Overcharging AGM on Solar?

Cupie · Guru

Overcharging AGM on Solar?

dabbler · Guru

A multistage dcdc controller set to rhe correct battery chemistry and working correctly will not overcharge your battery.

Cupie · Guru

Thanks for the prompt reply Dabbler. I will read the manual on my DC/DC charger more closely.

Sometimes (as in my case) 'a little learning is a dangerous thing'.

Edit ...

Well there it was on the first page of my Thunder, 8/3 stage, DC DC charger manual -

.............................................

'Auto charge mapping for AGM etc.'

'Overcharging etc protection'

..............................................

I'll sleep easier now. After perhaps reading the other relevant manuals that I got with my 12v stuff.

BTW .. There was discussion on another thread about wire sizes & I note that this manual specifies 6AWG cable if the cable from the Solar panel is >5M. Which is reassuring as mine is 9m & I used 6AWG.

-- Edited by Cupie on Sunday 12th of November 2017 09:58:23 PM

-- Edited by Cupie on Monday 13th of November 2017 08:05:13 AM

macka17 · Guru

You shouldn't OVER charge battery's on Solar.
MOST reg's have battery type settings to suit.
And float battery at that.

My Hybrid spiral cell AGM under bonnet.
Both the Alt and Regulator from panels (One, or both.) float it at 14.4v
When eng running.
13.2\13.3 with just solar. and 12.4 when under carport (No solar).
12.6\7 with Multi.

Pick one hey..

swamp · Senior Member

hi
Multi stage charges at least have 3 stages
This applies to many solar ,240v and dc2dc chargers
Once a multi stage charger has done all the stages Bulk then Absorption then finally FLOAT =13.8 v or below little charging occurs . Many float volts are 13.4-13.6 v.
Some chargers even have a storage mode also, which has a very low volts again.

The better charger have selectable chemistry as a bare minimum
Great chargers have the voltages and amps adjustable .
All this is to best suit YOUR battery and giving it the best chance for a long life .

Bad chargers have desulphate mode that's either on auto only and no details how often it cycles or set to disulphate every use . Batteries are all individual in there requirements refer maker is very important .

deverall11 · Guru

Fellas,
Can I assume from the above conversation that in order to float/trickle charge a 12v battery, one needs to source
a dc-dc charger as the solar panel will not cater on its own.
Regards
Larry

-- Edited by deverall11 on Tuesday 14th of November 2017 08:48:22 AM

rockylizard · Guru

Gday...

Between solar panels and the battery is a Solar Charge Controller. There is no need to have a DC/DC charger to charge battery from solar.

This site might give you some background info ...

http://www.aussiebatteries.com.au/blog/beginners-guide-to-solar-charge-controllers/

Cheers - John

Peter_n_Margaret · Guru

Overcharging of any lead acid battery can only occur if the charge voltages are set too high. It matters not if there is 6 stages or one.
Your alternator can charge at 80 amps or more, but it does not over charge the crank battery because the set voltage is limited to about 14.3V and it can offer that all day, even when the battery is full, without risk of damage.

Cheers,
Peter

Cupie · Guru

Peter_n_Margaret wrote:
Overcharging of any lead acid battery can only occur if the charge voltages are set too high. It matters not if there is 6 stages or one.
Your alternator can charge at 80 amps or more, but it does not over charge the crank battery because the set voltage is limited to about 14.3V and it can offer that all day, even when the battery is full, without risk of damage.

Cheers,
Peter

Thanks for that. Makes sense.

I understand you to be saying that once the battery voltage gets up to the 'set' voltage of the charging source (the alternator) then given that they are then at the same potential, there is no current flow. ie. charging stops. Just got to have the 'set' voltage right to prevent overcharging. Sort of takes me back to first principles learnt in my first year training some 60 years ago.

