AGM Battery

[cmgordon]

<p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica;">So after reading "How to Have Electricity" several times on the main site, it seems as though the AGM Battery is the way to go (I think...). I've found them on Walmart's site ranging from $115-$525 (that's 18 Amps-100 Amps).&nbsp; I know I could get a cheap deep cycle at Walmart for $65 but I think I'll be better off in the long-run with the AGM. My only question is how many amps do I need? I'm not living this lifestyle yet but I'm trying to become as prepared as possible. I know everyone uses different amounts of power so I may need to give more details but I have no idea about amps and I'm having trouble figuring out the mathematical side of this. Any comments, suggestions, and advice is appreciated. Thanks!</p>

 

[bee]

Deep cycle batteries are rated in amp hour(ah)<br>Like you said the requirements of each individual is different, but just to give you an idea. &nbsp;The most common recommended deep cycle battery suggested for use is two 6v golf cart batteries hooked up in series to give you 12v. &nbsp;When hooking batteries in series voltage goes up but AH stay the same. A standard golf cart battery is around 200AH. &nbsp;When you hook two golf cart batteries together for 12v, you still have only 200AH.<br><br>If you hook batteries up in&nbsp;parallel&nbsp;then voltage stays the same but AH goes up.<br><br>Remember that for decent battery life it is important to not fully discharge a battery. The general rule is 50% depth of discharge (DOD). &nbsp;This means that the two golf cart batteries with a rating of 200AH only gives you a usable 100AH before you should recharge. &nbsp;AGM battery can be discharged farther then 50% but they still need to be brought to 100% fully charged ASAP or their life will shorten dramatically.<br><br>Oh and I don't think you can get a cheap deep cycle for $65, in case the battery you are&nbsp;referring&nbsp;to is a marine battery you should be aware that they are not true deep cycle batteries they are somewhere in between start batteries and deep cycle.

 

[Zil]

I read a sailing forum, and they all seem to have problems with AGM batteries when used for house batteries.<br><br>The 6 volt gulf cart batteries are true deep cycle and last many years if well maintained. Disadvantige is the need to check water, clean the tops, and vent to outside not inside the van.<br><br>AGM deep cycle are very expensive. You could start with less costly gulf cart batteries from Sam, determine your needs and upgrade as you grow.

 

[user 423]

CMG: there's a lot of good advice on forums but there's no substitute for a good book or two that explains all you'll need for a 12V system. IMHO

 

[mockturtle]

I love my Optima AGM batteries!&nbsp; Have had them four years and they hold a charge just as long and charge up faster than lead acid batteries.

 

[Zil]

Glad to get some positive news about AGM batteries. They are the easiest to mount and use. What do you power? Charging, draw down, mounting location. thanks<br>

 

[mockturtle]

Since I have a Class C motorhome, the batteries are on a pull-out compartment under the coach.&nbsp; I run the furnace and refrigerator [on LP when I'm dry camping but it still uses a bit] and power all the lights I require for several days of camping.&nbsp; I have only a small portable inverter through which I run an air purifier at night [allergies].&nbsp; If I were to run the furnace all night, the batteries would draw faster, of course, which is why I just bought a catalytic LP heater which requires no electrical power.&nbsp; I never let the batteries go below 30% discharge and seldom under 50%.&nbsp; To me, paying more for AGMs has been worth.&nbsp;&nbsp; I like not having to drag the batteries out, some of the cells which cannot be reached easily, for maintenance every month or so.&nbsp; Just as big a plus is how rapidly they recharge while driving.&nbsp; But, then, I drive often rather than staying parked for long periods.

