Renewable Energy Deep Cycle Batteries
*NEW* Rolls Warranty Statement
Rolls 4000 Series
Rolls 4500 Series
The Rolls 4500 series combines the convenience and portability of the 4000 series, with the extended capacity and cycle life found in the heavy duty 5000 series batteries. They provide a battery with good cycle life at a great price.
- 2720 cycles to 50% DOD
- 1785 cycles to 80% DOD
- 7 year warranty
Rolls 5000 Series
These heavy duty batteries are designed for unsurpassed repeated deep cycling service in renewable energy applications. Thick plate design with high density active material and increased liquid reserve. Several 2V cells are pre-assembled together to give higher voltage blocks. These in turn are connected to form a battery bank with appropriate voltage and capacity. Unique battery design features dual container construction. Removable cells are fitted with a durable case giving double protection against breakage or leakage. Easy on-site assembly with no special tools or skills requires. Supplied fully charged with inter-connectors. Self Discharge: ~2-3% per month.
- 3200 cycles to 50% DOD
- 2100 cycles to 80% DOD
- 10 year warranty
The Rolls 5000 Series now come with:
- Free Water Miser battery caps - for reduced water loss
- Free Interconnection leads
- Free Nut and bolts
- Free Terminal caps
- Free Delivery to most of the UK mainland
Rolls OPzV Gel Batteries
Optimised for stringed use in large sized solar installations, Rolls OPzV Gel range is designed to maximise efficiency and cycle life, making them ideal for off-grid solar applications.
They feature highly effective tubular plate technology which maximises charge acceptance and a design which allows for excellent compatibility and space utilisation. In addition this, these batteries also feature all of the maintenance free benefits that come with gel technology batteries.
- 3200 cycles at 50% DOD
- High impact resistant ABS red case
- Product warranty - 5 Year*
- Tubular Plate Design with 20 year operational float life
- Easy transportation & system configuration
- M8 screw terminal poles for easy connection
- These cells should only be installed vertically
- Includes link leads with integral cover and terminal bolts
Rolls AGM Series 5 batteries
The Rolls Deep Cycle AGM battery range provide the performance and life of a true deep cycle battery with all the convenience of sealed construction and being maintenance free. They feature thick plates with a high density active material. This design allows for reserve energy to be stored deep within the battery plates and released during slow discharge. The Rolls AGM range are sealed, non hazardous, non spillable and completely maintenance free. They can be operated upright on their sides and are leak proof, shock and vibration resistant.
- 1250 cycles to 50% DOD
- 850 cycles to 80% DOD
- 5 year warranty
Rolls AGM Series 2 batteries
The Rolls AGM Series 2 batteries are an economy alternative to the red series 5. These batteries are deep cyle, sealed and maintenance free, perfect for smaller renewable energy projects.
- 2 year warranty
- 800 cycles to 50% DOD (depth of discharge)
Rolls Batteries AGM Terminal Covers
Rolls Batteries AGM Terminal Covers to help prevent the possibility of short circuiting the batteries by insulating the terminal.
Rolls Accessories
Water Miser caps
recombine gases produced during charging to reduce frequency and need to top-up batteries with distilled water. Compatible with 4000, 4500 and 5000 series Rolls Batteries*.
*excludes some 4000 series see 4000 series for details
Rolls Batteries Level Indicator
A handy device for quickly checking the level of
your Rolls Batteries. Simply unscrew your regular
cap and screw this one in, repeat for each cell in
your battery system.
- Different versions for 4000/4500 and 5000 series Rolls Batteries
- Compatible with 4000, 4500 and 5000 series Rolls Batteries*
Appropriate PPE should always be worn.
*excludes some 4000 series see 4000 series for details
Voltages, Specific Gravity and State of Charge
The information below describes how to correctly use and interpret both specific gravity and voltages readings and how to determine when your battery bank requires charging.
Specific Gravity Readings – “True” State of Charge
The specific gravity (SG) of the battery acid or electrolyte is the truest and most absolute measure of a battery’s state of charge. The SG reading is NOT greatly or adversely affected by the load on the battery. Basically if a battery is 50% charged, it will read a specific gravity of 1.200 (see Table 1), regardless of whether the battery is on charge, being discharge or being stored. This is not the case for voltage readings.
