100 a/h Lithium Battery for $215

[Lou Schneider]

For some reason the price of lithium batteries is dropping sharply. A month or two ago $350 was the price floor for a basic 12 volt, 100 a/h lithium battery. Now you can get ones with cold temperature charging protection for that price.

Amazon is offering the TimeUSB battery for $215 including free shipping. This is by far the lowest price I've ever seen for a 100 a/h lithium battery.

TimeUSB has decent reviews and their only drawback is like many other low cost batteries they lack cold weather charging protection, so keep them warm (above freezing) in the winter. I don't have any affiliation with the company and this is not an Amazon Affiliate link, I just want to pass along a great deal.

https://www.amazon.com/Timeusb-LiFePO4-Lifetime-Off-grid-Applications/dp/B0BBZL5BPR

 

[DonTom]

For some reason the price of lithium batteries is dropping sharply. A month or two ago $350 was the price floor for a basic 12 volt, 100 a/h lithium battery. Now you can get ones with cold temperature charging protection for that price.

Amazon is offering the TimeUSB battery for $215 including free shipping. This is by far the lowest price I've ever seen for a 100 a/h lithium battery.

TimeUSB has decent reviews and their only drawback is like many other low cost batteries they lack cold weather charging protection, so keep them warm (above freezing) in the winter. I don't have any affiliation with the company and this is not an Amazon Affiliate link, I just want to pass along a great deal.

Amazon.com

Question about battery voltage ratings. What does that "12.8" mean? I assume it is NOT the fully charged voltage as I expect that would be higher.

-Don- Barstow, CA

 

[Gary RV_Wizard]

That does seem low for a fully charged LiFePO4 battery - seems like it should be around 13.3-13.4. Maybe even 13.8. That said, 12.8v is entirely adequate for a 12v system. Remember that a fully charge lead-acid battery is 12.6v at rest (not active charging or loads).

 

[Ex-Calif]

Question about battery voltage ratings. What does that "12.8" mean? I assume it is NOT the fully charged voltage as I expect that would be higher.

-Don- Barstow, CA

I am sure there are experts that will jump in but you raised my curiosity.
Basically the amount of voltage per cell in lithium-ion is limited by the chemistry. Depending on the chemistry if the cell voltage is higher than 4.2 the negative anode in the cell can be damaged. If the voltage is too low the positive anode can be damaged.

The second consideration is the battery dimensions. If you are unencumbered by dimensions you can have large high voltage batteries. One clue in the product description of the OPs post is some reference to "using automotive" cell sizing.

So my working theory is that particular model is intended to replace a lead/acid battery and 12.8V is the voltage they decided to run for compatibility - and I assume cost. I assume 6 X 2.2V Lion cells are cheaper than 6 X 4.2V Lion cells.

 

[DonTom]

That does seem low for a fully charged LiFePO4 battery - seems like it should be around 13.3-13.4. Maybe even 13.8. That said, 12.8v is entirely adequate for a 12v system. Remember that a fully charge lead-acid battery is 12.6v at rest (not active charging or loads).

My lith battery said something similar, but when I checked it, it was more than one volt higher when delivered.

I think most batteries are spec'ed at the minimum, not the max. For an example an everyday 1.5VDC battery normally measures around 1.65 VDC when new and at 1.5 VDC it is time to trash it.

-Don- (at the Barstow, CA Denny's)

 

[Mark_K5LXP]

Practical capacity of an alkaline primary battery open circuit voltage is between 1.1 to 1.6 volts (0 to 100%). The testing discharge limit is .9 volts under load. One can argue that some devices may not operate below some voltage threshold but that's not a battery problem. If you do a resistive discharge test of an alkaline battery, from start to .9V under load is where nearly all the energy is delivered. I'm kinda anal about batteries and will keep somewhat discharged ones around for light duty/non critical use when they're done running heavy duty stuff. When I throw a battery out, there's absolutely nothing left.

Mark B.
Albuquerque, NM

 

[Lou Schneider]

That does seem low for a fully charged LiFePO4 battery - seems like it should be around 13.3-13.4. Maybe even 13.8. That said, 12.8v is entirely adequate for a 12v system. Remember that a fully charge lead-acid battery is 12.6v at rest (not active charging or loads)

Every LiFeP04 battery I've looked at states it's nominal voltage as 12.8 volts (3.2 volts per cell). Including the Lion Safari UT-1300 that sells for 4+ times this price. The one exception is Battle Born, which doesn't give technical details on it's web site, just that their batteries are "12 volts" at specified amp-hours. I don't know why, but I've always considered LiFeP04 batteries pretty much a drop-in replacement for lead acid batteries with more consistent operating voltages over the majority of it's discharge curve.

Most of the low pruce batteries don't have cold weather temperature charging protection. Like US made lead acid batteries, there are only a few manufacturers of lithium cells in China so everyone uses the same cells and BMSs. Since the BMSs now include cold temperature protection battery makers are probably trying to get rid of their inventory without this feature.

 

[DonTom]

Every LiFeP04 battery I've looked at states it's nominal voltage as 12.8 volts (

Yes, so why are they always around a half volt higher than that when delivered?

My Ampertime 300AH "12.8 VDC battery" right now, fully charged (but not charging) measures 14.0 VDC, unloaded. That is 1.2 volts higher than the 12.8 VDC. So when is the battery at 12.8 VDC? Is that where it is considered at the edge of fully discharged or what?

