Upgrading to 6V Trojans - Series Parallel Wiring - Battery bank build

[twh731]

Bold, we purchased 2 6v Lifeline batteries (300Ah) from BD batteries in Denver last July ( the actual company is in Ca. I believe) for $394 ea. with free shipping. Arrived here in Taos in 4 days from ordering. RV & Marine Deep Cycle Batteries by Lifeline Batteries

[BigButtUgly]

I don't understand why all that power is needed, but then again my 1958 22' Caravanner has every system (and interior configuration) different than any other Airstream ever built, modified or retrofitted. My T-105s weigh 62# each so I mounted them in the rear to mostly offset my 142# 3500 watt dual fuel electric start generator on the tongue. Might you run into a changed tongue weight issue? I obviously do not know how your 27 footer came from the factory (but for fun am going to try to locate the batteries on the floor pan). Note: My now tongue weight is the same as original at 300# and can never vary because my floor plan used the same formulas necessary for load planning any USAF cargo plane.. And yes, all interior contents use a nesting paradigm, fold, or inflate and are carried in the cargo bed of my Cadillac Escalade EXT.

[BigButtUgly]

Your new system, when properly installed w/ venting case, exhaust piping, stronger tie downs, heavier cables, etc. will put 1,000#s on the ball with empty water/grey/black tanks and storage. Perhaps more weight on your leading axle too. 16.6 % on ball is maybe a bit too much. Trojan AGMs must have ventilation according to Trojan guidance. Do not be fooled by claims to the contrary. For a 1500 Dodge, crew, 4 x 4, load levelers for OTR must be right. Note to prior post: I use "point of use " 1# refillable propane bottles so warm propane inside stays efficient even at -20 degrees F. outside. I keep 20 full and costs $.75 each to refill from a tradeable 20#er. No 20#ers on tongue to change tongue weight empty to full or vice versa. Where the queen bed platform hinges might have to change to get easier access.

[BoldAdventure]

Um... ok


Anyways, can someone clear this point up. The 75-50% depletion rule.

If I have two Lifelines for example at 300aH that basically means I only have 150aH available? Otherwise I risk the life of the battery discharging it further?

Originally Posted by BigButtUgly

I don't understand why all that power is needed

The reason for the 4 batteries is to have the larger number of aH available. So I'm assuming 4 batteries would give me the total of 300 aH if using Lifelines and 220 aH if using Trojans. Even though the combined banks would be 600aH and 440aH.

We boondock and dry camp a lot.

----

Also of note, those 300 aH Lifelines are bigger than the Trojan T105, the comparable Lifeline is the GPL-4CT which is 220aH and the same size.

[Seabloom]

We have a 1976 Overlander with useless curbside battery box mounted between the entry door and front axle. Only a group 24 battery appeared to fit this box. This spring I installed 2 x 6V batteries under my kitchen sink in a sealed box. Added a vent to the outside, note this requires drilling a 2.5" dia hole through the skin. Meausre twice and cut one was more like measure 10 times and cut once (still with a pit in my stomach in case I made a mistake). I must say the 2 volt batteries producing 235 AH in my case have been awesome. I also have a portable solar panel 85w which is wired through the battery box old leads. It has made a huge improvement.

In regards to your 2 x parallel and 2 x series this is how I have our off-grid cabin wired up. I used Crown 6 volt wet batteries for that application. Previous Trojan T-105's lasted 10 years in that application with an 85w solar trickle charge. WE only use the cabin on long weekends, and it is in a climate that sees temp from -32 to + 100 every year.

Note that numerous supplies have told me that in the last 5 years Trojan batteries have decreased their quality. I am not sure if this is the same for the AGM family, but the wet batteries Crown was highly recommended.

Good luck and happy camping "off-grid".

[BoldAdventure]

Some really big considerations here that the wife and I need to discuss as a couple for our Airstream.

Started this thread with a firm plan in mind, but now considering the GPL-6CT, but with it's increased capacity comes increased weight. Plus the price increase. And here is the thing, it's almost half way to 300 aH of lithium. But there are some hidden costs I suspect with Lithium. I am not sure if my solar charge controller is compatible and I know my converter is not compatible.

But lithium would way significantly less. So the costs and differences are all over. We are towing with a half ton, so there is that too.

Going to review all our options and reapproach this thread again later this week.

[alano]

Bold,

You could DIY a lithium LiFePO4 300 AH solution for less than $2000. You can find 3.2 V, 300 AH prismatic cells for about $400. Combine that with (4) BMS cell modules from EV Power, Australia (about $19AUS each) and add a BMS control unit from the same company with a disconnect switch for $175AUS, add a fuse and your there.

Not sure why your converter isn't compatible. Is it a single-stage supply? It shouldn't overcharge the cell. When you're connected to shore power you can also disconnect the cell and let your solar charge the lithium. And what's your solar charger brand? If you can change the voltage thresholds you might be able to make it work.

The reason lithium might make sense for you is that you're willing to put the battery pack inside the AS. LiFePO4 cells don't like freezing and they degrade with high temperatures so they're not a good option if you're trying to put them in the outside box.

[BoldAdventure]

As I understand it, lithium has a different charging profile than AGM and Lead Acid. My Powermax Boondocker is a 60 amp 4 stage converter.

The solar unit I have is a Bluesky 2512iX MPPT Charge Controller.

[alano]

Do you have the BlueSky IPN remote? With it you can change the voltage thresholds and disable the equalization cycle. The battery monitor is also good value!

Your Powermax Boondocker doesn't look incompatible with lithium batteries. Sure it would be nice to adjust some of the thresholds but the max voltage is 14.6 V, less than the max allowed by the bms system 15.1V. Preferably you would disconnect the converter from the batteries when connected to shore power anyway.

