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Damian
Guest

Mon Oct 29, 2012 9:47 am   



Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.

Toby Ponsenby
Guest

Mon Oct 29, 2012 10:24 am   



On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Quote:
Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Damian
Guest

Mon Oct 29, 2012 11:29 am   



Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years ago
and use as a battery charger as well. By manually manipulating the volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two batteries
are identical in size, condition, etc it's bad news for both batteries. But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
Quote:
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby


PeterD
Guest

Mon Oct 29, 2012 12:21 pm   



On 10/29/2012 4:47 AM, Damian wrote:
Quote:
Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.



If the batteries are the same yes, series will be fine. Most
applications (UPSs etc.) they are series and charged as a bank. Before
charging in series you must, however, ensure that each is identical in
capabilities (as well as specifications) and that each has an identical
level of charge.

Any charger to charge an AGM battery must be designed to charge those
types of batteries. You cannot use a generic charger, you need one with
an AGM setting.

--
I'm never going to grow up.

terryc
Guest

Mon Oct 29, 2012 1:22 pm   



On 29/10/12 19:47, Damian wrote:
Quote:
Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.

Yes and No.
Yes, it works fine, as long as you have an appropriate charger.
No, you need to make sure they stay as close as possible in voltage.
That said, you should source a 6v charger to sync them from time to time.

terryc
Guest

Mon Oct 29, 2012 1:25 pm   



On 29/10/12 21:29, Damian wrote:
Quote:
Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Erk. Rubbish. My rule of thumb is that you'll pay a similar amout for
the battery charger as you do for the battery.


Quote:

I also have a good regulated power supply(1V to 24V) which I built years ago
and use as a battery charger as well. By manually manipulating the volatage
and current with control knobs, I have been using it as a maintenance
charger.

You really need a charger that performes the appropriate stages for your
type of battery.

Quote:
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two batteries
are identical in size, condition, etc it's bad news for both batteries. But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.

Do regular voltage checks and work them monthly or quarterly.

Toby Ponsenby
Guest

Mon Oct 29, 2012 1:26 pm   



On Mon, 29 Oct 2012 21:29:31 +1100, Damian blathered:

Quote:
Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years ago
and use as a battery charger as well. By manually manipulating the volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two batteries
are identical in size, condition, etc it's bad news for both batteries. But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Ok - thought so re the Van - or perhaps a trailable boat.
The trick there is to use one of the new 'innovations' while on the
road.
You don't need monster cables to get sufficient Voltage to the caravan
any more.
There a device on the market which via trickery (OK, an invertor+ a few
bits) which supplies 'correct' voltage to the batteries in the van/boat.
Actually it does heaps more than that. Maybe there's one in the range
that doesn't run a few power sources. Have a dig about on and near this
link.
The important thing is the ability of the thing to FULLY charge your
batteries.

< http://www.batteriesdirect.com.au/shop/product/12569/d250s-dual.html >
Richie would say bloody maarvelos. Really.
--
Toby

Woody
Guest

Mon Oct 29, 2012 7:42 pm   



This probably explains all you need to know.

http://www.bdbatteries.com/mcharging_procedures.php


--
Woody

harrogate three at ntlworld dot com

Neil
Guest

Tue Oct 30, 2012 1:43 am   



On Mon, 29 Oct 2012 21:29:31 +1100, "Damian"
<damian_andrews75_at_yahoo.com.au> wrote:

Quote:
Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years ago
and use as a battery charger as well. By manually manipulating the volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two batteries
are identical in size, condition, etc it's bad news for both batteries. But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Ok - here's my two pen'orth:


1) The real issue with using two batteries together is when they are
connected in parallel permanently. Connected in series, there is not
really any difference to one battery, i.e. it is still 6 cells
connected in series, just that they are housed in two separate
casings.

2) Is the automatic charger up to the job of charging a 300Ahr
battery? If the spec is the same as the one in that link(350mA) I
seriously doubt it! It might be OK just to leave connected AFTER the
battery has been nearly fully charged at a more practical rate(say 10
to 25 Amps), just to top it off and supply a maintenance charge during
long periods of lay-up.

3) As has been said, the cost of the batteries, and their capacity,
probably justifies a high quality charger designed for such a bank.

4) In time one of the batteries will no doubt develop a faulty cell or
will have lost electrolyte in one of them. But again, this is no
different to one cell going down in a 12V battery - you're still going
to have to replace the bank. Meantime you're just going to have to
regularly monitor your battery bank for terminal votage, because with
AGM sealed units, you don't have the option of measuring the specific
gravity in individual cells(or topping up electrolyte) - which is why
after having used some sealed AGM batteries in the past(and also a
VERY big Gel battery many years ago), for leisure use, I now use a
conventional wet battery with screw caps to each cell so I can
maintain the battery properly.

