Lithium Stickies?

[dreadlocks]

sounds like y'all are trying to build a pair of mars rovers designed for a 90 day mission but hoping for 15 years.. not a part time overlanding rig..

most of the lithium info is for big boat banks, or EV vehicles.. few people on here are full timers, so 30-60 cycles a year and then sitting at partial charge the rest should yield a very long life even if only able to get 1000-2000 cycles outta em.. now if your cycling em daily in an off the grid style then yeah you'll get 3-5 years out of em without idealistic charging params.

I do agree for most of our audience tends to be abusive and frugal, so most ppl reading this wondering if they want to go lead or lithium needs to think long and hard about if the gains are worth the cost.. most folks looking at a 100AH lithium setup would save alot of money, and grief going with a cheap dual golf cart setup that will go 3-5 years easy and work with their existing charge schemes.. say you get 3 years outta dual GC setup, which is rather conservative, well for the cost of a drop in LFP you could buy over 15 years of GC batteries.

LFP makes most sense for expo audience thats driving short distances every day and are relying on engine charging, or severely constrained by weight enough as is.. which does cover alot of the folks here, right now they are on the very edge of making sense cost wise.. if they come down much more in price I think they will start becoming very attractive for the users here.

One thing you guys have hinted at but not just came out and said directly, is LFP can sit idle at partial charge in storage without kicking the bucket.. Lead needs a maintenance charge, if someone unplugs your charger while its winterized and in storage it could totally nuke your batteries.. whereas with LFP its best to drop all the loads and leave it at 40-60% SOC until next season.. mebe just cycle it once to keep SOC gauge calibrated/accurate.

 

[Hillbilly Heaven]

I haven't had the chance yet to read all the info on this lithium ion batteries but sounds interesting.
https://www.trojanbattery.com/trillium/

 

[john61ct]

Yes as stated, even a drop-in philosophy will get a few thousand cycles or at least a few years, great precision is only required if you care about getting longer, I've been consistently clear about that.

However, the bank-murder events still need to be prevented even if life-shortening practices are acceptable.

Decide what protections you want from solid information, don't screw up due to ignorance.

There is no difference between marine House usage and many off-grid land travel scenarios,

taking cues from best practices for smaller cruising boats is far better than the mainstream US RV industry that's for sure.

Yes if your rig burns, at least you can bail out and run away, but living in the same space as your bank does mandate caution.

In fact I'm surprised how big a bank many rigs "need", owners increasingly wanting mod cons like full size fridge, an all-electric galley, powerful computers, big entertainment AV systems etc.

would save alot of money, and grief going with a cheap dual golf cart setup that will go 3-5 years easy and work with their existing charge schemes.. say you get 3 years outta dual GC setup, which is rather conservative, well for the cost of a drop in LFP you could buy over 15 years of GC batteries.

LFP makes most sense for expo audience thats driving short distances every day and are relying on engine charging, or severely constrained by weight enough as is.. which does cover alot of the folks here, right now they are on the very edge of making sense cost wise.. if they come down much more in price I think they will start becoming very attractive for the users here.

Exactly!

Even Duracell GCs from Sams can last 5+ years with decent solar for the long tail charging required.

One thing you guys havent hinted at but not just came out and said directly, is LFP can sit idle at partial charge in storage without kicking the bucket

Yes in fact low SoC storage is important foe longevity, storing Full is bad.

if someone unplugs your charger while its winterized and in storage it could totally nuke your batteires.. whereas with LFP its best to drop all the loads

Note that should ideally mean isolating the cells completely, including from the BMS gear.

Then self-discharge rates are very low compared to lead, say 2% per month in cool temperatures.

In longevity-killing hot ambients, it's important to check in a bit more frequently, personally I'd just routinely top up to say 12.5 every couple months.

 

[john61ct]

The best SoC meter now is Balmar SG200, no resetting 100% or re-calibrating SoH manually required, it uses several algorithms and combines them ** to tell you ** what your current capacity is as the bank ages, apparently performs very well with LFP even more accurately than with lead.

Takes a dozen+ deep cycles to "learn" your bank.

But the current version of the firmware does not actually display AH in/out, you just rely on the (now more trustworthy) SoC %.

