Towards the end of my last holiday, the fridge stopped cooling, as the onboard charger had decided to stop working. I decided to do a bit of investigation and have got the charger working....I just want the electrical experts to check the following information to verify all is well. On the test, I've used an Aldi smart charger both to obtain first set of figures and to give voltage levels on both tests. The fridge was on for approximately 24 hours for each test. Charging with "smart" charger - From fully charged (14.1v) dropping to 12.7v Charging with onboard charger- From fully charged dropping to 13v As someone who, before coming on this forum, thought a fully charged battery read 12v and a flat one 0v , I wanted to check if the above figures are ok and my onboard charger is indeed now working. Sorry for long post !
AFAIK Charging will be at 14.1V and a fully charged battery should drop down to 12.7v (once the surface charge dissipates) so it looks like its fine.
The general rule of thumb - 15+ volts : your battery is a hot smelly mess. Stop charging it. Throw it away.. 14.2 volts is the "absorbtion charge voltage" . The charger should maintain this for a while once the voltage is reached, then back off. It may go higher voltage, depends on charger manufacturer. Main thing this shouldnt be maintained or the battery will gas off all the electrolyte. 13.8 volts is the "trickle charge voltage". The battery can cope with this for a long time. It will maintain a previously charged battery at 100% 12.7 volts is the typical voltage of a fully charged battery, after "resting" for a while. 12.1 volts is the typical voltage of a nearly flat battery 11 volts is really flat. Below this voltage you are damaging it.
Good to know....if I've a fully charged leisure battery, how long should it hold its charge before it's at risk of being damaged? Or is that a " how long is a piece of string" question!
A useful set of numbers thanks. I've just been and checked mine ( 2 Aldi chargers, one for each battery )and just about agree with your figures.
If its put away without anything connected to it it should still be good after an entire winter for example. Lead-acid batteries have one of the best self-discharge characteristics. Certainly better than some lithium batteries. Main thing is charge it up then leave it.
It lives in the garage on electric hook up, so leisure battery is on constant charge, in addition the starter battery is on a conditioner. I just wondered if this was the best way to look after the leisure battery.
Hi gang, I was thinking of starting a new thread but since the original question seems to have been answered I'll tag along here with what I think is a related query. Pretty much since year dot I've had a leisure battery installed and charged via a standard 30 amp relay, switched by alternator output. Times have moved on in those 20+ years and voltage sense relays are now widely available for not too much money. So I've been thinking of swapping out the plain 30A job for one of these. The ones I'm looking at are rated to switch on at 13.3V and off at 12.8V. What I'm hoping to achieve is to be able to leave the main starter battery on an intelligent charger over winter and for the voltage sense relay to allow me to also charge the leisure battery simultaneously from the same charger. Assuming my charger maintains a trickle of about 13.8V, do you think this should work?
I know people use that setup but it doesn't appeal to me. You are trying to charge two different capacity batteries in different states of charge so neither would be getting the optimum from the charger. I prefer to leave my leisure battery on the ctek for the majority of the time and then once every 4-6 weeks I swap it to give the starter battery a week on charge. Sent from my Pixel 4 using Tapatalk
Yes that will work.. provided neither battery is below 10 volts, the VSR will connect when either side reaches 13.3 Volts.
Just fit the VSR and take the van for a decent 50 mile run every 3 or 4 weeks - you're better off using it to charge the batteries than chargers .... Sent from my SM-G960F using Tapatalk
^this. It'll charge your batteries and give the van a good run. If you are buying a VSR (nothing wrong with a relay, BTW), get the "green label" one from folk like 12V Planet. The Durite ones have lowered the cutoff voltage too close to the terminal voltage of a fully charged battery. It'll stay connected possibly for days. The green label ones have the cutoff set slightly higher.
Agreed that would be the ideal solution but my van lives in the garage so I'm reluctant to take it out when there's a chance it'll get wet with no chance of drying out before going back to bed. So in all intents it's off the road over winter other than when a warmer, dry day might coincide with me having a day off work, which given the form over the past month is pretty much never .
