Sealed Battery Bank (house) ?

[grantgoold]

I am looking for input from anyone using sealed or AGM batteries for their house battery bank. I have seen 6 volt 220 amp hour golf cart batteries but am looking for a sealed system to eliminate off gases as I have already seen the effects of an 8d exploding.

Am looking for experiences, comments, concerns and most importantly model, type and cost.

Thanks

Grant
1984 MCI 9.

[TomC]

I'm using 2-8D Lifeline AGM deep cycles.  While they are about twice the money, where my batteries are is hard to service.  So the sealed AGM's work for my.  And the Lifeline AGM's are 255 amp hour each.  Plus they are made about 4 miles from my bus warehouse.  And if need be, they can be mounted in any position with upside down not preferred.  Good Luck, TomC

[H3Jim]

I bought 6 4D AGM's from Dick Wright about a year and a half ago.  I have two of them mounted on their sides.   The two on their sides are over the rear wheels, mounted on some diamond plate for strength and protection. The other 4 are mounted where the bus bathroom holding tank used to be, next to the engine on the passenger side.  They are on the cool side, and mounted low.  I always try to keep them fully charged.  All connected with 0000 wire.  Because I bought my generator there, and the batteries, he let me make my cables using his stuff and only charged me his cost on the cable, under $3 a foot!

When installing them and working around them I have not always removed the ground wires first, and have done a little impromptu welding. Other than that, I have had zero problems with them, they are great!   Not much else to say.  I'm very happy with them.

A little under $300 each, 200 amp hours each at 12 volts.  I installed them in series parallel to get 24 volts.

[niles500]

I have 8 - 4d lifeline AGM's - depending how long this batch lasts I'll probably go with Trojan next time at half the price - last time I called around I got a price from them for about $180 each (think that was 8d's though) - IMO you pay for the warranty at some point, and not the battery - HTH

[Jeremy]

By their nature, 'sealed' batteries and gell batteries have limited charge and discharge rates compared with vented batteries. If you are happy to work within these limitations, or plan to add more battery capacity to compensate, they will do the job just fine, and with the added benefits of easier installation as has been mentioned. Having looked into the idea myself I chose to go with vented batteries instead - but then I haven't yet experienced a hydrogen explosion!

Jeremy

[H3Jim]

Although if your total capacity is large such as having 6 or 8 or more of these monsters, I don't think the rate of charge or discharge is much of an issue.  Having them last longer, and less risk of explosion, no maintanance, and abilty to mount them in unusal place (on their sides) to me is more important. 

I have never noticed that my rate of discharge is less. I've run microwave / oven and air conditioning for short while with no ill affect.  I keep the charge level high so they will last longer - charge rate is never an issue either.

[Jeremy]

I have never noticed that my rate of discharge is less. I've run microwave / oven and air conditioning for short while with no ill affect.  I keep the charge level high so they will last longer - charge rate is never an issue either.

Hi

You misunderstood what I meant - is not that the battery will somehow discharge or charge more slowly - it will behave exactly the same way when being used under the same circumstances - but if you put a very big load on it (ie. force it to discharge very quickly), or put a powerful charger on it (ie. charge it quickly) you will damage a sealed or gel battery, whereas an unvented batery would just boil a bit (ie. produce hydrogen) and keep on working quite happily (albeit, eventually needing topping up).

House batteries in a bus are never likely to suffer big discharge rates, but they could easily be overcharged by a fancy 3-step charger.

On the capacity issue - you're right in that a house battery bank has got lots of capacity, and probably more than you will normally need. But if, for instance, you were camping for a week and using all your usual electrical toys, you would eventually run out of power if you didn't recharge the batteries occasionally - say by running the generator for a couple of hours each day. A two hour charge may be sufficient to fully recharge a set of vented batteries, but not a set of gel batteries due to the lower charge rate they will accept. Because you would then be taking out more than you were putting back, eventually you would run out of power with the gel batteries - but the point at which happened could be delayed by 'compensating' for the lower charge rate of the gel batteries by adding extra capacity.

I've probably explained that really badly, but hopefully it makes more sense now.

Jeremy

For a good 'no-nonsense' explaination of different battery types and their advantages & disadvantages when used in boats (or buses) see: http://www.sterling-power.com/htm/faqmain.htm

[NewbeeMC9]

I had two Grp31?(or were they 4D's) in series for 24v, I had one bad one but took me a while to figure it out because I thought it was something I was doing.  I finally had it out and it tested bad at Batteries Plus.  The Guy I lifeline showed his A$$ saying I had 12v loads in my set up.  I had to convince him repeatedly that I did not and that my 12v loads were on the Bus Batteries where I have a 100amp 24/12 equalizer.  he finaly honored the warranty.  I lost one in a shed fire before i got them back to the bus so I have 6 volt batts from sams now.  less up front expense.

[TomC]

Jeremy- hate to disaggree with you, but a wet cell deep cycle battery will not take a charge nearly as fast as an AGM battery.  I had 2-8D wet cell deep cycle, and I could only charge at 45 amps for the both.  Now with the AGMs, I have the charger at 105 amps (out of 130amps) since the resistance on the AGM is quite a bit lower than a wet cell.  So now my batts recharge much faster, and because of the low resistance in the batts, they do not get hot when charging like the wet cells would.  Personal experience that parrallels what Lifeline says about their AGM batts.  Good Luck, TomC

[Sean]

We have eight size 8D AGM batteries and are thrilled with them.  We have surplus Xantrex units, no longer available.  When I replace these, I will probably go with Trojans.  Lifeline is a better brand, but it's hard to justify the price difference.

