I need to replace my on board charger. I can get a 5 amp or 10 amp charger. I realize one will take longer to charge batteries, using A 5 vs a 10. I seem to remember slower charge of the deep cycle batteries is better? I always have 8/10 hours to charge my trolling batteries so time should not be an issue. The 5 amp is $100 cheaper, but do not wish to buy on price alone. Your thoughts, get a 5 or a 10? Thanks