LiFePO4 batteries are becoming more and more common for use in powering astronomy equipment either in the field at a dark site where no power is available or in a remote observatory with only solar power. There are many very good LiFePO4 batteries on the market and I have reviewed two of them on this Blog page previously: Battleborn's 100Ah and Bioenno Power's 50Ah batteries. While both of these are very good options, they are on the expensive side, costing ~$8.7 and ~$10.8 per Ah, respectively. So I
searched for another option with a much better price point and found Ampere Time's 100Ah LiFePO4 battery which sells for ~$4 to $4.7 per Ah. Ampere Time also makes 200Ah, 300Ah batteries for even less per Ah and a smaller 50Ah for ~$5.8 per Ah. With a cost of half the other two batteries and many excellent on line reviews the Ampere Time battery caught my attention. So I contacted them and they agreed to send one of their 100Ah batteries to me to test.
The Ampere Time 100Ah battery weighs only 22.25lbs which is nearly 1/3 the total weight of a 100Ah lead acid battery making it much easier to carry back and forth out into the field or even just the back yard, especially with the included strap. The 100Ah battery is 13" long x 6.82" deep x 8.48" tall which is similar in size to any other 100Ah battery. The battery is expected to have a 10 year life and provide 4000 or more full discharge cycles. It also comes with a 5 year warranty and Ampere Time claims they will respond to questions and service requests within 24hrs although I have not verified this myself. The battery includes the best documentation for operation and care of any of the three batteries I have tested.
Since this is a Li battery it comes with a Battery Management System (BMS) which is internal to the battery case itself. The BMS works in the background to monitor the individual lithium cells and make sure that the battery is operated in a safe mode at all times. It provides protection from short circuits, over current, over charging and over discharging. The later means that one can safely fully discharge the battery at which point the BMS will shut down the output. While considered "fully discharged" there is still sufficient voltage on the internal cells to avoid damage and maintain the projected useable life of 4000 or more such full discharges. Operating temperatures are -4 deg F to 140 deg F (-20C to 60C ) for discharging and 32 deg F to 122 deg F (0C to 50C) for charging, which is typical of most LiFePO4 batteries on the market. It should be noted that unlike the other LiFePO4 batteries I reviewed, this Ampere Time battery does not have a low temperature sensor to automatically prevent charging or discharging below the lower temperature limit. This means that the BMS cannot protect the internal cells from damage if one attempts to charge the battery below 32 deg F or discharge it below -4 deg F. However, for astronomy applications I think it is very doubtful that we would be in a situation where we would attempt to recharge the battery when the temperature is below 32 deg F and most do not work in temperatures below -4 deg either. While an unlikely scenario, if one has the need to recharge below freezing Ampere Time makes a battery with an internal self heater that allows charging down to -4deg F.
Inside the Battery
Besides the low cost of this battery the other reason I decided to review it was the tear down video on Ampere Time's 50Ah battery by Will Prowse which shows the internal components (Li cells, BMS, Wire Gauge, etc.) and build quality to be quite good. I recommend anyone interested in an Ampere Time battery to take a look at that video. The tear down also shows that Ampere Time uses prismatic cells instead of the cylindrical cells used by Battleborn and Bioenno Power. Because prismatic cells are larger and have greater capacity than cylindrical cells only 4 cells are needed to achieve the 100Ah capacity compared to the 120 cylindrical cells found in the 100Ah Battleborn battery. The four prismatic cells are arranged in series with each cell having a nominal voltage of 3.2V and a capacity of 100Ah. In this configuration a nominal voltage of 12.8V is obtained. While less cells has its obvious advantages, damage to a single cell will result in a drop in the voltage making the battery no longer useable. In contrast, damage to a few cylindrical cells in the Battleborn battery may hardly be noticed by the user.
Capacity and Discharge Voltage Tests
The first test of any battery that I review is a full discharge capacity test. Since these types of batteries are shipped with less than a full charge the battery must first be charged to full capacity. I used a 10A AC charger from Bioenno Power designed for lithium batteries to fully charge the battery. Next, I used a battery capacity tester from MakerHawk to measure the actual full discharge capacity of the battery to compare to its manufacturer's spec. I used a discharge current of 5A which is equivalent to ~65W since most typical astronomy setups will use less than this and the ones which use more will not be much more. Once fully discharged I repeated the process to check for consistency. The results were 102.8Ah for the first discharge and 103.1Ah for the second discharge. These are equivalent to 1307Wh and 1314Wh, respectively. So the results from both tests are consistent and show that the battery exceeds its specification of 100Ah by ~3%.
Now, while the full capacity is important, the voltage drop off versus capacity is even more important since some equipment will not work properly if the voltage drops too much below 12V. So I captured the voltage versus capacity data during the discharge tests and this data is shown in the graph above. The average of both tests showed that the battery maintained its voltage above 12.0V for 98.5Ah or 1262Wh which is excellent compared to other batteries I tested or am aware of. By comparison the voltage of a typical lead acid battery drops below 12.0V at ~44% SOC. This means that you will get twice the capacity of a typical lead acid battery with this Ampere Time battery without risking damage to the battery.
There are multiple ways to recharge a battery and I tested the two most common. First, using the above mentioned 10A AC charger I was able to fully recharge a depleted battery in 10.5 hours. This matches very well the measured capacity of 103Ah and the fact that the charger is supplying 10A. Now there are higher capacity AC chargers like the 20A charger from Ampere Time or the much cheaper 20A charger from Expert Power which will charge the battery in half that time if desired.
