It's that time of year again

Page 3 of 4 Previous  1, 2, 3, 4  Next

Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by BornAgain on Wed Nov 01, 2017 4:08 pm

PB, I said earlier that the documentation didn’t cover the operation that you described but I just checked and its exactly as you said. Thanks again. Not sure why mains hook-up would only charge one battery but as it all works fine I am not really questioning it. Certainly the standard system and solar panel seems to maintain the batteries fully charged for several weeks with the alarm activated (no Tracker) so it seems that it is just a question of getting the electronics to do the right thing. One thing I like about AS is that because the models haven’t changed much over several years you get incremental improvement (no doubt some will disagree!j. It certainly seems to be the case with the control system judging by what others have said.
BornAgain
BornAgain
Member
Member

Male

Posts : 88
Joined : 2016-03-27
Member Age : 73
Location : Bourne End, Bucks
Auto-Sleeper : Broadway EK TB LP
Vehicle Year : 2016

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by naki585 on Wed Nov 01, 2017 8:39 pm

Hi Peter.

I am interested in what you say about the solar charging being unpredictable on the EC500.

Our Burford has the EC500 with a 100 watt solar panel and an another 100 watt panel going through a separate controller. The second controller shows current going in while the EC480 display panel always shows current discharge and little or no current coming in via the connected solar panel.

I am wondering if this just the EC480 not displaying correctly or whether I have a problem with the panel or EC500.

PS: I understand the EC480 will not be able to display solar current coming in from the second panel, but should it be able to display total current in or out?

Your thoughts would be appreciated.

Thank you.
Keith


Last edited by naki585 on Wed Nov 01, 2017 8:48 pm; edited 1 time in total
avatar
naki585
Member
Member

Male

Posts : 86
Joined : 2017-06-13
Member Age : 61
Location : New Zealand
Auto-Sleeper : Burford
Vehicle Year : 2015

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by bolero boy on Wed Nov 01, 2017 8:45 pm

to Pete Brown...

Hi, i dont have an AutoSleepers (just i terested in the MH 'world'....ive had two Swift Boleros so understand a bit about the 'ingredients' used in UK vans...
Ive also had two German Carthago MHs so have a balanced perspective pf their relative merits and 'foinles'...
ps.....if i knew how to quote your post, that wpuld help a lot.....lol

_________________
Chris.
Carthago c-compactline i138
bolero boy
bolero boy
Member
Member

Male

Posts : 615
Joined : 2017-10-28
Location : somerset
Auto-Sleeper : Carthago Compactline
Vehicle Year : 2017

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by -mojo- on Thu Nov 02, 2017 12:08 am

naki585 wrote:
Our Burford has the EC500 with a 100 watt solar panel and an another 100 watt panel going through a separate controller. The second controller shows current going in while the EC480 display panel always shows current discharge and little or no current coming in via the connected solar panel.

Do you mean that you have two solar panels, each connected via a separate solar controller to the same battery or batteries?

I don't think that is ever going to work well - I would expect one controller to dominate, and the other to be "shut off" most of the time.

The reason I suggest this is that (simplistically) a solar controller typically has 3 threshold voltages which determine what mode to be in, and due to natural component tolerances, one of the controllers will have a slightly higher set of voltages than the other. So the controller with the higher output voltage will tend to cause the other one to switch off or reduce its output - because it detects that the batteries are overcharging (which of course they are not - it simply has no way to detect that another controller is in-circuit).

The result is likely to be that one of the two panels will do very little in the way of charging.
-mojo-
-mojo-
Member
Member

Male

Posts : 4566
Joined : 2012-08-04
Member Age : 19
Location : Southeast
Auto-Sleeper : Trooper
Vehicle Year : 2006

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Peter Brown on Thu Nov 02, 2017 9:56 am

-mojo- wrote:
naki585 wrote:
Our Burford has the EC500 with a 100 watt solar panel and an another 100 watt panel going through a separate controller. The second controller shows current going in while the EC480 display panel always shows current discharge and little or no current coming in via the connected solar panel.

