Hello all...i have a question which i hope anybody with experience can help me with...
I do camping and offroading a lot. I have a lot of gadgets which i plug in the cigarette lighter. This is including a Power Inverter (150 Watt capacity) which converts 12V DC to 220V AC. It has an auto shutdown feature when the voltage is too low (below 10V).
My question is: if I put an extra battery (same size as the stock battery... I have a Suzuki Jimny 2010 model) and put them in series together....will this avoid the voltage dropping to below 10V?
Can my alternator handle the extra battery?
I do not have any experience with batteries I'm afraid...
The LAST thing you want to do is put two batteries in series - you'll burn a lot of stuff up if you do.
Parallel is what you probably mean - positive to positive, negative to negative - this can be done, but you'd probably be better off with some sort of isolator between the two to avoid running the start battery down to the point where you can't get a start.
You'd also probably be better off with some sort of deep cycle or possibly a marine battery as the second battery - automotive batteries are designed for cranking or starting services not deep discharges, and will fail rapidly if subjected to this sort of service.
thanks for the quick reply fordem!
hehe that's what i mean...parallel...
Marine battery? could i put it in parallel with the stock battery (as long as both are the same voltage)? do u think my alternator can handle both at the same time?
i'm using my gadgets while i'm running my engine so the stock battery will not drain out...or will it?
Let's start by drawing up a power budget - make a list of your gadgets, the amount of power they draw and an approximation of the number of hours per day you'll be using them - then give us an idea of how much driving you're going to be doing - that's the only way we'll know what's what.
GPS (don't know power consumption) - 5 hours
Mobile/ Iphone charger (5Amps) - 2 hours
Camping lights (24Watts) - 4 hours
Kettle (100Watts) - 1 hour
Power Inverter (150 Watts) - 4 hours
Spotlights (i will install these in the future) x2 (50 watts each) - 1 hour
I am driving on average about 5 hours a day...
You need to know actual power consumption, not rated max output. A phone charger is not going to pull 5 amps at 12 volts, you can probably run a phone off 7.4v @ 150 mah, so at 12 volts, probably less than 50 mah x 5 hours, 250 milliamps or .25 amps.
your GPS probably the same as the phone.
Camp lights. 24 watts = 2amps @ 12 volts that's 8 amps over 4 hours.
Kettle 100 watts = 8.3 amps @ 12 volts
Power inverter is supplying the power to everything, not actually using 150 watts, just supplying UP to 150 watts of AC power from your DC power source.
spot lights 100 watts= 8.3 amps @ 12 volts.
so if everything is running for the durration you indicated you'll have about 22 amps from your 12 volt battery, or about 740 watts of power over the course of 4 hours. most of that will be used in the one hour your spots and kettle are on. . A standard small 45 amp-hour battery should easily handle it and the alternator should easily recharge your battery, but when camping you should always run your gear off a backup battery if you are using it with the vehicle turned off. You shouldn't draw more than 4 or 5 amps per hour off a standard 45 amp hour lead acid battery, so a higher discharge capable battery would be better to use.
If you plan on getting spotlights, you'll need to upgrade your inverter. You have 150 watts of power available, and if you try to run your kettle and your two spots, you'll blow the inverter. It will handle the kettle and the camplights, or the camplights and the spots, but not the kettle and the spots simultaneously.
GPS will be no more than 1A and I assume the 5 hrs/day will be whilst you're driving, I think we can safely ignore that, if you don't already have a car charger for your phone, get one, and also charge the phone whilst driving (and again, we'll ignore that).
Camping lights - get yourself some LED lamp bars that run off of 12V - those are low current (the ones I have actually run off of 3 AA batteries and the battery last for forever)
Kettle - 100W - that's a pretty low wattage kettle, but I assume you know what you have, and also that this is what you're using the inverter for, 1hr/day - what else are you using the inverter for to account for the remaining 3hr/day?
By the way 12V kettles do exist, and they're not expensive. If possible eliminate the inverter (as a rule they are not particularly efficient and in my experience not that reliable), so if we can run the kettle directly at 12V we'll save some power there, and maybe just plug the kettle in and leave the engine idling for 10~15 mins after you park (or before you leave).
Just so that you understand where I'm going with this...
If we can reduce the amount of energy you're taking from the battery whilst the engine is off to the bare minimum, we might be able to do it all with the standard battery, and so far, I think we're doing pretty good.
Take a look in the back of your Jimny manual, it should tell you what the alternator output is.
hey guys sorry for the confusion...
i am running the kettle and camp lights all from the 12V cigarette lighter...not from the inverter.
i only use the inverter for running my laptop.
i plan to directly connect the spotlights to the battery...not from the inverter.
ok fordem, i will check the power output of my alternator from the manual...
like fordem said a deep cycle or marine battery for your second battery and i would recomend that you look into a dual battery system they dont let your cranking battery to be used while the key is in the off position but you can still run your camping appliances every one i know has put extra sockets in there car that run off the second battery. each dual battery kit is different so look for the one that best suits you.
See if you can get yourself a car adapter for the laptop and eliminate the inverter altogether - additionally - consider running the laptop off of it's internal battery and plug it to charge whilst you're driving.
What's the power consumption on the laptop like - they range from 30W on a netbook to as much as 120~150W on the larger "desktop replacements". 65W seems average for most 13" systems.
24 watts in 12V camplights is 2a x 4 hrs = 8aH
a 65w laptop from 12V is roughly 6a x 4 hrs = 24aH
You're looking at 32aH from a 45aH battery, not good at all. The rule of thumb if you want long battery life from a lead acid battery is not to discharge it by more than 20~25% of it's capacity at any one time, and that is for deep cycle batteries - automotive starting batteries have thinner plates and are not designed for this type of "cycling" service, so they deteriorate even faster.
Using the equipment you've outlined a marine or deepcycle battery of 150aH capacity will do what you need - but - I believe that for the same (or less) expenditure as you'd incur with a battery & isolator, you could take a more energy conservative approach, and organise as much of the energy consumption to coincide with the time of production (the period when you'll be running the engine) and you'd get by without needing an additional battery.
Very briefly ...
Lead acid batteries use plates made of lead suspended in sulphuric acid - the plates are usually made in the form of a grid into which a "spongy" lead paste is forced.
Automotive batteries are designed for high current discharges (anywhere from 600~1600A) for short periods of time (10~30 seconds) to start the engines after which they are immediately recharged - they use larger numbers of thinner plates.
Deep cycle batteries are designed for what is known as "cycling" service - to supply smaller currents (smaller than automotive cranking currents) for longer periods, these are found in many applications - solar-electric power, camping, etc. - these have smaller numbers of thicker plates.
With each discharge/recharge cycle, the plates expand & contract, and with the thinner plates used in automotive batteries. there is some shedding of the active lead paste, and this is what leads to the rapid deterioration if used in cycling service.
Marine batteries are a compromise between the two - designed with thicker plates to allow some cycling service - use of cabin & navigational lights etc., whilst the vessel is moored and also cranking to start the engines when necessary.
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