 

[john61ct]

I haven't had the chance yet to read all the info on this lithium ion batteries but sounds interesting.
https://www.trojanbattery.com/trillium/

Yes, very promising,

especially allowing high C-rates when needed, CAN-bus external comms, software updates, etc

Not so much "drop-in", more like the bigger proprietary packaged systems from Victron, Mastervolt, Lithionics, but in a cheaper smaller format.

But, haven't heard from anyone yet actually taken delivery.

OEM is K2 apparently, so the internal cell quality - chemical purity, layers / matrix construction techniques etc - are an open question, we won't know if as good as Winston / CALB / GBS / A123 for quite a few years.

They def aren't rated great at cylindrical cells compared to A123.

 

[luthj]

The lithium drop-in packs are around 1000$ per 100AH. That is a lot more expensive than a 200AH lead bank, such as GC2 class, at around 100$ per 100AH. However really the lead banks are about 200$ per 100AH of usable capacity. So the lithium drop-ins are 5x the price. Though with modest treatment, they should last at least 5x the cycles. Likely much more. PLUS, they weight 1/4 of the lead equivalent. Combine that with some savings from a smaller (or even no solar array), and it seems more reasonable. In fact the lithium drop-ins may only be 3-4x the cost as the lead when considered in the view of a whole system. Now add in 5x the cycles (or more in partial charge scenarios), and the cost outlay over a 5 year period may be lower.

While @john61ct is very focused on extending pack life, most of the changes discussed are quite easy to implement. Its just a matter of giving up 1-2% of capacity at the top end, and avoiding dumb lead chargers that age the battery with unnecessary absorb cycles.

 

[Hillbilly Heaven]

I see that BB has a 12v 100AH GC2 drop in. Should be more usable Ah and lot less weight than a 6v GC2 AGM setup. $1k per battery vs $200 for a tier one 6v GC2 AGM.

One of my favorite camper builders recently switched from 2 x 12v group 31 batteries in the storage tunnel to 4x 6v GC2 batteries on the tongue A frame between 2 x 30 pound propane tanks and the body. I guess they did this to balance out the weight since they added an Onan 3.6 KW propane generator to the standard package.

 

[Amp34]

The lithium drop-in packs are around 1000$ per 100AH. That is a lot more expensive than a 200AH lead bank, such as GC2 class, at around 100$ per 100AH. However really the lead banks are about 200$ per 100AH of usable capacity. So the lithium drop-ins are 5x the price. Though with modest treatment, they should last at least 5x the cycles. Likely much more. PLUS, they weight 1/4 of the lead equivalent. Combine that with some savings from a smaller (or even no solar array), and it seems more reasonable. In fact the lithium drop-ins may only be 3-4x the cost as the lead when considered in the view of a whole system. Now add in 5x the cycles (or more in partial charge scenarios), and the cost outlay over a 5 year period may be lower.

While @john61ct is very focused on extending pack life, most of the changes discussed are quite easy to implement. Its just a matter of giving up 1-2% of capacity at the top end, and avoiding dumb lead chargers that age the battery with unnecessary absorb cycles.

Are your sums right there?

I'm currently looking at batteries and have pretty much decided to go for a drop in LiPo (BB) because it works out at "only" twice the price.

Slightly different prices as I'm in Canadian but US prices are similar. The BB is $1200 for us, but a 100AH AGM battery $300, so that's $600 for the equivalent of the 100AH LiPo. GC2 batteries are around $300 for 220A, but only 6v, so you'd need two for the same capacity which is also $600.

US prices for a good AGM battery are in the $250 price for 100AH that I've seen?

Twice the price is a lot, but having something that weights 30lb instead of 130lb is worth a lot, as is the reduced requirement for maintenance and lower chance of destroying your batteries because you didn't charge them properly, at least for me.

 

[dreadlocks]

you can get 220AH Deka FLA 6v Golf Cart batteries for ~$100 USD each from bulk discount stores, thats 220AH of 12v for ~$200 USD.. they last 3-5 years of apathy, 15-25 years of battery banks for cost of LiFePo4.

If your going AGM then yeah, dont mess with the crap AGM get the good stuff which costs $600-$800 for ~200AH, now you find Lithium is not really that far away, especially given how big of a charger you need to pamper those and that any small scale solar setup is going to be abusive because it does not meet minimum charge amps.. AGM's are entirely a waste of money for almost everyone on these forums, they give nothing in return for the premium price they demand.. unlike Lithium, which does gain alot of benefits such as fast charge rates, very solar friendly, very light weight, more usable capacity, long term resting capability, less overall capacity required, etc..

