[farmer ted]

Jay,

I'm not familiar with the exact product you're talking about but in theory, hooking up a deep cycle/ marine battery to the charging system of your car should be ok as long as the charge is regulated by the adapter device.
       there are a few things to keep in mind though...The alternator in your vehicle is really designed to keep the charge in the electrical system 'topped off' and does best at a relatively low charging rate of 5-20 amps when the vehicle is running. Alternators are capable of charging at very high levels for short periods of time (i.e. to recharge the battery after starting) but these should only be sustained for a few seconds or the alternator will overheat.
        The alternator regulator is designed to charge at full blast until a certain preset voltage is reached. In real world terms this means that if you hook a dead battery up to your car's electrical system the alternator may try and charge it at 100 amps until the voltage comes up enough to reduce the charge, this could easily cook an alternator.
        On top of all this, deep cycle marine batteries do best with a low amp charge ...say 1.5-5 amps. quick charging them is really hard on them and will reduce their life. put a dead deep cycle on the car and the alternator will try to quick charge it which is hard on the alternator and the battery.
         With all of this in mind, I'm assuming that the device you are looking at will somehow regulate the charge to your marine batteries from the alternator thus providing the slow charge you are looking for and not overloading the alternator. if this is the case then it should be perfectly fine to install on your car.

 

[farmer ted]

Also what Ted said about the alternator topping of batteries isn't quite accurate.  I think they are designed to support the entire electrical load of the vehicle and a possible tow vehicle at night and still top off the battery after starting the vehicle in cold weather.  Output of 50 or 60 amps is quite a bit, and that is also regulated.

Alternators are designed to handle the electrical load of the vehicle but that load is designed to be an amperage that is well within the alternators output range...typically 10-30 amps constantly. the battery in the system actually acts as a 'shock absorber' or capacitor to handle sudden large amperage needs (such as starting) or when a high draw accessory (AC Clutch) is engaged.
     Essentially the alternator runs the car but at a relatively low amperage that's engineered to match the accessories the car has. A side note: the alernator regulates it's charging output via duty (or on-off) cycling that is measured in milliseconds. so that when it's charging it's constantly cycling on and off at full blast a larger or smaller percentage of the time to essentially average total output.  if anyone wants more info, let me know, I actually teach this stuff for a living.

 

[farmer ted]

No worries, I didn't mean to come off snippy...sorry, it's been a loooong week. you are correct in your analysis. O0

 

[farmer ted]

kirby,

If you're charging an automotive type of battery a slightly faster charge is ok. the plates inside a "starting battery" as it's called are thinner and will accept a fast charge better because of their larger surface area. in other words...a 12-20 amp charge is fine, but a slower 1.5-5 amp charge is better especially if the battery has been run completely dead.

Marine type DEEP CYCLE batteries use relatively thick lead plates to stabilize output and provide longer output at constant amperage draws. a quick charge doesn't really 'penetrate' the thicker plates which leaves you with something called a 'surface charge' which means the battery will appear to be charged but only last for a relatively short time. it is always best to charge a deep cycle battery on the lowest setting you can although sometimes we don't have time.

 

[farmer ted]

If a battery manufacturer gives giudelines for charging their batteries, then, obviously you can follow them. I don't claim to be an electrical engineer and everyone's experience is different. I was just trying to be helpful and pointing out some general rules that could benefit some people.

the only point I was trying to make was that as a general rule: the lower of a rate you charge ANY battery, the better it is for the battery. and the lower output an alternator runs the better it is for the alternator.

I probably got carried away, my bad.

 

[farmer ted]

I disagree but I'm done with this thread. that's all I'm going to say about that.