Inverter AGM questions

[S_Davis]

I have been thinking about installing a inverter in my truck, either a 2000-3000 watt. I would use it to run small power tools, air compressor, an electric blanket when on the ferry system as you can't run your vehicle. I would also like to set it up to power a truck camper when we purchase one in the next couple years. What I would like to do is remove my rear seats in my crew cab and build a storage box that would house two to four AGM batteries and the inverter, I want to install a 12v plug in the bed to connect to the camper batteries to form a larger battery bank as well as a 120v outlet to power a microwave, coffee pot, hair dryer. Will it work, is charging AGM batteries from the truck an issue?

[MEXICOWANDERER]

I try to be patient with customers but my tolerance vanishes when it comes to dealing with company "educated idiots" who are usually young, headstrong and utterly sloppy when it comes to researching data especially history and component integrity.

My longest history AGM battery has been measured on my mini platform scale. It resolves down to less than 1 gram, perhaps .3 grams.

In seven years it has not lost one measuring unit of weight.

AGM batteries are pressure sealed. People forget this. The batteries have a recombinant vapor to liquid recovery system built into the caps. They do not lose liquid ever ever ever, unless they are hideously overcharged. Not in the same universe of gradient overcharge as an open flooded battery. A flooded battery will lose 10x3 times the weight as an AGM battery over it's lifetime.

At high temperature, sulfuric acid eats lead. There is no way to stop it. Reduces voltage helps a lot but the majority of electrolysis is due to heat. Unless of course voltage is allowed to stray into 15.5 volt areas that no one is going to allow. Car computers will open loop and RVs will develop symptomatic negatives that virtually no one would ignore.

With influence of high temperature electrolysis the most influential counter action is to thicken the positive plate. I am convinced the Lifeline's double thick plate leads to near double the lifespan as far as electrolytic issues are concerned, How could they not? Does a Lifeline cost twice as much as competitive batteries? I have no idea because I have not the slightest interest in comparative shopping. Logistics wise I am crippled by being well outside the marketing area.

Thicker plates do zero to reduce the effects of abuse upon an AGM. Continual partial recharging, recharging a deeply depleted AGM with less then 20% of the rated 20 amp hour specification current. Having a 400 amp hour bank means an eighty ampere minimum charger. Wanna take a guess how many AGM 400 amp hour banks are recharged at lesser values?

So my take is unless an owner takes the time to understand AGM quirks and then rectifies his charging and management perhaps his best value choice would be chew & spit Chinese batteries.

[S_Davis]

No problem, I am here to learn.

[MEXICOWANDERER]

Dual channel charges engine battery through a diode. Are they idiots? This is the EXACT battery isolator issue that has plagued the industry for fifty years. Motorola found out the hard way forty years ago the effect of series silicon rectifiers when they tried to be smartassed as used it to power the voltage regulator on 8CR 40 amp alternators.

A well designed charge division management system would have the primary channel divert through a SILICON CARBIDE (METAL OXIDE) FIELD EFFECT TRANSISTOR with vf rated in millivolts. An emergency circuit would over-ride the MOSFET circuit and channel engine and chassis voltage direct to the engine starting battery if the MOSFET circuit faulted.

Charging systems that direct 14.4 volts to an AGM battery for mere hours a day will assist that AGM to live longer. A yacht can motor 24 hours a day for weeks -- a slight difference. A hot seat coast to coast semi can travel for MONTHS with six hour stops to change oil. The sleeper on those rigs hold a trade off driver.

Charge management has it's proper place and management of a intermittent 14.4 volt regulated power supply makes about as much sense as swallowing penicillin to prevent chapped lips. 14.4 volts IS the magic number in final charging of an AGM battery. ONLY calcium excess acid fat mat telecommunication batteries could use theoretical charge division management.

Here is a scenario where 14.4 volts would not be the best option

A quick starting vehicle that operates in 100-120 degree 5 hour daily commutes that endures zero cycling. Yet there are tens of thousands of vehicle batteries that successfully do just that. The southern USA, the mideast, africa, india, southeast asia.

Adding in inappropriate charging gizmo where it is not needed and is contraindicated is a fine way to buy into a bundle of problems.

Sorry to be so blunt but this is not a gray area. 🙂

[S_Davis]

Well I just can't get by the thought of a dc to do charger so if I can't plug in to charge the battery bank they will still be fully charged by the truck, I found this one that will do 130amps.


http://www.promariner.com/en/~/media/inriver/354427-37034.pdf

[S_Davis]

MEXICOWANDERER wrote:
Your truck voltage is fine the way you state. Millions of AGM batteries see this same voltage every day. You may well overthink your way into a problem 🙂

Ok thanks for the reality check.

