Battery Peace of Mind - Page 2

Marine359 · 02-10-2021, 11:50 AM

Here’s some simple math to help determine whether AGM or LiFePo4 batteries are right for you:

A 100ah AGM will survive 300 charge cycles if it is not discharged below 60%. So, the usable amp hours are 40ah. You can buy a lesser brand 100ah AGM for $175. This makes the cost of an AGM $4.37 per useable amp hour. You can of course discharge to 50%, but that will reduce the number of charge cycles to 200, which is less than 2 years. If you don’t bring the AGM indoors during freezing weather, it may not last one year.

A 100ah LiFePo4 will survive 3,000+ charge cycles if is not discharged below 10%. So, the useable amp hours are 90ah. You can buy a lesser brand 100ah LiFePo4 for $500. This makes the cost of a LiFePo4 $5.55 per useable amp hour.

So, if none of the other purchase criteria matter to you, the AGM is the way to go, especially if you don’t know if you’ll own your trailer for more than 2 years.

I went with LiFePo4 because I’m real sure I’ll own my trailer for at least 5 years, making the cost of LiFePo4 batteries per amp hour much lower over 5 years than AGM. I also favored LiFePo4 due to significant weight saving, faster charging profile, safer for pass thru mounting, and imperviousness to cold weather. My purchase price was $800 for 170ah. That’s $4.70 per amp hour, or $5.23 per useable amp hour. Bottom line is my 5 year battery costs with LiFePo4 will be roughly half the cost of AGM. If I thought there was a chance of selling or trading my MM in a couple of years, I would have chosen AGM.

Fasttimes · 02-10-2021, 12:36 PM

Quote:

Originally Posted by RocknRoll

IMHO, if you desire a positive battery experience, replace the stock 12V with a lithium battery/charger setup. This should be an option at the factory. Although not cheap ($650), it allows me "piece of mind"

Advantages

1. 2X the AH rating (can run from 90% to 10%)
2. Charge time is reduced by 50% (important for solar)
3. 10X the number of cycles (lifetime)
4. No maintenance
5. 50% of the weight

tinglett has an excellent write-up on how to replace the charger.

https://www.winnieowners.com/forums/...ml#post3886305

Why does the charger have to be replaced on a lithium battery? You can't just swap out my old 12v for a 12v lithium?

I see that BassPro has Tracker Lithium batteries advertised, the group 24 price is not that bad, $500. Currently I have a group 27 battery standard 12v battery but thinking an upgrade to the lithium group 24 would save me some nice tongue weight to justify the cost. But if I have to go down a rabitt hole of upgrading the house charger I doubt I would mess with it at this time.

https://www.basspro.com/shop/en/trac...marine-battery

Marine359 · 02-10-2021, 12:57 PM

If you’re buying from Bass Pro, make sure it’s a LiFePo4. They sell older chemistry lithium’s which most people buy for trolling motors. Not the same at all.

LiFePo4 has a near linear charging profile which drops off at 90%. That’s one of the reasons why you can charge a LiFePo4 twice as fast as a FLA battery. Also, the LiFePo4 can safely be charged at a much higher amperage than FLA because the charging process does not produce gas. An AGM cannot be charged faster or at any higher amperage than the mats can absorb, or kaboom. The standard charger in a MM is pre-programmed for FLA batteries and cannot be changed. I think most are 3 stage, but I’m not absolutely sure on that. It delivers bulk charge in 1st stage to 65-70% then float in stage 2 to 90-95%, then trickle to full. Using that charge profile can be done, but it will severely reduce the number of charge cycles. High charge cycles (3,000 - 5,000) is one of the main reasons for buying LiFePo4. If you’re not ready to shell out $250 for a good LiFePo4 Charger, stick with FLA. I chose to get a inverter charger with built-in programmable LiFePo4 charging profile.

Fasttimes · 02-10-2021, 02:00 PM

Yeah, I would I guess hold off on this idea in my case until the cost comes down a lot more. If I did a lot of boondocking I could maybe see the need, but rarely do I ever not have connections. Only up in your neck of the woods in GSMNP do I ever really fret about my battery usage.

