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Old 11-12-2022, 05:48 PM   #1
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External 12VDC battery pack

This is on our NoBo 19.6, but should be generic to any trailer.

Already had dual batteries on the tongue and wanted to add more without making any modification to the trailer.

External dual 12VDC battery pack w/ Anderson SB50 quick connects and battery monitor. The "battery box" is a Rigid wheeled toolbox from Home Depot.

1 foot 3/8" lug to SB50 leads on each pack and a 4 foot lead coming from a junction box mounted to the tongue. This arrangement allows the connectors to sit inside the battery boxes to keep them out of the weather.

The original coach wires come into the junction box to meet up with the 4 foot lead. Added the battery monitor for some flair (and because I did not trust the solar's capacity meter).

Eventually I want to get something like a Bluetti AC200MAX, but this will do for now.
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Old 11-12-2022, 06:12 PM   #2
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Nice job. I really like how you mounted the shunt and meter in water tight box. For myself, I wanted more capacity than the 2 lead acid batteries that came with our trailer. I chose to upgrade to 2 12V 100AH LiFePO4. A lot more $$$, but less weight. I am old enough, that I really don't want to move batteries around more than I have to.
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Old 11-12-2022, 06:37 PM   #3
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Hi IPcamper,

Thanks.

Right there with you on the weight. Spouse and I are young enough to be able to lift the pack in and out of the tow vehicle, but it's close. Neither of us can do it alone. I'll upgrade us if booning becomes a regular habit.

What the photos don't show is the toolbox has has a handle that slides out on the end opposite from the wheels. Once we get the box on the ground I slide the handle out and it gets much easier to move around.
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Old 11-12-2022, 10:13 PM   #4
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NoBoGoat,

How do you like the Renogy battery monitor?

I want to add a battery monitor and the Renogy monitor seems like a good mid-grade monitor price wise. Anything you like or dislike about it?
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Old 11-13-2022, 11:09 AM   #5
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NoBoGoat,
How do you like the Renogy battery monitor?
I like it with one nit which is probably due to user error.

First, the reason I have it is because the battery monitors that came with the trailer weren't helpful. They are based completely on voltage. As long as the solar panels are providing voltage higher than what the monitors consider "full" they show 100%. They also do not have any sort of load monitoring.

Enter the Renogy. It shows me what is going in/out of the batteries. I now know how much load the trailer draws and how much the solar panels put back in. In this sense it works perfectly.

The problem is in the setup, and where the user error comes in. The monitor can "autorange" if you connect it to an empty battery and go through a full charge cycle. Or do as I did and enter the parameters of the battery. I set the capacity to 81Ah (1/2 capacity of dual battery pack) with a "Full Voltage" of 12.7 . In discharge mode it works fine. Start out at 100% and the next morning I'm at 80% which is roughly what I expected. The problem is as the sun starts hitting the solar panels current starts going into the battery as expected, but when the controller increases the voltage over 12.7V the monitor jumps to 100% and I lose capacity tracking while charging.

I haven't tried it yet, but I believe the solution is to set the "Full V" to something higher than the charge voltage of the solar to force the monitor to stay in cumulative capacity tracking.
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Old 11-13-2022, 12:28 PM   #6
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NoBoGoat, I have the same Renogy monitor, I just keep it in our oversized battery box. You should set the battery capacity on the monitor to the total of all of the batteries that are connected. With 2 81Ah batteries in parallel, set the monitor to 162Ah for capacity, it will calculate the % accurately. If you have 4 batteries, then set it to 324Ah.
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Old 11-13-2022, 12:43 PM   #7
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NoBoGoat, I have the same Renogy monitor, I just keep it in our oversized battery box. You should set the battery capacity on the monitor to the total of all of the batteries that are connected. With 2 81Ah batteries in parallel, set the monitor to 162Ah for capacity, it will calculate the % accurately. If you have 4 batteries, then set it to 324Ah.
I have read one should not discharge a deep cycle below 50% in order to extend battery life, which is why I set the capacity to that of a single battery (81Ah).
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Old 11-30-2022, 10:28 AM   #8
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I agree, that ideally you should not discharge a led acid battery below 50%, as a general rule.

However, it really doesn't matter if you go off grid only a handful of times a year. When you fully discharge/recharge a led acid battery it will generally last about 500 cycles. Are you going to do 500 cycles before the battery ages out?