HTH

Neil

(Reply via group please)

Damian
Guest

Tue Oct 30, 2012 2:20 am   



Hi Neil,
Thanks for the information.
Dont they(AGM batteries) suppose to last for 5-10 years without needing any
maintenance(privided it's kept charged properly)?
I thought we pay extra money to get sealed AGM deep cycle batteries because
they suppose to last lot longer than wet cell batteries.
You don't think that's the case?!
Thanks

"Neil" <donotuse_at_thisaddy.com> wrote in message
news:217u88herhv5q3jr7a2fv60gbqt9smpao2_at_4ax.com...
Quote:
On Mon, 29 Oct 2012 21:29:31 +1100, "Damian"
damian_andrews75_at_yahoo.com.au> wrote:

Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years
ago
and use as a battery charger as well. By manually manipulating the
volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two
batteries
are identical in size, condition, etc it's bad news for both batteries.
But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single
12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Ok - here's my two pen'orth:

1) The real issue with using two batteries together is when they are
connected in parallel permanently. Connected in series, there is not
really any difference to one battery, i.e. it is still 6 cells
connected in series, just that they are housed in two separate
casings.

2) Is the automatic charger up to the job of charging a 300Ahr
battery? If the spec is the same as the one in that link(350mA) I
seriously doubt it! It might be OK just to leave connected AFTER the
battery has been nearly fully charged at a more practical rate(say 10
to 25 Amps), just to top it off and supply a maintenance charge during
long periods of lay-up.

3) As has been said, the cost of the batteries, and their capacity,
probably justifies a high quality charger designed for such a bank.

4) In time one of the batteries will no doubt develop a faulty cell or
will have lost electrolyte in one of them. But again, this is no
different to one cell going down in a 12V battery - you're still going
to have to replace the bank. Meantime you're just going to have to
regularly monitor your battery bank for terminal votage, because with
AGM sealed units, you don't have the option of measuring the specific
gravity in individual cells(or topping up electrolyte) - which is why
after having used some sealed AGM batteries in the past(and also a
VERY big Gel battery many years ago), for leisure use, I now use a
conventional wet battery with screw caps to each cell so I can
maintain the battery properly.

HTH

Neil

(Reply via group please)


Damian
Guest

Tue Oct 30, 2012 2:28 am   



Thanks

"terryc" <newsninespam-spam_at_woa.com.au> wrote in message
news:k6lsds$8jc$1_at_dont-email.me...
Quote:
On 29/10/12 19:47, Damian wrote:
Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.

Yes and No.
Yes, it works fine, as long as you have an appropriate charger.
No, you need to make sure they stay as close as possible in voltage. That
said, you should source a 6v charger to sync them from time to time.


Damian
Guest

Tue Oct 30, 2012 2:30 am   



Thanks. That link was very helpful.

"Woody" <harrogate3_at_ntlworld.spam.com> wrote in message
news:w6Ajs.50951$A%.12439_at_fx26.am4...
Quote:
This probably explains all you need to know.

http://www.bdbatteries.com/mcharging_procedures.php


--
Woody

harrogate three at ntlworld dot com


Damian
Guest

Tue Oct 30, 2012 2:32 am   



Thank you. I think this is a great product even though it's bit pricy. I
think I'm going get a one.

"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:lc51gal9i2yl.r62ymg6vacnt.dlg_at_40tude.net...
Quote:
On Mon, 29 Oct 2012 21:29:31 +1100, Damian blathered:

Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years
ago
and use as a battery charger as well. By manually manipulating the
volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two
batteries
are identical in size, condition, etc it's bad news for both batteries.
But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single
12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Ok - thought so re the Van - or perhaps a trailable boat.
The trick there is to use one of the new 'innovations' while on the
road.
You don't need monster cables to get sufficient Voltage to the caravan
any more.
There a device on the market which via trickery (OK, an invertor+ a few
bits) which supplies 'correct' voltage to the batteries in the van/boat.
Actually it does heaps more than that. Maybe there's one in the range
that doesn't run a few power sources. Have a dig about on and near this
link.
The important thing is the ability of the thing to FULLY charge your
batteries.

http://www.batteriesdirect.com.au/shop/product/12569/d250s-dual.html
Richie would say bloody maarvelos. Really.
--
Toby


Toby Ponsenby
Guest

Tue Oct 30, 2012 10:35 am   



On Tue, 30 Oct 2012 12:32:40 +1100, Damian blathered:

Quote:
Thank you. I think this is a great product even though it's bit pricy. I
think I'm going get a one.

