Charging multiple batteries

Hope somebody can help me with this. I have 1 cranking and 2 deep cycle marine batteries in my boat but I only have one batter charger (2,8 & 12amps with automatic cutoff and maintenance charge capabilities). Charging one at a time is a pain, and at the moment I'm too cheap to buy additional charger(s). Would it work to hook them all in parallel so the positive/negative voltage is still 12 volts and charge them all at once? Or maybe only the two deep cycle at the same time as I understand they are constructed differently from the cranking type battery?

Thanks.

If you have a 24 volt trolling motor, the batteries for it are connected in series and you'll have to charge them separately. If you have 12 volt motor, you could charge them together if they are connected in parallel (which they'd have to be for a 12 volt motor). Better to take the time and charge each separately. I have on board system which charges 3 batteries at the same time but it is really 3 separate chargers (with 3 pairs of leads) in one case.

you might want to take a look at this : http://www.uuhome.de/william.darden/carfaq.htm

OK ... it is a little "technical" & longwinded ... but, it does provide some key information about battery charging & maintenance. ..... cp :cool:

Thanks for the replies.
E

No, you don't want to do it. The reason is the batteries won't be discharged equally. When you connect them in parallel, the more charged one will start charging the less charged battery(ies), creating potentially unsafe or battery damaging charge rates.
A three-bank onboard charger will pay for itself pretty quickly in longer battery life.

You can't go wrong with a bank type charger. Then do yourself another favor and get one of those fancy fillers and use distilled water. I got mine from Cabella's. It uses a series of tubes and automatic shut offs for each cell. I was really suffering battery whoas and disappointments before I started doing this.
DP

Definitly, 3 bank charger is the only way to go. I too have 3 batteries, one for big motor and 2 trolling motor batteries. Don't neglect your main battery, a day on the water running depthfinders, livewells, etc., can sometimes put a drain on them and they don't always get a full charge by just running your big motor.