Deep Cycle Battery

[JJDT]

I do have one of these teleschopic LED camping lights that I mainly use when fishing and also do use it for light when I braai at the campsite. I normally use it with my 120ah deep cycle battery which is also used on my small rubberduck with a trolling motor. I usually remove the battery from the boat to use on the light and then back to the boat again when I want to use the boat. My thinking is to leave the larger battery in the boat and just buy a second battery just for the light.

Will a small 7ah deep cycle battery work with this light? I do not know the light output as there are different versions from 500w to 800w. A similar light at outdoor warehouse list these lights as 40w and 3200 lumens.

 

[kosmonooit]

Look a lithium alternatives - you get 12V 'drop-in' alternatives  that can be charged like a lead acid ....so many advantages, disadvantage is price.

[kosmonooit]

Can also add that the term 'deep cycle' is misleading, you should not discharge more than 50% if you want the Lead Acid battery to last, so monitor the voltage and check/reference the data sheet.

[JJDT]

@kosmonooit thanks for the reply...familiar with the deep cycle battery. My current deep cycle battery on my rubberduck is 6 years old.

 

How do you measure the current drawn from lights...I just want a battery for the LED lights...my thinking for a deep cycle battery is the slow discharge. I had a spare gate motor battery that I tried to use with those lights...after 10 minutes you could see the power loss as the light quality was fading.

[River Rat]

@kosmonooit thanks for the reply...familiar with the deep cycle battery. My current deep cycle battery on my rubberduck is 6 years old.

 

How do you measure the current drawn from lights...I just want a battery for the LED lights...my thinking for a deep cycle battery is the slow discharge. I had a spare gate motor battery that I tried to use with those lights...after 10 minutes you could see the power loss as the light quality was fading.

Rule of thumb a 40w light @ 12v uses 3.33 amps per hour so a 7ah battery will give you 2 hours of light. Alternatively a 7ah battery has 84 watt hours (multiply by 12). Just an aside a 40w LED is like a security light and I find that a 6w LED gives me more than enough light equivalent to a 60w normal globe. Two routes to go make up your own lights using these modules https://4x4direct.co.za/138-modules or get these solar lights https://www.takealot.com/cob-solar-power-motion-sensor-wall-light-pack-4/PLID54512447which have a built in battery gives about 600 lumen per light at circa R60 per light I got 4, they give about 4 hours of light per charge because with the motion sensor it only switches on when you need it.

 

The latter option is really cheap and cheerful but painless if you view them as a consumable item, although I have yet to replace one.

 

Edited December 10, 2020 by River Rat

[kosmonooit]

How do you measure the current drawn from lights...I just want a battery for the LED lights...my thinking for a deep cycle battery is the slow discharge. I had a spare gate motor battery that I tried to use with those lights...after 10 minutes you could see the power loss as the light quality was fading.

Besides the rule of thumb estimations, you could get a cheap 1/2 decent multi-meter, with those you measure current by putting the probes in series with the load. Will also be useful for monitoring batter voltages.

 

Something like this https://www.mantech.co.za/ProductInfo.aspx?Item=330M0441

 

You do get fancier ones with a coil probe that you clip over the leads, but that's an investment.

[WaynejG]

The cheaper 7aH batteries are normally 5aH if you lucky. This was tested across various cheap 7aH batteries with a digital load tester.

[kosmonooit]

Besides the rule of thumb estimations, you could get a cheap 1/2 decent multi-meter, with those you measure current by putting the probes in series with the load. Will also be useful for monitoring batter voltages.

 

Something like this https://www.mantech.co.za/ProductInfo.aspx?Item=330M0441

 

You do get fancier ones with a coil probe that you clip over the leads, but that's an investment.

Sad day when you quote yourself but I feel its my duty as an electronics professional to offer further unsolicited advice.

 

If like to buy good tools, and if you are going to get a multimeter and don't want to get a el cheapo, ,  the Fluke  brand is excellent and it's a good investment. I still use the first Fluke DMM I got 35 years ago practically every day, and I have plenty of others up the range, including bench instruments,

 

The entry level  now is the Fluke 107, Mantech has that for R1930