Charging deep cycle SLA batteries

[T Mac]

Hi all,

I got 2 100AH deep cycle SLA batteries for my camper and am planning on getting a DC to DC charger for it in the future, in the interim is there a less expensive way to charge them from your tow vehicle while driving or will just simply plugging them into the cars charging system damage them?? Should i just limit my trips to the amount of AH I have in my batteries and charge them from a wall charger??

Also can you use a normal car battery charger to charge these batteries aswell??

[TinkCT]

A SLA is charged just like any lead acid battery, nothing special. But if it is a an AGM battery, they prefer a slightly higher charge. For longevity, use a multi stage smart charger.

To charge your camper batteries from your vehicle, you will need to run cables direct from your vehicle's cranking battery to your camper batteries. You will need suitable fuses at each end of this cabling.

DC-DC chargers are only needed in certain installations. Often a simple VSR (voltage sensitive relay) will do everything you need. DC-DC manufacturers have good marketing campaigns To determine your actual needs, the first thing you need to establish is if your vehicle has a variable charge alternator. If it doesn't, go for the VSR. If it does, the DC-DC charger will help.

The cabling to your camper will also help determine your needs. If it is nice and thick, say 6B&S or above, then your voltage drop will be fairly low and you shouldn't need a DC-DC charger. If your cabling is light, then a DC-DC will help overcome the voltage drop.

Most DC-DC charges also have a built in MPPT, so if you intend to add solar panels at some stage, this could be helpful. But I personally prefer separate components so that I am not putting all my charging options in the same basket.

[robcaz]

You will not damage the vehicle battery or the camper trailer battery by connecting them together with 6B&S twin core sheathed cable. However you do need a suitably sized breaker on the ends of the positive cable next to both batteries. 6B&S is rated at 100 amps so perhaps an 80 amp breaker (not a fuse) would be suitable. Also don't forget you will need to disconnect the Anderson connector when stopped.

At a later date you can add the DC-DC charger next to the camper trailer battery. The DC-DC charger also acts as an isolator, so it will separate the vehicle & camper trailer batteries when stopped.

Also keep in mind that some modern vehicles only have a low voltage output alternator & will have difficulty charging an auxiliary battery, so a DC-DC charger is needed.

I do not know anything about the Matson DC-DC charger with an inbuilt MPPT solar regulator & a 13 volt start up, but the price looks good at around $200 http://www.everybattery.com.au/datashee ... ctions.pdf