Deep Cycle Battery

[bart simpson]

Hi All,

I am not sure if it is against forum rules, but does anyone know where I might be able to buy a deep cycle battery similar to the optima yellow tops available overseas for use as a second battery in a 4x4 (to power a fridge).

I have tried the usual battery shops without any luck. An sealed AGM type is what I am after.

Thanks,

[Sylvi]

bat simpson,

I do not think anyone imports this type of Batteries to S L. Due to the cost. Singapore you can try them..

I know few campers using in S L 4 12 volts Batteries OF 90 Amperes to get higher amperage during the full night as well as day time. They had few charging problems.

I correct them fixing modified Alternator to give high Amperage forom the running engine. To battery get discharged to 75%. A meter to monitor the discharge is about 50000/= Rupees. Only other way is to use a hydrometer.

Deep cycle batteries are efficient to your requirement. Lead acid batteries, when they drop below 50% have to use a external charger to recharge them.

Can you give discharge amperage of your equipment.

Please log into this link I do not know their quality.

http://dir.indiamart.com/impcat/deep-cycle-battery.html

Following batteries I have experience in USA.

http://www.usbattery.com/usb_index.html

Please contact me for further clarifications.

Sylvi Wijesinghe.

[Rumesh88]

All those who provide off-grid solar power solutions (there are so many, but just an example is http://www.superneat.lk) import deep cycle batteries of various capacities, sizes, makes, qualities, prices etc. Just search the Net to begin with but please keep in mind that some of them provide the battery only as a part of their solution package.

[MrCat]

Just a thought, based on your usage pattern of the fridge and how efficient the fridge is, you might not need a deep cycle battery at all.

For example, my 12v fridge will draw 2.5 AMPS max, so if I run it for 8 hours without charging the battery, it`ll consume 20 amp hours. Now this is one third the capacity of a normal cycle 60AH battery, so it shouldn’t cause any issues with it right? There are so many factors that may contribute to the running cycle of the fridge, but this is under the assumption that the compressor is running continuously. So in theory, you might be better off with a cheap battery with a relatively high AH rating.

Somebody else who`s proficient in electrical engineering please correct me if I’m wrong.

[bart simpson]

Just a thought, based on your usage pattern of the fridge and how efficient the fridge is, you might not need a deep cycle battery at all.

For example, my 12v fridge will draw 2.5 AMPS max, so if I run it for 8 hours without charging the battery, it`ll consume 20 amp hours. Now this is one third the capacity of a normal cycle 60AH battery, so it shouldn’t cause any issues with it right? There are so many factors that may contribute to the running cycle of the fridge, but this is under the assumption that the compressor is running continuously. So in theory, you might be better off with a cheap battery with a relatively high AH rating.

Somebody else who`s proficient in electrical engineering please correct me if I’m wrong.

Thanks MrCat. Your logic seems fine. My fridge says 'Variable from 0.5 to 4.2 AMPS Maximum' which is a bit of a worry. Imagine arrive at a camp site at 5.00pm and heading out around 10am next morning. Add some LED camp lights and charging of mobile gadgets for the mix and the situation is not so good.

We recently camped 2 nights in Kalpitiya and the fridge was sorely missed.

I might look at a 5W solar to keep the battery charging at least somewhat if I can't find a good deep cycle.

[Rumesh88]

Just a thought, based on your usage pattern of the fridge and how efficient the fridge is, you might not need a deep cycle battery at all.

For example, my 12v fridge will draw 2.5 AMPS max, so if I run it for 8 hours without charging the battery, it`ll consume 20 amp hours. Now this is one third the capacity of a normal cycle 60AH battery, so it shouldn’t cause any issues with it right? There are so many factors that may contribute to the running cycle of the fridge, but this is under the assumption that the compressor is running continuously. So in theory, you might be better off with a cheap battery with a relatively high AH rating.

Somebody else who`s proficient in electrical engineering please correct me if I’m wrong.

Your analysis is correct in theory but the common automobile batteries are meant basically for "float" operation ie they are not meant for repeated charge/discharge cycles but to provide a high cranking current for a short period at the time of starting the engine. If they are used for repeated charge discharge cycles it would invariably result in a shorter service life. Hence for applications requiring repeated charge/discharge cycles (like electrical fork lifts, golf carts etc) you have deep discharge batteries specifically designed for the purpose. AGM batteries cannot deliver high cranking current (this is why you should never use the auxiliary battery in your hybrid to jump start another car) but are good for repeated charge discharge cycles. As for the intended application bart simpson would have to find a deep cycle battery with a solar panel of at least 20W capacity. However the capacities of both battery and the solar panel depend on how long he intends to keep the fridge on standby.

Edit: Thought of adding a point further. Although not a perfect solution, you can prolong the service life of a normal automobile battery (ie. if you are willing to forego the convenience of a sealed AGM) in a low current (like 5A) deep cycle application like yours by using acid of specific gravity 1.24 instead of usual 1.26 - 1.28. To do this you need to dilute acid with additional water and measure sp gr. This is way you can compromise the cost of a deep cycle battery against bit of a inconvenience.

Edited November 21, 2013 by Rumesh88

[bart simpson]

Your analysis is correct in theory but the common automobile batteries are meant basically for "float" operation ie they are not meant for repeated charge/discharge cycles but to provide a high cranking current for a short period at the time of starting the engine. If they are used for repeated charge discharge cycles it would invariably result in a shorter service life. Hence for applications requiring repeated charge/discharge cycles (like electrical fork lifts, golf carts etc) you have deep discharge batteries specifically designed for the purpose. AGM batteries cannot deliver high cranking current (this is why you should never use the auxiliary battery in your hybrid to jump start another car) but are good for repeated charge discharge cycles. As for the intended application bart simpson would have to find a deep cycle battery with a solar panel of at least 20W capacity. However the capacities of both battery and the solar panel depend on how long he intends to keep the fridge on standby.

Thanks Rumesh88, I have a isolator for a dual battery setup purchased from a friend. It allows the vehicle to charge the second battery and has some protection to ensure the main battery is not discharged etc. Thanks for the info on the size of the solar panel, 20W would be out of budget so I will need to get the isolator and the dual battery wired rather than go solar, if I could find a deep cycle. Thanks for your help.