When you do 50% as the maximum, you might see 1200 cycles, a big improvement if your living off the grid and cycling the batteries daily. But for an occasional RV user, your just not going to hit 500 cycles in 2-3 week long camping trips a year, before the batteries age out.

I've run my lead acid fully dead several times, and it wasn't an issue.

My only question is why didn't you opt to go with a bigger battery box and GC2 batteries instead of the external pack? I did that on my microlite 21DS, put 4 GC2 batteries on the tongue.
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Old 11-30-2022, 02:22 PM   #9
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On a prior version of my system I did the same thing, but also included my complete solar setup of SCC, charger, inverter, DC to DC charger, and two lithium batteries. I kept the cart in the pickup bed connected to the trailer when camped. When we are doing a side trip in the pickup, I connect the DC-DC Anderson Connector to the alternator connector in the rear of the pickup and charge the batteries.

Works great and there is no lifting of the cart. The only thing I have to remember is to disconnect when leaving camp.
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Old 11-30-2022, 02:50 PM   #10
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On a prior version of my system I did the same thing, but also included my complete solar setup of SCC, charger, inverter, DC to DC charger, and two lithium batteries. I kept the cart in the pickup bed connected to the trailer when camped. When we are doing a side trip in the pickup, I connect the DC-DC Anderson Connector to the alternator connector in the rear of the pickup and charge the batteries.

Works great and there is no lifting of the cart. The only thing I have to remember is to disconnect when leaving camp.
Gotcha!

That makes good sense using your vehicle to charge the batteries. A lot of folks I've seen modify their vehicles when using truck campers to put in big alternators or dual alternators to charge their batteries with the tow vehicle eliminating the need for a generator. Smart. I like this solution as well.


I'm actually thinking of getting rid of my 2 100ah lithium batteries and going back to a 4xGC2 setup. We've been running lithium for 4 years now and we have found that in cold weather camping we run our 200ah of lithium dead (mostly running heat, lights, fridge (propane), and some entertainment) in 2 days. We have 200 watts of solar, but if its cloudy its not helpful. With solar working we can stretch it another day. Not anywhere as good as our old 4xGC2 setup.

The 430ah 4xGC2 setup we had never had any problems sustaining us without the aid of solar for 5 days off grid without dropping below 12Vs.

I've come to the conclusion that Lithium's specs maybe oversold (we paid $1600 for the 2 batteries). I really don't get 200ah's out of our batteries (monitoring).
We're lucky to get 150ah's out of the setup.

Also its a pain when you run lithium dead, as we've learned. When the BMS kicks on for low voltage protection your bat terminals show 0V. When that happens you can't charge them with solar. As our solar charge controller, says we're not connected to a battery as its showing 0Vs. So out with the generator, or the tow vehicle, to de-activate the BMS with some charging to allow solar to do the rest of the work. Ask us how we know ;-)

We've run the 4xGC2's completely dead, or more accurately the RV repair center by leaving the batts connected, and they were fine for another year.

We went to lithium mainly for weight savings.
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Old 11-30-2022, 09:15 PM   #11
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My only question is why didn't you opt to go with a bigger battery box and GC2 batteries instead of the external pack? I did that on my microlite 21DS, put 4 GC2 batteries on the tongue.
Time and inexperience. I went with the "brute force and ignorance" route.

The local Dick's Sporting Goods had the batteries that matched what I already had. Home Depot had the perfect tool box to hold them. I was short on time ahead of our first off grid trip so that's what I went with.

In hindsight yeah golf cart batteries would probably be a better fit. What I really want is a Bluetti AC200MAX, but we need a few more trips under our belts to justify that.
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Old 11-30-2022, 10:19 PM   #12
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There are multiple solutions to this problem. Batteries are the weak link.

The most expensive for value received are the solar generator, battery boxes like the Blueti.

I have 4 gc batteries. 300 lbs. about 210 usable amps. Have to be maintained.

I plan on installing a 400 ah lithium battery 370 amps. About 75 lbs. Pricey. Gets me three nights without charging. Some cold issues.

What was done here.

All have advantages and disadvantages.

Do your research. Spend wisely.
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Old 12-01-2022, 07:30 AM   #13
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I did something like this in the past but also added an A-B-AB-Off battery switch. This way you can run off one bank until its low, then switch to fresh bank.
If one bank of batteries is older they can actually draw down the other bank.
Plus its really nice being able to switch off batteries.
Your batteries only loose like 5% charge per month when not connected, and a charged battery will not freeze until like -80. (a discharged battery will freeze around 20 deg)
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Old 12-01-2022, 08:27 AM   #14
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There are multiple solutions to this problem. Batteries are the weak link.