Do you mean that you have two solar panels, each connected via a separate solar controller to the same battery or batteries?

I don't think that is ever going to work well - I would expect one controller to dominate, and the other to be "shut off" most of the time.

The reason I suggest this is that (simplistically) a solar controller typically has 3 threshold voltages which determine what mode to be in, and due to natural component tolerances, one of the controllers will have a slightly higher set of voltages than the other. So the controller with the higher output voltage will tend to cause the other one to switch off or reduce its output - because it detects that the batteries are overcharging (which of course they are not - it simply has no way to detect that another controller is in-circuit).

The result is likely to be that one of the two panels will do very little in the way of charging.

I agree with mojo, it would be better to parallel connect the panels to the controller in the EC500, unfortunately that can only handle up to a max of 120W.

_________________
Peter #1
Peter Brown
Peter Brown
Member
Member

Male

Posts : 5376
Joined : 2012-11-10
Member Age : 67
Location : Staffs
Auto-Sleeper : Malvern
Vehicle Year : 2011

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Peter Brown on Thu Nov 02, 2017 10:01 am

bolero boy wrote:to Pete Brown...

Hi, i dont have an AutoSleepers (just i terested in the MH 'world'....ive had two Swift Boleros so understand a bit about the 'ingredients' used in UK vans...
Ive also had two German Carthago MHs so have a balanced perspective pf their relative merits and 'foinles'...
ps.....if i knew how to quote your post, that wpuld help a lot.....lol

Press the quote button, top right corner of the box.

To your point about connection point; Sargent design and manufacture a connectorised wiring loom for each AS model so the factory operatives have no option to connect to the designed termination.

_________________
Peter #1
Peter Brown
Peter Brown
Member
Member

Male

Posts : 5376
Joined : 2012-11-10
Member Age : 67
Location : Staffs
Auto-Sleeper : Malvern
Vehicle Year : 2011

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by spanner on Thu Nov 02, 2017 8:14 pm

spanner wrote:I’ll be fitting the 160 watt solar panel tomorrow, if the Sargent “smart charge” still refuses to work as intended I’ll then be fitting a “Battery Master”  and a changeover switch.

I’m certainly no expert on this subject but this is my idea.....

As my solar charge controller is external to the EC500 I’ll connect the  battery + wire from the controller to a simple 3 position switch on/off/on  in the first position the power goes to EC500  third position to the leisure batteries +

In the first position there is no change to the original wiring and the EC480 will still give an indication of the state of charge etc, in the other ON position the “Battery Master” will do it’s job and utilise the solar charge to maintain both batteries, with the EC500 switched OFF and virtually no parasitic drain.


Other people on this forum and others forums  have simply fitted a Battery Master type device to EC500 equipped vans with excellent results.

I've now fitted a 160 watt monocrystalline solar panel (the largest size that will fit in the space where the 80 watt panel was) therefore I won't be tempted to route any solar power via the EC500, so a Battery Master type device will intelligently share the solar charge between both sets of batteries.
The Sargent EC500 is designed to cope with solar panels up to 120 watt maximum, according to Sargent technical a solar input of more than 7 amps could damage the EC500 or interfere with other items inside the motorhome.

From the EC480 display I'll still be able to check the battery voltages and the approximate remaining capacity of the leisure and vehicle battery but not the solar panel output. ( If I feel the need to easily view the solar charge output this can be easily done with a separate display.
spanner
spanner
Member
Member

Male

Posts : 123
Joined : 2015-12-04
Member Age : 99
Location : Telford Shropshire
Auto-Sleeper : Broadway Duo EL
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by naki585 on Thu Nov 02, 2017 10:19 pm

Hi.
You could install a separate Votronic Dual Output solar controller. These controllers will charge both the Leisure battery and the Start battery without any switching, at the same time. They supply 1 amp to the start battery to keep it topped up.

