Battery charger

[Allan Cathcart]

Hi everyone, new here, we question to you all. I was in Inverness at the weekend when my Battery charger/ battery appeared to fail, firstly I smelled an eggy smell that I traced to the battery tray, I opened this and lifted it out of the holder and placed it outside onto the ground as the battery was hot, question is I noticed my charger fan coming on a lot of the time, I assumed this was normal, however I am not sure If I only switch on the switch on charger when battery is flat, it was on all of the times we have been away, should the battery charger be on all the time? A couple of cells looked dry in the battery so obviously battery is done for but do you think my charger may be at fault also as when I went to switch the charger off it failed to stop,  I had to trip switch and disconnect to get the switch working again. Any help would be greatly appreciated. 

1. Should charger be on the on position  always.

2. Is the Charger cooked because of dry battery.

3. Should the charger have a standby so that the battery does not get damaged.

Thanks in advance

Allan

[Stevan]

Most people leave the charger on all the time that the caravan is in use, many leave it on 24/7even when not in use.

The battery is almost certainly scrap.

The charger may, or may not, also be scrap.

If both are scrap it is unlikely that you will know which failed first, destroying the other

It is important to test the charger before trusting it with a new battery.

With a full battery and charger on it should be delivering around 13.4V

[limecc]

Our old Bailey has a charging voltage of 13.9 which is on the high side, I would prefer it to be 13.7v which is ideal.

 

When connected to the tow car the charging voltage may even be as high as 14.4v but this would make the battery gas off if it were permanent.

 

Story is another vote for low maintenance unsealed batteries - provided the levels are periodically checked I think they are safer and generally have a longer life.

 

To answer OP's questions:

1. Yes

2. Probably ok - measure the voltage with no battery connected.

3. A modern caravan will have an intelligent 'smart' charger that will vary the charging voltage and amps according to the state of the battery. When the battery is fully charged they go into a 'float' mode hence should be permanently connected.

Edited October 1, 2020 by limecc

[David 38]

1 hour ago, limecc said:

 

 

When connected to the tow car the charging voltage may even be as high as 14.4v but this would make the battery gas off if it were permanent.

 

 

 

With cars with such as AGM and EDF batteries for Stop/Start initially these start to charge at 15v before dropping to something like 14v, does this mean when towing it is damaging the caravan battery?

[JTQ]

The most likely situation you encountered was as follows, a classic battery failure mode:

One cell shorted, something as simple as a clump of paste dropping from a plate can do this, that made your 6  X 2 volt cells into 5 x 2 volt cells ie it became a 10 volt rather than 12 volt battery.

This puts the chargers regulated charging volts way too high for the 5 cells the battery you now have require and it gases those off with vigour, everything getting hot and the once good 5 cells also destroyed.

 

Q1 Most caravans are fitted with budget end battery charger, dumb as opposed to "smart", these basic chargers should not be left on whilst the van is not in use. The smart type can and doing so can be beneficial to the battery.

Q2 The charger is probably not damaged. If with a good battery it settles to giving no more than 13.8 volts it is likely to be okay.

Q 3 Yes the charger really should be a "smart" charger reactive to the battery's sate, but these are dearer than the basic type so only some brands of van's use them, most go the budget route.

[David 38]

9 minutes ago, JTQ said:

 

Q1 Most caravans are fitted with budget end battery charger, dumb as opposed to "smart", these basic chargers should not be left on whilst the van is not in use.....

 

 

So when on site with hook up should we be giving it a rest at times during the stay, because I think we all will have them on all the stay?

[JTQ]

3 minutes ago, David 38 said:

 

So when on site with hook up should we be giving it a rest at times during the stay, because I think we all will have them on all the stay?

 

I would leave them on, the real concern is day after day stuck at 13.8 volts just into the area where some initial gasing off "can" happen.

[Stevan]

1 hour ago, David 38 said:

 

So when on site with hook up should we be giving it a rest at times during the stay, because I think we all will have them on all the stay?

That really won't help. Just giving it a "rest at times" will be recovered by the charger fairly quickly . Having it being overcharged, even slightly for (say) 20 hours per day is not much better than 24 hours per day.

What is important is to ensure that it never sits for prolonged periods at 100% charge. Trying to put any charge into a battery at near 100% will result in gassing .

13.8v should be viewed, in practice, as an absolute top limit to prevent gassing.

[Allan Cathcart]

Thankyou do much everyone,  very much appreciated ???