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RV deep cycle battery question

BDK said:
If you read through the description, it says they are good for 2,000 cycles. So that's less than half the amp hours and about the same life span you get with a decent AGM 6 volt for the same cost. Plus, you have to build the system and add a battery management system (BMS). Doesn't seem to me to be worth all the trouble to have less AH. Again, not cost effective.
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Yeah, those are cheap 32650 cells though.

What you're not appreciating is that with a 500AH AGM array, you have ~250AH usable, so an equivalent LiFePO4 array would be 250AH. That means it's not "less than half the amp hours" as you stated, because with lithium, you can use something like 95-99% of the rated AH without damaging the cells.

From the site I linked, this specific battery costs a shade over $1000, gives you 206AH (not too far off from your example 250ah usable AGM array), comes with a 7 year warranty, and is good for 2-4x the cycles of your AGMs. That seems pretty cost effective to me:

www.sokbattery.com

SOK Battery

SK12V100,SK12V206,SK12V206H,SK24V100,SK48V100
www.sokbattery.com www.sokbattery.com
 
For the people talking about lithium, there’s also the assemble-it-yourself setup. It’s looking a bit less attractive with that awesome deal on a 206ah ready made setup. But, I’m in the process of DIYing my first one right now. 280ah of Chinese grade B cells. The cells, the battery management thingy, the box, and some copper will be about $800. No idea if it will work right, but voltages are good. You still have to have a converter/charger capable of the LiFEPO4 settings, as has been said. I am also having to add some alternator protection to mine since it’s in a motorhome, which also adds to it. So, I think I’ll be into it about $1050, since I already had the charger.

Edit—oh, and lead acid lies its ass off. I have a fancy shunt that measures power usage. I have a 150ah lead acid setup. You know how you should only pull lead acid to half juice? My lead acids can only provide 85ah TOTAL. As in, that’s draining them all the way, leaving nothing on the table. That’s as measured by the shunt, and final voltage is like 10.5. Fully drained. Mine are 3 yrs old, and have seen a little abuse, obviously. But I’m not a fan.
 

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OHV Wildcat said:
For the people talking about lithium, there’s also the assemble-it-yourself setup. It’s looking a bit less attractive with that awesome deal on a 206ah ready made setup. But, I’m in the process of DIYing my first one right now. 280ah of Chinese grade B cells. The cells, the battery management thingy, the box, and some copper will be about $800. No idea if it will work right, but voltages are good. You still have to have a converter/charger capable of the LiFEPO4 settings, as has been said. I am also having to add some alternator protection to mine since it’s in a motorhome, which also adds to it. So, I think I’ll be into it about $1050, since I already had the charger.

Edit—oh, and lead acid lies its ass off. I have a fancy shunt that measures power usage. I have a 150ah lead acid setup. You know how you should only pull lead acid to half juice? My lead acids can only provide 85ah TOTAL. As in, that’s draining them all the way, leaving nothing on the table. That’s as measured by the shunt, and final voltage is like 10.5. Fully drained. Mine are 3 yrs old, and have seen a little abuse, obviously. But I’m not a fan.
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this is the best route because you can replace/add individual cells.

but you'll still be into it for a grand and it takes some nerdery.
and I wouldn't discharge below 20% for a super long battery life/better balancing.
 
If you can fit 6v do that, if not just get normal parts store replacement batteries.
Spend the money on solar.
 
welndmn said:
If you can fit 6v do that, if not just get normal parts store replacement batteries.
Spend the money on solar.
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but you're limited by lead acid batteries on how much current you can put in them.

They also charge way less efficiently than lithium.
Lithium stores nearly 100% of the electricity you stick in them. Lead acid is like 80%, with the other 20% just disappearing. So you can have a smaller solar array and get more usable watts.

so the argument is whether or not the greatness of lithium is worth it because it makes all your other shit work better.
and whether or not you can do it cheaply enough to justify it.

but I see sticking with lead acid and spending money on panels as backwards. The greatest advances for your money are in batteries.
 