To monitor the battery you could also fit a separate battery monitor connected to a shunt.

Cheers.
avatar
naki585
Member
Member

Male

Posts : 86
Joined : 2017-06-13
Member Age : 61
Location : New Zealand
Auto-Sleeper : Burford
Vehicle Year : 2015

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by spanner on Thu Nov 02, 2017 10:47 pm

naki585 wrote:Hi.
You could install a separate Votronic Dual Output solar controller. These controllers will charge both the Leisure battery and the Start battery without any switching, at the same time. They supply 1 amp to the start battery to keep it topped up.

To monitor the battery you could also fit a separate battery monitor connected to a shunt.

Cheers.

Hello,

Thanks for your interest and your suggestion is good, as I already have a Victron Blue Solar MPPT controller and found a "Battery Master" type device for only £20  I'll see how I get on.

Cheers
spanner
spanner
Member
Member

Male

Posts : 123
Joined : 2015-12-04
Member Age : 99
Location : Telford Shropshire
Auto-Sleeper : Broadway Duo EL
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Paramedic on Sun Nov 05, 2017 8:51 am

Couldn't have imagined my OP would generate so much debate,but this is how this forum is so proactive to members problems. With the gloomy skies of early yesterday, we were quiet gobsmacked to see 0.3 amps charging the vehicle battery.....Hooray !!!

_________________
In the land of the blind, the man with one eye is king
Paramedic
Paramedic
Member
Member

Male

Posts : 1672
Joined : 2016-01-27
Member Age : 72
Location : Chichester West Sussex
Auto-Sleeper : Broadway FB
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Update

Post by spanner on Wed Nov 15, 2017 11:26 pm

spanner wrote:
Paramedic wrote:Gentlemen, my gratitude extends to you all for all your comments and yes, our van has EC480 and EC500. Understand the PSU is left switched on for the system to operate intelligently to benefit both V and L batteries for solar charging. Yesterday it seemed odd that whilst the leisure battery was displaying 100%, the panel was still putting in 0.4 amp in same whilst the vehicle battery was in a low state (probably less than 10.9 volts ?) so unable to turn the engine over. However, it's been full sun today and taking the van out on Sunday and for MOT on Monday and will update you thereafter. Again, much obliged for your interest.
We have the EC500/EC480 setup and and have found the Sargent smart charge hopeless at managing to automatically charge the battery that’s most discharged, when I sought help from Sargent they told me to switch the EC500 on and off to reset the smart charge, well this sometimes works but needs doing every few days !
The parasitic discharge from the Sargent EC500 is more than the the solar panel can keep up with at this time of the year with very little overhead sun.

Fitting a Victron MPPT solar controller improved the solar panel charge but not enough.

I’ve just removed the factory fitted 80watt panel and fitting a 160 watt panel, if I still have the same problem I’ll fit a CBE CSB2 / Battery Master that will connect to the leisure batteries and trickle charge the vehicle battery and solve the problem as long as I switch off the EC500 between October to March it can’t can’t drain the batteries, not a problem for the rest of the year when the sun is higher and the days longer.

Update

With the new larger 160 watt panel fitted the Sargent EC500 was still unable to "smart charge" both van and leisure batteries, every few days I had to plug in to the mains to bring the batteries to fully charged.

All the batteries have been professionally tested and are not faulty nor is there any abnormal drain from the van battery etc.

Between March and October everything is fine with the solar charging.

I decided to fit a "battery master" type device and switch off the EC500 control panel which removes the 24/7  0.4 amp parasitic drain.

Result, immediate improvement and I now have fully charged batteries even with the poor performance of solar panels at this time of year  smile!

I've fitted a switch between the solar controller and the EC500 to give me 2 options, summer setting charging via the original method or winter setting via the battery master, it just works !


[You must be registered and logged in to see this link.]