Marine359 · 02-11-2021, 03:58 AM

Fasttimes,
If you have an absorption fridge running on propane, and you’re not using an inverter for stuff like a cpap, a single 100ah AGM will provide all the juice you need (50 amp hours) for up to two days of boondocking, unless you run the furnace through the night. You don’t have to change your charger. If you decide to do a bit more dry camping, your money may be better spent on a small generator to recharge your battery. You can buy a 100ah AGM for $175.

al1florida · 02-11-2021, 04:42 AM

Quote:

Originally Posted by Marine359

If you’re buying from Bass Pro, make sure it’s a LiFePo4. They sell older chemistry lithium’s which most people buy for trolling motors. Not the same at all.

I went to the Bass Pro website and was unable to find any lithium batteries that were NOT LiFePO4 labeled batteries.

Do you have a link for lithium batteries with other chemistries? I very curious to see what other chemistries they are selling.

Marine359 · 02-11-2021, 04:47 AM

Maybe not anymore. Probably the old lithium has been retired. Sorry, I should have checked the link first. You can still buy lithium ion, but looks like Bass Pro has switch over to LiFePo4

al1florida · 02-11-2021, 04:49 AM

Don't overlook the old fashioned FLA (Flooded Lead Acid) golf cart battery for about $80-$90 at Sam's Club or Costco.

They may only last 90% as long as AGM, but at 1/2 the price an excellent buy.

As long as you have easy access to the top of the battery checking the water level each month and perhaps adding water every 2-3 months is not difficult or time consuming.

I used golf cart batteries for years before switching to Lithium 5 years ago.

Marine359 · 02-11-2021, 05:15 AM

Al,
There are a number of Li batteries on Amazon. Here’s a link to a site that sells mostly lithium ion. Note you’ll see them being used for trolling motors, which is why I mistakenly believed Bass Pro was still selling Lithium Ion. https://lithiumhub.com/lithium-deep-cycle-batteries/

al1florida · 02-11-2021, 10:10 AM

Quote:

Originally Posted by Marine359

Al,
There are a number of Li batteries on Amazon. Here’s a link to a site that sells mostly lithium ion. Note you’ll see them being used for trolling motors, which is why I mistakenly believed Bass Pro was still selling Lithium Ion. https://lithiumhub.com/lithium-deep-cycle-batteries/

Everyone and their uncle are now selling lithium batteries, unlike 5 years ago when I bought and installed my lithium batteries.

Since we do a lot of dry camping and boondocking there is no way I would consider going back to any lead acid battery.

Marine359 · 02-11-2021, 10:55 AM

Are the batteries you bought 5 years ago still holding charge?

al1florida · 02-11-2021, 02:13 PM

Quote:

Originally Posted by Marine359

Are the batteries you bought 5 years ago still holding charge?

They are still going strong.

I have batteries from Elite Power Solutions: https://www.elitepowersolutions.com/...-ion-batteries
I bought the batteries from Starlight Solar along with a kit to connect the 100AH cells together and build a BMS for the batteries. https://www.starlightsolar.com/starl...lar/index.html

I also have 650 watts of solar from a pair of 325 watt residential panels. We changed RV's in 2018 so I moved the batteries & solar panels to the new RV.

RocknRoll · 02-12-2021, 04:08 AM

Quote:

Originally Posted by Marine359

If you’re not ready to shell out $250 for a good LiFePo4 Charger, stick with FLA. I chose to get a inverter charger with built-in programmable LiFePo4 charging profile.

I got a wfco-wf-8950l2-mba which from what I understand due to charging sequences (not to mention it's plug-n-play) is a better performer than the Progressive Dynamics. $150 to my door. It's $160 now, but still a good price.

https://www.boatandrvaccessories.com...xoCuesQAvD_BwE

After watching a Will Prowse video, I got a used, (practically new) 138 AH Valence battery off e-bay for $500 delivered. There was only 12 charge cycles on it, confirmed by the printed readout sent with the battery. Great deal!

https://www.ebay.com/sch/i.html?_fro...y&_sacat=48446

IMO, go with LifePo4 if you want a long lasting, low maintenance high performing setup. If you decide to sell your trailer later, it will add resale value.