[lewster]

Originally Posted by BoldAdventure

As I understand it, lithium has a different charging profile than AGM and Lead Acid. My Powermax Boondocker is a 60 amp 4 stage converter.

The solar unit I have is a Bluesky 2512iX MPPT Charge Controller.

Your Blue Sky controller is easily programmed to meet the charging needs of lithiums. In fact, you would have to revert back to your old Parallax, as the constant 13.6VDC output is better for lithiums than a multi-stage converter, which won't work with lithiums.

The best on-grid charger is the Magnum MS-2012, but lithiums will tolerate the Parallax, leaving the bulk of the charging (pun intended) to the Blue Sky.

Remember that lithiums don't need to see 100% state of charge to operate effectively. They are quite comfortable at charge states below full. The only down side is less available amp/hours at a lower SOC.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[BoldAdventure]

Have been doing some back and forth and made our final decision after chatting with Lew and Marvin and discussing some options with the wife. We're going with GBC/Elite lithium batteries.

And I guess I'm going to just be doing a do-over on a few components. Scheduled install is after Thanksgiving, and I'll start a new thread then.

[Rocinante]

Best wishes for a smooth, successful upgrade.!

[BoldAdventure]

Originally Posted by alano

Bold,

You could DIY a lithium LiFePO4 300 AH solution for less than $2000. You can find 3.2 V, 300 AH prismatic cells for about $400. Combine that with (4) BMS cell modules from EV Power, Australia (about $19AUS each) and add a BMS control unit from the same company with a disconnect switch for $175AUS, add a fuse and your there.

Not sure why your converter isn't compatible. Is it a single-stage supply? It shouldn't overcharge the cell. When you're connected to shore power you can also disconnect the cell and let your solar charge the lithium. And what's your solar charger brand? If you can change the voltage thresholds you might be able to make it work.

The reason lithium might make sense for you is that you're willing to put the battery pack inside the AS. LiFePO4 cells don't like freezing and they degrade with high temperatures so they're not a good option if you're trying to put them in the outside box.

You and another friend, I tell ya. Got the gears spinning.

I did some research to discover the source of AMSolars cells. PS, they come from China, and are made by Sinopoly.

You're right, and I've been reading EV forums, talking to some folks on Slack in an EV discussion group and watching tons of youtube videos.

I haven't put together a fun project in awhile, but I am thinking of getting cells and building a big battery bank myself.

The EV community has put together a lot of information and I'm surprised there is almost zilch in the RV community. I have found a lot of good info on one of the prepper forums for off grid living on building huge LiFePo4 banks for solar.

Lots of ideas. But when I started pricing components. Yeah, I want to try this.

[alano]

Bold, as a EE, I worked on a couple of custom lithium battery developments using another chemistry and I'd be happy to be a sounding board and help look into the necessary components. Send me an email directly.

[Ktholin]

I've got a related question I thought I would post here. I converted my two 12v flooded batteries over a year ago with two 6V Interstates (232 Ah). I modified the battery box to accommodate them, and I'm running two 125 watt solar panels which I'm very happy with.

I usually run an hour or two of TV, occasional furnace and fans. Also, Cpap machine all night. When batteries were new, by morning they still had more than 50% remaining capacity. In less than a year one of the Interstates went bad and was replaced. All was good for a few months. Now, I'm down to 75% shortly after the sun goes down while only running lights, which are LEDs. I'm suspecting the other Interstate battery is bad.

I'm thinking of switching to Trojan T-105s. Do you feel they are much better than interstates? The other option would be to install two more 6Vs to provide me additional capacity, but concerned about extra weight. Based on my usage, am I asking too much using two 6Vs only? Would switching to Trojans meet my needs, or should I consider four 6 volts?


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[lewster]

I replace more Interstate batteries due to premature failure than any other brand. That says something about the lack of longevity due to poor quality.

I think that Trojans are the best for liquid cells, but I install only Lifeline AGMs and now the new lithiums from AM Solar.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[BoldAdventure]

Originally Posted by lewster

I replace more Interstate batteries due to premature failure than any other brand. That says something about the lack of longevity due to poor quality.

I think that Trojans are the best for liquid cells, but I install only Lifeline AGMs and now the new lithiums from AM Solar.

My Interstates were purchased back in March, and they deplete fast. Part of the reason for all this planning.

I can't find a US distributor for the Sinopoly cells AMSolar is using, but I have found distributors for the GBS and Winston cells. I'm thinking of working with 200ah 3.7v cells instead of using 100ah cells to save on space.

Going to talk to Starlight Solar later today or tomorrow if I don't get to it to see it they'll sell the cells seperately.

[BoldAdventure]

Just acquired today. Like I said, could not get the cells AM Solar is using without waiting 3-4 weeks on shipment from UK or China. Winston cells are a bit more. GBS is reasonably priced in comparison. And I could pick them up at a US retailer here in Yuma. So, since I'm full time these are the cells I'm going to use.



I'll start a new thread shortly. We are going to figure out where to place these and build a battery box inside the Airstream, and I still have a few more pieces of the puzzle.

[switz]

Our 300 amp-hour AM Solar lithium battery was configured to be 11.25" x 14.5" and weighed 84 pounds. That is less weight than the two Interstate stock batteries that were removed from the battery box (which became storage for blocks for the stabilizers). We put it just in front of the street side wheel well and it fitted under the sofa with pull out mattress shelf.

Another configuration would be 5 ⅝" x 29". The third configuration is 7.25" x 22.5". One can safely use about 250 amp-hours out o0f the 300 amp-hour battery.

[Ted S.]

Holy crap that an impressive set of batteries. I want them, but I would know what to do with them.