OHV Wildcat said:
For the people talking about lithium, there’s also the assemble-it-yourself setup. It’s looking a bit less attractive with that awesome deal on a 206ah ready made setup. But, I’m in the process of DIYing my first one right now. 280ah of Chinese grade B cells. The cells, the battery management thingy, the box, and some copper will be about $800. No idea if it will work right, but voltages are good. You still have to have a converter/charger capable of the LiFEPO4 settings, as has been said. I am also having to add some alternator protection to mine since it’s in a motorhome, which also adds to it. So, I think I’ll be into it about $1050, since I already had the charger.

Edit—oh, and lead acid lies its ass off. I have a fancy shunt that measures power usage. I have a 150ah lead acid setup. You know how you should only pull lead acid to half juice? My lead acids can only provide 85ah TOTAL. As in, that’s draining them all the way, leaving nothing on the table. That’s as measured by the shunt, and final voltage is like 10.5. Fully drained. Mine are 3 yrs old, and have seen a little abuse, obviously. But I’m not a fan.
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Yup, agree, but didn't want to lead with that method when talking with a bunch of luddites :lmao:

I've got a 100ah LiFePO4 array powering my crawler, and a 280ah array going into my enclosed trailer. Solar will come, but batteries are always first like 87manche is saying.
 
BDK said:
If you read through the description, it says they are good for 2,000 cycles. So that's less than half the amp hours and about the same life span you get with a decent AGM 6 volt for the same cost. Plus, you have to build the system and add a battery management system (BMS). Doesn't seem to me to be worth all the trouble to have less AH. Again, not cost effective.
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I can't pretend to know how many cycles you will use but for my camping needs 2000 cycles would be 100 years at 20 cycles per year...

Obviously not realistic so I don't sweat cycle ratings too much.
 
I have them on near constant float charge when at home, and on constant solar (except for at night, of course) when dry camping so my batteries last a long time. I hardly use the amount of power I have available. When my new AGM's start to wear out in 7-8 years I will revisit the whole lithium better argument. They might be giving them away by then.
 
87manche said:
but you're limited by lead acid batteries on how much current you can put in them.

They also charge way less efficiently than lithium.
Lithium stores nearly 100% of the electricity you stick in them. Lead acid is like 80%, with the other 20% just disappearing. So you can have a smaller solar array and get more usable watts.

so the argument is whether or not the greatness of lithium is worth it because it makes all your other shit work better.
and whether or not you can do it cheaply enough to justify it.

but I see sticking with lead acid and spending money on panels as backwards. The greatest advances for your money are in batteries.
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You must use a lot more power than I do when camping, I"m just trying to run lights and water pump.
 
A thousand fucking dollars for 200ish useable amp hours? I can get enough lead acid from walmart to get 200ish useable amp hours for $350.

Everyone correctly pointing out all the ways that lithium is better, is ignoring the fact that it's for an RV where most of those advantages are not of as much concern as in other applications.

This discussion has gone the way of "you need a cummings to tow a jetski" or "don't get your 70yo parents an ipad to surf the net with, a custom built PC running linux is way better" :flipoff2:
 
Derp said:
A thousand fucking dollars for 200ish useable amp hours? I can get enough lead acid from walmart to get 200ish useable amp hours for $350.

Everyone correctly pointing out all the ways that lithium is better, is ignoring the fact that it's for an RV where most of those advantages are not of as much concern as in other applications.

This discussion has gone the way of "you need a cummings to tow a jetski" or "don't get your 70yo parents an ipad to surf the net with, a custom built PC running linux is way better" :flipoff2:
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Of course--every discussion here is always going to go that way, to some extent. My point is that, based on my experience, I think you'd need at least 500ah of lead acid to get 200 usable. I'd be pretty amazed if that could be had for $350, but maybe. The hilarity in my setup is that we really only use maybe 75ah/day. If we're in a perfect setup, I can actually replace most of that power with solar. So I'll for some reason have more battery life than tank volume. But it really wouldn't have saved me all that much to go small, so I did the right thing and went for the overkill. But fine--go tow with your Subaru Brat if you insist on it. :flipoff2:
 
A 200ah setup looks to last an 8 day dry camp running 20amps straight 24\8, before recharging due time?! My roight guesstimate.
sounds like an awful lotta capacity to me.
It should be interesting to see how this discussion shakes out.
 