Table 1. SG vs. Voltage
| % Charged | Specific Gravity | |
| 100% | 1.255 – 1.275 | |
| 75% | 1.215 – 1.235 | |
| 50% | 1.180 – 1.200 | |
| 25% | 1.155 - 1.165 | |
| 0% | 1.110 - 1.130 | |
Voltage Readings
Voltage readings will vary and are greatly affected and dependent on whether the battery is being charged, discharged or in storage (rest or “open cell” voltage). There are two terms for voltage readings:
- Load voltage (voltage under load or on charge)
- Open cell voltage.
Charge Voltage: When a battery is charged the plates will polarize and develop a resistance to the charge (surface charge). This resistance will add to the battery voltage and therefore using this voltage reading will not reflect the true state of charge. All the so-called “surface charge” will be removed when the battery is being discharged. In general, the battery voltage will recover or increase when the load is removed. This is especially true if the load is very high.
Open Cell Voltage is determined by taking all the loads off of the battery and letting the battery stand for at least 4 hours before taking a reading. This allows the surface charge to dissipate. To get around this problem either use table 2 or determine the 50% state of charge as described.
Determining the 50% state of charge Voltage Reading
Most three steps chargers or inverters monitor the voltage and have an adjustable set point that determines when the batteries are low (50% discharged) and should be charged. Once this set-point is reached the inverter will either sound an alarm or start a generator or tie the battery bank back into to grid power. The voltage set-point maybe factory set but could require verification. Consult your inverter manual for the section on “Cut-off voltage” or “Over discharge protection”. Since the voltage will change depending on whether or not the bank is on load the set point can be determined by a specific gravity reading. A gravity reading of 1.200 is equal to 50% discharged.
Battery cable lengths, system set-up and other variables can affect the voltage readings as well. Below is a procedure to verify the 50% mark and table 2 gives approximate cut-off voltages at various state of charge. Notice 100% is given as an open cell voltage and all other as under load.
When using a generator with a low voltage cut-off, set the generator to start at the 50% mark given by table 2 and put the bank into service (11.6 V for a 12V system). When the generator starts-up measure the specific gravity of one cell in the bank. Compare this to the table 1, Specific gravity versus state of charge. If the measured specific gravity indicates the state of charge is more than 50%, decrease the low voltage cut-off setting. Similarly if the specific gravity indicates the state of charge is lower than 50%, increase the low voltage cut-off setting. Note: 50% is the desired depth of discharge but it does not have to be exactly 50%. For practical purposes a range of 45-55% is acceptable. The actual battery voltage corresponding to 50% will change with a change in load. In general, the higher the discharge amperage, the lower the corresponding voltage.
To determine or verify the 50% voltage set point:
- Put all or as many loads as possible on the battery. Disconnect any in coming current inputs such as panels / windmills and grid power. Contact your dealer for specifics.
- Take the specific gravity of one cell.
- Take another reading 15 minutes and ½ hr later this should give you an indication of how fast the batteries are dropping.
- Continue to take readings until 50-55% state of charge is reached according to the specific gravity readings.
- Take and record voltage readings (when on load) of any meters to be used for monitoring the state of charge and take a voltage reading across the terminals of one battery.
- Compare to table 2.
- These readings will then give you a very accurate voltage reading which can be used in the future either as a set point for the inverter or as a day to day monitoring parameter.
Table 2.
|
% Charged |
Single Cell |
12V |
24V |
32V |
48V |
|
|
100% |
2.10 |
12.60 |
25.20 |
33.60 |
50.40 |
OPEN CELL |
|
75% |
2.01 |
12.06 |
24.12 |
32.16 |
48.24 |
UNDER LOAD |
|
50% |
1.93 |
11.58 |
23.16 |
30.88 |
46.32 |
UNDER LOAD |
|
25% |
1.84 |
11.04 |
22.08 |
29.44 |
44.16 |
UNDER LOAD |
|
0% |
1.75 |
10.50 |
21.00 |
28.00 |
42.00 |
UNDER LOAD |
Note: This will give you a very good idea on how your battery bank will behave and how long it will last with no power inputs. New batteries will give about 75% of the specified capacity until the battery has been cycled 40-60 times (1-3 months of service)