The most expensive for value received are the solar generator, battery boxes like the Blueti.

I have 4 gc batteries. 300 lbs. about 210 usable amps. Have to be maintained.

I plan on installing a 400 ah lithium battery 370 amps. About 75 lbs. Pricey. Gets me three nights without charging. Some cold issues.

What was done here.

All have advantages and disadvantages.

Do your research. Spend wisely.
I'm heading into 6 days of off the grid camping in an area that frowns on generator use. Big Bend Ranch State Park. So I'm re-evaluating my battery setup and I agree batteries are the biggest problem. My new to me 200ah lithium pack in 2018 just never delivered on its promise to be 50% of a 4xGC2 replacement. The GC2's capacity worked better for me, and at $400 for 4xDuracells vs $1200-1600 for 4x100ah lithium or 1x400ah lithium, the price for my use case seems hard to justify. Which is off grid camping a couple of times a year for a couple of weeks total. I'm also going to be powering starlink on this trip so I've added to my loads. By my calculations I should run 500ah of battery and 400 watts of solar to keep the whole she-bang running, without a generator. But I can't do that on the tongue easily due to the size format of 200-400ah lithium batteries (8D size). Really should get 2x300ah batts for 600ah total, but for cheapie taking a gamble lithium batteries that is 2K from amazon. Which makes the 430ah GC2 setup more appealing at $400~.

Yeah, there is more work to maintaining GC2's keeping them charged properly, watering, and etc. But mine lasted 3 years without any issues even with running them dead several times.

The other thing is all batteries degrade so its wise to size you battery bank larger to start with than you'll need, so that as it ages/degrades it still meets you needs.

The biggest advantage of the lithium I see is if your living off the grid and need the charge/discharge cycle, need to save weight, or don't have room for a large bank, then lithium makes sense. But its still so much more expensive than regular lead. Lead can be more cost effective if your an occasional off the grid like me. I did lithium for reducing tongue weight, but now I have a 3500 truck and I'm not limited by tongue weight like before.
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Old 12-01-2022, 09:04 AM   #15
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I'm heading into 6 days of off the grid camping in an area that frowns on generator use. Big Bend Ranch State Park. So I'm re-evaluating my battery setup and I agree batteries are the biggest problem. My new to me 200ah lithium pack in 2018 just never delivered on its promise to be 50% of a 4xGC2 replacement.



I would start a thread on this...
let people know your full setup ..... battery, solar any inverters involved?


and if you made any adjustments to the charging profiles.




loosing 50ah
something smells fishy in Denmark ...
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Old 12-01-2022, 09:23 AM   #16
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Sure, what I didn't say directly but was implying is that the lithium (especially cheap ones), battery specs seem to be exaggerated, or optimistically rated. Look at the amazon reviews on a lot of the chinese lithium batteries and you'll find lots of people who did load tests and never achieved the rated capacity.

I have renogy batteries and they were sold as 100ah batteries, but if you look at their 20 hr rate, its actually 95ah, when new under ideal temps. But in the real world after some aging and cold weather camping I've found that lithium doesn't deliver its rated capacity under my weather conditions. I have no complaints about the renogy batteries, they've been reliable, but just never lived up to the full capacity they claimed. In 2018 when I purchased them they were about $799 each on sale. No heater, no Bluetooth, these were earlier batteries they do not make any more.

I have in my trailer installed a progressive dynamics lithium converter to charge the batteries. I have 2 Renogy "100ah" lithium batteries on the trailer tongue wired up with 2 awg wringing to the trailer and a 600 watt xantrex inverter. I also have a 200 watt solar suitcase from Renogy with a lithium aware charge controller. Ran this exact setup on two trailers (I moved it from my 2017 microlite 21ds, to my 2020 microlite 21ds). We've just found in cold weather camping the setup just doesn't deliver 200ah (dipping into the 20s at night), under these conditions. Under identical conditions the 4xGC2s seem to provide a lot more usable capacity without having to dip below 50% soc.
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Old 12-01-2022, 12:01 PM   #17
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Sure, what I didn't say directly but was implying is that the lithium (especially cheap ones), battery specs seem to be exaggerated, or optimistically rated. Look at the amazon reviews on a lot of the chinese lithium batteries and you'll find lots of people who did load tests and never achieved the rated capacity.

