What battery and charger to use?

[Philthy]

Sorry for the noob questions here but I'm just not quite finding the answers I'm looking for. I need some help with recommendations for my battery and charging unit. First, let me explain a little of what I'm working with. For my electrical, I'm thinking I'll do the "super simple" AC circuit, essentially a power cord with a fuse/breaker. I only need a couple of 110 outlets for when we are hooked up to shore power maybe one inside and one in the galley. The DC circuits will only be a fantastic vent, a dome light, two porch lights, two reading lights and two usb or cigarette lighter outlets. I will use LEDs for all the lighting to keep the draw down.

I need recommendations for battery, location, power distribution and charging as they are all related. Is it worth it to buy an AGM battery to avoid any potential issues with fumes and put it in the galley or buy a standard deep cycle battery and put it in a box on the tongue? Seems like a long way to run wires. Also, is it worth it to buy the PD4045 or PD4135 or with my minimal setup or go with the super simple AC and a fuse block for the DC? And finally, what chargers are people using for their batteries? I understand AGMs need different chargers than the standard deep cycle batteries.

[Padilen]

I'm not sure that AGM's do need a different charger. They are still lead acid batteries right? Just a sealed "gel" not liquid.



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[working on it]

I'm not sure that AGM's do need a different charger. They are still lead acid batteries right? Just a sealed "gel" not liquid.
...

Actually, AGMs do need to charge differently than typical "wet" lead-acid, or a "gel" type (most AGMs are a "paste" of electrolytes between mats. Standard trickle chargers can charge all 3 types, at the lower charging rates, but when charging at higher rates you have to limit the voltage to under 15v max, especially on gel (unlike "wet" cells, where you can charge with a lot of amps at higher ending voltage). I may not have stated that correctly, but I have killed Gel and AGM batteries that way, but not any "wet" -cell batteries (using quick, heavy amperage charging of my race-car batteries between rounds). Currently, I have an Optima Yellowtop AGM in my trailer.I use a Battery-Minder trickle charger/maintainer year-round at home, and a Schumacher XC15 charger (with specific charging settings for std., gel, and AGM batteries) on the road (at campsites), or at home to check status & charge before trips. If you have to charge an AGM with a larger capacity charger, monitor it closely! The Schumacher has automatic shut-off, and the trickle-charger is auto also.

[Padilen]

That's good to know. I bought an AGM for my bike. I did check for my battery tender compatibility. It does say to read the charging details, but I haven't opened box yet.


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[MtnDon]

There is some misinformation above.

An AGM battery (like Optima and Odyssey) are not gel batteries. The electrolyte in an AGM battery is not a gel or a paste. The lead plates in an AGM battery are separated by a boron silicate glass mesh like thing. The AGM battery uses a regular sulphuric acid / water electrolyte liquid. The liquid is absorbed into the fine spaces in the glass mat. That's where the initials AGM come from. Even if the case is cracked or cut the liquid acid will not run out of the separator mats.

An AGM battery is not truly sealed. There are valves that will release pressure if the battery is charged at too high a rate. When treated properly they should never off-gas. It is possible though. When being charged hydrogen and oxygen are released just as with a standard flooded battery. However the AGM battery has catalyst material that causes the gases to recombine into liquid form. An AGM battery should have its maximum amp charge rate listed someplace; you may need to download a spec sheet. There are also some brands of AGM's that can sustain very high charge rates without damage. This is because the internal resistance of an AGM is usually considerably less than a flooded battery. Low internal resistance means less heat is produced. There will also be a maximum voltage recommendation. An Optima (any color top) can be charged at up to 10 amps and up to 15 volts going by the mfg specs. Higher amps can be used for rapid charging but then it is recommended to monitor the temperature. Keep the battery below 125 F.

It is true that a flooded battery is generally more forgiving to excessive charge amps and volts than an AGM or a GEL cell battery. As long as the plates are completely covered, that is. Excessive heat can damage a flooded battery so keeping the temperature below 125 F is important.

Both a flooded battery and an AGM battery can generally be charged with the same charger. Check the mfg specs though just to be certain. Look at it like this; Optima and Odyssey both sell AGM's for use a replacement batteries for all motor vehicles.There are other brands as well. None of those require any vehicle adjustments to use the AGM battery.

A GEL cell battery does require a different charge protocol. Usually the charge rate is critical; too high and the GEL battery dies early. However, once again check the specs. There is at least one GEL cell battery whose mfg claims a standard charger can be used, IIRC. I do not recall the name or details.

Hot Rod magazine article on AGM's as used by auto enthusiasts.

Some AGM batteries used in the renewable energy industry have no current limits for charging. Once again, read the battery mfg specs.Article from alt-energy dealer on batteries in general.

AGM's have a lower self discharge rate than flooded cell batteries. A trickle charger may be unnecessary, unless many many months pass between uses / chargers.. I leave an ATV with an AGM battery at our place in the mountains. In winter there can be as long as 4 months between uses. I have no problems and no trickle charger. Your experience may vary, but it is not nearly the worry as with a lead acid flooded battery.

