Starter Battery VERSUS Deep Cycle House Battery for the Minimalist

[One Awesome Inch]

My apologies if these seem like dumb questions. However, I am trying to figure out if I absolutely must have a house battery or I can get away with just using the vehicle's starting battery. As a minimalist my electrical needs are well... minimal. I just need to be able to get 10hrs (plus) use out of my smart phone (which I use for all entertainment needs) and I would like to be able to use one of the LED (1 watt / 10 LED) stick lights that power off a USB (meant to be charged via laptop). BTW, I will very likely end with a house battery down the road. This mainly applies to the initial phase of getting everything set up.

So....

Just *how much* power can I expect to get from my starter battery before it goes dead? Assuming the battery is in excellent condition to begin with...

Can I plug my smart phone into the cigarette lighter socket (and thus starter battery) and charge off of it two or three times per day?

Can I plug a ONE watt LED stick style light into the cigarette lighter socket and use it for 8 hours at a time without worry of killing the battery?

*********************

Regarding the Deep Cycle "house" battery connected and charged via the alternator....

How long do I have to run the van's engine to properly charge the house battery... say if it was half to two-thirds charged?

Can I just start the van for 15 minutes at idle or do I have to actually be driving for the charge to be robust enough?

 

[SternWake]

You should have no problems if you drive daily. But you don't say what vehicle or what size battery.

A smartphone takes about 1 amp current to charge initially, and less as the battery approaches full charge. I think my S4 mini takes about an hour from 15% to 100% so to fully charge it, consumes less than one amp hour.

A healthy fully charged 55 amp hour starter battery should, in theory be able to recharge it 55 times, but somewhere around the 40th time the starter might not spin the engine fast enough to start the engine.

Lots of variables so dont take these words as written in stone.

Also starting batteries really protest at being left under 80% charged, and it takes hours of driving to go from 80% to 100%, so the battery will not live a long life.

When it fails and if you do not find yourself needing a house battery, get a marine battery as they are more tolerant of deeper discharges.

True Deep cycle 12v batteries are very rare, and cost 20 to 30% more, as they weigh 15 to 30% more.

Marine batteries will say deep cycle on them, but are not built as tough as a true deep cycle.

 

[SoulRaven]

If you get one of those battery protector jobs, that will cut the power before the starting battery gets drained to low, you should be good to go.

Here's an example:

http://www.amazon.com/Battery-Prog-...=1400927808&sr=8-4&keywords=battery+protector

I'm using more power than what you're planning, and my starter battery will power my van for almost a week. Combined with my house battery, which will also give me a week before shutting down, I can go nearly two weeks in the boonies before I need to charge either battery.

I don't generally use the starting battery to power the house, but I have tested everything well so I know what I can do in a worst case scenario. Prior to adding a house battery, I used the vehicle battery all the time with no ill effects. Those battery protectors really keep you out of trouble. Highly recommended.

 

[Belinda2]

That's $60
Why not the INNOVA 3721 Battery and charging system monitor for $14?

 

[SoulRaven]

That's $60
Why not the INNOVA 3721 Battery and charging system monitor for $14?

The problem I see with that one is that it requires you to monitor it. I just listed the one on amazon as an example, I got mine at the recycled battery shop for $18 each. (I have two, one on my starter battery, and a second on my house battery.)

I'm afraid if I had to monitor it instead of it being automatic, I'd be in big trouble.

 

[Reno]

I keep the smartphone charged on the starter battery, as well as the laptop.

Note: Powering the laptop WILL run the starter battery down. Recharging the laptop is okay, though.

 

[highdesertranger]

just a heads up here, those battery protectors or auto disconnects whatever you want to call them also consume electrical power. so basically by having one you are cutting down on your available power. highdesertranger

 

[SternWake]

As HDR said, the low voltage disconnects do have a parasitic draw. Not sure how much it is though or how much of a factor it will be.

My laptop can consume close to 8 amps when running and charging a dead laptop battery and will still pull 3.6 amps with the laptop turned off and charging a dead laptop battery.

Either can and will deplete the engine battery. One is just faster than the other with a bigger Peukert factor.

 

[freenez2]

Does using the starter battery for charging these devices shorten it's life even if it's not excessively drained?

 

[GrayWhale]

Does using the starter battery for charging these devices shorten it's life even if it's not excessively drained?

