Batteries

[theresa p]

Good Day

We have like stated above a newer Trillium 2004. Of course when connected to electric we have no troubles with the 12v fridge. But we have a lot we like to go to and the fridge does not work well. Our trailer came with a 12v marine type battery. We have a 1200 w generator we have tried running thru the convertor but it doesn't seem to do much, even if we connect to the battery directly it again seems to do little. After talking to Trillium they are suggesting two 6 v gell cell batteries, but I am worried about the extra weight on the tongue. I guess an 80 w solar might be an option too. I plan to have the present battery tested although I don't see why this should cause so much trouble.

Thanks for any replies,

Dennis

[Chester Taje]

Dennis and I have been PMing back and forth on this subject.
I run 2--group24 batteries.I have never had a problem with my fridge this summer.I also purchased a intelligent battery charger from Canadian Tire and use this rather than the convertor/battery charger in trailer.Dennis also has a gen set.I beleive if he used his gen set hooked up to a battery charger his results would be much better.
Here hoping others will join in with some other good ideas.

[Brian B-P]

I don't know why anyone would suggest gel cell batteries for performance... maybe they meant AGM batteries? I think AGMs would be somewhat lighter for a given capacity than conventional flooded-cell batteries.

The existing battery capacity is unclear. Chester has two Group 24 batteries - the Group 24 indicates the physical dimensions - but we have no idea of the capacity of Dennis's existing battery. Since Group 24 is not very large (same as mine, about as small as anyone uses in a trailer), his single battery could have almost as much capacity as Chester's pair (if it is a Group 31 or bigger), or it could be an unreasonably small unit. You can't tell where to go if you don't know where you're starting...

I'm also unclear on the problem: does "not work well" mean that the refrigerator works fine until the battery runs out (too soon), or that it never does cool properly? The first seems like just a capacity issue, the second could be an appliance problem or maybe a bad battery giving insufficient voltage all the time.

[Brian B-P]

I agree that a modern charger could do a much better job than the one built into the converter, depending on the specific converter.

Attempting to charge a battery directly from the 12V output of a generator is generally acknowledged - including by the generator manufacturers - as a bad idea. They are not controlled appropriately for that purpose.

1200W is a lot more generator than actually needed to charge a moderate battery bank... that would provide up to 10 A of 120V AC power, which could produce 80 A or more of 12V DC current - way too much for 100 A-hour (for instance) battery. The extra generator size is harmless, since the charger regulates the current: I'm just saying that any problem appears not to be the result of an inadequate generator.

[theresa p]

Thanks for all replys....

I guess I have been unclear, the fridge does not work with the current battery, not at home right now but I believe it is a 650 with I think 605 cold charge amp. I ran the tralier thru the convertor on the trailer last weekend and if I left a light on to let the convertor know it was using some power the fridge did start to work....

Thanks again......

[Brian B-P]

The "650" and "605" ratings are presumably cranking amps, and cold cranking amps. Those measures are relevant to engine starting, and not deep-cycle RV use, but they do indicate a relatively small (maybe Group 24) battery. The relevant rating would be amp-hours.

This does sound like it was a converter problem, maybe in part with the automatic switching between converter and battery power.

[Pete Dumbleton]

You should be aware that not all Marine batteries are deep cycle batts; some are starting batts and they are more likely to go bad if not recharged almost immediately and will not have the same charge/recharge cycle life of DC batteries.

The best way to recharge batteries with a generator or shore power is with a multi-stage battery charger. I would connect the generator to the egg and also plug in the battery charger (I don't believe the battery charger and converter will interfere significantly with each other). I would also get something that would give me a continuing reading of the battery's voltage so you will know when the generator and charger are needed. I would turn the fridge off at night.

I would NOT use gel-cell batts as they are even more sensitive to proper charging than conventional flooded lead-acid (FLA) batteries. I also wouldn't be asking a trailer manufacturer about electrical equipment beyond what kind it was; in this case, I think they had gel cells confused with the two 6V golf cart battery setup used by boondockers.

