Bigfoot Lithium upgrade

[Jane P.]

Originally Posted by Raspy

Bob,

There are a number of reasons to put the batteries inside. Getting the weight off the tongue, making more room up front for the tailgate and/or propane, carrying the weight of the batteries directly over the axle, keeping the battery out of the wet weather and out of the cold weather. Even to reduce the chances of someone taking an expensive Battle Born battery.

Of course, putting lead acid flooded batteries inside is a problem, and they should be kept outside, or at least in a well ventilated cabinet.

As time goes by, I'm becoming less and less tolerant of flooded cell lead acid batteries. They are so 19th century, dirty, corrosive, high maintenance, heavy, etc. It is time to move on.

This particular thread addresses the following questions:

1. Lithium vs 2 deep cell lead acids
2. If Lithium, where to locate.
3. Optional electronic equipment that can support Lithium technology

After doing the research, installing a single, 100v lithium became a no brainer for me.

1. It is virtually the same size as one deep cell lead acid battery (I needed 2)
2. It provides a superior performance over that of 2 deep cell lead acid batteriers
3. It should last at least 10 years, if properly maintained
4. A second lithium battery can be added down the road
5. It doesn't leak any gases and is safe within the trailer cabin

Installing a Lithium in the cabin is advantages if you have adequate storage space:

1. I greatly reduces the possibility of degradation due to exposure to the elements, and
2. A locked cabin provides increased security.

Bob, when I bought my first fiberglass, I didn't need more than a single battery on the tongue and a generator on the back porch. But my circumstances changed and so has the technology now available to all of us.

I am thrilled to access relatively affordable technology that meets my specific needs. Anyone requiring a second lead acid battery should seriously consider Lithium.

[CarlD]

Jane,

You can add to your list of advantages:

reduced weight, BB 100 Ah is about 27 lbs.
no maintenance
faster recharge rate
mount in any orientation

[JonRaw]

Originally Posted by k0wtz

I have a regular car battery on the tongue of my 13f scamp I see no reason to put it inside where its a hassle to take care of.

That and a single propane tank rides outside where everything simple and easy to get to.

Bob

On the off chance that you're not actually trolling me I'll answer. I'm pretty sure nobody here is suggesting putting a propane tank or a car battery inside their RV. Not even sure a car battery (which is designed for high cold cranking amps) would be best for an RV but if it works for you, enjoy.

[Air Doug]

Originally Posted by Jane P.

Hi Doug,

I am curious. How does this 3 amp charger complement or add an additional element to a multi-stage replacement to the lower section of the converter? (For Instance, I got a Pacific Dynamic replacement.) I thougth this would protect the Li battery.

Thanks

Hi Jane, sorry for slow reply but we have been on the road.

Regarding the 3A charger, the reason I installed it was that I have a 60A regular charger and 100Ah battery, resulting in charging at .6 C-rate. Its not a big deal but BB and others recommend C of .5 or less. My primary reason for the 60A charger rather than something 50A or below was to minimize generator run time, for which I was willing to sacrifice a few battery cycles. So I found a cheap 3A charger that I can use when I am not in a hurry and thus keep C very low.

Another reason is that if I want to keep my state of charge at 60 to 80% when the Truckfridge or Propex furnace is running and I am off doing other stuff all day, I can just turn on the 3A charger and let it run.

After installing the 3A charger I eventually got a second 100Ah battery so now my C is .3 instead of .6, so any concerns about high C went away.

[Air Doug]

Originally Posted by JonRaw

DC/DC converter: Battle Born said I would not need a DC to DC converter. The alternator on my truck puts out 14.5V. To be more accurate, immediately after starting the truck, the truck battery was actually below the Battle Borns and there was about a -7A draw from the batteries to the truck. I am guessing that was because of the current draw to start the truck pulled the battery low. After a few minutes the truck was outputting 14.5V and the Battle Born was charging at about 6 amps. I talked to Battle Born about all of that and they said that no, I wouldn't need a DC/DC converter. I also expressed concern about the truck battery pulling from the Battle Borns and they said that was not a problem. I still feel a little concerned and when I start the truck, I now always unplug the trailer first, then plug back in after. I don't want the starting current from the truck pulling from the Battle Borns. A n isolating DC/DC converter would stop this I guess. I do have a shutoff switch so that's not an issue.

