Battery review: MRP 4S 1800 mAh 65-130 C
MRP (Multirotorparts) has it’s own battery line-up. All 4S, all purely dedicated to the mini quad racers of this world. The 1800 mAh version is the largest pack of the family. This review will have a closer look at the MRP 4S 1800 mAh 65-130 C battery.
The MRP lipo packs don’t feature any special design. The pack is protected by black shrink wrapping. The sides are made of some textured white material, holding the single cells together. The front side has a colored product sticker glued to it, stating name and type of the battery. On the back you find a silver sticker with the usual warning messages. Everything looks very well made and feels firm.
The MRP 4S 1800 mAh 65-130 C pack is a standard 4S1P config flight pack for high power use.
Build Quality: Very good. Pack feels very well made on the outside. Connection terminal looks solid. Shrink wrapping job is good. Cells seem to be wrapped in some foam-ish material. Might help on light impacts.
Plugs: The MRP batteries come with pre-installed XT60 connectors*. Plug and play for most of the pilots. The connectors sit very firm, good quality XT60s.
Cables: MRP uses 14 AWG wires on this packs. I rather would like to see 12 AWG on anything above 1500 mAh packs. The high flexible silicon layer is rated up to 200°C. Cable length is about 9 centimeters.
Balancing plugs: Standard XT-system*. Balance wires are rather short (3 cm) which is a benefit in terms of getting them out of the way on your quad. The balancer plug is equipped with some transparent housing for easier unplugging. The housing can be removed, if needed. Balancer and main power leads are placed on top and bottom of the pack.
The battery followed the standard break-in-process: The pack is charged at a rate of 1C until CV-phase ends with current of 1/10C. The break-in phase consists of four charging cycles at 1C and four corresponding discharges at 1 C / 4C / 10C and 20 C.
Anomalies: No anomalies during break-in.
Internal resistance measurements during break-in phase via iCharger 406B at 40°C pack temperature
|Cycle||Cell 1||Cell 2||Cell 3||Cell 4||Total|
|After first charge||1.5||1.7||1.6||1.7||6.5|
|After second charge||1.5||1.8||1.2||1.7||6.2|
|After third charge||1.5||1.7||1.1||1.5||5.8|
|After fourth charge||1.5||1.7||0.9||1.4||5.5|
CV-Phase is short on this cell type. Balancing in normal mode took 2:02 min. Cell drift during charge was unobtrusive. This is for 1C charge (1,8 A).
The main part of this battery test will consists of different load test settings showing the battery performance. Constant load testing is used to judge the advertised C-ratings as well as look at cell drift under high loads. We also check on internal resistance once more. Next up is the dynamic current test, which simulates a „real“ flight with changing (=dynamic) loads. For test methodology please check the dedicated methodology page!
Constant Load Testing
Constant load testing follows a certain load pattern of different constant currents. Base load is 10 C. Current pulses at 50 C, 35 C, 20 C and 30 C are maintained for time intervals between 10 and 20 seconds. For more details please refer to the test methodology page.
During this test the pack delivered 1303 mAh. This is 72.4 % of nominal capacity. A very good result.
Average cell voltages
The following table lists the average voltages per cell, of the total pack, as well as the averaged value per cell as fraction of total voltage during phase of active load.
|Cell 1||Cell 2||Cell 3||Cell 4||Total||Average per cell|
|Avg. Voltages||3.742 V||3.732 V||3.742 V||3.744 V||14.96 V||3.74|
Just looking at average values the MRP pack performs well. All cells stayed above 3.73 V on average. An average value above 3.70 to 3.75 V / cell can be considered very good in this class.
Exceptionally interesting when testing a battery under a constant load for a longer period of time: the lowest voltage per cell just before load impulse is disabled. On top, you should have look at voltage recovery rate, that is: how fast do cell voltages rise again once load impulse is cut.
|Phase||Cell 1||Cell 2||Cell 3||Cell 4||Total|
|End of 50 C||3.517 V||3.5 V||3.549 V||3.585 V||14.151 V|
|End of 35 C||3.519 V||3.505 V||3.531 V||3.554 V||14.108 V|
|End of 20 C||3.314 V||3.283 V||3.268 V||3.322 V||13.186 V|
|End of 30 C||–||–||–||–||–|
The average cell voltage stability on the MRP pack can be considered good. No cell fell below the benchmark threshold of 3.5 V during the first two current pulses.
Average voltage recovery per second
Those values are specific to the test setting and not valid for the pack in general! Still they allow an estimated guess about how fast voltages rise again after current spikes.
|Cell 1||Cell 2||Cell 3||Cell 4||Total|
|Avg. Recovery [V/s]||0.027||0.029||0.0248||0.021||0.103|
Excessive voltage sag isn’t a problem for this battery. Recovery rates after current pulses are decent, too.
