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Old 06-12-2012, 07:23   #16
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Re: Digital Duo Charge?

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Originally Posted by colemj View Post
Buy an inexpensive "normally open" relay, hook the coil leads across your solar panel outputs and the closed load leads across the power for your duo charge.

Then when the sun comes up, the duo charge is powered, and when it goes back down, the power is shut off.

Mark
Ah I think I get it, Boulter wants to use the duocharge using solar power, not engine power?

The relay should work to power it down when the sun is not out.
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Old 06-12-2012, 08:50   #17
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Re: Digital Duo Charge?

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Originally Posted by sailinglegend View Post
You know this will not do the same thing so why keep posting wrong information to try and promote your product?

I have been looking carefully at all three products and none of them actually do the same thing as each other.

The Balmar seemed to be the best because it is a 4 stage charger that will drop the starter battery, or bowthruster, down to float mode when the battery is charged. This will stop any overcharging. The Sterling seems to be designed to be connected to the starter battery first. It then "sucks" power out of an non-regulated alternator and delivers 4 stage charging to the service bank. The EchoCharge is simply a "voltage follower" that has a small volt drop so could overcharge a starter or bowthruster battery. Only when the service battery falls to a float voltage will the EchoCharge follow.

If the problems with the Balmar are true then non of these products seem to do the job properly.
From Echocharger manual: http://www.xantrex.com/documents/Acc...204-01-01).pdf


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.
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Old 06-12-2012, 09:06   #18
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Re: Digital Duo Charge?

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Originally Posted by cal40john View Post
.....When it reaches 14.4/28.8 volts, the
charge current will decrease, maintaining a float condition.........
It maintains a "Float Condition" because the battery acceptance decrease as its charge increases - it is nothing to do with the EchoCharge. Many people on here have made the same mistake.

See also in the manual:

"The Digital echo-charge is a voltage-follower, following the three-stage charge modes of the Freedom Charger. This method protects the starter battery from over-charging and ensures a long life for the battery. If using another charge source, the Digital echo-charge will follow the charge stages of the source. Refer to the source’s Owner’s Manual for charge modes."


The EchoCharge is a voltage follower not a multi-stage charger.
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Old 06-12-2012, 09:10   #19
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Re: Digital Duo Charge?

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Originally Posted by Maine Sail View Post
....I have also installed many of these still never had a single issue with "short start battery life" or one fail or cause the issues you purport will happen......
Thank-you for your detailed post - but you seem to have hijacked the thread into an argument about overcharging starter batteries - which I never mentioned.

If a battery combiner or VSR, or 1-2-both switch joins the two banks together then why do we need much more expensive units like the Balmar or the Sterling which do actually drop down to a float voltage when they detect the starter battery is fully charged. This is likely to be a long time before the service bank is charged, especially if it is very much larger than the starter battery.

You suggest that its not a problem with a 60$ starter battery, but my 150$ Red Flash AGM starter I think deserves a little more protection. A much more expensive Bowthruster bank also deserves more consideration.

The theory says that batteries determine their own charge current, so when fully charged the current will be down to nearly zero - fine in practice too - but theory also says that batteries gas at 14.4 volts - when they are fully charged. Overcharging in my book is not providing more current or voltage than they want, but holding that voltage at the batteries gassing voltage for too long.

My 37 Ah Red flash will be fully charged very quickly, whilst my 1050Ah service bank is still at an absorption voltage of 14.4 v for another 7 hours.

So can anyone explain why - in practice - it is OK for a battery to sit at 14.4 volts for 7 hours when fully charged, and why Odyssey Batteries say that their warranty is void if batteries are not charged with a regulator that goes to float when the batteries are fully charged - at a voltage of less than 13.8 v.
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Old 06-12-2012, 11:26   #20
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Re: Digital Duo Charge?

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Originally Posted by sailinglegend View Post
It maintains a "Float Condition" because the battery acceptance decrease as its charge increases - it is nothing to do with the EchoCharge. Many people on here have made the same mistake.

