# UPG UB121000 Deep Cycle AGM Battery

Universal Power Group UB121000 Deep Cycle AGM Battery is very popular BCI Group Size 27 marine battery. It is suitable for deep discharge applications, like trolling motor battery, RV battery, UPS batteries, and similar. It can be mounted in any position, it is spill-proof, and available at affordable price.

Universal Power Group UB121000 Deep Cycle AGM Battery is valve regulated, Absorbant Glass Mat (AGM) battery.

It can be used as standby battery or as battery for cyclic use. It can be used as starting battery for really small internal combustion engines, but if you do need deep cycle marine battery like UPG UB121000 and you need starting battery, perhaps you should consider dual battery system - or start your motor with lithium jump starter.

UPG UB121000 battery is optimized for deep discharge applications, and it should be used as such - nonetheless, avoid discharging it below 20% of its capacity.

Nominal voltage of the battery is 12 V. If it is used as standby battery, its maximum charging voltage should be limited to around 13.6 - 13.8 V and charging current to 15 Amps. For cyclic use, maximum charging voltage can be slightly larger - around 14.6 - 14.8 V and maximum initial current can be up to 30 Amps.

UPG UB121000 battery weighs ~63.9 lbs (~29 kg) and its physical dimensions are: length 12.2 inches (31 cm), width 6.6 inches (16.8 cm), height 8.3 inches (21.1 cm) and total height 9.2 inches (23.4 cm), with small tolerances, of course.

Nominal capacity of the battery is 100 Ah, however, that capacity depends on many factors, like discharging time/current, temperature, battery condition and similar. Capacity dependency is given in the following table:

## UB121000 Capacity - Discharge Current Dependency - at 77°F (25°C) |
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20h (5 A) | 10h (9.3 A) | 5h (17 A) | 1h (60 A) |

100 Ah | 93 Ah | 95 Ah | 60 Ah |

## UB121000 Capacity - Temperature Dependency - at 77°F (25°C) / 20h rate |
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104°F (40°C) | 77°F (25°C) | 32°F (0°C) | 5°F (-15°C) |

102 Ah | 100 Ah | 85 Ah | 65 Ah |

As expected, capacity of UB121000 battery is decreased with the higher discharge currents and with the lower battery temperature - optimal temperature for the battery is around 68°F to 77°F (20°C to 25°C), away from the sun, in well ventilated room, compartment or power center/battery box.

Note that recommended charging temperature range is between 32°F and 104°F (0°C - 40°C), recommended discharge temperature range is between 5°F and 113°F (-15°C to 45°C) and recommended storage temperature range is between 5°F and 104°F (-15°C and 40°C).

## UPS UB121000 Self-Discharge Rates

Self-discharge rate of UB121000 is acceptable - when stored at 68°F (20°C), fully charged battery will keep after 3 months ~91% of nominal charge, ~83% after 6 months and ~64% after 12 months (1 full year!).

Battery shelf life depends on the storage temperature:

- if the storage temperature is 41°F (5°F), battery will keep ~80% of nominal charge after being stored for 18 months,

- if the storage temperature is 86°F (50°C), battery will keep ~80% of nominal charge after being stored for 3 months,

- if the storage temperature is 104°F (40°C), battery sill keep ~80% of nominal charge after being stored for ~3 weeks.

To preserve the battery, keep it cool, but not freezing cold :)

Nonetheless, it is good practice to recharge the battery every month with some intelligent AGM battery charger.

## UPS UB121000 Cycle Life vs. Depth of Discharge

Although deep cycle batteries are optimized for cyclic use, depth of discharge has adverse effect on number of expected charging-recharging cycles. For example:

- when battery is being fully discharged at 77°F (25°C), first ~150 cycles battery will operate almost without the loss of capacity. However, after that, capacity will drop to 50% of nominal capacity after total of ~250 cycles.

- when battery is being discharged down to 50% of nominal capacity at 77°F (25°C), first 350-400 cycles battery will operate almost without the loss of capacity. After that, capacity will drop down to 50% of nominal capacity after total of 500-550 cycles.

- when battery is being discharged down to 70% of nominal capacity at 77°F (25°C), first 1000-1100 cycles battery will operate almost without the loss of capacity. After that, capacity will drop down to 50% of nominal capacity after total of 1200-1250 cycles.

