By Mike Sokol
Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.
I noticed something on your Facebook Group last week about Lithium batteries not really being a direct replacement for my old batteries.
“Beware of ‘plug and play’ lithiums – you may not get their full capabilities without additional changes to your system…”
So what’s the scoop? Can I just drop in a new Lithium battery or not? After all, that’s a lot of money to goof up. —Kevin J.
This is something I’ve been studying for the last year or so, and I’ve reached a few conclusions. First of all let me say that this group posting was done by one of my very sharp moderators in the RVelectricity group.
So I would like to thank moderator Mike Ehlert for posting this screenshot from the Lion Battery website and starting this discussion. And you can read the full thread of this Facebook Group discussion HERE, including the response from Lion Energy. No, you don’t have to join Facebook to read this discussion, but you will need to join if you want to make any comments on this thread.
What does “plug and play” suggest?
The marketing literature for Lion Energy Lithium batteries (and many other brands) suggest that all you have to do is pull out your old battery, drop in a new Lithium battery, and begin enjoying all the benefits of this new battery technology. So is that all there is to it, or do you have to replace something else like the converter? And what happens if you don’t upgrade the converter at the same time?
What are the main benefits of Lithium Iron Phosphate (LiFePO4) batteries?
Well, first let’s do a little checklist of the important items for this discussion:
- Most Lithium batteries are designed to be discharged down to 0% without any damage to battery life. So you can get a full 100 amp-hrs of energy from a 100 amp-hr battery.
- Flooded cell batteries can only be discharged down to 50% of rated capacity without damage to battery life, so a 100 amp-hr capacity rating really only provides 50 amp-hrs of energy storage.
- Lithium batteries can be rapidly charged with up to 100 amps of current, allowing them to be recharged from 0% to 100% in less than 2 hours, or from 50% to 100% in less than an hour.
- Most flooded cell batteries should only be recharged at a maximum rate of less than 20 amps of current, so recharging a 100 amp-hr battery from 50% to 100% can take 3 to 4 hours.
What are the downsides of plug and play?
While you certainly can drop in a replacement Lithium battery in place of your original lead-acid battery, how well it performs depends on if your converter/charger has a Lithium setting, as well as its maximum available charging current.
Since Lithium Iron Phosphate batteries require a higher charging voltage to reach full capacity, your original converter/charger probably won’t be able to recharge your new Lithium battery to 100% – maybe reaching only 75% of full charge. So instead of 100 amp-hrs that you paid for, you might only have 75 amp-hrs of energy after recharging with your conventional converter/charger.
What about charging rate?
Secondly, if your converter/charger thinks this is a lead-acid battery it will limit the charging current to perhaps 1/4 of what a Lithium battery could actually accept. While that may not be a big deal if you’re plugged into shore power overnight to recharge your batteries, if you need to run a generator to recharge the batteries that could mean 4 to 6 hours of generator run time, when 60 to 90 minutes would do the job with a proper converter/charger. So Lithium batteries can recharge at a lightning rate, but only if your converter/charger is capable of providing all the needed amperes.
Does this hurt Lithium batteries?
UPDATE: I’ve recently learned that some RV battery chargers have a desulfator mode that can’t be disabled. This process uses high voltage or high-frequency pulses to “zap” the sulfates that have built up over time in a lead-acid battery. In a flooded-cell battery these pulses loosen the sulfates which drop back into the acid and dissipate. However, these same pulses can damage or destroy a Lithium Battery. So if you can’t disable the desulfation mode in a charger, you can’t us it for your Lithium battery.
But in general, connecting your new Lithium battery to an older charger/converter without a Lithium setting shouldn’t hurt anything (as long as you can disable desulfation mode). But you won’t be getting all the storage capacity you just paid for. And you can’t recharge your new Lithium battery in an hour or so. You’ll still be limited to the amperage rate of your converter/charger.
What is the solution?
If you’re planning on installing new Lithium batteries soon, first check the brand and model of your converter/charger to see if it has a Lithium setting. If not, then best practice is to have a new converter/charger installed with a Lithium setting that provides a higher charging rate and voltage profile to keep your Lithium battery investment fully charged.
