Lithium battery upgrade questions

[Semievolved]

Originally Posted by dstreight

They are tied together horizontally (in my application) with 4 threaded rods through the holes meant for same, located at each corner of the cells. Then the array is anchored to the floor of the nose box also by threaded rods and 3/4"x3/4" square steel tubing.

But, not fully understanding the torsional load imparted on them while traveling over rough terrain, I did not have them all tied together using ratchet straps until I discovered a couple cracked buss bars from fatigue/stress risers (combination of issues) last year. There was just enough side-to-side movement the 4 horizontal threaded rods and top to bottom compression clamps could not eliminate...

Subsequent to adding the ratchet straps there is zero play/movement in any direction/plane. This is a known strapping solution...

If you've ever travelled across Saline Valley Road just outside of Death Valley National Park, you fully understand the type of washboard vibration that isn't kind to suspensions or anything trailer or pull vehicle related. Its the longest and roughest stretch of gravel "road" I've travelled across. Sometimes its graded well enough to do 50mph in certain areas yet most often its 10-15mph at best. Although we haven't pulled the 15A there...its just a matter of time until we do.

you're definitely on top of it. yes, i have been on the saline valley although it was decades ago. there were several stops to fix car as i recall!

[wjwoods01@gmail.com]

Would 1 Lithium battery plus 190 watt solar panel be enough to run my camper for a few days just using lights, water pump, fridge on propane and heater? I like the weight reduction and will get two if needed but not if the second is not necessary.

[dstreight]

Originally Posted by wjwoods01@gmail.com

Would 1 Lithium battery plus 190 watt solar panel be enough to run my camper for a few days just using lights, water pump, fridge on propane and heater? I like the weight reduction and will get two if needed but not if the second is not necessary.

It depends. Direct summer/high angle sun and you should be fine. Shoulder months, winter low angle with clouds, etc.,: Maybe not (more lighting used during darker months, etc.).

But, you really need to let us know what size battery (watts or Ah) you are using/going with and the electrical current draw for the various "appliances". Having said that a fridge on propane is a HUGE factor for conserving battery.

We have a 2-gallon accumulator that cuts down on the water pump cycling on/off. Otherwise we'd use more battery current...

190w panel will probably net you around 6-8amps of current to the battery per hour of direct summer time sunshine. Partial clouds will take that down to 1-2amps if you're lucky.

[wjwoods01@gmail.com]

Originally Posted by dstreight

It depends. Direct summer/high angle sun and you should be fine. Shoulder months, winter low angle with clouds, etc.,: Maybe not (more lighting used during darker months, etc.).

But, you really need to let us know what size battery (watts or Ah) you are using/going with and the electrical current draw for the various "appliances". Having said that a fridge on propane is a HUGE factor for conserving battery.

We have a 2-gallon accumulator that cuts down on the water pump cycling on/off. Otherwise we'd use more battery current...

Thanks for your reply. I think that the Lithium is 100 AH and we wouldn't be using any appliances except those stated. I usually cook outside and am getting the outside propane for a Blackstone griddle.

[Semievolved]

Originally Posted by wjwoods01@gmail.com

Would 1 Lithium battery plus 190 watt solar panel be enough to run my camper for a few days just using lights, water pump, fridge on propane and heater? I like the weight reduction and will get two if needed but not if the second is not necessary.

190w panel and 100Ah lfp battery is a nice combination for much camping for many conditions imo. You can pretty much ignore the lights if they're led. The pump pulls around 7a if I recall. The heater fan is the big one from your list and its drain is totally dependent on how many times and for how long it comes on. Finally, will you be in a sunny area where you'll get plenty of recharge time every day? In other words, it's hard to say. Personally, I feel the extra few pounds for another 100Ah battery would be a nice buffer that you will appreciate.

[wjwoods01@gmail.com]

Thanks, appreciate the input. When we are on the road we prefer State Parks which usually have some type of hook ups but the National Parks don't. We are on the road for 8 weeks in the Spring and 8 weeks in the Fall.

[brroberts]

I personally would camp 5 days in the summer with 2 6V and no solar because I’ve done it for years even before LED lights. However, in the winter a day with the heater and lights is all you get.

[Perry Butler]

Originally Posted by brroberts

I personally would camp 5 days in the summer with 2 6V and no solar because I’ve done it for years even before LED lights. However, in the winter a day with the heater and lights is all you get.

I see the poster is from Maine and can/will encounter shade issues, similar to those we encounter in Minnesota and many other states. Being in the southwest for the winter we really don't encounter any charging issues. It's a whole different environment in western Texas, or southern NM, Arizona, or California where we winter.

However, I don't care how much solar you have on your roof, when in shade for a few days you'll probably need a portable. A 100 watt portable with 45' of cable (three 15' sections) works for us.

OTOH, we just added three 100 watt panels so we'll need the portable fewer times. We don't like portables with their issues of having to setup, orient, take down, possible theft, and taking storage space. However, to camp like we prefer, a portable is a necessary evil.

For us, the furnace is the #1 draw on our batteries. We can control the other draws, but we need at least 50 degrees in the camper for us to sleep. YMMV.