Simple .. Why didn't I think of that. Perhaps trying to over complicate things. I'm getting too old and my comprehension, reasoning and memory going, going, gone.

edit .. spelling going too

-- Edited by Cupie on Tuesday 14th of November 2017 03:11:17 PM

macka17 · Guru

Never seen the point for an exxy Dc-DC charger.
I'd rather put cash into a genny. Much more useful. (I have. several times)

Panels will float your battery's fine.
As long as you have the panel numbers to charge too, over the power you using.
A good quality Reg will give you choice of battery type.

rockylizard · Guru

Gday...

Happy for those with more knowledge than me to slap me down ... but I think modern alternators will not charge a 2nd battery ... ie aux battery in tug and/or house battery in van.

They only "read" the voltage in the "main battery" and when that is 'charged' the voltage/amps drop back. Something to do with emissions control or some other modern technology thingy. hmm

Therefore, a dc>dc charger is required to get charge from the alternator to the aux tug and/or van house battery/s.

cheers - John

Ron-D · Guru

Decided to test the new 160w panel to day I put the panel in the sun and connected my amp meter to the end of the long cable from the reg on the panel no reading ,but the regulator connected to the portable panel was flashing it's just a cheap looking thing.

next step I did the same thing with my old 80 w panel that I know works reading 4amps good.

now back to the new 160 panel this time I simple put the amp meter directly on the panel pv connectors 8amps now showing ,would this be an indication that the new panel is working and it is just a failed reg on the new portable panel.

a new good quality reg would fix the problem surely any thoughts..

-- Edited by Ron-D on Tuesday 14th of November 2017 11:50:40 PM

swamp · Senior Member

Hi
Some of the reasons why u need a dc to dc
different chemistry batteries require different voltages different amperage limits
voltage drop between main battery and aux batt
Volt drop cause batteries to charge at slower rates in a direct connect system

Batteries preferably need to be at the same size and type located next to each other not as per a typical car batt/ van batt layout . Another reason why dctodc were invented .

Cable sizes
9mtrs long
6b&s 13mmsq 25amp .4 volt drop
3B&s 25mmsq 35amp .4v /drop
2 B&s 35mmsq 45amp .4v /drop

A dc to dc will current draw more than its advertised eg25 amp might draw upto around 30amp
Make sure your altenator can supply the amps

Tony Bev · Guru

Ron-D wrote:
Decided to test the new 160w panel to day I put the panel in the sun and connected my amp meter to the end of the long cable from the reg on the panel no reading ,but the regulator connected to the portable panel was flashing it's just a cheap looking thing.
next step I did the same thing with my old 80 w panel that I know works reading 4amps good.
now back to the new 160 panel this time I simple put the amp meter directly on the panel pv connectors 8amps now showing ,would this be an indication that the new panel is working and it is just a failed reg on the new portable panel.
a new good quality reg would fix the problem surely any thoughts..

-- Edited by Ron-D on Tuesday 14th of November 2017 11:50:40 PM

Hi Ron

Hope that I am not hijacking the thread

In a normal situation, if there is power at the regulator, (on the solar panel), but no power at the end of the cable, then the problem is somewhere in between

I have come across a MC4 type connector (between the regulator and the end of the cable), which had a loose wire
They crimp the wire onto the MC4 connector, and then tighten the weatherproof gland nut on the end
The wire appears to be sound, because the gland nut is gripping the cable
Loosening weatherproof gland, and very gently moving the wire, may tell you if this is the problem

A cheap multi meter, set on ohms, should tell you which of the two (positive/negative) wire is faulty

deverall11 · Guru

rockylizard wrote:
... but I think modern alternators will not charge a 2nd battery ... ie aux battery in tug and/or house battery in van....

John,

In an environment like a motorhome isn't the aux or house battery connected to the start battery anyway or is it a separate circuit?

Larry

rockylizard · Guru

Gday...

Sorry, I did say those with more knowledge should slap me down

I was talking about vehicle and van ... didn't think about motorhomes. hmm

I have no idea, but praps the charging for motorhomes between alternator, main battery and 'house' battery/s is handled by an electronic device.

