Xantrex Echo Charger: current limiting feature - SailNet Community
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post #1 of 29 Old 10-29-2019 Thread Starter
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Xantrex Echo Charger: current limiting feature

Most people consider its 15A ceiling a limitation.

In the case of even a small LFP bank, drawing its charge current from a high-amp power source that only has "latching" or "hiccup" over-current protection,

I'm thinking such a device could be useful to protect both the source, and the bank from a stressful charge rate.

15A would be just fine for a pack size between say 40Ah (smaller in warm temps if fast charging is desired) up to say 100Ah if a slow rate is acceptable.

I am aware of the other various features/limitations of the EC, so please do **not** divert the thread about those, keep it to current ampacity issues only.

My question:

Is there an upper limit to "current available" on the input side, where the current-limiting component(s) in the echo-charge begins to get stressed, reducing its reliability / lifespan?

For example, a 200+A large-frame alternator + stock VR, with the engine at high rpm.

I assume the same ampacity factors apply whether used with a nominal 12V or 24V circuit

TIA

Last edited by john61ct; 10-29-2019 at 05:42 PM.
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post #2 of 29 Old 10-29-2019
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Re: Xantrex Echo Charger: current limiting feature

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Originally Posted by john61ct View Post
Most people consider its 15A ceiling a limitation.

In the case of even a small LFP bank, drawing its charge current from a high-amp power source that only has "latching" or "hiccup" over-current protection,

I'm thinking such a device could be useful to protect both the source, and the bank from a stressful charge rate.

15A would be just fine for a pack size between say 40Ah (smaller in warm temps if fast charging is desired) up to say 100Ah if a slow rate is acceptable.

I am aware of the other various features/limitations of the EC, so please do not divert the thread about those, keep it to current issues only.

My question:

Is there an upper limit to "current available" on the input side, where the current-limiting component(s) in the echo-charge begins to get stressed, reducing its reliability / lifespan?

For example, a 200+A large-frame alternator + stock VR, with the engine at high rpm.

I assume the same ampacity factors apply whether used with a nominal 12V or 24V circuit

TIA
The echo charge is connected between batteries. On Shiva all charging sources charge the 500 AH AGM house bank and the house charges the 55 AH AGM start bank. I don't believe the Echo charge "sees" the voltage or the current of these charging sources...

15 A maximum charge current
Automatically adjusts for 12 or 24 volt battery banks (both battery banks must be the same DC voltage and battery type)
Automatically switches on/off without affecting the in-house battery bank or over-charging
Utilizes excess current from the primary charging source
Built-in thermal and over-current circuits

pay attention... someone's life depends on it
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post #3 of 29 Old 10-29-2019 Thread Starter
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Re: Xantrex Echo Charger: current limiting feature

Thanks, as I said I already have all that down,

just that one question there is (still) outstanding.

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Originally Posted by SanderO View Post
I don't believe the Echo charge "sees" the voltage or the current of these charging sources...
Not sure what you mean, but given a lead-only setup, charging from the source to target side only happens when a charge source is active.

That is of course the whole point of all such combiner/isolator type units, (should) in a normal use case prevent the source-circuit battery from getting discharged by the target side when voltage falls below 13V. Actual battery-to-battery energy transfers are **very** wasteful.
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Re: Xantrex Echo Charger: current limiting feature

John,
They may be wasteful... but I have a small solar charge on all the time or the alternator when the engine runs... no charge at night.

The start batt is used so little and seems to be fully charged all the time.

This works for me and don't see the need to push a lot of amps into the start batt.

I can't answer your question, but I can tell you that this approach works for me. I only turn both batt switches to on when I come aboard and everything works in the background.

pay attention... someone's life depends on it
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Re: Xantrex Echo Charger: current limiting feature

OK thanks.

I don't mind letting the thread sit a bit until someone with an answer to that one specific question comes along.
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Re: Xantrex Echo Charger: current limiting feature

I don't understand what you are asking. As explained, the echo charge sits between two batteries and is a voltage follower with a 15A current limit.

How much maximum current each side of it could supply is irrelevant. Even a small car battery can provide tremendous current. There is no practical difference in this regard between a small car battery and a large LFP bank.

Putting huge amounts of current into the battery on one side of the echocharge doesn't effect in any way how the echocharge works - it is a voltage follower. The battery itself is the current sink - not the echocharge.

Mark
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Re: Xantrex Echo Charger: current limiting feature

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I don't understand what you are asking. As explained, the echo charge sits between two batteries
The EC sits between two circuits, and current passes through it.

For a clarifying thought experiment, imagine only a PSU (without current limiting itself) on the source side circuit, the only bank is a large LFP on the target side, none exists on the source side.

So the PSU being capable of delivering (A) 200A, as opposed to (B) 20A.

The LFP is trying to suck 1000A through the 15A straw. Which a lead Starter bat would not.

Is there any significant extra stress (reduced reliability / longevity) on whatever component(s) are limiting the current within the EC

under scenario A, as opposed to scenario B?

IOW, is the fact that the EC is "filtering down" to that maximum 15A rate more "effort"

when a very high rate is both demanded from the target side, and also

potentially available from the source side?

If your answer is "I don't know" that is of course just fine.
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Re: Xantrex Echo Charger: current limiting feature

I think you are complicating your question and misunderstanding how electricity works.

LFP doesn't "suck" current, it just accepts whatever it can get. People's chargers do not burn out, dry up, or cave in because of the giant sucking LFP does on them. Likewise, LFP has so far failed to suck our solar panels off the roof.

A lead start battery can take more than 15A for sure, so it has the same possibility of overloading the echocharge under your thesis. However, it does not. For the same reason that an empty 1000Ah LFP bank will not.

There is no sucking, nor pushing going on there. It isn't how electricity works in a current limited voltage follower.

Mark
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Re: Xantrex Echo Charger: current limiting feature

So your answer is no problem?

I'm not going to argue with you on the rest, thanks for contributing.

If others come along, please keep the focus on the question asked.
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Re: Xantrex Echo Charger: current limiting feature

If it helps, instead of thinking of the echocharge as having its shoulder against the door trying to limit the pushing hoards of amps to just 15 getting through - think of it as requesting 15A to be given to it.

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