Enjoy,

Perry

[rubicon327]

Finally getting back to the upgrade project. Removed the dual 6V lead acid batteries and battery box and got the Bestgo 400AH lithium mounted. As a test I hooked up the battery and moved the jumper to lithium profile on the upgraded Progressive Dynamics main board. The integrated battery monitor indicated it was taking a charge. This charger will be eventually taken offline in favor of the integrated and programmable 80A charger in the Xantrex Freedom unit. A mount was needed to properly secure the battery and get it raised over one of the trailer body mounting bolts. I furnished it from some wood I had laying around. It took some time to figure out but it allowed me to solidly attach loops for the battery strap and it is large enough to also mount the Victron battery monitor shunt and the 250A fuse for the inverter DC connection. The battery is as far forward as possible and the integrated battery monitor can still be conveniently seen when flipping open the dinette seat. I will mount the main inverter disconnect switch on a board that will be connected vertically on the stock seat support (not pictured). I have figured out the routing of all the wiring and it should be really clean in the end. Hoping to get some wiring done tomorrow and at least get the Victron battery monitor working.

[Centex]

Oh man, this is looking nice, Dave!

[dstreight]

Nice Dave! You're going to love 6500w/400Ah of 12v juice!

[rubicon327]

Thanks guys. Doesn’t seem like much but excited to get my first 4/0 crimps under my belt on the negative line between shunt and battery and getting the Victron BMV-712 battery monitor online.

[Centex]

The crimps/lugs on that 4/0 battery negative look great. Were you able to source 4/0 lugs with a 5/16" hole (I've found plenty with 3/8" hole)?

[dstreight]

Never have a problem finding 4/0 with 5/16" tinned copper lugs...or any gauge & hole combo...

Here's one source I use:
(Sorry, the hyperlink was hideously long...)

[Centex]

Thanks, Dan.

[rubicon327]

Originally Posted by Centex

Were you able to source 4/0 lugs with a 5/16" hole (I've found plenty with 3/8" hole)?

You got me. The 3/8" hole is a little large for the Bestgo terminal bolt. It's torqued down real good and I'm figuring that the primary contact is the bottom face of the lug with the top of the post. Am I misguided?

[dstreight]

In theory, less conductive surface, by using a lug with a hole diameter larger than the post it is being held by, could induce more resistance. In theory.

I suppose with very high current demands such a difference, say using a 3/8" diameter lug and mating it to a 5/16" diameter post, might make a difference; dunno.

Might even be the basis of Phd thesis...for us I doubt if the difference would...make a difference. But just my $.02 and maybe all its worth.

Brian?

[Centex]

Dave, I'm gonna defer to Dan (and Brian) on that one, though I'll venture suspicion Dan's correct that in this application it's not a worry.

As I now recall, in your case that particular cable to the M8 (~5/16") BestGo bolt is 'as supplied by AMS' with a kit? I'll be DIYing all of my cable ends, want to match the lugs to studs throughout to assuage my OCD, that's the only reason I asked. I'm in the midst of compiling an order-list for these bits-and-pieces.

[dstreight]

In the grand scheme of things, relative to using 3/8" hole diameter lugs on a 5/16"/8mm post...the type of crimp job imparts a much larger potential for increased resistance. Crimping is a critical process especially with larger diameter cables.

[Brian B-P]

Originally Posted by dstreight

In theory, less conductive surface, by using a lug with a hole diameter larger than the post it is being held by, could induce more resistance. In theory.

I suppose with very high current demands such a difference, say using a 3/8" diameter lug and mating it to a 5/16" diameter post, might make a difference; dunno.

More area is good, as long as contact pressure is maintained. If the entire bottom face of the lug were in contact with the battery terminal (not overhanging the sides), the difference would seem negligible, although in the photo all of the lugs (of various sizes) appear to overhang. In an installation to a larger terminal, if the lug with the 3/8" hole is larger in outside diameter than the one with the 5/16" hole, the one with the larger hole might even have more contact area. Even in this case it doesn't seem likely to be an issue.

The Bestgo battery has very small terminals; a cable lug with a very large hole would be an issue for them, but we're not talking about that large.

I assume that an M8 flanged head bolt plus washer (perhaps supplied with the battery unit) is used to press down on the lug appropriately - it's not completely clear in the photo.

Originally Posted by rubicon327

The 3/8" hole is a little large for the Bestgo terminal bolt. It's torqued down real good and I'm figuring that the primary contact is the bottom face of the lug with the top of the post.

While the ideal current path would be between those faces, in this case I wouldn't discount the significance of the path through the washer, bolt, and threads. The contact pressure at the threads is pretty high, so electrical contact should be good, and the length of thread is significant... perhaps important given that small terminal top face. Ground connections to vehicle body structures routinely depend on the threads, not the face of the nut welded into the body (which is painted!).

Originally Posted by dstreight

In the grand scheme of things, relative to using 3/8" hole diameter lugs on a 5/16"/8mm post...the type of crimp job imparts a much larger potential for increased resistance. Crimping is a critical process especially with larger diameter cables.