[You must be registered and logged in to see this link.]

I found Complus excellent to deal with, quality at a great price.
spanner
spanner
Member
Member

Male

Posts : 123
Joined : 2015-12-04
Member Age : 99
Location : Telford Shropshire
Auto-Sleeper : Broadway Duo EL
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Peter Brown on Thu Nov 16, 2017 8:08 am

spanner wrote:

I've fitted a switch between the solar controller and the EC500 to give me 2 options, summer setting charging via the original method or winter setting via the battery master, it just works !



That's the key to making it work, a nice bit of lateral thinking. I've been too blinkered about this problem. Maybe you could prepare a simple schematic to show how the elements involved (panel, controller, switch, battery master, EC500 and batteries) are interconnected to aid the many others who have the same problem.

_________________
Peter #1
Peter Brown
Peter Brown
Member
Member

Male

Posts : 5376
Joined : 2012-11-10
Member Age : 67
Location : Staffs
Auto-Sleeper : Malvern
Vehicle Year : 2011

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by meanchris on Thu Nov 16, 2017 8:33 am

Although all this talk is about the more recent vans with the EC328 onwards, is it worth a mention that older vans without a power supply built-in solar controller may benefit from having a solar panel and external solar controller in the winter months?

I was very impressed with the SunWorks controller that our previous 2005 Exec came fitted with.

It had a simple fused two wire feed to each battery and two wires to the solar panel. It also has a simple two line dot matrix display to tell you which battery is being charged, the charging current, and both battery voltages.
It never let me down in the two years that we had the van.

In fact, I've just fitted this one to our new van along with a 100W panel.

[You must be registered and logged in to see this link.]
avatar
meanchris
Member
Member

Male

Posts : 2381
Joined : 2013-08-10
Member Age : 65
Location : North West
Auto-Sleeper : None
Vehicle Year : N/A

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by naki585 on Thu Nov 16, 2017 9:04 pm

Hi.

We have our Burford booked in next week to have the issue with the solar panel running through the Sargent EC500 not working fixed. Which will be covered under warranty.

We are also having a Votronic Battery Monitor fitted which will show us all power going in and out of both solar panels.

Cheers.
avatar
naki585
Member
Member

Male

Posts : 86
Joined : 2017-06-13
Member Age : 61
Location : New Zealand
Auto-Sleeper : Burford
Vehicle Year : 2015

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Paramedic on Sat Nov 18, 2017 2:04 pm

Yesterday morning full sun and very pleased again to see 'V' battery receiving 1.4 amps from SP and batt state 12.6v. So it appears that on good days, the EC500 is readily operating the intelligent charging system whereas on gloomy days throughout winter, the 80 watt SP isn't sufficient to prevent the  parasitic discharge of the PSU (in our case) draining the 'V' battery. This was initially highlighted by Peter and more recently by spanner. Therefore in order to prevent another starter battery failure, we need to: 

Visited the van say, once a week to check states of both batteries.

Switch the shutdown button to the PSU on and off to revert to 'V' charging if possible.

Take the van out for 20 mile run if any battery looks compromised.

Interestingly there has been mention of disconnecting the starter battery to avoid any parasitic drain which brings to mind another option. A friend who knows our previous plight with a ruined battery has given us a small solar panel. Ring RSP600 12v ((suitable for leisure vehicles). Power rating (max) 6.0 watts, suitable for batteries up to 250 Ah, current (at max power) 343mA. Dimensions 345x498x15mm. Therefore is it viable to switch off the EC500 so only the leisure batt is charged from the SP and connect the Ring to the starter batt. It can be directed externally towards any sunlight by positioning it on the windscreen. In doing so, does it need to be fitted directly to batt (under cab floor) or possibly under the bonnet to the respective positive and earth points? Of course, I could be proven a complete dunce to even suggest it. confused3