[MEXICOWANDERER]

Your truck voltage is fine the way you state. Millions of AGM batteries see this same voltage every day. You may well overthink your way into a problem 🙂

[S_Davis]

pianotuna wrote:
S Davis,

Most of us just want the starter battery to be kept from discharging. An inexpensive continuous duty solenoid with a 200 amp rating will do that inexpensively and reliably (mine are 9 years old now).

I did add a trik-l-start to keep the starter battery charged for the long times between trips which has continued to offer perfect service for 7 years.

I was thinking it would be better using a dc to dc charger that can buck the voltage to properly charge the agm batteries, my truck charging system voltage sits at 14.2 to 14.4.

Don't agm batteries need higher voltage to properly top them off and or condition them?

[MEXICOWANDERER]

Un needed



I do not like battery management that uses wires and switches, because wires and switches turn out to be 80% of the problems that plague management systems.



Easier to install. A fraction of the price. And it keeps your engine battery maintained when connected to shore power for extended lengths of time. It's all automatic and no stupid wires and switches to run.

[MEXICOWANDERER]

Un needed



I do not like battery management that uses wires and switches, because wires and switches turn out to be 80% of the problems that plague management systems.



Easier to install. A fraction of the price. And it keeps your engine battery maintained when connected to shore power for extended lengths of time. It's all automatic and no stupid wires and switches to run.

[pianotuna]

S Davis,

Most of us just want the starter battery to be kept from discharging. An inexpensive continuous duty solenoid with a 200 amp rating will do that inexpensively and reliably (mine are 9 years old now).

I did add a trik-l-start to keep the starter battery charged for the long times between trips which has continued to offer perfect service for 7 years.

[S_Davis]

Ok starting to move forward again, I am looking at battery isolation relay/chargers. I have found this one, any thoughts?

https://smartercharger.com/products/dcdc/smartpass-120/

[S_Davis]

The buss bars will be within 2' of the battery terminals so I will take your advice and just use breakers on each circuit off the buss bar.

[MEXICOWANDERER]

If the distance is short and uncomplicated between the battery positive terminal and the buss bar, then no protection is demanded. En example would be mounting the batteries then passing cables through a wooden partition. Both batteries would then be wired to the buss bar then things coming in and out of the buss bar would see a circuit breaker at each cable or wire.

(1) battery 2 cables. One positive and one negative. The buss bar does all of the manifolding. Battery cable count should be kept to the bare minimum.

[S_Davis]

BFL13 wrote:
I thought you were using a breaker at each end as your "fuses". You asked if you also needed fuses. Mex did not answer that. I do not know the answer. I get confused over "slow" vs "fast" acting and when to use which.

I am using 120amp bussmann breakers on both ends of the charging circuit from the truck as well as the line to the bed plug for the truck camper charging circuit. I was asking about the two 8D Lifeline batteries that I am installing in the rear seat area of my crew cab and the wiring to the 650amp buss bar where it all ties together.

[S_Davis]

MEXICOWANDERER wrote:
FUSES are EXACT and almost instantaneous. They are also a pain-in-the-ass to have to change. Fuses are wonderful to protect sensitive electronics, the inverter, converter, stereos, computers etc.

Circuit breakers are sloppy. Not exact. React instantly only when badly overloaded, are forgiving and heal themselves quickly and automatically.

BREAKERS are perfect to protect main line trunk power cables. FUSES will blow if a power source is hooked up backward. But small appliances will still burn out with reversed polarity.

The actual only NEGATIVE with using 400-amp T class fuses on main battery cables is you'd better carry spare(s), and the fusing block should be in a very easy to get to place. If a fuse fails what do you do? Try another fus...****! ?

That's why I prefer breakers. Class T fuses are not cheap and an inadvertent "OH NO!" does not become an exercise of feeding more fuses by trail and error until the problem is found.

There is nothing wrong with using a ultimate limit fuse ahead of a circuit breaker. An example by toad has a 30-amp fuse, then a 20 amp breaker protecting the radiator fan motor. When the fan motor shorted, it blew the fuse -- telling me the 20-amp breaker reacted slowly. Then the circuit went "open circuit". Diagnostics were a snap. The motor is now open circuit but before that it had shorted. No sense in troubleshooting further. Motor bad. Bad motor. Recycle motor.

Ok thanks, so what size breakers should I get for each battery?