400Ah of battery.

[uncle_bob]

Hi

I vary much agree that job one is to understand how you killed your existing batteries. They should be good for at least 4 years if used properly.

Budget is the next question. Only you can figure out how big that is. Balancing rooftop solar with batteries is *usually* the best way to maximize off grid time. Getting more than two panels on a 16' ... unlikely. Even getting one up there will involve a bit more work than a normal install. The only way to get more battery without taking more space is lithium. A pair of 100AH units will double your onboard power.

The gotcha still comes back to killing the original batteries..Doubling the usable capacity probably isn't enough battery to keep you out of trouble. Going from one panel to two ( or maybe three) ..... same thing. A pretty good guess is that about a 4X to 8X increase in capacity is what "gets you out of trouble".

Hint: Never / ever turn on the inverter ... ever.

Next hint: Figure at least 12 hours on shore power to get lead acid's to 80%. Figure 24 hours to get them to at least 100%. Yes, it may happen faster.


Bob

[jftompkins]

We Have a 2017 FC23FB... and for Boondocking I think the key is how you want to manage the demand side. Some tips: A. agree never turn on the inverter B. Turn the water pump switch off at night and during the day time when not using water. C. An extra blanket rather than the heater fan D. LED lighting... very helpful; just don’t leave on what you don’t need. F. No radio...Remaining loads are the electronics for the refrigerator propane detector are minimal. We have a Zamp 120 W solar panel... and with a little bit of astronomy ...can approximate the angle set up to the path of the sun for best collection... about 6 amps x 8 hours per day = 49Ah/day; I estimated the demand on the devices that I use....about 30Ah/day.

[jftompkins]

And in the process of replacing the great 24 with the group 27 AGM batteries that hold the charge better... and a few extra Ah; use a 5 W solar maintainer... when in stores he.

[uncle_bob]

Originally Posted by jftompkins

And in the process of replacing the great 24 with the group 27 AGM batteries that hold the charge better... and a few extra Ah; use a 5 W solar maintainer... when in stores he.

Hi

Ok, a bit of math. 5W solar widget probably puts out about 1/4 A running full out. In about 8 hours a day will give you about 2 AH into the batteries. If the trailer is still connected, your parasitic current may be around the same 1/4A. Net result is that you loose about 4 AH a day.

Bob

[rossdn]

Thank you all for your input very helpful!!

By-the-way for those who asked about the batteries that was my own stupidty, I'm not used having to check water levels anymore in batteries so I forgot and cells ran dry damaging the batteries.

So looks like best bet to start would be to replace the damaged batteries with good AGM batteries, our portable solar panels seemed to do pretty good keeping up with demand so far in our testing. We do plan to be very energy wise and efficient and use as little as possible, thanks for the tips on some areas to think about here too (ex. water pump).

The one remaining, possibly dumb, question I have is when you say we could run our laptop (we have one chromebook) off 12V, how would we do that with the standard Airstream outlets not working? If I understood that I think we would be all set.

Thanks again for all your help. Dave

[SilverHouseDreams]

Originally Posted by rossdn

The one remaining, possibly dumb, question I have is when you say we could run our laptop (we have one chromebook) off 12V, how would we do that with the standard Airstream outlets not working? If I understood that I think we would be all set.

This all depends on the model of the laptop in question. If it is a new model that receives power via USB-C, then there are plenty of 3rd party 12V USB power adapters. You need to know how many watts your laptop needs to charge and then just find an appropriate charger.

The first place to start is likely with a Google search for a "12V car laptop charger" and include your laptop model number. There some "universal" ones out there such as those sold by PowerStream: https://www.powerstream.com/ADC-p006.htm

[Paprika]

Dave, try a Google search for 'chromebook car charger'. There are plenty of choices.

You'll need a 12 VDC outlet to plug it into, of course, but it's easy to replace the cheap USB chargers that Airstream put in with 12V outlets--they fit the same hole, so you just have to swap 'em and plug in two wires on the back. I did all of mine--I'd rather use plug-in USB adapters than the ones Airstream supplied, and I have 12 V appliances such as fans and my CPAP that won't run on USB power.