So, is this misleading advertising as noted in the thread?
Yes, I would say it is. I don’t consider installing a Lithium battery to be “plug and play.” You really should do some research to find out if your existing converter/charger has a Lithium setting or not.
Of course, if you have a non-Lithium charger and know about the reduced storage capacity and less-than-fast recharging capabilities using an old charger, then that’s your decision. It won’t really hurt the Lithium battery, and you will get a little extra storage boost over your old battery (75% rather than the 50% of the rated capacity of a lead-acid battery). So you pay your money and you make your choice. However, if it were me I would install a new converter/charger during the battery installation that would allow me to reap all the benefits of a Lithium battery.
What’s the takeaway?
The key point is that if you simply replace an existing lead-acid battery with a Lithium battery without upgrading your converter/charger, you may not be getting all the battery performance you paid for. So yes, Mike E is exactly right….
Will there be more on this topic later?
Yes, I’m planning on making a full article and YouTube video discussing this topic in more detail next month, so stay tuned. In the meantime, find the model number of your existing converter/charger and you can discover if it’s Lithium ready or not by looking up the brand online, if you don’t have the information handy.
OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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From reading the comments I’d say there is quite a bit of misinformation on the subject. Based on this I guess I will remain uninformed the rest of my life or until the industry changes completely over to the next technology. At 77 it may all be settled before I turn 100. Lol
If you’ve ever seen a lithium battery burn you wouldn’t even consider it!
Actually Lion Energy recommends a DC to DC charger to protect your alternator from being overtaxed. You will also lose being able to crossconnect the house battery to the chassis battery for emergency starting. I bought a compressor powerpack to carry. I also upgraded the converter/charger with Lithium jumper pin.
I had not heard that you lose the emergency start “cross-connect” option by going to Lithium house batteries. Isn’t that a matter of having enough Amps to start the engine?
I kept my old charger when I installed a lithium battery. It only charges to 13.6V, not to 14.2V. While I don’t fully charge the battery, I should get longer life from it. Charging at high temps or fully charging the battery are what age it faster due to higher activation energy applied to the chemical process that eats away at the anode. Most of the useful energy in a lithium battery is available around 13.3V anyway, so going to 14.2V doesn’t offer much more run time, but will age it faster as I mentioned above.
Great article and discussion. Thanks Mike. I recently upgraded from (2) AGM 12v batteries to (3) Lithium. Did as much homework as possible on the requirements for charging as well as that heavy amp requirement to start the house generator (3000watt Onan). According to one source: BattleBorn, the charger setting for AGM batteries is appropriate for Lithium batteries as well. Hopefully this was not misinformation.
Be careful of your alternator charging system. I installed a Victron DC to DC charger in my coach along with a upgrade to my WFCO converter. That way I can charge my lithium batteries while running the engine. I only have 2 100amp lithium’s with 200watts solar and a 30amp DC TO DC charger and 3000 pure sine inverter..and have never gone below 60% just for ha ha I ran my 15000 btu ac for 2 hours on the batteries and was down to 22%….try that with two 100 amp lead cells..
PS I have a class c sprinter might be different charging with a gas Ford or Chevy chassis..
Mike, One other factor I’m confused on is when connected to my tow vehicle how does it charge? I’ve seen devices that seem expensive and require additional wiring in the truck.
I’ve written about this several times already. The standard 7-pin connector between your tow vehicle and RV will probably only pass 4 or 5 amperes of current at 12 volts DC. That’s not enough to even keep a residential refrigerator running which probably needs 5 amps at 120 volts AC (that’s 50 amps at 12 volts DC). Whats required is some sort of DC to DC charger and a separate charging connector (and wire) between the TV and RV. Yes, they cost some money, but it’s generally a bad idea to try to mix battery chemistries, such as the Lead-Acid battery in your truck and Lithium-Iron batteries in your RV.
There are other ways to charge the Lith batteries.
The engine alternator will charge them while driving down the road.
