Hmmm… When the voltage difference between a charging source and battery being charged is high, the amperage flow is high as well, and vice versa.
The Operation Manual for the EchoCharge says: "When the input voltage is 13.0/25.5 volts DC or higher, echo-charge automatically switches ON. The LED glows a steady green. When the input voltage is lower than 13.0/25.5 volts, the echo-charge automatically switches OFF, and the LED blinks green. The output voltage of echo- charge is limited to 14.4/28.8 volts. When it reaches 14.4/28.8 volts, the charge current will decrease, maintaining a float condition. The starter battery will be fully charged without overcharging. No load current drain on the house bank is less than 50 milli-amps. If the input voltage is above 14.4 volts (or 28.8), output will be limited to a maximum of 14.4/28.8 volts. My interpretation is that when the output voltage of the echo-charge reaches 14.4 volts, it assumes the start battery is full and lowers the applied voltage to float level, around 13.5. This reduces the charge current and keeps the electrolyte in the battery where it belongs. I suggest looking at this paper for more insight into the three stage charging process. http://xantrex.com/documents/Inverter-Chargers/Freedom-458/MS20070308_3-stage-whitepaper.pdf <http://xantrex.com/documents/Inverter-Chargers/Freedom-458/MS20070308_3-stage-whitepaper.pdf> In any event, I have had an Echo Charge unit on my boat since before 2000 and have had the same start battery since then. The house batteries, two 400 series Surrette batteries, finally reached end of service after 14 years. I have installed echo charge units as part of rewiring the primary systems on many boats over the years, and, other than a couple of units that died due to water exposure, they all perform very well and the owners don’t have to do any switching at all to maintain their battery systems. Rich Knowles Nanaimo, BC INDIGO LF38 For sale in Halifax, NS. On Mar 28, 2015, at 10:41, Peter Fell via CnC-List <cnc-list@cnc-list.com> wrote: It also says when the output voltage reaches 14.4 volts, it reduces the output current to maintain a float condition. There’s also a curve in the owner’s manual that relates difference in voltage between banks to output amperage. When the voltage difference is low, the amperage is high and it decreases as the voltage difference increases. From: Josh Muckley via CnC-List <mailto:cnc-list@cnc-list.com> Sent: Saturday, March 28, 2015 10:26 AM To: C&C List <mailto:cnc-list@cnc-list.com> ; Rich Knowles <mailto:r...@sailpower.ca> Subject: Re: Stus-List New Wiring Diagram Draft (Edd Schillay) Rich, Great explanation but don't the other combiners turn off once the starting battery is greater than or equals to the house? As was pointed out to me the echo-charge is simply a voltage follower with a limit of 14.4v. At least one relay style combiner I've seem has an adjustable high voltage shutoff. Josh On Mar 28, 2015 10:51 AM, "Knowles Rich via CnC-List" <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: > I didn’t realize I’d start such a lengthy discussion. Sorry for the late > reply. Work… > > I like the EchoCharge unit for the following reasons: > > When you combine batteries for charging using an automatically actuated > combiner, or by manual switching, all the batteries combined will receive the > same voltage at their terminals. While each battery will absorb different > amounts of amperage depending on their state of charge, a battery that is > fully charged will start losing electrolyte if it is continuously provided > excessive voltage when it is combined with a battery needing high voltage to > efficiently recharge it. > > In a well designed system, the engine start battery should be reserved for > just that and nothing else. Although it will need to deliver high amperage to > the starter, it will do so for only a few seconds to start an engine in > reasonable condition, and that energy can be quickly replenished, usually > within a few minutes. An average size 27 or 24 fully charged battery in good > condition should be capable of starting a 30 hp diesel many times before > requiring recharging. Once recharged, the presence of excessive voltage as > charging of house batteries continues will cause the start battery to lose > electrolyte. If this process is repeated often or long enough, the start > battery will eventually lose enough fluid to be unable to start the engine. > This situation is exacerbated by the use of smart alternator controllers and > multi step AC chargers which cause higher charge voltages to be present than > those produced by internally regulated alternators and simple single voltage > chargers. > > Directing all charge capacity direct to the house battery, and using the > EchoCharge or a similar device to maintain a single purposed, isolated engine > start battery, ensures that the start battery only receives enough charge > voltage to recharge it to full capacity. Barring a failure, there will always > be reliable power to start the engine. Switching should be provided to enable > emergency use of the house battery to start the engine or the engine start > battery to provide house power. > > I have also used EchoCharge units to provide charge power to windlass > batteries installed in the bow near the windlass. That saves a stack of money > for expensive heavy copper wires to feed the windlass from the main house > battery. If you install an EchoCharge, make sure it is in a dry, ventilated, > relatively cool location. It is not waterproof, the principal cause for > failure I have seen. > > Multiple output AC chargers are OK to use but should be carefully chosen and > installed. If batteries are in parallel, only one charge leg should be > connected to that bank. If an automatic combiner is used, only one battery > charging source is required. For systems I design, I use a single output > smart charger to charge the house battery and rely on devices such as the > EchoCharge to distribute charge current as needed to start and other > auxiliary batteries, one device for each battery. That charger is connected > to the same point in the system as the alternator, as are any wind generators > and solar panels on board. > > As an aside, I’m intrigued by the discussion about installing ever larger > battery banks. Is this based on real calculated daily need, inefficient > charging systems or other factors? Average daily power consumption for our > boats including refrigeration, modern nav gear, sailing instruments, lighting > and entertainment should not exceed 150 A/hrs per 24 hour period and > generally will be much lower. A well maintained 450 A/hr house battery bank > should be plenty in my opinion. More than that is excessive weight that > simply slows down the boat and extends time between longer charges. > > Controversy is welcomed! > > Rich Knowles > Nanaimo, BC > INDIGO LF38 > For sale in Halifax, NS. > > > > > > Rich Knowles > Nanaimo, BC > INDIGO LF38 > For sale in Halifax, NS. > > > > > > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com <mailto:CnC-List@cnc-list.com> > To change your list preferences, including unsubscribing -- go to the bottom > of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > <http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com> > > _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
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