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Lithium Ion Drop in Batteries
Once upon a time we Prevost owners debated about slides, over the road air and Cruiseairs versus roof airs. Now we have a new subject to debate, and I hope this thread opens the discussion. Lithium Ion batteries are here to stay, and by every unit of measurement except cost they are far better than AGM batteries that most coaches have. I started out with lead acid batteries, went to gel cell, then to AGM. I am now a lithium ion battery guy.
Lead acid were fine, they were cheap, and their drawback is how they had to be mounted and the ongoing maintenance of retaining the proper level of electrolyte. Those problems went away with gel cell batteries that could be installed in any position and provided the same number of amp hours as lead acid. The problem with gel cell is they are a little fussy, they don’t like heat, and their charging voltage is very important because if it is too much they fail. Too much means the charging voltage is sensitive to temperature and a voltage that is OK on a cool day, will destroy the same batteries on a hot day. When AGM came along they possessed the tolerance for a range of charging voltages, along with a no maintenance requirement (except for charging) and flexibility in mounting position.
But all of the batteries above don’t hold a candle to lithium ion batteries. Batteries are heavy. An AGM 8D battery will weigh 165 pounds. A 250 amp hour rated battery is really good for about 125 amp hours. The current AGM battery price in the 8D size will cost about $660.
A “drop in” lithium ion battery in 8D size will have a 200 amp hour rating, but will be good for about 190 amp hours or about 50% more power than its AGM counterpart. Equally important it will weigh 60 pounds for about 100 pound savings per battery. The current price is about $2500. Obviously cost is going to be the deciding factor.
Or is it? We all have different needs and preferences. If all I got was less weight and more power I would be installing replacement AGM batteries. I opted to replace my 1000 AH battery bank (about 500 AH usable) with an 800 AH (about 720 AH usable) Lithium Iron Phosphate bank so I got more power available, reduced my coach weight 400 pounds, and based on projected recharge cycles my batteries will last the life of the coach if used as I have always used them. That means I never have to struggle with entertainment center or heavy battery removal ever again.
If I assume my batteries are truly used up every five years (they are not) then the way I use batteries with Li batteries my battery life is projected to be 10 times or more longer. Wouldn’t it be nice if we could buy a coach with tires, air bags, brake chambers, and Norgen valves that also lasted 10 times longer?
There is one other benefit and that is safety. Our coaches can suffer damage from unregulated alternator output as a result of a failed voltage regulator. But it does happen and if undetected continued excess voltage is going to do a lot of expensive damage to the coach. Batteries will burst, wires will burn their insulation and a lot of connected electrical devices will fail. These batteries have a built in battery management system that will shut them down in the event of excess voltage. That feature alone has value.
My choice is not for everyone, but if anyone needs batteries making the switch does not have to cost almost 4 times what AGM costs because each Li battery has more available power than its AGM counterpart, and it may be possible to retain the same amount of power with fewer batteries bringing costs closer together.
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44 Replies
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I’m impressed. you will be getting a smart phone next.
Do the inverters like the new batteries? Anything new or different?
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Jon was extremely diligent in researching all the pieces to this puzzle and his install went without a hitch. As you’re probably aware, his Liberty is 24 volt, so for someone with a 12 volt coach, it’s even easier with battery choices. Relion was also very helpful with our questions. Like Jon said, it’s not for everybody, but it’s coming folks.
Now for some self pro motion, I’m your Relion guy, so if you want to go down the Litium path, contact me for pricing.
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Try not to wait too long for me to get a smart phone. Because of robo calls and telemarketers we are getting close to no phone.
I monitored my system before the change starting with the AGM batteries in float, discharged them to near 50% SOC, and monitored the charging process until it reached float. I then observed the inverters go through the “silent” phases and to float and back to silent, and back to float etc.
All parts of the charging protocol were within the requirements specified by Relion who makes the batteries.
When the batteries were installed I again observed the entire charging cycle and bulk and absorb voltages were the same as noted on the AGM. Without changing any programming on the Outback inverters I did notice the float voltage was a tenth of a volt lower than what it was with the AGM. I assume that just might be a normal variation in the inverter. The inverters upon reaching float also cycled through the “silent” phases so if I did not know they were changed I would not be able to tell by monitoring the remote display panel.
I may be a poor evaluator because I do not push our batteries. We have a perfectly fine generator and we aren’t “campers” so our batteries on any of our coaches rarely were depleted lower than 30 to 40% SOC and almost always were being charged at or before 50% SOC. The last time I changed batteries on the coach a friend got them. That was almost 4 years ago and he is still using them with no issues so I suspect these new Li batteries will be around longer than me.
Dry campers will see the greatest benefits because in a given amount of space the batteries are going to supply much more power, and if they use auto-start that added power availability is going to mean less generator starts and charging cycles. If they are willing to accept the same performance they have with AGM for example they may actually use fewer batteries to not only free up space but to make some serious reductions in weight with costs less extreme than the ones I incurred.
I’ll let Tom throw around some ways different conversions can use various combinations of batteries to increase power, retain the same amount of power and provide different cost differences between Li and AGM.
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Roger, don’t listen to all of Jon’s BS, he is doing advertising for Tom.
He had enough balance due him from his share of the PC dues that Tom gave him the batteries.
Maybe you need to get on board and talk highly about the Pressure Pro system and maybe Tom will give you one.