 

[john61ct]

No question quality FLA is better value economically in some markets, but in others where AGM have taken over, you just can't get good FLA or need to pay Rolls / Surrette sort of pricing.

That said, even in the NA market, where quality FLA is cheap and plentiful, there are some use cases that do justify the higher cost per year of AGM or GEL chemistries:

Installation space requires sideways, or access is very inconvenient.

Higher CAR in Bulk / CC stage needed to reduce ICE runtimes (yes danger of PSOC abuse)

Or the owner just can't be bothered topping up and doesn't mind paying more for that, not a sin if you can afford that.

 

[jacobconroy]

you can get 220AH Deka FLA 6v Golf Cart batteries for ~$100 USD each from bulk discount stores, thats 220AH of 12v for ~$200 USD.. they last 3-5 years of apathy, 15-25 years of battery banks for cost of LiFePo4.

If your going AGM then yeah, dont mess with the crap AGM get the good stuff which costs $600-$800 for ~200AH, now you find Lithium is not really that far away, especially given how big of a charger you need to pamper those and that any small scale solar setup is going to be abusive because it does not meet minimum charge amps.. AGM's are entirely a waste of money for almost everyone on these forums, they give nothing in return for the premium price they demand.. unlike Lithium, which does gain alot of benefits such as fast charge rates, very solar friendly, very light weight, more usable capacity, long term resting capability, less overall capacity required, etc..

Dude...you are going to spend a lot of my money with these types of arguments.

Weight is a big issue in my rig. Already over GVW, so LFP fits that need. How about size? Is a 100 Ah LFP battery physically smaller than the AGM equivalent (Group 31)?

 

[dreadlocks]

its physically the same size, the thing is you dont need two 100AH's to get 100AH of usable capacity.. you can get 95AH out of one w/out really hurting it.. though for long lifespan should stop around 80AH, I keep that last 15AH as reserve capacity I can use in a pinch like furnace shuts off in middle of night and im not going out and firing up genset.. requires my physical intervention to get to that last 15%..

Also you have to figure in Peukert's law is no longer applicable for LFP, my 100AH battery still has 100AH capacity running my microwave.. where FLA/AGM is going to have dramatically less capacity running those loads thanks to the exponential losses experienced the higher the loads you use.. If I run my microwave for 10m and use 10AH of capacity, on FLA/AGM that same 10m with the same appliance could easily consume >15AH

Weight was my issue too.. not GVW but tongue.. Toy haulers are naturally tongue heavy vehicles because for the sake of cargo room everything goes infront of the axles... +250lbs of FLA on the front of my trailer woulda put me waaay over.. I'm just slightly over right now, hoping mounting genset and solar panel off the back bring me back within spec.. the only other option was an under-body battery bank which woulda taken away my valuable clearance.

I said in another thread, if your going just off engine/genset runtime things swing largely to LFP favor.. for example, I can use 80AH a day, and run genset for 2h a day.. in 4 days I can burn through 320AH for a mere 8h of combined total engine runtime.. thats about the average time it takes to charge a FLA bank, so to get 8h total every 4 days of runtime equivalent I'd need a 640AH FLA bank.. thats six 6v batteries for like ~$600 and will weigh >360lbs.. with LifeLine AGM's your looking at ~$2200 in batteries.

 

[john61ct]

Yes even in the usually deep-pocket boat / cruisers' market, the main justification for spendy LFP installs is the space / weight / usable Ah argument.

Some I know have saved over 800lbs, and that means a lot to sailing performance for a small liveaboard 30-footer.

In this context, a Unimog expo vs a tiny teardrop make a big difference. . .

 

[Amp34]

Yeah, basic flooded batteries are cheaper, but they need ventilation. From everything I've read it's not a good idea to stick those in the same space as you live/sleep. Fine for those that have external storage locations, not so much for those with truck campers.

My battery is going to go in the truck bed where I'll be sleeping, which is why a sealed battery is important AFAIK?

Also like the weight savings. It's going in a GFC build so weight is important to me, and saving over 100lb of weight and a batteries worth of storage is another positive - alongside the reduced maintenance requirements for intermittent use.

 

[john61ct]

Yes, fumes are NBD for most people in a bigger space with decent ventilation, but a small cap I'd stick to AGM.

Odyssey, Lifeline or Northstar.