For short, if you use battery every day and you don't discharge it below 50% of nominal capacity, it will last for about a year, without noticeable loss of capacity. And yes, these batteries come with 1-Year warranty :)

## UPG UB121000 Discharge Characteristics

To find out how much 'juice' a battery has, one must check battery discharge tables:

## UPG UB121000 Constant Current (Amps) Discharge Characteristics @ 77°F (25°C) |
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Final Voltage (V) | 5 min | 10 min | 15 min | 30 min | 1 hr | 2 hr | 3 hr | 4 hr | 5 hr | 8 hr | 10 hr | 20 hr |

9.60 V | 351.5 | 256.5 | 180.5 | 109.3 | 57.0 | 33.3 | 24.4 | 19.0 | 15.7 | 11.0 | 10.0 | 5.4 |

10.20 V | 309.7 | 233.7 | 161.5 | 103.6 | 53.6 | 31.7 | 23.8 | 18.5 | 15.4 | 10.8 | 9.7 | 5.3 |

10.50 V | 298.3 | 222.3 | 152.0 | 100.7 | 52.3 | 31.0 | 23.2 | 18.2 | 15.2 | 10.7 | 9.5 | 5.2 |

10.80 V | 286.9 | 210.9 | 142.5 | 97.9 | 50.4 | 30.2 | 22.6 | 18.0 | 14.8 | 10.5 | ~9.3 | 5.1 |

11.10 V | 275.5 | 199.5 | 133.0 | 95.0 | 48.5 | 29.5 | 21.9 | 17.4 | 14.4 | 10.2 | 9.0 | 4.9 |

**Note:** we have really tried to verify all the data in this table (and this article, after all), however, errors are always possible. Also, value for 10 hr current down to 10.80 V is given as approximation, since we are 100% sure that official data given by UPG is - wrong. As said before, errors do happen to everyone ...

## UPG UB121000 Constant Power (Watts) Discharge Characteristics @ 77°F (25°C) |
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Final Voltage (V) | 5 min | 10 min | 15 min | 30 min | 1 hr | 2 hr | 3 hr | 4 hr | 5 hr | 8 hr | 10 hr | 20 hr |

9.60 V | 3732.6 | 2818.7 | 1917.1 | 1160.0 | 660.3 | 384.8 | 283.1 | 220.4 | 181.5 | 128.3 | 115.9 | 62.4 |

10.20 V | 3438.1 | 2594.5 | 1792.7 | 1149.5 | 620.4 | 367.7 | 275.5 | 214.7 | ~178 | 125.4 | 113.1 | 60.8 |

10.50 V | 3383.0 | 2521.3 | 1723.3 | 1141.9 | 600.4 | 359.1 | 268.9 | 210.9 | 175.8 | 124.5 | 111.2 | 60.0 |

10.80 V | 3339.3 | 2454.8 | 1658.7 | 1139.1 | 584.3 | 351.5 | 263.2 | 207.1 | 172.9 | 121.6 | 110.2 | 59.8 |

11.10 V | 3278.5 | 2374.1 | 1582.7 | 1130.5 | 576.7 | 350.6 | 260.3 | 206.2 | 172.0 | 120.7 | 107.4 | 58.0 |

**Note:** value for 5 hr power down to 10.20 V is given as approximation, since we are 100% sure that official data given by UPG is again, wrong. Don't think that these two errors devaluate these batteries - they are NOT. In fact, personally I respect manufacturers that give detailed data like this about their products even more, than manufacturers that simply say 'our batteries are good for 500 cycles' and that is it :)

So, if you want to know what your battery is really capable to do, chose battery like this one.

**How to read these to tables?** Simply, charge your battery to 100% of its capacity and than:

- if you are going to discharge your battery down to, for example, 10.50 V for 2 hr, your battery will provide 31 Amps of current constantly. Battery voltage will change over time and hence the power of the battery, but the minimum power of the battery will be at the moment when battery reaches 10.50 volts:

**P _{min} = I * U = 31 A * 10.50 V = 325.5 W**

During these 2 hours, battery will provide 62 Ah of current - battery is NOT discharged down to 38% (100 Ah - 62 Ah = 38 Ah, which is 38% of 100 Ah battery), unfortunately, it is discharged much more, because of the capacity loss due to high discharge current. Nominal capacity of UB121000 battery when being discharged for 2 hours is ~ 70 Ah, which means that the battery is discharged down to ~11%:

**(70 Ah - 62 Ah)/70 Ah = 0.114 = ~11%**

Regular discharging down to 11% will significantly reduce the operating life of every AGM battery, not just UPG UB121000 battery.