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You would trust a guy with that avatar?
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As I said around New Years after Jon so shamelessly shilled for Li-Ion batteries on the forum, I might have had the last set of AGM Lufelines installed at ETLC. Only time will tell.
Jon: I know you self manage your generator start-ups when you dry camp and rarely if ever rely on the Liberty installed WatchDog System. Have you determined if the WatchDog will Auto start the generator before voltage in the batteries gets down to a point where the batteries’ will shut themselves down?
The AGMs if left unattended can be drawn down to the point where they are damaged and have to be auxiliary charged before the 50DN or the inverters will charge them. As I understand it, this is something we don’t have to worry about with the Li-Ion batteries. Please confirm.
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If a lithium bms cuts out on low voltage to protect itself it’s the same pain in the ass ( or more) to revive it so it will wake up and charge. Whereas with an agm it just has to look like approx 8-9v for the charger to pick up.
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I believe the Watchdog voltage for auto-start is 10.9 volts. It might work but at that voltage the curve from a 12 volt charged state to the battery shut down voltage is almost vertical so the time between 10.9 volts and shut down volts is almost nothing.
If the Watchdog can be fooled into auto-start when the actual battery voltage is 11.8 it should work well because that voltage is at the point where the voltage curve is beginning to go from its almost steady 12+ volt line to the near vertical drop off.
https://relionbattery.com/products/lithium/rb200
Discharging a Li to the low voltage shut down does not damage the battery, but if it shuts down it needs to be recharged ASAP.
As long as an alternator has power to the field wire such as in a single alternator set up where the alternator charges both chassis and house I see no reason for any other charging from a different device prior to using the alternator.
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Depends on the bms. Many cutoff at 2.5v/cell which is 10v. So 10.5 is pretty close with how steep the discharge curve is at the bottom shoulder. Many cut off even a little lower – but it’s actually better to cut off slightly higher as you are reaching down to the last few percentage points there. So depending upon where the manufacturer sets the watchdog to start – this will determine whether it will trip before the lithium battery cuts itself out.
but in terms of discharge – lithium’s actually dont need (or want to be topped off) a severe discharge will damage the battery and shorten the life just like agm batteries. They have high cycle counts but the life is shortened with regular deep discharges you are better off going from 20-90 over and over than 5-100. Lithium’s don’t like being in their “shoulders” – which means not fully charged and not fully discharged. It’s a misconception that you can go to 5 percent with no degradation in performance/cycles. Lithium batteries usually have several times the cycles of agm – and certainly for deeper discharges- but if you take it to 5 percent regularly (whereas for agm it’s 50 percent) – you will be shortening the cycle life significantly (like from thousands of cycles to hundreds )
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I feel I may have been lied to.
Jon complains no money, etc, etc, but now he is buying very expensive batteries, posting pictures, wow.
What is next Jon’s Face Book page??
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I’ve been selling vegetables from my garden and saving up to buy these batteries. But Tom said he is going to pay me dues money tomorrow so all is good.
As to questions or information specific to Relion batteries I have been going by their extensive literature and information about voltages, temperatures, voltage curves, etc from their web site. If information is not available on the specific battery PDF, go to their documents which has greater and more complete detail.
I do not know or care how their battery management system works but I am very comfortable knowing they have the confidence in it and their batteries to offer a very good warranty.
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this is kind of funny in a way. We dont stick our heads in the sand for anything else but it seems batteries. But its even funnier when the warranty you are relying upon is from a battery company that is offering warranties longer than the company has been in existence. . . .. . . maybe they are now slightly past that longevity point – but it isnt by far. . .
but dont get me wrong – I think Relion make one of the better lifepo4 “drop in” batteries out there. I would choose Victron first, Relion second, battleborn/Lithionics next.
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Jon, as much as you helped Harry with advice on His Coach and Life, think He’d spring for about 3 or 4 Lithium’s for ya!
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I’m not an Electrical Engineer, but I’ll take the positive approach to converting to Lifepo4’s and not worry about all the internet disinformation coming from the self proclaimed experts that are out there.
Relion has been great to work with and Jon and I spent 2 full days with Charlie their factory guy. We wore him out by the time he left West Palm and and all our questions and concerns were satisfied. They have a team of Engineers eager to help with installation questions. It was kind of funny, he was spending so much time with us for such a small order potential, while he was busy on the phone handling pallets of batteries to various OEM’s, vehicle manufacturers and solar.
More to come I’m sure…
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Anthem, I do not stick my head in the sand regarding batteries and I have read as much as I can about “drop in” replacements, I have always babied my batteries, and I have always replaced them at 5 years regardless of how much life they may still have left.
I am not going to ever use the full potential of my Li batteries, I will not pretend to know how they work down to the molecular level, but do fully expect to benefit from less weight, more power if I should ever decide to need it, and most of all I fully expect they will have so many cycles of recharging available based on how I use batteries that I will never have to replace a house battery again.
I am not going to question their safety or engineering because that is as irrational as a non-pilot judging a pilot’s skills or a patient judging a surgeon’s skills because he is still alive.
One thing is for certain……my decision was made based solely on their claims and if their product fails to live up to their claims I have a venue at my fingertips to make many people aware. I seriously doubt if I will ever need to complain because everything points clearly to how well those batteries will do.
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