And solar is the other common way of charging Lithiums.
Please discuss these methods as part of the plug & play scenario
Be aware that one of my readers with a Sprinter Class-B RV directly connected a pair of Lithium batteries to the alternator, and managed to burn it out. Sprinter alternators are very expensive. I always suggest that you use some sort of charge controller between your chassis battery and house batteries.
You use the word “converter/charger” interchangeably and it confuses me, a Class A DP owner. I’m charging when I’m going down the road from the engine or when I’m plugged in to shore. What “converter/charger” piece of hardware hardware am I looking for? Is the a switch to flip? A box? Maybe I’ll ask my user’s group. Good article Mike.
Ken, most converters for RV’s (the thing that converts 120 volts AC from shore or generator power into 12 volts DC for your RV lighting and control circuits) also charges your house batteries with a separate circuit. Since they’re integrated together, you need to figure the entire story of what you’ve got. Same goes for many inverters that also include battery chargers. Of course, you can have a separate converter, charger and inverter, but I don’t know of any manufacturer that builds them that way. Too easy for them to install an inverter that also includes a transfer switch and battery charger. The point of the article is to figure out what you’ve got, then decide what you’re willing to live with.
Many of the older inverter chargers, like my Xantrex SW3000 don’t have a preset lithium charging option, but they do have a custom setting option, where you can set up the proper parameters to fully charge lithium batteries. I talked to Xantrex c/s & they said they have worked with many of the lithium manufacturers regarding their particular charging parameters & the older Xantrex chargers can be set up to work perfectly with most lithium batteries. So, for many rvers, with a good quality, older inverter/charger, they won’t have to upgrade them to accept lithium batteries. Check with your charger manufacturer to get the right information. Also, another commenter was concerned about cold weather. Many of the lithium mfgs are now building heat blankets into the casings or wrapping the batteries in a heat blanket that automatically warms the battery in cold temps.
Good info, Fred…
I consider lithium ion to be plug and play for exactly the reasons you say it’s not. Fully charging or discharging any lithium type (li-ion, li-poly, LiFePo4) will damage the battery. Generally, by the time you do 500 full charging cycles, you have lost 20% of the battery’s capacity. And fast charging batteries also has a detrimental effect – look at both cell phones and Tesla. If a Tesla vehicle owner uses a SuperCharger enough times, their vehicle will lock them out of the network to prevent further damage fast charging damage.
TL;DR – if you do “plug and play” a lithium battery, you won’t get the full capacity or super charging speeds, but that means your really expensive batteries will have longer lifespans.
I’m discussing this with several Lithium battery manufacturers and will publish a detailed article later…
It’s my understanding that lithium batteries and cold do not mix. Slow charging, lower power output, etc. If this is true, that takes points away in my book. We do winter camping. So far, my Trojan six volters have served us well. I was thinking about taking the plunge until I read of this downside.
Yes, most people don’t need lithium in their campers unless they have a huge power usage. They are a very expensive solution to a non existent problem for the vast majority of those who think they can’t live without them. Personally I love 6v flooded golf carts!
I agree, after a lot of research, that is what I landed on. I use 2-6V AGM batteries and have never run out of power (yet) when dry camping. 440Ah with 2- 170 watt solar panels on the roof and an extra 120 watt portable panel when in shade or overcast day as a booster.
How are getting 440Ah with only 2 6v batteries?
Sink, are you sure about the 440 amp-hr number. If you wire a pair of 6 volt batteries in series that are 220 amp-hrs each, it only makes 220 amp-hrs of capacity at 12 volts.
Lead acid batteries also don’t play well together according to a study by Battle Born. https://vimeo.com/465831129 If that link doesn’t work web search battle born battery videos. Marketing? Of course, but that doesn’t make the information false. When lithium ion batteries get too cold they self protect and turn off until warmed back to operating temp, no harm done. When lead acid get too cold they continue to discharge and then can freeze which permanently ruins the battery. To each their own. I get along well with my two 100 ah battle born batteries in temperatures into the mid teens Fahrenheit. The batteries tolerate the cold better than I do.