See also in the manual:

"The Digital echo-charge is a voltage-follower, following the three-stage charge modes of the Freedom Charger. This method protects the starter battery from over-charging and ensures a long life for the battery. If using another charge source, the Digital echo-charge will follow the charge stages of the source. Refer to the source’s Owner’s Manual for charge modes."


The EchoCharge is a voltage follower not a multi-stage charger.
At first I thought your were saying that the Echocharger would overcharge the start battery since it is only a voltage follower. Reading more carefully I see you were referring to the Combiner. Yes it is a voltage follower, but with a max voltage setpoint so it won't overcharge the start battery.
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Old 06-12-2012, 11:36   #21
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Re: Digital Duo Charge?

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Originally Posted by sailinglegend View Post

The EchoCharge is a voltage follower not a multi-stage charger.
The Duo Charger does the same thing as the Echo with the exception of an adjustable secondary voltage cap setting.

The Duo Charger does not do three or four stage charging it "follows" a 3 or 4 state regulator. BUT, it allows a second adjustable max voltage set point on the output side, which the Echo Charger does not.

The Echo simply caps the voltage output at 14.4V + regardless of the supply side input, plus the inherent voltage drop in the unit.. The Duo will only go into "float" when the main regulator does otherwise it is capped at what you set it for until the main regulator goes into float...

I know the Duo manual is confusing on this. As far as I know the only one of these products that can go into float, independent of the main regulator, is the Sterling B2B charger. You could program the Duo to permanently cap at GEL or custom if you want but this is not an "absorption/float" scenario...
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Old 06-12-2012, 12:06   #22
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Re: Digital Duo Charge?

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Originally Posted by Maine Sail View Post
....The Duo Charger does not do three or four stage charging it "follows" a 3 or 4 state regulator....
I've been researching these systems for a longtime and got my information from the most well respected dealer in the UK. They say:

"the Slave unit will switch on and deliver a proper 3 stage smart charge to the battery - it's like a DC in/DC out battery charger."

I agree that the Balmar manual, which I have now downloaded, doesn't say - three stage charging, and I find this confusion - and that from EchoCharge - totally unacceptable.

So what is the Balmar "second adjustable max voltage set point on the output side"?"

How is the average skipper mean't to make any sense of all this - I know, he gives you a call and you sort it out!
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Old 06-12-2012, 15:16   #23
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Re: Digital Duo Charge?

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Originally Posted by sailinglegend View Post

You suggest that its not a problem with a 60$ starter battery, but my 150$ Red Flash AGM starter I think deserves a little more protection. A much more expensive Bowthruster bank also deserves more consideration.

The theory says that batteries determine their own charge current, so when fully charged the current will be down to nearly zero - fine in practice too - but theory also says that batteries gas at 14.4 volts - when they are fully charged. Overcharging in my book is not providing more current or voltage than they want, but holding that voltage at the batteries gassing voltage for too long.

My 37 Ah Red flash will be fully charged very quickly, whilst my 1050Ah service bank is still at an absorption voltage of 14.4 v for another 7 hours.
A fully charged start battery, when combined with an uncharged house bank, will not be at bulk or absorption voltages until the entire combined bank reaches those voltages.

Seven hours past reaching absorption voltage for AGM batteries seems like excessive charging. If you aren't worried about your house bank gassing at 14.4V for 7hrs, why are you worried about your start battery being treated the same?

It doesn't matter how fully charged the start battery is at the beginning, it only sees the voltages the entire combined bank sees during the charge cycle and it regulates its current acceptance independently of the house cells.

So you can happily send 100A or more charge to the combined bank during the 13.0-14.4V bulk regime, and the fully charged start battery will only accept a fraction of an amp and never reach gassing voltage until the entire bank reaches gassing voltage.

At that point, I would be more concerned about the environment of the expensive house bank than the less expensive start battery.

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Old 06-12-2012, 23:45   #24
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Re: Digital Duo Charge?

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Originally Posted by colemj View Post
A fully charged start battery, when combined with an uncharged house bank, will not be at bulk or absorption voltages until the entire combined bank reaches those voltages.