IR measurement is conducted using the four current pulses. Resistance for each cell is calculated in all four discharge phases. Shown values are averaged to cancel out different temperature points due to different discharge states during measurements.
Interpretation: The internal resistance of 2.28 mΩ average per cell indicates a „true“ C-rating of around 38.2 C (68.8 A). A very good value. This calculation is on the conservative side and represents a current draw that will make the pack last for a long time. See load testing for further categorization. The pack had no problems delivering during high C discharge pulses.
Cell drift under load
|Discharge Phase||50 C||35 C||20 C||30 C|
|Max Cell drift (V)||0.036 V||0.049 V||0.054 V||–|
The MRP 1800 mAh has a low drift during main discharge phase. To the very end of the cycle cells drifts only little stronger.
Key Temperature Facts
All temperature probes reported values below cut-off point at 58°C. Max. temp during discharge was around 57.9 °C on top of pack. Note that heating of stressed LiPo packs will continue for some more time even when load is cut. The pack had to be cooled immediately after discharge end to prevent rise of temperature way above 60 °C.
The following chart shows all reviewed LiPos in the same product segment for direct comparison of performance. Higher values under load are better.
Constant 25 C Discharge
Pretty much a standard benchmark in the LiPo industry.
Cut-Off /warning value for this battery should be chosen 3.5 V minimum. After this point voltage drops very quick. The battery provided 1306 mAh (72.5 %) during the 25 C discharge.
Comparison of different reviewed 1800 mAh batteries under 25 C load.
Dynamic Load Testing
The dynamic load testing setting consists of two separate discharge scenarios that have been developed of two different real-life FPV flights. Pattern one represents a high speed low proximity flight around the open field with some hovering to the end. Average load is around 22 A. Second pattern is a free-style flight around trees in the park with some current spikes near 70 A. Average load on this flight is around 13 A due to longer floating periods.
During the test of pattern 1 the pack delivered 1322 mAh. This is 73.4 % of nominal capacity. A good value. In patter 2 testing 1310 mAh (72.8 %) could be used until first cell reached cut-off voltage.
The following charts give an overview of all tested packs in the 1800 mAh class so far.
The last chart of this review sums up the usable capacity during all four load scenarios. Please note that this is only the capacity consumed by the electronic load! There are losses due to heating of the pack, which could be approximated (see testing methodology page). All four tests are cut when any cell goes below cut-off voltage of 3,3 V (or pack goes above 58 °C on any of the three probes). If you would push further and go down to 3,0 V/cell you will be able to squeeze out some mAh more, but at the cost of excessive heat generation and shortening of pack life-span. This value will most likely differ from what you get when flying on a quad as most people don’t monitor voltage on a per cell basis and therefore don’t even notice if voltage drops below 3,3 V/cell during punsh-outs (what’s not necessarily a good thing, though). For comparison, used capacity until 3,3 V/cell is reached is the base line in all battery reviews on Drone-Zone.de.
The MRP 4S 1800 mAh 65-130 C battery is a usual sized pack with a decent capacity to weight ratio of 8.87 mAh/g. The outer appearance of the pack is best described as puristic. Nevertheless, MRP does a good job when it comes to build quality. The pack is very well made. XT 60 connectors are of high quality and the extra balancer plug housing improves handling. A little odd is the fact that MRP uses 14 AWG wires on the largest pack that’s potentially able to push the most amps. Smaller packs of the series are equipped with 12 AWG wires. Maybe a weight thing? I didn’t find another reasonable explanation. The advertised C-rating of 65 C continuous current is a little over the top, as for almost all of the high C-rated batteries. Regarding internal resistance measurements I would not hesitate to use the MRP 1800 mAh pack for application of constant currents up to 38 C / 68 A. That’s a good result. The pack tends to have a higher voltage level in the first half of the discharge cycle and sags a little below competitor’s performance in the second half. For smaller currents (25 C) voltage level is exceptionally high! Usable capacity is good, too. Don’t worry about the fact that the battery will become a little bigger under high loads. This is just the type of cell chemistry working. After a short cool down period the pack is back to normal again. Other manufacturers try to prevent this by the integration of two thin metal plates on each side to hold the cells together even more firmly. Average voltage stability and recovery rates are good, absolutely nothing to complain. Temperature wise the pack will get rather hot under higher loads. It did not reach 60°C, but came relatively close (~57°C) – what’s still okay. Of all the four packs of the MRP 4S 65-130 C family, this 1800 mAh version performed best. Looking at the price of about 36 € there is really nothing you could do wrong when choosing this pack for your quad!
Other packs of this line up tested:
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