Battery

Ver

RV's

1/18/22

Battery

List

The 12volt Side of Life (Part 1)

Notes

https://www.marxrv.com/12volt/12volt.htm

Black Water

Temp

Batttery

State of Charge

Products

Battery

100%

12.6

12.5

12.4

12.3

12.2

12.1

90%

12.5

12.4

12.3

12.2

12.1

80%

12.42

12.32

12.2

12.1

11.9

70%

12.32

12.22

12.1

11.9

11.8

60%

12.2

12.1

11.9

11.8

11.7

6V, #2

50%

12.06

11.96

11.9

11.8

11.7

11.6

40%

11.9

11.8

11.7

11.6

11.5

11.4

30%

11.75

11.65

11.6

11.5

11.4

11.3

20%

11.58

11.48

11.4

11.3

11.2

11.1

10%

11.31

11.21

11.1

10.9

10.8

10.5

10.4

10.3

10.2

10.1

6V, #1

Notes:

You should recharge a deep cycle battery as soon as possible after each use.

It is very hard on a deep cycle battery to sit for extended periods in a partially charged state.

A battery "cycle" is one complete discharge and recharge cycle.

It is usually considered to be discharging from 100% to some point not lower than 20%, and then charging back up to 100%.

Battery life is directly related to how deep the battery is cycled each time.

If a battery is discharged to only 50% each cycle, it will last about twice as long as if it is cycled to 20%.

Running the battery down totally flat will have a very negative effect on the lifespan of the battery.

12 V

Dimensions in inches

Weight

Capacity

Battery Type

( L x W x H )

in lbs

Amp hours

Voltage

Group 24

10.87 X 6.58 X 9.97

70-85

A lot of RVers have switched from the "standard" group 24 or 27 12 volt batteries to the larger 6 volt golf cart batteries.

Group 27

12.60 X 6.60 X 9.97

85-105

If you have room for at least 2 of them, they are a good choice.

Group 31

12.94 X 6.74 X 9.88

95-125

They are true deep cycle batteries and will last a lot longer than most common 12 volt batteries in your RV.

4-D

20.73 X 8.66 X 10.27

130

180-215

They are physically larger, so you must measure carefully before buying them, but I recommend you use them if you can.

8-D

20.62 X 10.95 X 10.17

158

225-255

I have a set of Trojan Golf cart batteries that are going on 5 years old and they still have almost all of their original capacity.

10.37 X 7.13 X 11.57

180 to 220

They are priced about the same as (or a bit lower than) the common 12 volt deep cycle battery.

L-16

11.69 X 7.13 X 16.69

114

340 to 380

Golf cart & T-105

Open Circuit

Approximate

Average Cell

Battery Voltage

State-of-charge

Specific Gravity

Check both the specific gravity in each cell with a external hydrometer AND the battery terminal voltage with a digital voltmeter without the engine or converter/charger running.

12.70 / 6.35

100%

1.265+

If the state-of-charge is BELOW 75% using either the specific gravity or voltage test then the battery needs to be recharged BEFORE proceeding.

12.45 / 6.23

75%

1.225

Replace the battery, if one or more of the following conditions occur:

12.24 / 6.12

50%

1.19

12.06 / 6.03

25%

1.155

If there is a .050 or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell(s),

11.89 / 5.95

1.12

If the battery will not recharge to a 75% or more state-of-charge level.

If digital voltmeter connected to the

[A shorted cell is caused by plates touching, sediment build-up or "treeing" between plates.

or if the digital voltmeter indicates 10.45 to 10.65 volts (5.2 to 5.35 volts for a 6 volt battery), you have a shorted cell.

The 12volt Side of Life Part 2

https://www.marxrv.com/12volt/12volta.htm

Notes:

https://www.forestriverforums.com/forums/f16/is-the-battery-disconnect-on-a-georgetown-supposed-to-close-when-on-shore-power-244571.html

Generally the house battery disconnect/connect system is always a manual operation.

The Battery Control Center or whatever equivalent you have may not do something until 13.2 volts but that's different.

The battery disconnect relay is a latching relay and must be actuated to on and also actuated to off (not automatic).

Yes both batteries (coach/chassis) should charge while on shore/genny power if the relay is closed to on.

Conversely, the coach batteries should charge via the engine alternator with engine running (the coach battery disconnect switch can be off and the alternator charging will still take

I think this last statement is true.

If your battery disconnect switch looks like this the illuminated bar will illuminate no matter the batteries disconnected or not when shore power or genny power is on the coach.

Actuating the top half will assure the batteries are connected for charging.

It is not an automatic thing.

If sure the batteries are connected before applying shore/genny power no need to actuate switch.