IMO, the word "nominal" is meaningless in this case. It needs to be explained.

-Don- Barstow, CA

 

[Isaac-1]

Lou, I think it is dangerous to refer to LiFePo4 batteries as drop in replacements for lead acid, as that implies one can substitute them without consideration of their differences, though when it comes to voltage ranges for low amp draw appliances I will agree that LiFePo4 makes a good direct substitute for 12V lead acid in automotive settings, like one finds in an RV, as the voltage ranges seen by such devices closely overlaps the voltages seen with lead acid, if you include voltages seen during charging. This is due to the relatively higher charging voltages seen on lead acid.

 

[Isaac-1]

Don, the thing you need to take into consideration there, is that if you withdraw just 1% of the charge from that fully charged LiFePo4 battery that the voltage will drop to about 13.4VDC, as LiFePo4 state of charge is very nonlinear at the top 1-2%

 

[Tulecreeper]

Yes, so why are they always around a half volt higher than that when delivered?

My Ampertime 300AH "12.8 VDC battery" right now, fully charged (but not charging) measures 14.0 VDC, unloaded. That is 1.2 volts higher than the 12.8 VDC. So when is the battery at 12.8 VDC? Is that where it is considered at the edge of fully discharged or what?

IMO, the word "nominal" is meaningless in this case. It needs to be explained.

-Don- Barstow, CA

 

[Lou Schneider]

Yes, so why are they always around a half volt higher than that when delivered?

My Ampertime 300AH "12.8 VDC battery" right now, fully charged (but not charging) measures 14.0 VDC, unloaded. That is 1.2 volts higher than the 12.8 VDC. So when is the battery at 12.8 VDC? Is that where it is considered at the edge of fully discharged or what?

IMO, the word "nominal" is meaningless in this case. It needs to be explained.

-Don- Barstow, CA

The 3840 watt-hour rating divided by the rated 300 amp-hours gives a nominal 12.8 volts. Same for 1280 watt-hours for a 100 amp-hours battery. I don't know why they specify the voltage this way, other than it may be the average over the entire discharge cycle including the sharp peak and drop-off at the each end of the curve.

 

[Isaac-1]

Lou here is an SOC chart for LiFePo4 just for comparison

 

[Lou Schneider]

Lou here is an SOC chart for LiFePo4 just for comparison

Thanks, I've seen that before. Like I said, I don't know why the battery makers say they're a nominal 12.8 volts, but it's on every "12 volt" battery I've seen.

 

[ButchW]

Can these just be used as replacements in an older trailer, without doing any other modification? My Son needs new batteries for his older toyhauler…
Butch

 

[Lou Schneider]

Can these just be used as replacements in an older trailer, without doing any other modification? My Son needs new batteries for his older toyhauler…
Butch

Yes, but if if the converter charges at 13.5 volts you'll only get about 80% of the rated capacity. Lithium needs 14.4 volts to reach full charge. Undercharging won't harm the battery, unlike lead acid which can sulfate if it's not fully charged. Just make sure not to charge them if their internal temperature has dropped below freezing.

 

[Isaac-1]

Lou, I will partly disagree with you there, Undercharging occasionally will not harm the batteries, however in order to top balance the vast majority of LiFePo4 need to reach 14.2 - 14.4VDC from time to time. This can be done a number of ways, depending on how the RV is used / stored. One simple solution is adding a 100-200 watt solar panel setup which will often cost less than a new converter ($110 -$175 from Amazon, etc. for turn key kits with wiring and mounting brackets), if the existing converter does not supply high enough voltages to fully charge.

As to drop in replacement, make sure any LiFePo4 battery has low temperature charging protection, as charging a LiFePo4 battery in freezing conditions will kill them otherwise. Note many cheaper LiFePo4 batteries don't have this feature, though many of them advertise that they do.

 

[DonTom]

Lou here is an SOC chart for LiFePo4 just for comparison

That charge seems to indicate that the so-called "nominal voltage" is the voltage at near the end of the cycle, just before getting into the red. IOW, most of the time the battery, when in use, will probably never see the voltage that low before the next charge.

IOW, when 80& of the charge has been used and 20% is left (in the red).

That is similar to my claim with 1.5 -volt batteries, they are considered discharged at 1.49999999 volts and then should be replaced (but can still be useful for some items). With the LiFePo4, they need to be recharged by that 12.8 volts. IOW, the way they rate batteries in consistent.

-Don- Barstow, CA

 

[John From Detroit]

https://www.mobile-solarpower.com/uploads/1/2/9/6/12964626/published/msf4vpdl-1_14.jpg

The link is to a "State of charge " chart for LiFePO4 12.8 is 17%

 

[DonTom]

The link is to a "State of charge " chart for LiFePO4 12.8 is 17%

Yep, it is telling you when you should recharge. IOW, before it gets below 12.8 VDC.

IMO, it is now quite clear what "nominal voltage " means. It is the end of the useful charge (or useful life of nonchargeable) of the battery.

IIRC, EV battery voltage is rated the same way. We have to listen to what they mean, not what they say with "nominal battery voltage". But it does make sense to rate them for the voltage where the stuff can still be used. It's just that we expect max ratings, which is not the case with batteries. This also explains why 12.7 volt lead-acid battery is not called a 13-volt battery. At 12.0 VDC it is near the end of its useful charge.

-Don- Barstow, CA