 

[mockturtle]

PS:&nbsp; Of course, the water pump also runs off 12V.&nbsp; My water heater is just LP.&nbsp;

 

[bee]

mockturtle points out what I think can be a huge benefit of agm, the faster charging, many people don't seem to realize the importance of this. &nbsp;I forget the exact number I could be off by an hr or two, but my two wet 6v golf cart batteries take about 10hrs to fully charge from 50% DOD. This is with a quality 3 stage 30amp charger. &nbsp;Rarely being fully charged is the number one cause of batteries failing, lead acid and agm. &nbsp;Most people don't want to run a generator for 10hrs straight, and Solar systems do not put out very much power except for peak light 4-6 hrs a day.<br><br>Most people rarely fully charge their batteries they never get past 85% charged. &nbsp;This shortens the life of both regular wet cell and agm batteries equally.<br><br>My 220ah batteries I think will barely handle what I expect my final loads to be. &nbsp;It is an estimate because I don't have the fridge yet.<br>12v danfross fridge<br>lights (led)<br>laptop use~6hrs a day<br>occasional&nbsp;fan<br>charging cellphone and toothbrush<br><br>I expect the batteries to last 1-2 days before hitting 50% DOD before I must recharge. &nbsp;My current charge sources are vehicle alternator, and 120v outlet. &nbsp;I am using ANL catastrophe fuses, Sure power smart relay, iota dls 30 amp converter, trimetric 2025-rv monitor.<br>I am currently using my truck camper for relatively short time period trips where I drive a lot so it works out. &nbsp;In the future I hope to add solar for extended stays where I don't run the motor much.<br>Hope this info gives you a better idea on what some of your options are.

 

[cmgordon]

All this information is so helpful. I'm really glad there's so much input on both types of battery. I'm still going to do a lot more research on the matter for sure. Slowday, I definitely agree with you about reading; I've already read the book by Robert Wells from the main site and I've been looking at others. Vanabode by Jason Odom looks interesting so I may pick that up. Any suggestions on some good books with quality information about van dwelling?

 

[wrcsixeight]

Bee, expect a 1.8 cubic foot Danfoss powered fridge to use about 1 amp hour per hour at 75f ambient. &nbsp;Unless I load mine with warm items, mine rarely ever exceeds this figure and is more like .75a/h per hour, but I have added extra insulation and the condenser fan pulls cooler air from the floor below and can't recycle heated air. This is apparently the best way to ensure maximum efficiency, making sure the compressor and condenser are adequately ventilated and not sitting in a compartment that they themselves have heated.<br><br>While it is true that AGM's can accept much higher charging currents, I do not know how much faster they are going to reach full charge compared to a flooded battery. &nbsp;Once the voltage gets into the mid 14's on either type battery, only enough amps required to hold that &nbsp;voltage level are going to be produced by the charging source. Whether higher amps are going to be required by the AGM to hold 14.x volts is unknown by me, but with their lower internal resistance, I think they might even require less amps to hold 14.x volts than a flooded. Not sure.<br><br>The AGM will be able to take more amperage until 14.x is reached, but this might not translate into a big difference in recharge times. &nbsp;Some battery Nazi's on Rv.net found no &nbsp;significant difference in the amount of time required to return the same amount of amp hours comparing AGM to flooded.<br><br>Also if Adequate cabling is used from alternator to AGM battery, a depleted AGM battery can ask the alternator for everything it can make at every rpm, and vastly shortening the life of the alternator, and in this scenario the AGM will recharge faster at the expense of alternator longevity and MPG, as it requires 1 engine HP for each 25 amps the alternator produces.<br><br>Regardless, most people do overestimate their alternator contribution and battery state of charge, and underestimate how much battery power they use. &nbsp;Using a grid powered charger weekly to ensure a 100% recharge is the best thing one can do for battery longevity and best performance. &nbsp;The alternator is extremely bad at returning a depleted battery to 100%, but does good upto the 80% level is the rpms are sufficient(not idling).<br><br>While My batteries are under the body, with an access hatch from above, I am considering AGM replacements as checking the water levels is kind of a PITA, and last summer I put it off too long and let them get too low, reducing the battery capacity and ultimately longevity.<br><br>Also while I have room for 2 group 27's,(230 a/h) &nbsp;I find I do not really need this much capacity with 200 watts of solar on the roof. &nbsp;<br><br>I am looking at weight reduction as my around town mileage is pretty poor with all the weight I can stuff into my Van, and the batteries are a good way to remove weight.<br><br>My van apparently requires only a 550 CCA to start the engine, but can fit a flooded battery capable of 850 CCA. &nbsp;I could put in a smaller lighter AGM battery there and save myself ~ 20 lbs of battery weight right there. &nbsp;My engine battery never sees any house loads and never gets discharged so a smaller capacity battery there with enough cranking amps is all that is required, and all AGM batteries have significantly higher CCA ratings than their similarly sized flooded counterparts.<br><br>Do note CCA ratings do not indicate battery capacity, only cranking power.<br><br>Beware of marine batteries that claim deep cycle. &nbsp;True 12volt deep cycle batteries are a rare breed and are 30% more expensive, but if treated properly will last much more than 30% longer than a similarly treated marine/rv/"deepcycle" that are easily obtainable.<br><br>The Golf Cart batteries ensure deep cycle construction and ability to handle and recover from deep discharges that will degrade a 12 volt marine battery much faster.&nbsp;