[jftompkins]

Originally Posted by uncle_bob

Hi



Ok, a bit of math. 5W solar widget probably puts out about 1/4 A running full out. In about 8 hours a day will give you about 2 AH into the batteries. If the trailer is still connected, your parasitic current may be around the same 1/4A. Net result is that you loose about 4 AH a day.



Bob

Maintainer does well...mounted on top of propane enclosure, made by the company that just bought Zamp...
Good point...If you loose 4AH...a day?...I don’t. Put my propane detector on a toggle switch so I can turn it off in storage...disconnect the hoses for safety; and with the AGM’s hold charge...look in on it every month or so...the maintainer does what it says as it does...

[uncle_bob]

Originally Posted by rossdn

Thank you all for your input very helpful!!

By-the-way for those who asked about the batteries that was my own stupidty, I'm not used having to check water levels anymore in batteries so I forgot and cells ran dry damaging the batteries.

So looks like best bet to start would be to replace the damaged batteries with good AGM batteries, our portable solar panels seemed to do pretty good keeping up with demand so far in our testing. .......

Hi

Ummm ..... errrr ..... not so much. Assuming the batteries were "ok" when you got them from the dealer ( which is a mighty big assumption ) *and* you only used the stock charger in the trailer .... you didn't kill your batteries by not checking the water.

I'm sure they were low on water once you found there was a problem. It's a chicken and egg issue. Did the water go low before or after the battery failed? By far the best guess ( with the stock parts working correctly ) is that they went dry after a cell shorted out. Yes, the converter / charger could also have broken ( and need replacing ... ) and nuked them as well.

Back another layer on the onion ... what damaged the batteries? Before you spend more money on more batteries that needs to be figured out ....

1) Parasitic loads can take the batteries to zero easily.

2) Running the inverter can take the batteries to zero in very little time

3) Broken parts here or there can take the batteries to zero

4) Yes, storage / use in 140F sunshine can be an issue. That's not real common.

Running the batteries past "half full" ( if they are lead acid's) is a really bad idea. It's likely to ruin them pretty fast. Any time they read below 12.2V, it's a good guess they are below half full.

Modern lithium's with built in BMS systems come a lot closer to "forget about it" battery use. If you are already looking at AGM's .... it's not that much more money.

Bob

[rossdn]

Thanks that sounds like a great idea

[TheHoff]

I cannot get back to my original post on this topic, but I would like to post a 14 month follow up on my resolution of the pitifully poor battery performance on my 2016 Interstate. I installed two 100w flexible solar panels to the existing one factory panel, left all the original wiring in place , did not upgrade the original Atkins solar controller, and upgraded the original 12 v agm 80 amp hr batteries with new 12 v agm 100 amp hr batteries. My goal was to be able to get through the night without dead batteries and keep them charged when boondocking.
The cost was low- about$600 in parts. This has worked very well. I never have to plug it in when storing it outside-the batteries are always 90-100% charged with the main switch off. Even on cloudy days I am ok. I did have one rainy very dark day when I had to recharge with the generator twice. So far so good. If I have to park under dense trees, I have portable Zamp 160w solar panels and 75 feet of cord and I put the panels in the sun.

[PKI]

Look at the pauper solar thread. Ray and the gang have some good info. New ideas comming to the table.

Lion ..... still expensive.
AGM ..... a mixed bag.
Wet cell .... still least expensive.

Keys to low cost - battery disconnect and better converter that does not boil bank.
Keys to charging - portable solar and small generator.
Key to AC off grid - Easystart or a low cost 3000watt inverter genset.

For a Bambi ..... go low cost. A lot of sunk cost in a small coach is hard to get back at trade-in sale time. Some folks just keep the little guy if budget allows. So use it a while and see if it's your life long trailer. When you know that, the decisions get better.

Hope to see your smile down the road. The little Bambis make a lot of smiles. Pat