Clb said:
A 200ah setup looks to last an 8 day dry camp running 20amps straight 24\8, before recharging due time?! My roight guesstimate.
sounds like an awful lotta capacity to me.
It should be interesting to see how this discussion shakes out.
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What?? If you’re pulling 20 amps, then a 200ah battery will last 10 hours.
 
BDK said:
Yeah, but $1000 would be about 500 AH of AGM GC2's, which seems to be just right for most dry campers with solar chargers.
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a trojan 240ah 6v battery is currently $380 on amazon.
and it says right on it's label that at it only achieves it's 240ah rating at a 20hr draw rate.

draw more than 12 amps and it's capacity doesn't reach it's label.

now subtract half of it to be kind and make them last 5 years because the trojan discharge curve has no regard for any of it. They discharge it right down until it's 100% dead.

so four batteries to make a 12V 480ah pack, that gives probably around 200-250ah of usable capacity depending on useage.
so 1500 dollars for your lead acid equivalent to a 200ah lithium pack.

or you could buy two 100ah lithium batteries for $1500 that have all their own battery management in them and are drop in replacements. $750 after coupon.
End up at 1/3 the weight, faster charging/discharging, longer life and less battery cabling.
They'll sell you a 300Ah one for $1200.

or do it even cheaper if you build your own using individual cells.

spending thousands of dollars on lead acid batteries doesn't make sense to me anymore, but we're all free to make whatever choices you want.
 
OHV Wildcat said:
What?? If you’re pulling 20 amps, then a 200ah battery will last 10 hours.
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no it won't, because those amp hour ratings are derived from incredibly low discharge rates so they get the maximum number.
at 25 amps trojan says their 6vagm battery lasts 385 minutes. That's only 160 AH. and that's all the way to dead dead, greater than you want to discharge them for maximum battery life.

 
Derp said:
Everyone correctly pointing out all the ways that lithium is better, is ignoring the fact that it's for an RV where most of those advantages are not of as much concern as in other applications.
Click to expand...

Totally depends what you're using the RV for. If you're plugged into shore power at campsites all the time, shit no you don't need lithium, because you have unlimited power anyway. A couple of lead acid batteries will do you fine. If your RV is not often plugged into shore power, the added energy density, lower weight, and much smaller footprint as compared to lead acid are all welcome improvements. Sure you have a "bay" or "locker" that's dedicated to huge lead acid batteries right now, but that space could be repurposed as extra storage, which is always welcome.

No one here is saying take out your perfectly serviceable lead acid batteries to pop in an equivalent lithium array. That's just throwing money away. However, next time you need to replace your lead acid batteries, and don't want bottom of the barrel wal-trash batteries that last a few years when lightly used, then take a look at lithium.
 

Robot or human?

www.walmart.com

Ok I was wrong on my math, it would be $356 (not counting tax) for 460 nominal, 230 useable amp hours, made by exide (and I don't remember who actually makes exide). I've done lots of dry camping. I've never encountered a travel trailer, motorhome, or slide in camper where you couldn't fit enough lead acid relative to the power demands between periods when you'd want to fire up a generator or the vehicle to recharge. Sure, I could cherry pick situations like "well what if you want to run a 120v heater and the AC at the same time, for days on end? You can't get that kind of output with led acid, you need lithium!"

Speaking of, what would root source power options be for a lithium setup on an RV? Solar seems like everyone's go-to, but how easy is it to charge off of the vehicle when running, or a generator while at camp? Do the usual solar charge controllers have provisions for those sources, or would you need additional equipment? ...I'm genuinely curious
 
Totally over it. You do lithium, I'll do my AGM's because they work fine for me and always have.
 