Seven hours past reaching absorption voltage for AGM batteries seems like excessive charging. If you aren't worried about your house bank gassing at 14.4V for 7hrs, why are you worried about your start battery being treated the same?

It doesn't matter how fully charged the start battery is at the beginning, it only sees the voltages the entire combined bank sees during the charge cycle and it regulates its current acceptance independently of the house cells......
Your response suggests that you do not fully understand battery charging curves. Yes batteries limit the current they will accept, but battery gassing is all about voltage. Gassing is good for batteries to mix the electrolyte, but not excessive gassing. Sealed batteries can die quickly with over gassing because the water lost cannot be replaced.

I suggest your read this link:
Deep Cycle Battery FAQ

Put simply during the boost stage the voltages rises slowly to the pre-set voltage limit (about 14.4v). It stays at this "Absorption Voltage" for a time set by the regulator - say 4 hours - and then the voltage drops to a "Float" of 13.2-13.8v to avoid gassing. On a good regulator all these parameters are adjustable and you should set them to match the capacity and type of your batteries.

So the batteries are sitting at their gassing voltage of 14.4 volts for 4 hours or more with no problems, there can be a very small amounts of gassing but the electrical energy from the current is charging the batteries. It is only when the batteries are fully charged, and sitting at the gassing voltage, that this current will causes the batteries to gas heavily. By reducing the charge voltage from 14.4v to 13.8v gassing will stop. It is worth noting that gassing voltage are based on battery temperature. 14.4v of 25 Deg C - 13.98v at 40 Deg C. It is also worth noting that batteries gas when discharged heavily too!
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Old 07-12-2012, 07:21   #25
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Re: Digital Duo Charge?

Nothing in that article that I could find supports your thesis. It simply describes how multistage charging works and the different types of batteries available.

Your response suggests you did not understand what I wrote or the experiences of those of us who have operated this way. The absorption voltage will not be reached by the start battery until the entire bank reaches absorption voltage. That is a fact.

Once the absorption voltage is reached, all the batteries are potentially gassing (if the voltage is at the gassing point). There is nothing special about a completely charged battery vs an undercharged battery at this point - each will take just enough current to maintain this voltage. For the house bank, that may be 100A and 0.5 amps for the start battery.

At this stage, if gassing is occurring, it will occur equally for all batteries because it is the current in each battery that is holding the voltage. Like the example above, that may be only 0.5A for the start and 100A for the house, but they are both being gassed equally for the same amount of time. If you are worried about your start battery here, you should also be concerned for the house bank.

Actually, I know from experience with our batteries during absorption that the start battery at 0.5A will be gassing much less than the house batteries at 100A. Our start batteries need water once every 5 years compared to every 6 months for the house bank (both are flooded and charged at 14.8/14.8/13.2V).

I also know from direct experience that we keep our start batteries charged using combiners and have never overcharged them or shorten their lives. As I wrote earlier, our last set of start batteries lived 13yrs under this charge regime. Mainsail described the same experience with several boats. Andina has also described this often based on many years of experience with this system. Yet you tell use this is impossible based on your personal understanding of battery chemistry and not on any actual experience or fact.

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Old 07-12-2012, 08:41   #26
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Re: Digital Duo Charge?

Sailinglegend,

If you want to PM me I will be glad to share more information about Odyssey batteries with you that I will not post on-line for fear of it being taken out of context or misinterpreted.. I have spent a great deal of time talking with Odyssey engineers (like Kalyan J.) over the last few years and there is a LOT of info that is not in their tech manual.

Suffice it to say that every Wal*Mart truck in the USA uses Odyssey batteries. These alts are 14.4V+/- for hundreds of thousands of miles. The Sears Die Hard Platinum series are also Odyssey batteries. They are so reliable for Sears that Sears puts a 3 year full warranty on them. Most cars in the US run 14.2V - 14.6V alternators. On 14.2V regulated cars Odyssey batteries actually die sooner than with cars regulating to a higher voltage.This comes directly from a conversation with Kalyan J. at Odyssey.

