Optima Batteries 8071-167 D51 and 8073-167 D51R YellowTop Dual Purpose Batteries

Optima D51 and D51R YellowTop are two very similar dual purpose, automotive batteries. The only true difference among these two batteries is the in the layout of their terminal posts: D51 has positive post to the left and D51R has its positive post to the right (hence the 'R' right after 'D51'), when looked from their front side.

Optima D51 and D51R YellowTop are recommended for vehicles with the single battery electrical systems requiring battery that features good starting characteristics, but also can support broad range of the onboard electric and electronic devices like winches, alarms, audio systems and similar.

Published: May 8, 2019.

Optima D51 and D51R YellowTop Features and Specifications

Optima D51 and D51R YellowTop belong to the BCI Group 51 and have physical dimensions of (W x L x H) 5.06 x 9.31 x 8.94 inches (~12.9 x 23.7 x 22.7 cm) and they weigh 26 pounds (~11.78 kg).

Case is made using polypropylene, leading to the reduced weight and sturdy casing.

Optima D51 and D51R YellowTop are AGM (Absorbent Glass Mat) SLA (Sealed Lead Acid) batteries that can be mounted in virtually any position and are truly spill-proof batteries.

Optima D51 and D51R YellowTop batteries are light-gray on the sides and feature yellow top - hence the 'YellowTop' label.

Their nominal voltage is 12 volts and their 20h capacity is 38 Ah - new, fully charged battery is able to provide 1.9 Amps current for 20 hours, when being discharged down to 10.5 volts at 77°F (25°C).

As typical automotive battery, Optima D51 and D51R YellowTop batteries come with SAE posts (just different orientation - keep this in mind when ordering battery for your vehicle!).

Their Reserve Capacity is 66 minutes - new, fully charged battery is able to provide 25 Amps for 66 minutes, without the voltage dropping below 10.5 volts at 77°F (25°C).

Their CCA (Cold Cranking Amps) value is 450 Amps - new, fully charged battery is able to provide 450 Amps for 30 seconds, with the voltage NOT dropping below 7.2V at 0°F (-18°C).

Their MCA (Marine Cranking Amps) or CA (Cranking Amps) value is 575 Amps - new, fully charged battery is able to provide 575 Amps for 30 seconds, with the voltage NOT dropping below 7.2V at 32°F (0°C).

Manufacturer doesn't state their HCA (Hot Cranking Amps - maximum current that a new, fully charged, 12V battery (at 77°F; 25°C) can deliver for 30 seconds, with the voltage not dropping below 7.2V.), but using their CCA and MCA, one can calculate approximate HCA value:

HCA = CCA x 1.66 = 450 Amps x 1.66 = 747 Amps

HCA = MCA x 1.33 = 575 Amps x 1.33 = 765 Amps

So, approximate HCA value of Optima D51 and D51R YellowTop batteries is ~750 Amps.

Optima D51 and D51R YellowTop batteries feature wound cell configuration utilizing Optima's proprietary SPIRALCELL technology and high purity lead grid - leading to low discharge rate and sturdy vibration resistant design.

Also, Optima D51 and D51R YellowTop tolerate 300+ charging/discharging cycles (down to 10.5 volts) and allow faster recharging.

For example, these batteries can be charged:

- alternator: 13.65 to 15.0 volts,

- battery charger (constant voltage): 13.8 to 15.0 volts (10 Amps max),

- float charge: 13.2 - 13.8 volts

- rapid recharge: 15.6 volts max. No current limit as long as the battery temperature remains below 125°F (~52°C) - charge until current drops below 1 Amp.

- cyclic applications: 14.7 volts max. No current limit as long as the battery temperature remains below 125°F (~52°C) - charge until current drops below 1 Amp, finish with 2 Amps constant current for 1 hour.

Personally, if you don't have these batteries mounted in your vehicles and charged via onboard alternator, consider getting intelligent AGM SLA battery charger - such chargers are able to test/analyze the battery and charge it according to its condition.

Recommended intelligent AGM SLA battery chargers are Optima Digital 400 and Optima Digital 1200 battery chargers and maintainers, which charge the batteries using 6, fully automatic charging modes.

Recharge times (assuming 100% discharge - 10.5 volts) to 90% of charge:

- 100 Amps charging current: ~25 minutes,

- 50 Amps charging current: ~65 minutes,

- 25 Amps charging current: 130 minutes.

Note: These are very high charging currents and they are allowed only while monitoring the battery temperature. Personally, if You plan on charging these batteries regularly with battery chargers, go for either Optima Digital 400 (4 Amps Max.) or some similar 4-6 Amps intelligent AGM battery charger.

 Optima D51 and D51R YellowTop Batteries as Trolling Motor Batteries

Although Optima D51 and D51R YellowTop batteries feature SAE terminal posts, it is not uncommon practice by many fishermen to take out the battery (this or any other battery) from their vehicle, to use it as trolling motor battery and then to mount the battery back in the vehicle and use it to start the vehicle, as if nothing happened in the mean time.

First of all, Optima D51 and D51R YellowTop batteries can be used for deep cycle applications - as trolling motor batteries, too.

However, their starting characteristics decline as they are being discharged - for how much is NOT known as manufacturers (Optima Batteries included) don't state very often such data for their batteries.

Generally, if these batteries are not discharged below 70% SoC (30% DoD), they are more or less, fine. However, when discharging them below 50% SoC (50% DoD) and especially below 20-30% SoC (70-80% DoD), their CCA/MCA/HCA Amps are lower than CCA/MCA/HCA Amps of a fully charged batteries.

So, if you like fishing using electric trolling motor in the wilderness, consider either getting dedicated trolling motor battery or at least good lithium jump starter!

Dedicated trolling motor battery (second Optima D51 is just fine if its capacity is large enough for your trolling motor) is IMHO better choice, but having fully charged lithium jump starter gives the fishermen at least a chance to start the vehicle when the main battery is discharged - and any battery can be discharged during trolling since people often lose track of time and amps!

If the battery is discharged and can't start the vehicle, jump start the vehicle and let the vehicle's alternator charge the battery (and the jump starter) while driving.

Note: don't forget - safety first. Call me paranoid, but having a good jump starter when going on the fishing/hunting/camping trip is a smart and not so expensive backup option.

Long Story Short: If you are looking for a BCI Group 51 battery for your vehicle, especially if it has various electric and electronic devices onboard, consider Optima D51 or Optima D51R YellowTop battery - just be aware of the terminal posts orientations.

Optima D51 and D51R YellowTop batteries are spill-proof, AGM dual-purpose batteries, highly resistant to vibrations, having good charging/discharging characteristics and 450/575 Amps CCA/MCA.

For more reviews and recommendations, check Optima Batteries D51 YellowTop Dual Purpose Battery and Optima Batteries D51R YellowTop Dual Purpose Battery Amazon links (links open in the new windows).