Problem with leisure battery

[Jango]

I am new to the van Mount system. Probably 6 weeks of usage. 

Today for the first time my controller the blue streamline one, started the battery light flashing. Which has never happened before. Do I need to remove the leisure battery and charge it, with it been winter. It is on a split charger. It's a brand new battery. Any help appreciated. 

 

[Guest]

Chuck a voltmeter over it. It probably needs a good charge. Winter is bad for batteries.

 

[Jango]

Ok thank you. Someone told me it would not need charging, that's why I thought you guys would know better. 

 

[Part Timer]

If you're saying that the battery is only 6 weeks old and is running low then you're either doing a lot of work and no mileage or your split relay isn't working. My batteries are nearly 7 years old and I still get 5 hours a day out of them. 

 

[Jango]

If you're saying that the battery is only 6 weeks old and is running low then you're either doing a lot of work and no mileage or your split relay isn't working. My batteries are nearly 7 years old and I still get 5 hours a day out of them. 

I am doing a lot of work and not many miles, I have a lot of houses one after the other. Do you think this is the problem? And if so is the answer to charge the battery? 

 

[Part Timer]

I am doing a lot of work and not many miles, I have a lot of houses one after the other. Do you think this is the problem? And if so is the answer to charge the battery? 

If you're busy and the van isn't moving much then you probably will need to physically charge the battery. If this is a pita try just running the van whilst filling or when you're working in a safe area. 

 

[spruce]

We find that our split charge relay doesn't keep up with our daily useage @Jango

I have a volt/amp meter in the van. Our pumps draw about 4.5 amps an hour each. We estimate that we spend about 50% of our day actually cleaning windows. You might find that with a compact run it could be higher.

Lets look at a single operator. For us a 6 hour day would mean 3 hours of pump running and that would take 13.5 amps from our 110 amp leisure battery. That would leave us 96.5 amps left in the battery provided we started off the day with it fully charged.

During the day we moved the van around a bit and went up to the chippy to buy some lunch. At the end of the day we drive home. It takes us less than 20 minutes to drive home and we could add another 10 minutes of running around time during the day.

On the way home I notice that the van is charging my leisure battery via our split charge relay at about 7 amps. (I have a Citroen Relay Hdi with a 90 amp alternator. The voltage sensing relay is rated at 140 amps and I have 75 amp cable linking the batteries together.)

Lets focus at 7 amps charging rate on my way home. If the engine running time is 30 minutes, all I have returned to the battery is 3.5 amps. So I have a deficit of 10 amps for that day. If I then consider the drive back to the same area of 20 minutes the following morning then I've added 2.3amps to the battery. I'm still minus 7.7 amps for the previous day. If I get stuck in a morning traffic jam and leave the engine running then I might get a little more charge into the battery. I might take the back roads to get home rather than the motorway as a longer driving time gives the battery a greater opportunity to get more charge. What ever I do in our situation we will always have a battery deficit at the end of each day. Sooner or later our battery is going to be flat if we don't supplement its charge.

Now this battery charging malarky isn't as simple as I've made it seem. As a battery looses charge the electrical resistance inside it also reduces, which means that the vans alternator could charge the leisure battery at a higher rate. I've seen mine at 22 amps. So if you have a nearly flat leisure battery then there is the possibility that your van's alternator will just about keep up with your daily power draw. (On the opposite side of this, a nearly fully charged battery will only accept a very small charge. On my way to work this morning I will probably see less than an amp going into the battery. My battery was on charge all night. My charger's peak voltage is 13.9v where my vans alternator will peak at 14.5v. This voltage gives a little more pushing power to put a slight bit more charge into the battery.)

Now for your leisure battery to last you need to keep it above 50% charged. So I only actually have 55 amps of my 110 amp leisure battery available if I adhere to this 'rule' of longevity. Yes I can take much more than that, but each time I do it I'm 'killing' my battery - shortening it life cycle. This is why Numax refuse to give warranties on batteries sold to window cleaners - their statement calls us battery abusers.

We get around 3 to 4 years from our leisure batteries. In summer I plug my charger in every 2nd night or after a hard day. In winter I plug my charger in every night. For me its easy as my van is parked on the drive way.

An article on leisure battery charging in a motor home reported that it would take a journey of 750kms to fully charge a flat leisure battery.

 

[Jango]

SPRUCE Many thanks for the detailed explanation, some of it I must say has gone over my head but I get the gist of it. As your illustration shows that’s how my days usually go, so I need extra charge in it for sure then. Many thanks for taking the time to explain.