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From: Flying_Cloud (no email)
Date: Fri Aug 20 1999 - 13:27:09 EDT
Randolph
In addition to all of the advantages of gels over flooded:
And add to all of that:
- AGM lifespan is double the number of deep cycles as Gels
- AGMs don't have the voltage sensitivity that Gels have
- AGMs accept 25% more amps in charging than Gels
Sandra
> -----Original Message-----
> From:
> [mailto:]On Behalf Of Randolph
> Stroschein
> Sent: Friday, August 20, 1999 12:39 PM
> To: liveaboard
> Subject: Re: lv-ab: Battery Charging: How Charge Large House Bank?
>
>
> I beg to differ. There are several advantages to gel over flooded (wet).
>
> 1) They hold their voltage longer through the discharge cycle
> than wets. This translates into a lower rate of discharge as you
> approach the 50% level, because to supply, say 60w, takes only 5A
> at 12v, but takes 5.22A at 11.5v.
> 2) They tolerate a much greater level of discharge. Wets should
> not be discharged below 50% (on a regular basis, once or twice
> probably is no big problem). Gels can regularly discharge to 75%.
> 3) Gels have a much greater USABLE capacity (largely due to 1 & 2
> above). A local chandlery, known for their technical expertise,
> did some testing of their own to satisfy their curiosity. They
> took 2 different manufacturer's wet cells and a Pow-R-Surge
> (Prevailer in the USA) 8D's and ran several iterations of the 20
> hour discharge test on them. The wets were rated at approx 225AH
> and the gel at 200AH. After several discharges, they discovered
> the wets only provided approx 175-185AH and the gel 220AH !!
> This leads to the proper capacity comparison of 50% x 185AH vs
> 75% of 220AH. In other words, the wet cells yielded 92AH USABLE
> capacity and the gel 169AH. If you apply that relationship to
> physical size and sticker price, you get a whole different
> appreciation of value.
> 4) They are MORE resilient to abuse. You flatten a wet cell a few
> times and it is NOT coming back. A gel doesn't like this either,
> but they can be crowbarred multiple times and returned to full
> life. In fact, this is the recommended way to rejuvenate one if
> it has been severely abused by many, many, many very shallow
> discharge cycles (hysterisis (sp?) developed).
>
> If you take all this in addition to the mounting flexibility
> (don't have to worry about charging gasses), minimal/no
> maintenance (a big thing in my mind), safety (no acid spills,
> like during a knockdown), and ability to accept a MUCH higher
> charge rate (meaning with a high cap alternator, reduced run time
> to recharge), the gel represents a far superior solution.
>
> The only potential concern IMO is that gels are more sensitive to
> correct charging regimen. High/incorrect charge voltage can wreck
> them faster then wet cells. However, in this day and age of
> sophisticated chargers and regs, that should not be a problem.
>
> I have no comment on AGM's as I have no direct experience with
> them, but from what I've read and heard, everything said above
> about gels applies to AGMs, but better/more. When I have to
> replace batteries, I will likely go AGM.
>
> Disclaimer: all battery manufacturers are NOT alike. The above is
> not intended to include extraordinary wets like Surrette. Gel
> quality varies significantly and I have been referring to East
> Penn batteries, the best AFAIK. I am not affiliated with any etc etc etc.
>
> All the above is based on my own research and experience. I have
> 3 x 8D East Penn gels, with a 147A Ample alternator, Smart
> regulator, EMON II, and Heart Freedom 10. Fantastic system, I am
> most pleased. It has been installed and running for approx 6 years.
>
> Regards.....Randy
> mv Island Time
>
> ----- Original Message -----
> From: Pierre Mitham <>
>
> > Sandra,
> >
> > Unfortunately your comparison of gel vs. Flooded batteries is incorrect!
> > The primary advantages of Gels over flooded are mounting
> options, and charge
> > acceptance. They certainly don't last as long as a comparably priced
> > flooded, they can't be brought back to life as reliably. Gel's
> can however
> > survive user abuse more often. Flooded batteries are far
> supperior in most
> > cases,IF you learn how to take care of them (water them,
> measure specific
> > gravity each month, and equalize them occasionally) dollar for
> dollar, you
> > get more Ah's per $ with a flooded battery, a little common
> sense and flood
> > batteries will last many years. People who replace marine
> batteries every
> > season on 2 are usually murdering there batteries. draining
> them too far,
> > and using an automotive charger to charge (really bad!)
> >
> > Pierre.
> >
> > ----- Original Message -----
> > From: Flying_Cloud <>
> > To: <>
> > Sent: Thursday, August 19, 1999 10:48 PM
> > Subject: RE: lv-ab: Battery Charging: How Charge Large House Bank?
> >
> >
> > > I have a similiar setup; and my responses reflect on how I'm
> doing it. I
> > > have a Lehman as well (135hp); Heart 2500 (just upgraded to
> the new 3000);
> > > Link2000r (Cruising Equip upgraded it for me free of charge);
> Balmar 200
> > > amp; Had 4 gel cells 8Ds (banks 7 and 8 years old so upgraded
> to AGMs).
> > > Here are my thoughts.
> > >
> > > Why are you going with golf cart batteries? Regular lead
> acids can only
> > > absorb 25% the rated amp hour capacity; gel cells 75%; and
> AGMs 100% of
> > > capacity (AGMs can take twice as many deep cycles as gels which is way
> > more
> > > than reg lead acids). Also AGMs are 155 amp/hr per 8D which
> is 55 more
> > > amp/hr than a gel 8D. (I paid $134 per 8D) Going with
> regular lead acid
> > > rather defeats the purpose of going with a high output
> alternator because
> > > they cannot absorb the amp the high-output the alternator
> puts out. If
> > you
> > > are insistent on going with the golf cart batteries - save
> yourself a lot
> > of
> > > money - and put a smaller capacity alternator on it.
> > >
> > > I have a Lehman 135 (almost the same as the 120) and I had
> (because the
> > > engine is out of the boat right now) mounted the Balmar 200 amp
> > alternator -
> > > only I use only one belt. I checked with my mechanic at the time of
> > > purchase and he seemed to think this would be okay - just
> that I will go
> > > through the belt a bit faster (since I never gone through one - seemed
> > > reasonable to me). I have only done an overnight passage
> since then so I
> > > have no real data to support the mechanics advise. You know
> how it goes -
> > > there are more opinions that you know what.
> > >
> > > Delco make a 140 amp which is single belt driven as well, as I'm sure
> > other
> > > manufacturers do too. I had one of those too. Actually in
> practicality,
> > the
> > > 140 amp alternator was sufficient for my draw on a 54 footer
> - even with
> > the
> > > 3/4 hp ac refrigeration running on top of the stereo and all
> the cruising
> > > load etc. (the partial flooding is the reason for its demise).
> > >
> > > Question re the alternator on the genset: I presume you were
> only talking
> > > about doing this if you could not put the high output
> alternator on the
> > > engine. I I see no reason why you have to buy another charger
> - go with
> > the
> > > alternator on your engine even it's a bit smaller than you'd
> like - for be
> > > my advise. As for an alternator on the genset - why have one?
> - when the
> > > engine is not running why not use the generator to run the
> Heart 175 amp
> > > battery charger on the inverter to do the work? This is what I've been
> > > doing.
> > >
> > > Anyway you can add this to your list of opinions.
> > >
> > > Sandra
> > >
> > >
> >
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