[Padilen]

So my battery is hype! It's says True GEL AGM not like those cheap imitations! The other thing is others were saying how much smaller and lighter than stock - which is lead acid they are. Mine is as big and heavy as stock.


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[Rferg800]

I am very interested in this information as well. As I was about to start shopping for my build too. I heard that a third type of battery that can cut about 50% of the weight / AH is a LiFEPO4, but I think this type also takes a special charger.

[MtnDon]

So my battery is hype! It's says True GEL AGM not like those cheap imitations! The other thing is others were saying how much smaller and lighter than stock - which is lead acid they are. Mine is as big and heavy as stock.


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If you compare comparable batteries from a main line manufacturer such as Trojan, you will see the weight of a flooded type and an AGM type are very close. AGM are not necessarily lighter; often they weigh a few pounds more, on comparable BCI sizes and capacities. That may be because the flooded battery has much more electrolyte in the case. That is just my theory, but seems reasonable when you look at how much excess fluid is in the typical flooded battery.

...and I'll state again, AGM are not GEL, no matter what some batteries hype / ad words, state.

An GEL cell is suited for loads that are small. They do not provide large bursts of current very well. However, in general, GEL can be discharged more deeply than AGM. GEL do perform a little better than AGM or flooded batteries at slightly higher ambient temperatures. GEL batteries big drawback is the special charge profile that is required and the ease of damage with the wrong charger.

This from Optima may be of interest

[MtnDon]

I am very interested in this information as well. As I was about to start shopping for my build too. I heard that a third type of battery that can cut about 50% of the weight / AH is a LiFEPO4, but I think this type also takes a special charger.

LiFePO4, or LFP are good batteries. Much lighter weight than flooded, AGM or Gel. They can be damaged more readily by a too high charge voltage or by being discharged to too low a voltage. If you are going to charge from 120 VAC there are chargers designed for them. It may be best to source the LFP batteries and charger at the same time from the same vendor. There are a few sellers that can supply the LFP cells and chargers as a kit. Elite Power is one. I supply the link simply for easy reference.

For solar charging, many of the better PV chargers have the adjustability required to limit voltage and terminate charging.

LFP also need, or do not need, a BMS. BMS = Battery Management System. This device manages a real-time control of each battery cell, communicates with external devices, manages SOC calculation, measures temperature and voltage, etc. The idea is that the electronics limit the upper voltage at each cell, as well as protecting against discharging to too low a voltage. There are some folks who manage well without a BMS. There are others who will emphatically state they are very necessary. Both are probably correct, depending on the individuals involved. IMO, since LFP generally require no user involvement, many users will be better off with a BMS included. Anyone who has ever damaged a wet cell battery because they let the fluid drop below the plate tops should probably invest in a BMS, IMO. That'll start an argument in some corners I am certain.

[ajpat3]

Here's another link that might help https://www.batterystuff.com/kb/article ... s-agm.html and inside that article there is a link to chargers. Hope this helps.

[Shadow Catcher]

I will inject a note of, you might want to think about. What you think you want and what you may find useful are two different things. Our tear is admittedly at the far end of elaborate, but you have no idea all the useful things that electrical power can do. we have four 120AC duplex outlets in the cabin and all of them have been used at one time or another, chargers for cell phones, laptop TV... Two duplex outlets in the galley, one powers the refrigerator and often an electric fry pan (why pay for propane) and of course the coffee maker. Two exterior duplex one dedicated to the air conditioner when used.
12V outlets, four inside the cabin, the small inverter which powers the TV chargers for cell phones. The one in the galley which powers the refrigerator and reading lights...
Bottom line, at least plan for more than you think you want, these things take on a life of their own.

[MtnDon]

I agree that there is much potential for the capacity requirements to grow a lot. Capacity deserves very careful consideration, with an allowance made for growth.

[noseoil]

All said & done, I just figured on 2x the power capacity I would need in a battery, since it would still fit inside a "normal" size battery box. I ended up with a group 27 Trojan AGM battery & it's been working very well for us. With the 100 watt solar panel mounted on the roof & a Morning Start charging module, we have never run out of power or charging capacity. A couple of cheap volt meters (in the galley & in the cabin) let us monitor the state of charge in a simple manner to watch power consumption & storage capacity.

Although our system is a bit heavier, larger & more costly than perhaps it might have been, I don't regret spending the extra $ on a system which is capable of working all the time & never running low on power for lights, charging phones, watching movies & running the coffee grinder for our morning brew. As Don & the Shadow have said, have enough for future needs, it's just good planning.

[Philthy]

I appreciate the advice and will take that all into consideration. Now can I ask what batteries did you guys use, why did you choose it, and where did you mount it?

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[Socal Tom]

I appreciate the advice and will take that all into consideration. Now can I ask what batteries did you guys use, why did you choose it, and where did you mount it?

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I use a Walmart marine battery. Its about 100 amp hours, was cheap and had a decent warranty, and is easy to return. I use a PD9145 for charging/converting , the battery is in the galley for weight balance reasons. Its not vented, but my galley isn't air tight.
Tom

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