Comparing Hybrid Battery With Deepcell

[bblotus]

My wife and I recently became full time RV'ers. We almost immediately developed a dislike for the expensive RV parks and instead go boondocking in the Cities and National Parks. Our generator runs good but eating up .5-.8 gallons of gas an hour causes us to only use it for cooking. We did however pick up a brand new 110 pound hybrid battery. It can run our two laptops for about a day and a half before needing to get recharged.  It'd be great for it to also handle a LCD screen and run 3-4 days.

Hybrid We must of paid $250+ for. AH is 6.5 amps at 25 hours.
http://www.interstatebatteries.com/cs_estore/content/product_info/marine_f.asp
Mine is the SRM-4D at the bottom of the first column.

I'm eyeing a Gel Cell with 31 AH. (measured at 20 hours?)
http://www.batterystuff.com/batteries/rv-marine/gel-cell/8GU1.html


If I understand this right... Which I probably don't. The Gel sell battery is almost 5x stronger than the hybrid???! This is confusing to me since both websites use different measurements of power. It couldn't possible be that much stronger, especially at nearly half the weight - but that's all I can come up with.


There's no more space in the Engine for a third battery (first is the car battery for turning on engine.) So I'd probably just stick
the Gel in the Cab by the front seats and hook a converter up to it. The annoying thing with this setup will be needing two separate chargers
for both batteries. But small price to pay for not running our generator 8 hours a day.

 

[Tom]

You have it backwards. That gel battery has a capacity of 31 amp hours, compared with approx 160 amp hours for the ASRM 4D. The larger battery has more than 5X the capacity. It's also 5X the weight.

 

[Lou Schneider]

Welcome to The RV Forum!

An Amp-hour is delivering 1 ampere of current for 1 hour.  The 4D is rated at 6.5 amps for 25 hours, or 162.5 amp-hours.

The gel cell is rated at 31 amp-hours.  That's 15.5 amps for 2 hours, 6.5 amps for 4 3/4 hours, etc.

In this case, hybrid means a cross between a true deep cycle battery and a starting battery.  As it's name implies, a deep cycle battery is designed to deliver relatively small amounts of power over long periods of time, until the battery is deeply discharged.

Starting batteries are designed to deliver a lot of power all at once to crank an engine.  They're not made for deep discharges and will be damaged if you discharge them too deeply.

A hybrid battery is somewhere in the middle.

 

[bblotus]

Oookay, it was late at night when I posted that, must of really crossed my numbers. Thanks for straightening it for me.

Don't see why "true" deepcells are so expensive if they don't have superior amps per weight/price.

Will settle with another 110 pound hybrid for my cab for the same amount of cash.

Wish I could just get some solar panels on the roof but with us spending most of our time in the midwest (in December) it just wouldn't be feasible.

 

[Ned]

The most common battery used in RVs is a set of golf cart 6V batteries, either 2 or 4 in a bank.  You can get 2 6V 225AH batteries for little than the $250 you paid for that hybrid and have 225AH vs. 162.5AH.  Being true deep cycle batteries, they will perform better and last longer in your application than the hybrid.

 

[Mopar1973Man]

Ok... This is 820 Amp / hours. (also weighs 1,000 pounds)
http://i56.tinypic.com/30wxo94.jpg

Which doing the math to give you a feel of time.

4kw Inverter / 24 Volts = 166.6 Amps

820 Amp hours / 166 load Amps = 4.9 Hours of  Battery till dead.

So now you can figure out your RV using the same kind of math.  You can change your load amps number to reflect a single device and see how long it would run.

Another thing to consider any sealed batteries like AGM or similar are going to have shorter life span. Because as you charge and discharge a battery a certain amount of water is lost from the electrolytes. With a flood cell battery you can maintain the level with distilled water and go on. Once a AGM or similar is dries out its done.

The last batch of batteries here for the stick house lasted 12-13 years roughly. Even the batteries in my pickup truck lasted 10 years.  Something you can't do with a sealed battery.

 

[Bobtop46]

If you are looking for lightest weight and most battery try these.

http://www.lithionicsbattery.com/rv.html

just my 2 cents worth.

 

[Gary RV_Wizard]

It's just economy of scale - the hybrid batteries use most of the cranking battery design and components, so they can be built on the same assembly lines at mass production prices. Deep cycles deliver better deep-cycle capacity and life (charging cycles), but cost more because they are low-volume production.

The major drawback of a hybrid are that it will die after a relatively small number of discharge/recharge cycles, whereas a true deep cycle will keep motoring on up to twice as long. But there are other factors of use and abuse that can mask that, so for some people the hybrid (aka "marine") battery is just as good a deal because they will ruin an expensive deep cycle in a fairly short time anyway.

 

[bblotus]

Lots of great information on this thread!

Ned - I keep hearing about those Golf Cart batteries; solar, electric cars, rv's - 225Ah in that price range sounds like a deal.

Mopar - Ahhh so that's why sealed has shorter life spans. Make sense now, also I suppose their plates would warp much sooner as well.

Bobtop - The "charges in 2 hours instead of 8" that would pay for itself very quickly, when most of our recharging will be done via generator. Have you personally tried these? It looks like a brand new business, I couldn't find prices anywhere on the site.

Gary - ruining a real deepcell, perhaps by charging it too quickly, or letting the power drain below 50% for prolonged periods of time? We really should only need these batteries for a couple of years - RV wise, but then again, having a couple of solid deep cells around could come in handle. Solar power or in case of backup.


I'll start researching the prices of golf cart batteries in our area. This city has an enormous golf course... Maybe find some lightly used ones.

 

[Tom]

If you go with golf cart batteries (and I agree they're a great solution if you have space), remember that they're 6 volt batteries. You need two connected in series to give you 12 volts. More info in this illustrated article in our forum library (it's a pdf file).

 

[John From Detroit]

he math you used for the kilo-pound battery has a flaw.  You are taking the battery to ZERO percent charge.. That does not work.

Second flaw, Can't spell it but the effect that says "The faster you discharge a battery the faster STILL it runs down.

You might get oh, say an hour and a half (Note this is a WAG.. IF you don't know what a WAG is the W is Wild and the G is Guess) but for sure it won't be four hours plus

 

[Bobtop46]

The 200ah battery is about $1000.  not sure about the 400ah battery.  They are out of clearwater florida.

 

[Gary RV_Wizard]

You should be able to get new, 6v GC2 (golf cart) batteries for around $100 each. That's $200 for 225 AH (measured at the standard 20 hour test rate). For $1000 you can get 1125 AH (if you have room for 5 pairs of batteries).

Beware of comparing amp-hours measured at rates other than the 20 hour test rate.  You can't compare numbers obtained by different test rates, e.g. AH measured over 25 hours cannot be accurately compared to Ah measured over 20 hours because the rate of discharge alters the total. The lower the amp rate (or greater hours), the higher the total AH will be.  The industry standard for AH comparison is the 20 hour rate. If the battery company touts their numbers based on more than 20 hours, they are blowing smoke at you, trying to look good.