Thread: Decisions, decisions, which dual battery system??

im not charging at a lower voltage, so its not an issue.

Hi Eevo and just keep doing what you are doing, your battery will be fine.

You are charging from an alternator, so once again, as the info above relates to battery chargers and not to alternator charging. It’s irrelevant!

Hi Noki, and in Nap situation, where wants to link batteries while winching but he is also worried about forgetting to separate the batteries once the motor is off, as all other isolators use a switch to manually switch the solenoid/relays on, and bypass the isolators electronics, he will still have the same problem.

Other isolators recommend you fit a push-button momentary switch, to link the batteries together for jump starting but this is next to useless for linking batteries together for winching.

To link batteries for winching, you need to fit an on/off type switch and again as this type of set up bypasses the isolators electronics, Nap would be right back in the same position of risking leaving the switch in the wrong position and ending up with two flat batteries and no way to start.

This is where the USI-160 differs. It is a micro processor controlled system that “REMEMBERS” to automatically separate the batteries if the operator forgets. So you can’t accidentally flatten both batteries.

Oh, ffs, For the last time and in large print so you can't miss it:

THE VOLTAGE DROP GOES TO ZERO AS THE CHARGING CURRENT GOES TO ZERO.
It will still fully charge albeit a little slower.

Hi folks I am trying to avoid dealing with the erroneous statements being post in this and other threads, but you need to be aware of the problems that will occur if you follow these erroneous statements.

First off, as the temperature of ANY TYPE OF BATTERY rises, the maximum charging voltage MUST DROP.

With the average AGM, the Standby type, because they are not specifically designed to tolerate the heat of an engine bay, for a number of reasons, you will SHORTEN their life span if you fit them there.

Furthermore, charging them with a constant 14.7v, while in the engine bay, or any where else, will further reduce their life span.

What Eevo and many others have done, fitted their auxiliary battery in the rear cargo area, is the IDEAL SETUP that will give these batteries the greatest chance for a long life span.

If you want to fit an auxiliary battery under the bonnet, either fit two cranking batteries or fit an AUTOMOTIVE GRADE AGM, like an Optima.

Optima batteries have been specifically designed to be used as direct drop-in replacements for any cranking type battery, and they will tolerate the high temperatures, high voltages and have an unlimited charge current tolerance.

you may have a reliable source for charging the battery, but the situation they are covering has nothing to do with vehicle use.

The charge time is based on a 24 hour cycle of 8 hours of use, and 16 hours of charging.

This would apply to someone using that battery for powering something like a golf cart, where it is use for 8 hours that recharged 16 hours over night, or are you suggesting, that someone needs to drive for 16 hours straight, just to recharge their auxiliary battery.

Once again, the document has nothing to do with RV use or charging via an alternator, and specifically states a 16 hour recharge time is needed.

Why would you even bother with an auxillary battery, if only using it for 10% of the year and if you have a DBS, would you just connect the charger to the main battery and leave it to float charge, or am I missing something here.

I'm no expert, in fact not that good with electrics, Tims gear and info is quite complex, but at the same time simple, easy to use and fool proof, in the almost 10yrs of using Tims gear, never had an issue with any of the info or gear, as far as I can tell, everything that Tim has said to me or Kerry over the years has been spot on.

BUT I find you confusing(maybe it's me) people are not saying you're wrong, just that your info is about a standing item or object that can't re-charge itself(I think that's right) so you've made your point.

Baz.

This is why I do not debate the things you say. You only ever provide throw away facts. That is, you can never supply any independent source to back up your statements. The only reason I finally decided to address this point is that you keep on stating it.
There is no material difference in an alternator charging a battery compared to a battery charger.
Both will supply a consistent number of amps during the bulk state. However, the amps supplied by the alternator may vary a little if you switch electrical items on or off in the vehicle. To suggest otherwise goes against how an alternator works. Both charger and alternator will slowly reduce the amps applied during the absorption stage. However, the voltage applied by the alternator might increase slightly as the amp draw drops. The only main difference is that a charger can and does supply a float charge. Whereas the alternator cannot. So instead of just maintaining the current in the battery will continue to try and increase it. So an alternator can to lead to overcharging a battery, particularly an auxiliary battery that is no used 90% of the year. So you should disconnect the auxiliary battery once charged and not in use.[/quote]

Hi again, and for a starter, YOU posted up the wrong document. A document that has nothing to do with RV or automotive battery charging or use.

That's your doing, not mine.

Next, unless a battery is damaged or fault in the first place, an alternator ?€œCAN NOT OVER CHARGE ANY TYPE BATTERY?€?

This is one of the HUGE advantages alternators have over things like battery chargers and DC/DC devices, both of which can and do over charge batteries.

You can leave home on the first day of a long trip and you should have fully charged auxiliary/house batteries when you start your trip.

You can drive all day and get to where ever you are going and ALL the batteries in your vehicle and caravan/camper trailer will still be in a fully charge state and in good condition.

The same does not apply to batteries being charged by a DC/DC device, because some of them, if you have a fridge connected to the battery, will cook the battery by the time you get to the end of your drive.

So once again, you are posting up totally erroneous info.

Once again you posted up a document that is about the commercial use of batteries. A document that has nothing to do with RV or automotive battery charging or use.

Then you make the erroneous claim that alternators will overcharge batteries.

I don?€™t have to do anything because it is a well known fact throughout the auto electrical industry that alternators do not overcharge batteries.

So being as you made the claim that they do, you post up a credible document to back that erroneous claim!