Batteries Again!!!

[Birder]

Am I doing wrong by leaving my batteries in situ & hooked up to home electrics whilst at home? They (2 x 85 A/h) can be left like this for about 4-5 weeks at a time; no longer as we like to be away as often as possible.

I ask because someone recently told me that they can overcharge &/or burn dry? Not heard that before!! :$

[artheytrate]

I do the same during winter never had a problem.

 

John.

[Brian Kirby]

You need to give details of your van make and model, its year of manufacture, and especially the make, and if possible model, of on-board charger installed. It might also help if you can give as much detail of the batteries as you can find. Type (flooded, AGM, gel etc), age, make, plus model or ident no.

 

Some chargers are what is called "smart", and read battery condition and charge level, and then charge accordingly. These can be used as you presently do without problem.

 

Others however do no more than supply a charging current to the battery at a more or less flat rate, and these can, indeed, over charge batteries. This usually affects the battery through loss of electrolyte. This is due to the charger not recognising when the battery is fully charged, and continuing to feed it as though it were discharged. This causes gassing, the gas resulting from the breakdown of water in the electrolyte into hydrogen and oxygen. The electrolyte level therefore falls and, if not regularly topped up, can fall to levels at which the battery is terminally damaged. Other consequences of maintaining a relatively high rate of charge when not required also cause lasting damage, so if the charger is of this type, the best approach is to use it periodically - but mostly keep it off.

 

The frequency at which a non-smart charger should be used depends on how well the battery holds its charge, and this needs to be monitored. All batteries will self-discharge to some extent so, even if left disconnected, will require an occasional charge to keep them in good condition. If your batteries are in good condition, and there is little to no "silent" consumption when the van is not being used, there should be no need to use the charger during the 4/5 weeks it is standing. Inevitably, whether "use" of the van will enable the alternator to fully charge the habitation batteries will depend on the duration of your drives, as the alternator will first charge the starter battery before getting to work on the 170Ah of habitation batteries. To be safe, therefore, I'd suggest you put the charger on for 24 hours before using the van each time. Then, if you have actually been camping in the van as opposed to just driving it around, if your control panel gives a read out of battery charge state, leave the van parked overnight, see what the battery charge state then is, and give it a further 24 hours on charge if necassary.

 

The rider to the above, whatever the type of charger fitted, is whether it also charges the starter battery. Some do, some don't, and some have to be manually switched between starter and habitation batteries. I assume yours must, since you haven't mentioned starting problems, and most starter batteries will become quite heavily discharged by the on-board electronics over a 4/5 week period, unless topped up. Something to check and confirm?

[Derek Uzzell]

Birder

 

At the end of 2012 your motorhome was an Avondale Seascape that you'd owned for 7 years.

 

If you still have that vehicle and you've always been in the habit of continuously running its onboard battery-charger from your home's 230V mains, it seems to me that you might as well keep on doing this.

 

As Brian says, the advisability of 'continuous charging' will depend on the equipment involved. There is also always the possibility that a fault will develop with the battery-charger or the battery during the prolonged charging period, but I can't see how that risk can be quantified.

 

I don't trust equipment to cooperate, so I don't do this. But, If you are comfortable with the (probably pretty small) risk that continuous charging MIGHT cause significant problems, I don't see why you should stop.

 

(Plainly it would be commonsense to take some care to minimise risk. For example (assuming it's practicable) ensuring that your motorhome's batteries' electrolyte-level remains correct.)

[grandadbaza]

I was worried that leaving my van on hook up while at home , it is Auto Trail Comanche with sargent EC325 psu , so I asked Sargents if it would hurt the batteries , this is the reply I got

 

Hi Barry,

 

It is fine to leave the power turned on, although it is always advisable to check your batteries periodically.

 

The charger will initially have an increased voltage as it charges the batteries, and will then drop to a float charge to maintain a healthy voltage.

 

Regards

 

Craig