 

[VanLifeCrisis]

How often should you check the water in your batteries?

 

[Zil]

mockturtle, thank you fro the up date. wrcsixeight, good information from one who has been there.<br><br>Check water? as often as you can until you establish how your battery bank is performing. No less than 1 x month.

 

[VanLifeCrisis]

Thanks for the info <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle">

 

[cmgordon]

I've read through all this information and more (including Bob's book) and still think AGM is the way to go as for batteries. However, now I'm wondering if I should just go with solar and wait on the batteries for later. My needs are pretty small, at least they will be in the beginning&nbsp;(I plan to move/travel eventually).&nbsp;My job allows me to cook and store food there so I don't have to worry about microwaves, refrigerators, etc. I can also charge everything (laptop, phone, etc.) at work during the day. The only thing I need powered is a fan or several small computer fans. I have a small dog so it's really important to keep the van cool during the day. Of course, the van will be parked where I work so I can check on her several times throughout the day and get her out during lunch. So anyway...fans and solar power. I'll have the reflectix on the windows so I'm thinking some computer fans operated by a small solar panel will do the job. My questions are.. how easy would this be? Is this my best option? If so, how do I do it? If you comment, the more layman's terms, the better! You guys are awesomely helpful!

 

[Scott_1776]

<div style="text-align: left;">You can run a fan off solar if the fan voltage is 12V and the solar is 12V output, but that can be problematic as the amperage probably won't match.&nbsp; You need the solar to charge a battery and then run the fan, off that.&nbsp; I use a Harbor Freight Solar Battery charger, sits on my dashboard and it charges AA, AAA, D, C and 9V batteries, you need to buyt the rechargeable ones and then get a battery operated little camping fan and run it off the rechargeable batteries and just rotate two sets of batteries around every day or so depending on how much you use them, I do it daily and my fan take 4 D but the solar charger only charges 2 D's at a time so I'm always moving them around.&nbsp; Works if you want to go low tech.&nbsp; The charger is from Thunderbird (loved that Malt liquor back in college, more like loved the price and the effect) any way here's the link: <a href="http://www.harborfreight.com/portable-household-battery-solar-charger-68690.html" rel="nofollow" target="_blank">http://www.harborfreight.com/portable-household-battery-solar-charger-68690.html</a><br><br>Good luck!</div>

 

[cygvan]

AGM is the way to go. Not the cheapest initially but a properly cared for AGM battery will outlast a regular battery. They also dont require watering or metering. A proper smart charger (which are not magical impossible to find items) is all you need.<br><br><a rel="nofollow" href="http://www.solar-electric.com/deep-cycle-battery-faq.html" target="_blank">http://www.solar-electric.com/deep-cycle-battery-faq.html</a><br><br>