Battery review: MRP 4S 1000 mAh 65-130 C
MRP (Multirotorparts) has it’s own battery line-up. All 4S, all purely dedicated to mini quad racers in the world. The 1000 mAh version is the second smallest pack of the family. This review will have a closer look at the MRP 4S 1000 mAh 65-130 C battery.
The MRP lipo packs don’t feature any special design. The pack is protected by some 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 yellow sticker with the usual warning messages. Overall build quality is solid. No need to complain. Everything looks very well made and feels firm.
The MRP 4S 1000 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.
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. Perfectly fine for this capacity class. 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. 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||2.2||2.5||2.3||2.5||9.5|
|After second charge||2.5||2.4||1.5||2.5||8.9|
|After third charge||2.5||2.5||1.9||2.5||9.4|
|After fourth charge||3.0||2.9||2.1||3.1||11.1|
CV-Phase is really short on this cell type. Balancing in normal mode took 1:10 min. Cell drift during charge was unobtrusive. This is for 1C charge (1 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 660 mAh. This is 66 % of nominal capacity. That’s just okay.
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|
Just looking at average values the MRP pack generally performs decent. All cells stayed above 3.70 V on average. An average value above 3.70 V / cell can be considered very good in this capacity class. It becomes visible that cell number four can not keep up with the performance of the other three cells.
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||3.501||3.525||3.511||3.530||14.066|
|End of 35 C||3.498||3.519||3.504||3.502||14.022|
|End of 20 C||3.446||3.518||3.453||3.287||14.049|
|End of 30 C||N/A||N/A||N/A||N/A||N/A|
The average cell voltage stability on the MRP pack can be considered okay. Cells dropped below 3.5 V quiet a few times during the first three current pulses. Again cell number four is clearly weaker than the rest. You get the impression that 50 C continuous already might be a little too much for this battery.
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]||0.0428||0.040||0.0404||0.036||0.159|
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 4.4 mΩ average per cell indicates a „true“ C-rating of around 37 C (36.9 A). An average value. This calculation is on the conservative side and represents a current draw that will make the pack last for a long time. The pack never made it to the last current phase in the constant current pattern, though. That’s the result of one cell not being able to keep up with the rest.
Cell drift under load
|Discharge Phase||50 C||35 C||20 C||30 C|
|Max Cell drift (V)||0.059||0.055||0.095||N/A|
The MRP prototype has a low cell drift during main discharge phase. To the very end of the cycle cells drifts a little stronger. Performance wise that’s not a problem as it happens within the last seconds before cut-off. With cell #4 being closer to the rest, we would see really good results right here.
All temperature probes reported values below cut-off point at 58°C. Max. temp during discharge was around 55.0 °C on top of pack. Note that heating of stressed LiPo packs will continue for some more time even when load is cut.
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, very quick. The battery provided 656 mAh (65,6 %) during the 25 C discharge. Again cell number four gave up first.
Comparison of different reviewed <=1000 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 640 mAh. This is 64 % of nominal capacity. Average at most. In patter 2 testing 636 mAh (63.6 %) could be used until first cell reached cut-off voltage. That’s below average. High current spikes aren’t exactly friends with the 1000 mAh version of the 4S MRP battery.
The following charts give an overview of all tested packs in the <=1000 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 1000 mAh 65-130 C battery is a usual sized pack with an ordinary capacity to weight ratio of 8.26 mAh/g. The pack has compact measurement and therefor will fit perfectly on anything in the 150 to 180 mm frame segment. There is no need to complain about outer appearance or build quality. This battery fells high quality. The IR measurements show a „true C-rating“ of around 37 C. Looking at the average performance of the battery during the various tests a 45 C sticker would have been more appropriate. Voltage will sag quite substantially when higher current spikes occur. Keep constant loads below 35 C and you will be golden. This will be enough for a lot of applications. 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 development stayed within the safe zone over the whole discharge process. The pricing of around 25 € is a little too far away from the 850 mAh version (~16.50 €) which almost plays in the same performance class.
Other packs of this line up reviewed:
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