I also asked Battle Born about a low current (3a) Li charger and they said that also was not necessary. They said there would be no issues charging the Li batteries using the PD4045.

I'd love to give a review of how the batteries perform while camping but I haven't been able to actually go camping anywhere since I got the batteries installed. I have moved the Bigfoot a few times but haven't taken it out overnight yet. I will say that just running it in my driveway it's infinitely better than that battery I had. The original battery would be dead after a very short time but these batteries are great. I have done some testing of the furnace blower, testing the Fantastic Fan and the batteries were down to 76% full. I decided to see how long it would take to fully charge them so I hooked up my solar panel and in 2 4-5 hour days of light they were 100% charged.

I'm glad your truck seems to be charging your batteries just fine. When I did my installation I relied on an Airstream forum post from someone who checked voltages over time after starting a 4Runner (same as my TV) and noted that the BB battery charged initially, with current going to the alternator to the trailer, then gradually changed to the trailer discharging to the TV. It appeared that the alternator output decreased as the TV/starter battery got charged. I have not verified myself. I just went with the DC/DC converter, also so that I could set the charge voltage at a constant 14.2 volts.

I agree that the PD4045 should be fine. I have a 60A charger, so therefore a higher C, not so okay with a single 100Ah BB.

Great news about your experiences so far. We have been really happy with our conversion too. I think a single 100Ah battery is fine, especially if you have a generator along. Now with two BBs, I find that I check charge state much less and don't worry so much about turning lights and fans off.

[Air Doug]

Regarding keeping the batteries in the cabin, that is where Lil Snoozy had the original battery, so it made sense for the "drop in" replacement (ha!).

For others, though, BB has a battery heater if you want to keep them in a cold place, but they are $220! Battle Born's CEO says they will soon sell a battery with an internal heater. I think ReLion has a battery with internal heater already. I am probably going to design and install a heater some day.

[Tightline]

JonRaw. I’m just wrapping up essentially your same plan (plus more) on my 25RB.

I did connect my 2 BBs to the right side of the battery disconnect solenoid and its working great.

Also having those expensive batteries inside is a load off my mind.

[JonRaw]

Originally Posted by Tightline

JonRaw. I’m just wrapping up essentially your same plan (plus more) on my 25RB.

I did connect my 2 BBs to the right side of the battery disconnect solenoid and its working great.

Also having those expensive batteries inside is a load off my mind.

Thanks for the info. Where did you run the ground lead?

[Tightline]

So, I mounted the shunt (Victron BMV712) in the bench near the disconnect solenoid.

I ended up drilling through the floor and running it to a grounding stud welded to the frame. You have a different rig but I suspect you have one in that area too. The layout looks similar.

When you connect the (-) wires... 1st shunt to frame then 2nd shunt to battery. Learn from my mistakes :-)

[JonRaw]

Originally Posted by Tightline

So, I mounted the shunt (Victron BMV712) in the bench near the disconnect solenoid.

I ended up drilling through the floor and running it to a grounding stud welded to the frame. You have a different rig but I suspect you have one in that area too. The layout looks similar.

When you connect the (-) wires... 1st shunt to frame then 2nd shunt to battery. Learn from my mistakes :-)

Makes sense. Thanks. What's stopping me from moving my batteries is the hole in the floor. As Jane and other's have mentioned, drilling the hole is the way to go and is easy. I just have this fear of putting a hole in my floor. I'm not exactly very mechanical so I'm worried I'll mess it up.



I see you are in Arizona. I'll be in Phoenix, later this month. I'd love to take a look at your install if you are in that part of Arizona.

[Tightline]

I feel ya Jon. I had to think about it for a week or two before I convinced myself that since Bigfoot drilled holes in the floor, why can't I? Just look before you leap. Use a strong-ish drill and a sharp bit...that fiberglass grabs a bit. Then after you are happy with the wire placement, silicone seal around the hole top and bottom. Easy.

I'm just a couple of miles north of downtown Phoenix. Feel free to hit me up. Happy to show off the install.