I have renogy batteries and they were sold as 100ah batteries, but if you look at their 20 hr rate, its actually 95ah, when new under ideal temps. But in the real world after some aging and cold weather camping I've found that lithium doesn't deliver its rated capacity under my weather conditions. I have no complaints about the renogy batteries, they've been reliable, but just never lived up to the full capacity they claimed. In 2018 when I purchased them they were about $799 each on sale. No heater, no Bluetooth, these were earlier batteries they do not make any more.

I have in my trailer installed a progressive dynamics lithium converter to charge the batteries. I have 2 Renogy "100ah" lithium batteries on the trailer tongue wired up with 2 awg wringing to the trailer and a 600 watt xantrex inverter. I also have a 200 watt solar suitcase from Renogy with a lithium aware charge controller. Ran this exact setup on two trailers (I moved it from my 2017 microlite 21ds, to my 2020 microlite 21ds). We've just found in cold weather camping the setup just doesn't deliver 200ah (dipping into the 20s at night), under these conditions. Under identical conditions the 4xGC2s seem to provide a lot more usable capacity without having to dip below 50% soc.
I don't mean to hijack the thread, but a couple of responses indicated dissatisfaction with lifepo4 capacity retention at cold temps. These responses caused me to ask why? All batteries capacities are usually rated at a base room temperature of 25C or 77F. As the temp falls, capacities diminish for all batteries. LA rates of loss are significantly greater than lifepo4.

Unanimously, predicated on my WEB search, lifepo4 out performs LA at low temps with the exception of charging at an internal temp of below 32 degrees F (which can be easily mitigated).
https://www.power-sonic.com/blog/lit...cid-batteries/
https://battlebornbatteries.com/lead...e-paper-study/
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Old 12-01-2022, 12:43 PM   #18
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I don't mean to hijack the thread, but a couple of responses indicated dissatisfaction with lifepo4 capacity retention at cold temps. These responses caused me to ask why? All batteries capacities are usually rated at a base room temperature of 25C or 77F. As the temp falls, capacities diminish for all batteries. LA rates of loss are significantly greater than lifepo4.

Unanimously, predicated on my WEB search, lifepo4 out performs LA at low temps with the exception of charging at an internal temp of below 32 degrees F (which can be easily mitigated).
https://www.power-sonic.com/blog/lit...cid-batteries/
https://battlebornbatteries.com/lead...e-paper-study/
You're right all batteries loose capacity as temperatures drop.

There are reasons to do lithium batteries. Lithium is lighter, easier to maintain, takes less room, and can retain 80% capacity with 1000-2000 recharges depending on quality.

When I use a lead acid battery bank in 20 degree weather, I get 200ah out of a 430ah bank (4xGC2) no problem with out dropping below 50% SOC and at $400. Which means this lead bank will continue to deliver 200ah even after 1200-1500 cycles. But when I ask the same out of my lithium bank 200ah in cold weather, I don't get 200ah, more like 150ah for 4 year old batteries at a cost of $1600 so I get about 80% of the original rated capacity (190ah rounded up by manufacture to 200) in cold weather.

Here's the rub, Lithium at 4x the cost of Lead I don't get 4x the performance in this scenario. I can get 150ah (maybe not even that much) for $1600 or I can get 300ah (20% safe state of discharge and cold temp compensation) from lead for $400.

The real issue to me is that I can get more usable capacity out of a lead bank for 1/4 the cost as compared to lithium. But at the cost of more weight and space on my trailer, and some maintenance to top the water off. But over the 5 year life expectancy of a typical lithium battery I'm no longer convinced its a superior trade for a lot of RV users. Those who live continuously off the grid or who are weight constrained will have a different view. Those who want the most capacity for the $ and use the setup several times a year, lead is a better choice fincially.

Bottom line to me, batteries are the weak link in off the grid setups. Lithium was the new hot trend 4-5 years ago and everyone was convinced of the superiority of lithium and hopped on the band wagon. Now after the binge, I've lived through I see that and you can spend a ton of money on lithium but not get your monies worth from a capacity perspective. I'm not certain I will continue with lithium setups when I'm not weight and space constrained. I'm probably going to switch back to lead to meet my capacity needs and sell my lithium batteries.
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