Hi Eric,
Will slower charging ie solar panels reduce cycle life? While I have not any testing done in this area, it is possible, if the charge rate is interrupted by nightfall and the batteries are not protected by desulfators.
Sulfation is a problem that can be cured with desulfators. What can not be cured is the permanent damage caused by overheating a cell with high charge rates. Even moderate charge rates will damage a sulfated cell as it causes overheating.
Often, equipment manufacturers design systems that return battery driven devices in the shortest time possible. It is a tradeoff between time to return to service and permanent damage (grid corrosion) done by heat.
While slow charge rates are best for battery health, the interruption of a charge while the sun is absent might be a concern as the battery self discharges during this period.
Personally, I would have no problems with absurdly low charge rates provided my battery has a desulfator on it and I am not operating the device until full charge is achieved.
When recovering batteries, I'll use a 1 amp trickle charger with a desulfator on a pair of 400AH L-16's. The trickle charger arrests self-discharge and provides sufficient charge amps to recharge the battery.
Don
--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Richard,
>
> Will slower charging ie solar panels reduce cycle life?
>
> Most battery manufacturers recommend bulk charging rates between 0.10 and 0.40 C, where C = the batteries amp hour rating.
>
> For example, a 200Ah battery should be charged at 20A to 80A. Keeping the batteries closer to full reduces the need for high amp charging. Leaving batteries partially charged, even for a few days, will age your batteries prematurely. If you drained your 200Ah battery to 75% DoD (150Ah), and your panels only produce 5A (250-300W for a 48V system) charging current, you'll only get 30Ah back per day. After the first full day of charging, at sunset your battery will still be 60% discharged and stay that way overnight. 2 days later, you'll still be 30% discharged. I believe that doing this regularly may start to cut into your battery life, others may disagree.
>
> Here's a quote from West Marine on "How to kill a battery":
> Undercharging: Consistently failing to fully recharge batteries leaves them with lead sulfate that hardens on their plates–they become sulfated–and gradually lose their ability to perform. Increased resistance when charging causes falsely elevated voltage readings, essentially fooling the battery charger, leading to further undercharging, in a downward spiral. Beyond a certain point, a sulfated battery cannot be returned to a healthy state, and you need a replacement. Keep your batteries charged, and equalize your wet cell batteries every six to eight weeks in temperate climates, and more frequently in the tropics.
>
> Another knowledgable member here, desulfator, may chip in on restoring sulfated batteries.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
>
>
> --- In electricboats@yahoogroups.com, Richard Mair <fullkeel2000@> wrote:
> >
> > New to the list and my intro e-mail seems to have got lost in space.
> > I thought I had read that T105s could take 80% DOD better than AGMs.
> >
> > Will slower charging ie solar panels reduce cycle life?
> >
> > If this goes thru I will send more intro details
> >
> > Richard
> >
>
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