Anyway, time for those with more knowledge than me to clarify.

cheers - John

Ron-D · Guru

Thanks for your reply Tony Iam the one higjacking this thread it was meant to go elsewhere I don't think it's a mc4 problem I tested the panel with the pv wires hanging loose off the panels connected directly to the Anderson plug with 5meters of cable and received 8 amps on my amp meter ,just a cable running to a Anderson plug from the pv to an amp meter nothing in between producing 8 amps surely the panel itself should be ok.

put the panel back to normal as supplied by the factory, with the regulator back on the panel there's nothing on the amp meter must be a dud amp meter?

What this is leading too is this a good way of testing a new portable solar panel without hooking things through the caravan I think it is but Iam no expert,is this method of simply putting a hand held amp meter on the end of the cable good enough.

Tony Bev · Guru

Ron-D wrote:
Thanks for your reply Tony Iam the one higjacking this thread it was meant to go elsewhere I don't think it's a mc4 problem I tested the panel with the pv wires hanging loose off the panels connected directly to the Anderson plug with 5meters of cable and received 8 amps on my amp meter ,just a cable running to a Anderson plug from the pv to an amp meter nothing in between producing 8 amps surely the panel itself should be ok.
put the panel back to normal as supplied by the factory, with the regulator back on the panel there's nothing on the amp meter must be a dud amp meter?
What this is leading too is this a good way of testing a new portable solar panel without hooking things through the caravan I think it is but Iam no expert,is this method of simply putting a hand held amp meter on the end of the cable good enough.

Hi Ron

I am not interpreting exactly what you mean

I am led to believe that some panel regulators, will not show anything, until they are connected to the battery
Something about not giving any current, until it sees the state of the charge of the battery, so that it knows how much current to give

Perhaps if you put the positive and negative wires, on a battery, just to double check

Perhaps a techi can enlighten us all

Tony Bev · Guru

rockylizard wrote:
Gday...
Sorry, I did say those with more knowledge should slap me down
I was talking about vehicle and van ... didn't think about motorhomes.
I have no idea, but praps the charging for motorhomes between alternator, main battery and 'house' battery/s is handled by an electronic device.
Anyway, time for those with more knowledge than me to clarify.
cheers - John

I only have experience of my own motorhome (2006 Jayco Conquest build)

There is a very under size wire from the Engine battery to the Setec (so called) charger, then onto the leisure battery/s
Apart from a one way diode, to stop the leisure batter/s current, from feeding back to the engine battery, the Setec does not control this current
This wire also controls the electric door step, before it reaches the Setec charger

I can confirm that with this set up, the leisure battery/s did not get fully charged, when the engine is running

On 240 volt the Setek has two main functions
Firstly it gives 12 volt, to run the 12 volt system, of the motorhome
Secondly it is suppose to be a battery charger, which charges the leisure battery/s

As charges go it looks OK on paper, but in practice, it was hopeless at charging the leisure battery/s

I was lucky enough to have bumped into Billeeeeee, the partner of Jules47, not long after I had got my RV
As they had the same but one year newer model RV than me, I picked their brains, about their charging system

Following that advice, (they had by-passed their original system, and went solar plus DC/DC charger)
I now have the wire from the engine battery, isolated just before it connects to the Setic

I have a DC/DC charger, which charges the leisure batteries, from either the engine battery, or the roof solar
When the leisure batteries are fully charged, the DC/DC charger then puts current into the engine battery, if it is required

I can only say that (for me), charging the original leisure battery, from the engine battery, with the original Jayco set up, did not work
Since fitting the solar, and the DC/DC charger, I have no complaints

Aus-Kiwi · Guru

Fit a voltage sensitive relay between house and motor batteries . So BOTH charge !! But the motor batteries donât drop below around 12.5 volts or there about ?