_________________
In the land of the blind, the man with one eye is king
Paramedic
Paramedic
Member
Member

Male

Posts : 1672
Joined : 2016-01-27
Member Age : 72
Location : Chichester West Sussex
Auto-Sleeper : Broadway FB
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by spanner on Sat Nov 18, 2017 2:33 pm

Paramedic wrote:Yesterday morning full sun and very pleased again to see 'V' battery receiving 1.4 amps from SP and batt state 12.6v. So it appears that on good days, the EC500 is readily operating the intelligent charging system whereas on gloomy days throughout winter, the 80 watt SP isn't sufficient to prevent the  parasitic discharge of the PSU (in our case) draining the 'V' battery. This was initially highlighted by Peter and more recently by spanner. Therefore in order to prevent another starter battery failure, we need to: 

Visited the van say, once a week to check states of both batteries.

Switch the shutdown button to the PSU on and off to revert to 'V' charging if possible.

Take the van out for 20 mile run if any battery looks compromised.

Interestingly there has been mention of disconnecting the starter battery to avoid any parasitic drain which brings to mind another option. A friend who knows our previous plight with a ruined battery has given us a small solar panel. Ring RSP600 12v ((suitable for leisure vehicles). Power rating (max) 6.0 watts, suitable for batteries up to 250 Ah, current (at max power) 343mA. Dimensions 345x498x15mm. Therefore is it viable to switch off the EC500 so only the leisure batt is charged from the SP and connect the Ring to the starter batt. It can be directed externally towards any sunlight by positioning it on the windscreen. In doing so, does it need to be fitted directly to batt (under cab floor) or possibly under the bonnet to the respective positive and earth points? Of course, I could be proven a complete dunce to even suggest it. confused3



Why not just try it for a couple of days with the EC500 switched off, the solar then defaults to charge the leisure battery only, you may find that the leisure battery will be fine.

The mini solar panel will give very little output but why not try it propped against the bottom of the windscreen and clip the cable direct to the jump start points under the bonnet (positioning the panel inside the van cuts the solar panel efficiency too much)

After a few days just switch on the EC500 to check the voltages of the batteries.

The worst that could happen is that someone nicks the little solar panel  think_smiley_46


Chris
spanner
spanner
Member
Member

Male

Posts : 123
Joined : 2015-12-04
Member Age : 99
Location : Telford Shropshire
Auto-Sleeper : Broadway Duo EL
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by -mojo- on Sat Nov 18, 2017 2:46 pm

Either connection point will do - in fact you can connect via the cigar lighter socket if it's on while the ignition is off (but I think it may not be on a Broadway).

As spanner says it won't make a massive difference but it will probably help - my Dad has a similar small panel mounted inside the windscreen of his Yaris and it helps a bit, even in mid-Winter.
-mojo-
-mojo-
Member
Member

Male

Posts : 4566
Joined : 2012-08-04
Member Age : 19
Location : Southeast
Auto-Sleeper : Trooper
Vehicle Year : 2006

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Paramedic on Sat Nov 18, 2017 3:37 pm

Grateful thanks spanner and mojo, your replies confirm I was not a dope after all. It certainly gives more confidence on battery management during the period of October till March when not able to access permanent EHU. If and when battery states become compromised, we will certainly try the supplementary panel and advise accordingly. Must mention mojo for his input not only during this thread but many others previously and not forgetting other members for their excellence on all matters electrical. Regards

_________________
In the land of the blind, the man with one eye is king
Paramedic
Paramedic
Member
Member

Male

Posts : 1672
Joined : 2016-01-27
Member Age : 72
Location : Chichester West Sussex
Auto-Sleeper : Broadway FB
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Snow1 solar charge 0

Post by spanner on Sun Dec 10, 2017 5:00 pm

It’s been 4 weeks since I left the EC500 switched off and the solar charge has been left switched to run through a simply “Battery Master” type device, without any mains charging.