Out in the field we usually do not have access to AC power so we cannot use the AC charger to recharge the battery. In that case, the battery can easily be recharged with one or more solar panels and a solar charge controller. I used a pair of 100W solar panels from Jackery connected to the battery through a 20A solar charge controller from Bioenno Power. It is important to make sure that the solar charge controller is programed for a Li battery with the correct charge profile and voltages. With this setup, I was able to fully recharge the fully discharged battery in less than 11 hours on a sunny day. The two 100W panels supplied 11A during the bulk of that time while the sun was high in the sky. The charging current obviously falls off quickly as the sun gets lower in the sky. Now, one will not always have 11 hours of sunlight available but the battery reached 84% of full charge in just 8 hours. Also, It is likely not necessary to fully recharge a 100Ah battery during the day since typical astronomy power draws are 60W or less which would only use half the battery capacity over a 10 hour long night. So using a strategy of topping off the battery during the day one could run indefinitely so long as the days are sunny.
Typical Astronomy Use Tests
Before taking the battery out to a dark site I first set it up to power my astrophotography/EAA setup at my home observatory over a period of a month. My home setup includes a Celestron 11" Edge SCT, a Software Bisque MX mount, an ASI1600MC uncooled imaging camera, an ASI224MC guide camera, a Celestron Motorized focuser, a Pegasus Pocket PowerBox Advanced Power/USB Hub, a Beelink Mini-PC, a GL-iNET GL-AR750S-EXT wireless router and a Dell 15.4" laptop. Power was supplied directly to the Pegasus which then powered the MX and the Beelink. The cameras and focuser drew power from the MX while the router drew power from the Beelink. I connect from the laptop to the mini-pc through the wireless router from inside my house where I was able to power the laptop separately with house AC.
Since the Ampere Time battery does not come with cables I needed to make my own to connect from the battery terminals to the Pegasus. I made a pair of 12 gauge cables with lug nuts on one end to connect to the battery and Anderson Power Pole connectors on the other end. Since the Pegasus uses the standard 5.5mm x 2.1mm connectors I made a cable with 5.5mm x 2.1mm connectors on one end to Anderson Power Pole connectors on the other end to connect the battery to the Pegasus. I prefer the Anderson Power Pole connectors wherever I can use them as they make a solid connection which is not easily dislodged in the dark. I prefer the genuine Anderson Power Poles compared the slightly less expensive imitations made in China. If you make your own you will need a crimping tool and the proper gauge wire for your current. This silicone wire will remain flexible in cold weather. If you do not want to make your own cables you can always buy one like this.
Running in my home observatory I encountered no issues with the Ampere Time battery. All told, the load on the Ampere Time battery was ~30W so I was able to run many nights before I needed to recharge the battery.
The final test was a field test at a dark site over multiple nights of astrophotography. For this setup I had all of the equipment mentioned above ( Celestron 11" Edge, ASI1600MC uncooled camera, Celestron motorized focuser, Pegasus Power Box Advanced, Beelink Mini-PC, GL-iNET GL-AR750S-EXT wireless router) but this time mounted on my travel mount, a Software Bisque MyT mount. Also, because I was using Hyperstar no guide camera was needed. But, because of significant dew I has to turn on the dew heater. In this configuration the power load was 52 watts over each of 3 nights. I did not recharge during the day and used a total of 60Ah (784Wh) in 15 hours over the 3 nights leaving me with 40Ah capacity remaining in the battery. That means that I could have run for another 10 hours for a total of 25 hours at my consumption rate before needing to recharge the battery.
Now everyone has a different setup and a different power consumption. For instance, a cooled camera can add another 10 to 20W of power required depending upon the depth of cooling bringing the total power needed to 62W to 72W. That would still have allowed over 17 hours of run time before a recharge would be necessary. Also, if using a laptop directly connected to the setup instead of a mini-pc the power load could be as high as 100W. Even then, the Ampere Time 100Ah battery could supply all the power needed for a full 10 hours which would likely necessitate recharging during the day to enable multiple nights in the field. Regardless of your power requirements, the Ampere Time battery seems to be up to the challenge.
Overall I found that the Ampere Time 100Ah battery delivered the full capacity promised, is very light weight especially compared to a 100Ah lead acid battery and was straight forward to use and re-charge. Obviously I cannot comment on the long term reliability of this battery or any other manufacturer's battery through the simple tests I have available and testing only one battery. But I have no reason after having used it and checking out other reviews to expect it to be problematic. After my tests I even recommended this battery to my friend to replace the AGM batteries in his RV who purchased 3 of these and already installed them and tested them out when he joined me on my field tests.
What I like about the Ampere Time 100Ah battery:
1. It is one of lowest cost LiFePO4 batteries on the market with an excellent reputation.
2. At 103Ah capacity it exceeded its 100Ah specification.
3. It comes with the best care, use and charging instructions of any battery I have tested.
4. They claim 24hr response from their technical support team.
5. It comes with a convenient carry strap.
What I do not like:
1. No US based support hot line. Support is obtained either on line or by calling their number in Hong Kong.
So, if you are looking for one of the least expensive of the LiFePO4 batteries on the market, you should seriously consider Ampere Time. I was not paid by Ampere Time for this review nor did they have any input to it but they did send the battery at my request and at no charge to me.
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