AGM/Gel Hybrid Batteries.

waveboy32
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Re: AGM/Gel Hybrid Batteries.

Postby waveboy32 » Thu Sep 24, 2015 8:35 am

Hey Mike

I am also going through the process of specifying a from scratch 12v system for my caravan. I was originally looking at the Ctek250s also, however Yachty pointed me in the direction of this nifty piece of kit from Aussie http://enerdrive.com.au/product/dc-to-d ... y-charger/

It seems to have a couple of significant benefits over the Ctek, first it is 30 amp out of the box which in my set up I think will be enough. It also takes input voltage up to 32V so brings some of the larger panels back into play. Probably most interestingly for your situation it appears to have the ability for custom setting of voltage outputs. Might be worth a look for you.

Grayson
2001 7.0m Traillite Caravan

divxmaster
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Re: AGM/Gel Hybrid Batteries.

Postby divxmaster » Thu Sep 24, 2015 3:15 pm

Hi Grayson,
Thanks for pointing that out,
that's a very interesting bit of kit, although you pay for it!
I found it online on sale of $499AU.

You can get the 250S for $255AU on ebay and the Smartpass for $255AU also. My latest plan is to
get just the D250S and wire it up leaving space for a smartpass. Then I can see how basic 20A charging
from the D250S works out (or more accurately, how well my solar system charges, meaning how much
charging is required from the alternator).
If I am regularly finding I need alternator charging, then I can look at adding the smartpass and get
80A charging. Not sure if I want to load up the alternator with this much draw. Pity you cant set
the amps in the smartpass like you can in the enerdrive.
Although I cant find any info on the max panel for a D250S, I presume it is around 350w. 20A x 18v.
I'm looking at probably a 250w panel.

I notice the enerdrive has an ignition feed, so not sure if it includes a VSR. It says optional on the feed, which
seems to make no sense. I have read a thread about a new vehicle running CANBUS (which most cars from 2004+ do),
and apparently it can be very hard to find an alternator on +12v with these, even the alternator connects directly into
the cpu for voltage regulation.

Cheers,
Mike.

Neddy
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Re: AGM/Gel Hybrid Batteries.

Postby Neddy » Thu Sep 24, 2015 6:15 pm

"If I am regularly finding I need alternator charging, then I can look at adding the Smartpass...."
If you are regularly finding you need alternator charging..... you need more solar power.
This can be achieved by raising the output of your existing panel(s) or by adding more panels.
Increasing the output of existing panels is quite simple - all you need to do is raise the charge voltage
(up to a 14.9 volt maximum).

"..... then I can look at adding the Smartpass and get 80A charging."
You wish! There is only one way to increase the charge current, and that is by increasing the charge voltage.
With its charge voltage pinned at 14.4 volts, this is not an option with the Ctek, however.

"Not sure if I want to load up the alternator with this much draw."
Worry not - it isn't going to happen. Ever. With the charger limited to 14.4 volts, charge current is held at a relatively low level - especially so in the Absorbtion charging phase.

"I can't find any info on the max panel for a D250S, I presume it is around 350w. 20A x 18v. I'm looking at probably a 250w panel."
It really doesn't matter what the maximum is because regardless of how much solar capacity you add, the Ctek is limited to a 20 amp output and the input will be correspondingly restricted to an equivalent figure. It's just the same with an alternator or generator input. You could hook up a 100 kilowatt generator if you liked - but the controller output will never be more than its capped maximum of 20 amps, and most of the time it will be a LOT less than that.

There are quite a few very good quality DC-DC chargers available but all are relatively expensive.
To my mind, they are only worth the expense if :-
(1) You have inadequate solar power and
(2) When running the motor, you need the maximum possible charging input at all times
(ie, there is a very substantial deficit).

Neville.

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Re: AGM/Gel Hybrid Batteries.

Postby divxmaster » Thu Sep 24, 2015 7:16 pm

Hi Neville,
How I understand the smartpass to work, is it is capped at 80A and the D250S caps
at 20A. When using the smartpass the d250s is not used, except as a solar feed.
The smartpass has a VSR that only enables it at low BULK voltage. As soon as the voltage
is above bulk, the input is passed through the d250s and drops to 20A Max.

Are you sure the smartpass cannot pass 80A? From all the reviews of the various dc-dc
chargers, sterling etc, they do pass that much from the alternator, or the maximum the
alternator can produce?

As mentioned previously, I can see alternator charging required if you park up for
a day or two and there is no sun and your batteries are 50%. You have no choice, either
alternator charge or plug in a 240v charger at a campsite with associated cost.

