Are all truck batteries created equal?

You can usually get an extra two/three inches of depth in truck boxes.

Why do you desire a deep-cycle battery in an automotive environment, Ig? They're recharged every time you start the engine.

-- Experience is a good teacher, but she send in terrific bills. -- Minna Thomas Antrim

He's a tech addict with a lot of auxiliary loads :)

First of all, what kind of truck? What sized battery? There are cheap junk batteries, expensive junk batteries, reasonably priced good batteries, expensive good batteries, all the way up to insanely expensive very good batteries.

The cheap and expensive junk batteries are the easiest to find.

My experience with the Interstate MegaTron batteries has been excellent.

Red Optima. You won't go wrong, but your wallet will feet the pinch.

I recently diagnosed the charging system on my car. The manuals and such (I have a few) weren't much help beyond what-wire-connects-where, but there were some very odd indications.

You can charge a battery, give it a known discharge, and see if it is holding enough energy. My battery was OK.

You can monitor the charge voltage to see if the normal operation causes the correct charging voltages (in the

But almost nothing else; there was no easy way to test the generator ex-situ, or any clear indications what the voltage regulator was doing except as part of the full assembly of components.

So, there was no clear determination of what to replace. The generator came with a helpful little pamphlet that said 'replace the voltage regulator at the same time', and it's a common recommendation to replace the battery after any charging problems. So, I'm thinking a 'professional' would replace battery, regulator, generator all at the same time. Whether they need it or not. Without ever diagnosing to the individual faulty part.

That's just bad engineering.

My problem was an intermittent short inside the generator, which clobbered the battery charge four times in the space of a year (but usually worked when the meter was attached).

Blue top is the combination if I remember correctly. Yellow is deep cycle.

Fine. Add an aux battery, also non-deep-cycle. It'll be recharged daily, too. ;)

-- Experience is a good teacher, but she send in terrific bills. -- Minna Thomas Antrim

Gel cell batteries are just lead-acid batteries that have the electrolyte gelled by adding silica-gel (I think). As they are sealed batteries they should be charged at a lower voltage to avoid over heating which could cause excessive gassing and high pressure inside the sealed case.

Trojan Batteries recommends a maximum charging voltage of 2.35 - 2.40 per cell or 14.1 - 14.4 volts for a 12 volt battery..

While I cannot quote references, my experience is that few, if any, common automobile alternators will produce a higher voltage then is safe for a gel-cell.

As an aside - a gel cell's real advantage is that if you turn them upside down they don't leak acid all over your new levis.

I would not really trust the dash gauge too much when a couple tenths of a volt is critical.

John

Err ... Actually battery manufacturers recommendations are:

Lead-Acid Maximum charging voltage 2.45 - 2.7 VDC/Cell or

Gel-Cell Max Recommended voltage 2.35 - 2.4 or 14.1 - 14.4

AGM Max Recommended 2.35 - 2.45 of 14.1 - 14.2

My own experience is that few, if any, automobile systems will put out a voltage high enough to be of danger to any of the three batteries and that gel-cells, at least, can be a direct substitution for lead-acid with no problems, and I certainly know people that installed AGM batteries in their boats and didn't report any difficulties.

It is useful to note that the only advantage that Gel-Cell or AGM have over lead-acid is that they don't spill if you turn them over.

Run a deep cycle in a car and you will kill it in short order. They are not designed for the high current output required by the starter. It warps the plates and shorts them out. The combination units will handle your typical outboard engine. They don't work well in vehicles with large engines though, for the same reason. If you have a vehicle with constant draw requirements you're better off installing dual batteries with an isolator.

Sounds like your regulator points are sticking or welding shut once in a while draining the battery back through the generator. The contacts on the regulator close when the output of the generator reaches about 12 volts, below that they should be open. You could put a heavy current diode in series with the generator to prevent this back current flow. New technology combined with old. :)

John

Not the ONLY advantage. They also do not gas under normal charge or discharge.

In aircraft use a "wet" battery needs to be in an enclosed and vented battery box, while AGM and Gel batteries can just be strapped down anywhere. Gel and AGM batteries are not considered hazardous cargo either (which is mostly due to not being spillable) but there are valved spill-proof wet batteries as well - which are NOT non -hazardous.

I have a laptop and sometimes I forget to turn off the inverter for it. If I had extra capacity, I would be better off with that.

I thought that those optima batteries were designed for cars!

They are. Trucks too.

There are at least three different versions of the Optima spiral cell AGM batteries designed for different applications.

They make more than one type of Optima battery. They make a conventional starting battery like you need in a car. They also make a combination battery that is a marine starting and trolling battery. The problem is that they are NOT intended for use in a car. They are intended to start a typical outboard engine. They can tolerate being discharged more than a starting battery but not much more. Then you have the deep cycle type. They are intended to run something like a trolling motor, they will deliver current over a long time and take being discharged well. BUT they won't work long in a vehicle since the starter draws a LOT of current and that will warp the interior plates of the battery and short it out.

In your case you would be MUCH better off with a couple items. One a duel battery isolator and dual batteries. AND a battery saver unit which will shut off the current when the battery hits a set voltage level. That will protect the batteries.