We have been living aboard our bus full-time now for over two years, and the battery bank is pushing three years "old" (in service), having been installed several months before completion.  On top of that, the batteries were surplus, so they were probably already two years old when we got them, and were likely abused by being left on a shelf without benefit of charging for most of that time.  So these batteries are close to the end of their design life, yet they are still providing us with excellent service.  We generally run our whole coach on battery alone for two days at a time, unless we need air conditioning, in which case we need to run our generator about 50% of the time.  (Yes, the batteries run the air conditioning the other 50%.)

About a year ago, we had a full-discharge episode, where the genny failed to auto-start and the bank ran all the way down to LBCO for the inverter and beyond that to LBCO for our 24-volt fridge.  After that, the batteries lost about 20% of their capacity, and, since they were at end-of-life anyway, I thought I'd replace them.  With little to lose, I did three equalize-discharge cycles and the bank is back up to perhaps 95% of where it was when we first installed it.  I expect to get another full year of service from these, which will make them an incredible value, considering the bargain-basement price I paid.  I do equalize the bank every three to six months.

I am compelled to jump in here on a couple of other points.

1.  The Sterling Power battery "FAQ" referenced above is about the worst drivel I have ever read on this subject.  The writer clearly has a bias, he does not cite any evidence for any of his claims, and it is poorly worded to boot.  There are several much more comprehensive and unbiased treatments of battery technologies available on the web.  Two sites that come immediately to mind are Ample Power's site, and Phrannie.org.

2.  There is no single "best" answer.  You need to do the research and then the analysis.  For many people, traditional "flooded" cells will be the most economical long-term cost-of-ownership solution, IF they are willing to do all the regular maintenance.  (Many people simply forego the maintenance, making flooded cells very expensive indeed, as well as dangerous in some cases.)  For others, VRLA battery technologies such as AGM will be the best choice.  In our case, for example, we had no choice because we had to locate the batteries in the passenger area, making conventionally vented batteries unusable.

3.  "Sealed" is a meaningless word when talking about batteries, because there are many "sealed" batteries that are nothing more than conventional flooded cells without user-accessible caps.  Which is perhaps where Jeremy is confused about "sealed" batteries needing a lower charge rate -- true for flooded cells with inaccessible caps, but far from the truth for AGM's, which can generally be both discharged and charged much faster than flooded cells.

4. Speaking in general terms about the relative merits of different battery technologies is a fine starting point for research and analysis.  However, when it comes time to buy batteries, there is no substitute for looking up the actual specification for each battery you are considering.  Even within a single technology, such as AGM, different manufacturers, and even different product lines within the same brand, have different design points, and may require different charge rates, depth-of-discharge floors, and charge voltage ceilings.  You will find, for example, that a battery designed for telecommunications backup purposes has very different design characteristics from one designed to run a forklift.

Since Grant has already decided against flooded cells (IMO, a wise choice), I will close with one piece of concrete advice:  shop around, pay careful attention to the specs on what you are looking at, and particularly to the date of manufacture.  Flooded batteries start their life when they are filled, which, at a reputable dealer, will be the day before you pick them up.  AGM's, though, start their life when they are manufactured, and dealers can have them sitting on the shelf for a year or more.  Good brands will have date codes stamped into the casing, and ask to see these before you agree to buy.  Try to get a set that were all made the same month, or, at most, one or two months apart, and don't take anything over four months old unless you get a discount.

HTH,
-Sean

[Jeremy]

Jeremy- hate to disaggree with you, but a wet cell deep cycle battery will not take a charge nearly as fast as an AGM battery.  I had 2-8D wet cell deep cycle, and I could only charge at 45 amps for the both.  Now with the AGMs, I have the charger at 105 amps (out of 130amps) since the resistance on the AGM is quite a bit lower than a wet cell.  So now my batts recharge much faster, and because of the low resistance in the batts, they do not get hot when charging like the wet cells would.  Personal experience that parrallels what Lifeline says about their AGM batts.  Good Luck, TomC

If you re-read you will note that I didn't mention AGM batteries at all.

I referred only to sealed batteries and gel batteries. Sealed batteries I suppose could describe a whole variety of types, but as Sean says (and as I assume the original poster meant) I was describing a 'conventional' wet battery that cannot be topped-up (sold as 'maintenance-free' or whatever). A gel battery as I understand it is fundamentally similar in design, but the liquid is 'gellified' to overcome the various problems with having liquid acid sloshing about.

As I understand it (and this is probably an oversimplification etc etc) the 'gel' electrolytes by their nature limit the rate at which the battery can be safely charged, when compared to batteries of a similar capacity / plate area etc with a conventional liquid electrolyte. The lifespan of a sealed battery, on the other hand, will be considerably shortened by fast charging simply because any electrolyte lost cannot be replaced.

Other than sharing those two points I don't have any particular axe to grind in this discussion, and am quite happy to believe that AGM batteries are totally wonderful things, if that has been your experience. My knowledge about batteries is limited to what I have read or been told - which, I admit includes the 'Sterling Power' piece, which I came across months ago when I was looking into this issue myself. I agree that it is badly written and, as it happens, I spoke to the author on the 'phone once and was disappointed by his very brusque approach to customer enquiries. However I did take the essential points of the article 'on faith', mostly I expect because it seemed unbiased - which it is, insofar that the guy doesn't sell batteries for a living.

I also suspect that reading the Sterling Power article was 'pushing an open door' with me, because I was already biased against spending the large amount of extra money that would have been necessary to go the 'gel' or AGM' route - I dare say if I had been seriously considering those options (if, for example, I was relying on the battery bank as a liveaboard) I would have done more research and perhaps come across information that discredited the Sterling Power piece. As it is I hope I am always open to learning new things, or changing my opinion based on new information!

Jeremy