Yes. All batteries have a finite number of times that they can be discharged and recharged, even if you are careful to not discharge them pass their recommended percentage. The worse would be your car's starting battery, which doesn't like to go under 80% and is meant to primarily start your car by exerting a lot of juice all at once and then get recharged right away by your alternator. It's not meant to power & recharge a lot of devices when the car's not running.

Also, if you notice when your starter battery goes dead and you jumpstart your car with another battery, most newer car goes into warm up mode at very, very high idle and keeps it there while you're driving. It does this to overwork the alternator into quickly recharging your dead battery. This quick charging process, greatly stresses the alternator, battery and wiring. All may fail if this is repeated often, with the worse case being the wires melting and causing a fire (which is rare, unless you upgraded to a bigger alternator but didn't upgrade the stock wiring).

 

[concretebox]

If you do this, your chances of having a dead battery when you need to move your vehicle go up. If you're really trying for minimist, how about a flashlight and a GoalZero portable solar panel?

 

[One Awesome Inch]

Well, I definitely want to have some sort of portable small solar panels like the GoalZero stuff that would fit on the dashboard. Problem is where I am in the PNW it rains or is cloudy 5 or 6 months out of the year so I cant rely on solar.

However, I have recently had the insight just to use a small 3 inch fan to vent air outside that is battery operated. I saw a website that had small fans that ran for two days on AA batteries. Charging up 2 or 4 batteries of that size should be easy enough.

Thing is I feel like I am missing something somehow as I really dont think I would need much electricity in the van. Small rechargeable batteries would cover everything (lighting, fan ) except heat.

I still get this nagging feeling I'll need electricity for something else but I haven't pinpointed it yet.

 

[highdesertranger]

unity gain the problem with that is you would be better off just running fans off your 12v system. charging batteries to run fans uses more power then just running them strait off the battery. remember there is a loss with every conversion. highdesertranger

 

[LeeRevell]

Don't know about the small solar chargers, but both my small AC-plug in chargers take 12 to 14 hours to recharge four AA batteries. Would hope solar is faster(?).

 

[GrayWhale]

Don't know about the small solar chargers, but both my small AC-plug in chargers take 12 to 14 hours to recharge four AA batteries. Would hope solar is faster(?).

That would depend on the charger. You have a really slow charger, which is actually good for the batteries as it doesn't heat it up as much as the fast charger, which is good for battery life. It also gives you a fuller charge.

I have a fast charger that came with my Ennelope batteries from Costco (3-4 hours?) but I haven't used it in a while because I use a slower charger from Harbor Freight (that's labeled "Fast Charger" but takes like 6-8 hours), because the battery charge lasts significantly longer.

 

[RogueRV2]

Hopefully you have enough power for your computing needs. To charge most laptops one needs a minimum of 30 watts and 6 hours of solid sunshine to charge a laptop battery. A netbook runs on about half that. I pads and such will need a whole bunch less. Some laptops will require up to 50 watts. To run the typical laptop that has a fully charged battery, 24/7, one would need about 100 watts, a deep cycle battery or a Marine type battery if that's all you can do, and 5 to 7 hours of insolation. A typical laptop might use only 2 ah if it is not charging it's internal battery. That's 24 watts @ 12vdc, one third less than the old RV incandescent interior light bulb. Standard #1141 bulbs used in older RV's are using about 35 watts!

I use a Marine as starting battery in all my vehicles. Marine batteries provide less cold cranking amps(CCA) as the trade off for it's doubled in size reserve capacity. The marine type battery I have in the motor home only has about 600 cold cranking amps that easily turns a 454 motor with 15-50w synthetic oil at 20 degrees F. This is about a 600 CCA battery, about the same power that standard automotive batteries had in the 70's-80's when this motor was design, and before increasingly higher and higher CCA batteries were marketed. More CCA are seen as better, but the battery plates construction became thinner and thinner... The older designs used heavier plates and lasted longer, IHO. A modern marine battery is adequate for my 454ci motor and because of it has double the reserve capacity and heavier plate construction, it may remain serviceable for longer period than a standard automotive battery. It may also be a worthwhile compromise for those who will charge their batteries often, and when driving an hour or more per occasion. Add only a 30 watt panel and one may have a minimalist's system. Of course adding more watts is better, as it will prolong the life of your dual use Marine type battery that much more. For example, fans or other draws run during the day, will tend to take power directly from the panel, and preserve the battery.

 

[RVTravel]

There have even been people to use marine batteries as their only car battery, to be used also as house battery. That is only for the minimalist. It was Laren Corie over at the yahoo group that does that.