Recommended final voltage depends on the discharge current and for low currents (below 0.25C, in this case 25A), it is around 2V per cell (12 V for 6 cell battery), and for 1C or larger (100 Amps or more) currents, it is around 1.9V per cell (11.4 V for 6 cell battery). Many people argue that battery under such load is underutilized, and up to the point, that is true. UB121000 battery does come with 1 year warranty and using it down to 20% every single day, one can expect the battery to last almost a full year without significant capacity loss.

- if you are going to discharge your battery down to, for example, 10.50 V for 2 hr, your battery will provide ~360 W of power constantly (constant power discharge). Many electric trolling motors require ~350-360 W to provide ~35-36 pounds of thrust. Since such motors are rarely used all the time at the same power level, decreasing its power levels can significantly prolong battery operating time.

Note that UB121000 battery can provide 351.5 Amps of current for 5 minutes down to 9.60 volts. If you have small internal combustion motor onboard and want to use this battery as starting battery for it, if cranking amps are less than 350 Amps, this battery can provide it easily. Personally, battery can provide even more current in short 3-5s bursts, but that is not what this battery is designed for - this is excellent, cost effective battery for electric trolling motors, solar, wind and power generator systems, RVs, electric scooters, wheelchairs etc.

## UPG UB121000 vs Exide XMC-31 vs Optima D31M BlueTop vs VMAXTANKS MR127-100

Characteristics of the UPG UB121000, Exide XMC-31 abd Optima D31M BlueTop are given in the following table:

Battery | Exide XMC-31 | UPG UB121000 |
Optima D31M BlueTop | VMAXTANKS MR127-100 |

Photo | ||||

BCI Group Size | 31 | 27 | 31 | 27 |

Battery Type | AGM | AGM | AGM | AGM |

Dimensions | 13 x 6.6 x 9.4 inches | 12.2 x 6.6 x 8.3 inches | 12.81 x 6.56 x 9.38 inches | 12.1 x 6.7 x 8.2 inches |

Weight | 71 lbs | 63.9 lbs | 59.8 lbs | 68 lbs |

Capacity (20h) | 100 Ah | 100 Ah | 75 Ah | 100 Ah |

CCA | 925 A | - | 900 A | 640 A |

CA | 1110 A | - | 1125 A | 800 A |

RC | 200 min | ~195-200 min | 155 min | 200 min |

Price on Amazon | Check Price | Check Price | Check Price | Check Price |

**Note:** Amazon links in the table are affiliate links, links open in the new windows.

As one can see, we are comparing two BCI Group Size 31, dual purpose batteries and two BCI Group Size 27, deep cycle batteries.

Main reason is - weight. Don't know about you, but if I am going to carry around SLA battey, I want it to be as light as possible.

**Optima D31M BlueTop** is the lightest of them all and it has very similar cranking characteristics to Exide XMC-31 battery, which is the heaviest of them four. Optima D31M BlueTop is more optimized for high power discharges than other three batteries, hence it has the lowest 20h capacity and lowest Reserve Capacity (RC) value of 155 minutes.

**Exide XMC-31** is the heaviest of them all, but it is also excellent dual purpose battery - it has cranking current values very similar to Optima D31M battery and RC value very similar to deep cycle batteries UB121000 and VMAXTANKS MR127-100. IMHO, one of the best balanced batteries.

**VMAXTANKS MR127-100** is very good deep cycle battery, with possible use as cranking battery for smaller engines. It is lighter than Exide XMC-31, has significantly lower CCA and CA values, but RC values and 20h capacities are the same - 200 minutes and 100 Ah, respectively. Price difference is also very small, with VMAXTANKS MR127-100 generally being slightly cheaper. But price also depends if the batteries are found on sale or not.

As starting battery, **UPG UB121000** is almost useless :) However, it is lightest of all three 100 Ah batteries in the table and have almost the same RC value of 195-200 minutes (we couldn't find exact RC value for UB121000 battery, so we extrapolated the value from the Discharge Time - Cell Voltage graph). It is very good deep cycle battery, comparable with similar batteries found on the market. And when compared with the batteries in the table, it is the cheapest of them all (price of other three batteries is very similar - again, try to find them on sale).

For short - UPG UB121000 is affordable, very good, deep cycle battery.

For more reviews and recommendations, check UPG UB121000 12v 100AH Deep Cycle AGM Battery Amazon link (link opens in the new window).