Derp said:

Robot or human?

www.walmart.com

Ok I was wrong on my math, it would be $356 (not counting tax) for 460 nominal, 230 useable amp hours, made by exide (and I don't remember who actually makes exide). I've done lots of dry camping. I've never encountered a travel trailer, motorhome, or slide in camper where you couldn't fit enough lead acid relative to the power demands between periods when you'd want to fire up a generator or the vehicle to recharge. Sure, I could cherry pick situations like "well what if you want to run a 120v heater and the AC at the same time, for days on end? You can't get that kind of output with led acid, you need lithium!"

Speaking of, what would root source power options be for a lithium setup on an RV? Solar seems like everyone's go-to, but how easy is it to charge off of the vehicle when running, or a generator while at camp? Do the usual solar charge controllers have provisions for those sources, or would you need additional equipment? ...I'm genuinely curious
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it's just a battery charger. feed it whatever. most of the lead acid ones also do lithium these days and operate just like any other.

BDK said:
Totally over it. You do lithium, I'll do my AGM's because they work fine for me and always have.
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yeah, that's what i said.
:flipoff2:
 
Here's my annual dry camping experience.
2 Sam's Duracell GC2 6v batteries, victron 100/30 mppt and 4 100w compact HQST solar panels.
2000w inverter powering the entire trailer.
We have ran the ice maker everyday and still charged the batteries sufficiently each evening.
 

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Let's all buy one of those stupid LOUD Chinese generator noise makers and be happy pissing off the entire Forrest.
Yes that's it
 
Derp said:
Speaking of, what would root source power options be for a lithium setup on an RV? Solar seems like everyone's go-to, but how easy is it to charge off of the vehicle when running, or a generator while at camp? Do the usual solar charge controllers have provisions for those sources, or would you need additional equipment? ...I'm genuinely curious
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The charging profile of a LiFePO4 array is slightly different than lead acid chemistry batteries. MPPT charge controllers can be configured for either lead acid or lithium, same with battery chargers (think noco style), but old school RV style "converters" can't be configured AFAIK. Lithium can also charge directly off of alternators, but if the lithium is very discharged, it will try to draw a ton of amps from your alternator. I suppose that's the same with lead acid batteries.

In my crawler, I charge my LiFePO4 directly off of the alternator, no DC-DC charger, but it's a smaller array (100ah). From 25% SOC on up, it's perfect, but below that, the array will draw a bit over 100a for the first couple of minutes to charge up. Not an issue in my situation, but something to be aware of.
 
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Clb said:
Let's all buy one of those stupid LOUD Chinese generator noise makers and be happy pissing off the entire Forrest.
Yes that's it
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I have a inverter generator for cloudy days, it's quite.
 
anyone tried charging their shitty old lead acid batteries backwards?
you'd just have to run them totally flat and then somehow figure out a foolproof way to mark them so you don't ever accidentally hook them up wrong
Seems that only one of the plates gets ate up, wonder if switching them up would effectively double the life
when totally discharged both plates are lead sulphate after all, they only end up being different things when you put a charge to the battery
 
[486] said:
anyone tried charging their shitty old lead acid batteries backwards?
you'd just have to run them totally flat and then somehow figure out a foolproof way to mark them so you don't ever accidentally hook them up wrong
Seems that only one of the plates gets ate up, wonder if switching them up would effectively double the life
when totally discharged both plates are lead sulphate after all, they only end up being different things when you put a charge to the battery
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That's way above my knowledge of batteries or chemistry.
These $99 batteries aren't really worth fucking with it after 5 years just rinse and repeat.
 
CarterKraft said:
These $99 batteries aren't really worth fucking with it after 5 years just rinse and repeat.
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oh lah tee dah look at this guy just throwing away good hundred dollar bills without even using them as toilet paper first:flipoff2:
 
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