Remember these batteries can be charged as high as 15V with 14.7V being the preferred absorption voltage. I have two cars in my driveway that are 14.4V+ regulated a Honda and a Subaru. Our BMW convertible was 14.5V steady... The Honda currently has 155k on her and has the original Honda factory wet cell and the Subaru has 144k and also has the factory battery.

As I have explained "combining" or the uses of "Echo" or "Duo" chargers does not lead to shorter starter battery life, that I have been able to measure. The start batteries always far outlast the house bank, as they should...

There are many more pressing issues you should be concerned about with Odyssey batteries such as making sure that with deep discharges you have as close to 40% of "C" charge current and that you are charging them at 14.7V. Chronic undercharging, resulting in sulfation, is far more of the cause of death in boat batteries and I can't recall the last time it was due to over charging, even with starting batteries.

Again the real world is often quite different than "in-theory".....
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Old 07-12-2012, 08:53   #27
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Re: Digital Duo Charge?

+1 Maine Sail's Post #26

I have extensive experience with thin plate pure lead (TPPL) AGM batteries which are more energy dense than Odysseys and a bit more temperamental regarding absorption voltage and, equally important, absorption time. That said, AGM batteries, in general, are murdered (they don't "die") by insufficient absorption voltage and inadequate absorption time leading to chronically under charge batteries leading to sulfation, electrolyte stratification and an early death.

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Old 07-12-2012, 09:00   #28
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Re: Digital Duo Charge?

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+1 Maine Sail's Post #26

I have extensive experience with thin plate pure lead (TPPL) AGM batteries which are more energy dense than Odysseys and a bit more temperamental regarding absorption voltage and, equally important, absorption time. That said, AGM batteries, in general, are murdered (they don't "die") by insufficient absorption voltage and inadequate absorption time leading to chronically under charge batteries leading to sulfation, electrolyte stratification and an early death.

Charlie
The Odyssey battery is a TPPL battery. EnerSys/Odyssey invented the TPPL technology...
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Old 07-12-2012, 13:39   #29
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Re: Digital Duo Charge?

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Hi:

They do a pretty good design on this, then they shoot themselves in the foot with the parasitic load of 500mA in sleep mode unless you manually switch it off.
Boulter
I forgot I had one in the shop so I connected it and measured it. Beats reconnecting a customers battery bank and doing this on the boat...

In sleep mode it draws between 0.036A & 0.043A or just about 1A per day in standby mode. It usually hoovered around 0.040A - 0.041A or 40mA - 41mA, which is about the same as the Echo Charger.

Interestingly enough it does not draw much more when ON & passing current than when sleeping. This is very good for those with solar systems as the current to power the Duo is about 0.04A even when ON...

0.04 X 24 Hours = 0.96Ah per day
0.96 X 7 Days = 6.72Ah per week


Below is a shot showing it doing its thing. I left it on charge for about 6 hours with an absorption voltage for the "house bank" at 14.7V and the Duo set to the GEL setting.

You can see the Duo limiting the voltage to the "start" battery when in the GEL setting. It will not go into "float" until the "house bank" does because it is a voltage follower with a voltage limit. Right now it is limiting the voltage to the start battery to 14.1V but the house battery is getting 14.7V...

Left DVM = Start Battery voltage
Middle Clamp DVM = Current flowing to Start Battery
Right DVM = Duo Charge Power consumption

Power Supply Left Reading = Current to House Bank
Power Supply Right Reading = House Bank voltage set point
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Old 07-12-2012, 15:34   #30
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Re: Digital Duo Charge?

Sorry, in my post above I stated that the "sleep" current for the Duo Charger is roughly 0.04A and that was incorrect. It is actually less.

When sleeping the draw of the Duo Charge is between 0.014A & 0.017A. I must have inadvertently hit my power supply on and the surface charge on the "house bank" must have been over the turn on voltage of 13.0V... I was not watching the house bank voltage carefully enough and paying more attention to the "start bank"...

So, current usage for the Duo Charger is as follows...

ON (house bank above 13.0V) = 0.036A - 0.043A
SLEEP = 0.014A & 0.017A

Sorry for the error....
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