BTW, this excerpt from a WiKi site leads me to believe that AGMs are NOT lighter than FLA for equivalent energy:

"Absorbent glass mat (AGM) is a class of VRLA lead-acid battery in which the electrolyte is absorbed into a fiberglass mat. The plates in an AGM battery may be flat like wetcell lead-acid battery, or they may be wound in a tight spiral. Their unique (for lead acid chemistries) construction also allows for the lead in their plates to be purer as they no longer need to support their own weight as in traditional cells. Their internal resistance is lower than traditional cells, they handle higher temperatures better, and self discharge more slowly.

These batteries have a pressure relief valve which will activate when the battery is recharged at high voltage (typically greater than 2.30 volts per cell, a 12 volt battery has 6 cells). Valve activation allows some of the active material to escape thus decreasing the overall capacity of the battery.The lids (covers) typically have gas diffusers built into them that allow safe dispersal of any excess hydrogen that may be formed during overcharge. They are not permanently sealed, but are maintenance free; and they can be oriented in any manner, unlike normal lead-acid batteries which must be kept upright to avoid acid spills and to keep the plates' orientation vertical.

Their specific power is very good and they can be charged and discharged quite rapidly, however their specific energy tends to be lower than traditional flooded batteries. They are often used in high performance electric vehicles due to their high power density."

[Curtis F.]

Let me add my $0.02 to the mix also. Good info from the other posters.

A Group 24 is a small battery for an electric only refrigerator. A starting battery may only have 40 or 55 amp hour capacity. Trillium installed a single Group 27, 105 amp hours on my 2005.

The NovaKool fridge draws 2.2 amps per hour if it is cooling continuously. A little math, 2.2 times 24 hours in a day equals 52.8 amp hours. It has a low voltage cut out (shut off) at 10.4 volts, so it will not kill a battery. The fridge will shut off for low voltage after about 12 hours of continuous running with out the battery being charged.

What other 12 volt items are you using at the same time?
Are you only putting already cold items in the fridge? Putting in warm items for the fridge to chill will take a lot of battery power.
Keep the frigde door closed. When necessary to get something from fridge, open door, get it, and close door.

As others have indicated, you have not provided the relevant capacity numbers from the battery. We need to know the battery amp hour rating. The important number for deep cycle use on a camper is Amp Hours (A/H).

I shortly had the battery rack converted to hold two Group 27s. Gives me a total of 210 amp hours, with 105 usable. The extra weight on the tongue is not an issue for the frame or for inducing sway. The only issue would be the tongue capacity of the tow vehicle. Which by the way is ?

My Trillium came with a WFC 8712 converter distribution pannel. It is only a 12 amp charger. But it is a 3 stage intelligent charger, so is a good one for leaving trailer plugged in and shouldn't boil the batteries dry. Being a 12 amp charger doesn't mean it pushes 12 amps all the time. Battery charger logic is: when less than 13.2 volts is detected chager will start 4 hours of charge at 14.4 V. After 4 hours, charger will drop to 13.6 volts which is a slow charge. After 48 hours of no activity (which will not occur because of the propane detector) the charger switches to maintenance mode of 13.2 volts. While in MX mode the charger will charge at 14.4 V for 10 minutes every 10 hours (stirs the acid and combats sulfation) and then resumes 13.2 V.

You will get much faster charging with a generator by using a good quality battery charger to charge the battery/ies. It won't hurt a group 24 or 27 to push 20 or 30 amps charge into it for a short period of time. You could safely set an intelligent charger for 30 amps and expect your battery to be 90 percent re-charged after only a couple hours.

You do not need a gel cell or AGM battery for use on the trailer tongue. A conventional deep cycle battery will work just fine and give better performance. Gel cell and AGM are mostly for special applications where the battery is not accessable or can't be in a vented location.

Before you buy another size battery or batteries, make sure you can get boxes for them and know how you will mount them. I went to a nearby welding shop and had a new tray built and mounted to the tongue.

Curt