"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:lc51gal9i2yl.r62ymg6vacnt.dlg_at_40tude.net...
On Mon, 29 Oct 2012 21:29:31 +1100, Damian blathered:

Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years
ago
and use as a battery charger as well. By manually manipulating the
volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two
batteries
are identical in size, condition, etc it's bad news for both batteries.
But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single
12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Ok - thought so re the Van - or perhaps a trailable boat.
The trick there is to use one of the new 'innovations' while on the
road.
You don't need monster cables to get sufficient Voltage to the caravan
any more.
There a device on the market which via trickery (OK, an invertor+ a few
bits) which supplies 'correct' voltage to the batteries in the van/boat.
Actually it does heaps more than that. Maybe there's one in the range
that doesn't run a few power sources. Have a dig about on and near this
link.
The important thing is the ability of the thing to FULLY charge your
batteries.

http://www.batteriesdirect.com.au/shop/product/12569/d250s-dual.html
Richie would say bloody maarvelos. Really.
--
Toby

Them's the goods - there may be others out there, as I'm sure there will
be others attempting to compete with the function, which is essentially
a better way to charge remote batteries than previouly existed outside
of uber epensive commercial stuff.
The people who've installed the stuff I linked to are mightly pleased
with it.
Only downside I can see so far is that the device should be in a well
ventilated location. Goes without saying that given what it does,
there'll be a little heat to dispose of.
Additionally the solar cell charging function ain't so redundant soon
given the prive of the PV arrays falling day by day.
--
Toby

Neil
Guest

Tue Oct 30, 2012 6:32 pm   



Quote:
"Neil" <donotuse_at_thisaddy.com> wrote in message
news:217u88herhv5q3jr7a2fv60gbqt9smpao2_at_4ax.com...
On Mon, 29 Oct 2012 21:29:31 +1100, "Damian"
damian_andrews75_at_yahoo.com.au> wrote:

Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years
ago
and use as a battery charger as well. By manually manipulating the
volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two
batteries
are identical in size, condition, etc it's bad news for both batteries.
But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <me_at_privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg_at_40tude.net...
On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single
12V
battery and charge they equally without any issues.
Thank you for any advice.

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

Ok - here's my two pen'orth:

1) The real issue with using two batteries together is when they are
connected in parallel permanently. Connected in series, there is not
really any difference to one battery, i.e. it is still 6 cells
connected in series, just that they are housed in two separate
casings.

2) Is the automatic charger up to the job of charging a 300Ahr
battery? If the spec is the same as the one in that link(350mA) I
seriously doubt it! It might be OK just to leave connected AFTER the
battery has been nearly fully charged at a more practical rate(say 10
to 25 Amps), just to top it off and supply a maintenance charge during
long periods of lay-up.

3) As has been said, the cost of the batteries, and their capacity,
probably justifies a high quality charger designed for such a bank.

4) In time one of the batteries will no doubt develop a faulty cell or
will have lost electrolyte in one of them. But again, this is no
different to one cell going down in a 12V battery - you're still going
to have to replace the bank. Meantime you're just going to have to
regularly monitor your battery bank for terminal votage, because with
AGM sealed units, you don't have the option of measuring the specific
gravity in individual cells(or topping up electrolyte) - which is why
after having used some sealed AGM batteries in the past(and also a
VERY big Gel battery many years ago), for leisure use, I now use a
conventional wet battery with screw caps to each cell so I can
maintain the battery properly.

HTH

Neil

(Reply via group please)

On Tue, 30 Oct 2012 12:20:04 +1100, "Damian"

<damian_andrews75_at_yahoo.com.au> wrote:

Quote:
Hi Neil,
Thanks for the information.
Dont they(AGM batteries) suppose to last for 5-10 years without needing any
maintenance(privided it's kept charged properly)?
I thought we pay extra money to get sealed AGM deep cycle batteries because
they suppose to last lot longer than wet cell batteries.
You don't think that's the case?!
Thanks


Damian,

I don't know whether AGM batteries last significantly longer than
conventional flooded cell batteries, they may well do - do the
manufacturers guarantee them for that long? It would be my guess that
AGMs would last longer than a "maintenance free" flooded cell battery
of similar capacity. The bottom line is that it's a trade-off between
cost and longevity I guess.

I personally prefer to be able to measure the specific gravity of the
electrolyte in the cells in my vehicle, leisure and other lead/acid
batteries, and be abe to top-up if necessary. The battery I have in
my caravan at present is a 110Ah semi-traction battery with big, wide
screw caps to each cell. It's about 7 years old, and showing no signs
of loss of capacity, or deterioration of any cell above any other. I
do occasionally give it an "equalising" charge, and top up the cells
as necessary. It cost me no more than a vehicle starter battery at
the time, and next year it will have lasted as long as my last sealed
AGM battery did, before it's capacity started to fall significantly.

HTH

Neil

(Reply via group please)

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