Cheers,
Mike.

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Re: AGM/Gel Hybrid Batteries.

Postby markcraven » Thu Sep 24, 2015 7:33 pm

Hi Mike I have both a D250S and a SmartPass and have had both for over 4 years. I can confirm that when my 400Ah lifeline AGM batteries are around 50% the Smartpass pushes in 80+ amps according to my battery monitor (via a shunt) but then reduces down as they accept the charge like all lead acid batteries do.
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Re: AGM/Gel Hybrid Batteries.

Postby divxmaster » Thu Sep 24, 2015 8:25 pm

markcraven wrote:Hi Mike I have both a D250S and a SmartPass and have had both for over 4 years. I can confirm that when my 400Ah lifeline AGM batteries are around 50% the Smartpass pushes in 80+ amps according to my battery monitor (via a shunt) but then reduces down as they accept the charge like all lead acid batteries do.


Great, thanks, I was going to post a thread asking you specifically about them, as I saw you had the combination.
How do you find them? any downsides?

Cheers,
Mike.

edit: just found this video https://www.youtube.com/watch?v=aN6oF-wj9XQ
explaining the complete operation of the d250s/smartpass. It is even more complicated/clever
than I thought. I passes BOTH the 20A from the D250S and the 80A from the smartpass at the
same time. So up to 100A.

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Re: AGM/Gel Hybrid Batteries.

Postby Neddy » Thu Sep 24, 2015 9:44 pm

"Are you sure the Smartpass cannot pass 80A?"
I'm quite sure that it can.
I'm equally sure that your battery too could pass an 80amp Charge current, but it shouldn't. Ever. EVER.
Quite apart from the fact that your battery's maximum charge rate is probably about half that, consider the Voltage.
The Maximum charge voltage that your battery should be subjected to is specified by the manufacturer as 14.9 volts. Ask yourself this. What would the charge voltage have to be to pass a charge current of 80 amps? I cannot answer this, but I can assure you of one thing. It will be way, way more than the specified maximum of 14.9 volts. I once fitted a home-brew manually variable alternator controller to my boat. I could crank the charge current up to 80 amps, no trouble. The problem of course was that to do so, the charge voltage had to be set to over 20 volts! Boiling the batteries and wrecking on-board electronics would be certainties.

"Do DC-DC converters pass that much from the alternator, or the maximum the alternator can produce?"
Neither. As I say, it is not going to happen (or shouldn't ever happen). They won't take that much from the alternator because that is too much for the battery and the controller should protect the battery from such overcharging. The maximum alternator current is also irrelevant. While it may be a 200 or 300 amp alternator putting that into a battery will quickly destroy it. Again, the controller is there to regulate the charge and protect the battery from overcharging.

"As mentioned previously, I can see alternator charging required if you park up for a day or two and there is no sun."
Some people are surprised to find that solar panels do not need sun. They run on light, not heat.
In fact, solar panel output is higher on days of "bright overcast" than full sun.

"....and your batteries are 50%."
After just a day or two? That would be evidence of insufficient solar power or insufficient battery capacity.
Or both. With 300 watts of solar power and 200Ah House batteries, we can count the number of times we have been as low as 50% on the fingers of one hand - and that's in over 8 years of use. While it is true that we move on almost every day, we do not have to use any engine charging at all, except in extreme conditions that we have experienced only once (deep South in the Winter) and that's never going to happen again!

Mike, the experience of MarkCraven is of little relevance to you and your situation.
(1) His battery capacity is triple what you are considering.
(2) He is using AGM batteries which can take a higher charge current than your (proposed) AGM/Gel battery.
(3) He does not say what charge Voltage he is subjecting his batteries to.
(4) He could have three 12 volt batteries in parallel and the 80 amps that he sees would translate to a quite acceptable 27 amps per battery.
(5) He could be overcharging his batteries, resulting in their reduced life expectancy.
(6) He could have voided his battery warranty by discharging his AGMs so deeply - and charging them at too high a rate as well.

Good luck with that 100amp charge rate Mike.
If you ever see it, you'll wish you hadn't!

If you really do want charge currents that high you should be buying a Lithium battery, not an AGM/Gel hybrid.

Neville.

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Re: AGM/Gel Hybrid Batteries.

Postby nisseven » Thu Sep 24, 2015 11:41 pm

Neville if you had a dedicated house battery alternator that was capable of say 80 amps and you ran it at the same time as you were using an invertor drawing say 180 amps, would the alternator take up some of this draw?
Bruce


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