Ron-D · Guru

Tony Bev wrote:
Ron-D wrote:
Thanks for your reply Tony Iam the one higjacking this thread it was meant to go elsewhere I don't think it's a mc4 problem I tested the panel with the pv wires hanging loose off the panels connected directly to the Anderson plug with 5meters of cable and received 8 amps on my amp meter ,just a cable running to a Anderson plug from the pv to an amp meter nothing in between producing 8 amps surely the panel itself should be ok.
put the panel back to normal as supplied by the factory, with the regulator back on the panel there's nothing on the amp meter must be a dud amp meter?
What this is leading too is this a good way of testing a new portable solar panel without hooking things through the caravan I think it is but Iam no expert,is this method of simply putting a hand held amp meter on the end of the cable good enough.
Hi Ron
I am not interpreting exactly what you mean
I am led to believe that some panel regulators, will not show anything, until they are connected to the battery
Something about not giving any current, until it sees the state of the charge of the battery, so that it knows how much current to give
Perhaps if you put the positive and negative wires, on a battery, just to double check
Perhaps a techi can enlighten us all

Yeah Tony I understand where your coming from but when my. Other 80W panel that. I have been using for many years gives a reading when tested in the same manner inot connected to a battery.

macka17 · Guru

For charging second\third battery's.
IN van or tray.
Get an "Electronic". NOT solenoid, dual battery unit.
It charges main. then switches to secondary charge when main topped.
with a small push button to over ride\start dual charge
WHEN you press it.

I'm on my second one in 15 yrs.
MUCH more efficient than the REDARC solenoid units.

And DON'T buy Cheap Regulators with decent panel setup.

Morningstar
I've used since forever. Can't fault them personally
Even the little 5a Sealed units for outside on carport panels.
That's over 12 yrs. never been touched. Just Multi occasionally.

OFF track.

I got a new nice little Clamp Multi off net for $28 del last month.

And yes. a panel will show reading on Multi at ends of cables.

17.??? v anyway. I think AMPS come in under load.\connection.
Can't remember.

Jaahn · Guru

Hi Ron smile

I am not sure what you are doing really ?? Macka is not helping either !! BUT all regulators say in the instructions that they should be connected to the battery first before you connect the solar panel. Otherwise you risk ' blowing' the regulator. I have observed one that I misconnected and it refused to read until disconnected and reconnected correctly. Pheww it cost a bit of money too but better quality regs are self protected usually. hmm

Just saying Jaahn

-- Edited by Jaahn on Thursday 16th of November 2017 04:05:32 PM

Ron-D · Guru

Jaahn wrote:
Hi Ron
I am not sure what you are doing really ?? Macka is not helping either !! BUT all regulators say in the instructions that they should be connected to the battery first before you connect the solar panel. Otherwise you risk ' blowing' the regulator. I have observed one that I misconnected and it refused to read until disconnected and reconnected correctly. Pheww it cost a bit of money too but better quality regs are self protected usually.
Just saying Jaahn

-- Edited by Jaahn on Thursday 16th of November 2017 04:05:32 PM

Your a good source of information Jaahn much appreciated the old 80 watt panel stock set reg glued to the folding panel ,battery lead with an Anderson plug on the end ,instead of connecting it to the load (caravan)I simply put it in the sunlight and put my amp meter across the bare connectors and had a reading in full sunlight of 4 amps .

Now with the new panel I did the same thing no reading at the bare Anderson plug at all,maybe this panel needs as you described to be connected to the load,because I had a reading with the old panel not connected to the load (battery) it confused me,any way next step with the new panel in the sun not connected to anything I simply put the amp meter across the pv wires only and received a reading of 8amps,so the panel itself should be ok,

now today I ordered a new 15 amp reg from Victron and after speaking to there techie for a while he was of the opinion this was all that would be required to run my 160 watt panel ,and he even said that if I wanted to add the 80 watt panel this reg will handle the extra load something about the controller will throttle up and down so as to add more load when required and it will not let too much load through as well Iam no tecki but Iam learning blankstare .hopefully. wink