This afternoon the batteries were all reading a healthy 12.7 volts with the habition lights on.
As the snow has covered the solar panel for the last 2 days and more on the way I’ve been out and plugged in the mains cable ☃️
spanner
spanner
Member
Member

Male

Posts : 123
Joined : 2015-12-04
Member Age : 99
Location : Telford Shropshire
Auto-Sleeper : Broadway Duo EL
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Peter Brown on Sun Dec 10, 2017 5:12 pm

Thanks for the update, I was wondering how you were getting on. Any chance of the schematic I suggested you produce?

_________________
Peter #1
Peter Brown
Peter Brown
Member
Member

Male

Posts : 5376
Joined : 2012-11-10
Member Age : 67
Location : Staffs
Auto-Sleeper : Malvern
Vehicle Year : 2011

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by spanner on Sun Dec 10, 2017 5:27 pm

Peter Brown wrote:Thanks for the update, I was wondering how you were getting on.  Any chance of the schematic I suggested you produce?
Hello Peter,

I’ve asked a friend to improve my effort of drawing the wiring diagram to make it look even easier to follow for the benefit of others, still waiting, unless there is an electrician listening ?

Chris
spanner
spanner
Member
Member

Male

Posts : 123
Joined : 2015-12-04
Member Age : 99
Location : Telford Shropshire
Auto-Sleeper : Broadway Duo EL
Vehicle Year : 2013

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Askit on Fri Feb 02, 2018 5:10 pm

Askit wrote:I would be grateful for clarification as well. As I have the same set up as you Dave, I understood that the solar panel routinely charged both batteries with nothing switched on. Our motorhome has been left for up to six weeks in storage during winter with no noticeable loss of battery charge.

Went over today to check the motorhome in storage after a lay up of about 8 weeks. Both batteries reading 13.7v and, to my relief, it started first time. Took it for a run in the sun to get things warmed up a little. Electric step was a bit sluggish, but I'm a bit the same at this time of year   snigger  Guess I'll need to get down and dirty with the WD40 when I visit next   Whistle1

_________________
Tony
Askit
Askit
Donator
Donator

Male

Posts : 1960
Joined : 2015-05-16
Member Age : 70
Location : West of Scotland
Auto-Sleeper : Neuvo EK LP
Vehicle Year : 2015

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by -mojo- on Fri Feb 02, 2018 5:36 pm

Askit wrote:  Guess I'll need to get down and dirty with the WD40 when I visit next   Whistle1

It's probably worth considering something that leaves behind a thicker layer than WD40 - in that location I would be tempted to use a spray grease, possibly with a Waxoyl-like coating over the top so that grit and other crud is less likely to stick to it?
-mojo-
-mojo-
Member
Member

Male

Posts : 4566
Joined : 2012-08-04
Member Age : 19
Location : Southeast
Auto-Sleeper : Trooper
Vehicle Year : 2006

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by groundhog on Fri Feb 02, 2018 5:42 pm

Agree with mojo, WD40 as good as it is for freeing things off is not ideal as protection, much better off with a silicone spray grease that will last.
groundhog
groundhog
Donator
Donator

Posts : 2380
Joined : 2011-08-01
Location : Poldarkland
Auto-Sleeper : Worcester

Back to top Go down

It's that time of year again - Page 3 Empty Re: It's that time of year again

Post by Askit on Fri Feb 02, 2018 6:38 pm

Thanks Mojo and Hog up!

I’ve no idea what to expect when I get under the van but the advice will be taken on. My WD40 comment was a bit throwaway but, nevertheless, it’s important that the right stuff is used for the job. Biggest pain of the van being in storage is ensuring I take all the things I need when going over there

_________________
Tony
Askit
Askit
Donator
Donator

Male

Posts : 1960
Joined : 2015-05-16
Member Age : 70
Location : West of Scotland
Auto-Sleeper : Neuvo EK LP
Vehicle Year : 2015

Back to top Go down

Page 3 of 4 Previous  1, 2, 3, 4  Next

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum