I bought a "smart charger" to charge the 12v "deep cycle" batteries I have for the TT. The TT remains in storage (no hookups there) and the batteries come home and are stored in my garage until next camp out.
The charger's amp settings are: 15amp, 10amp & 2amp. Yes, I did read on the web: "12v side of life." I learned a lot from that information. Yes, I did read the charger's instructions. With all that, i still could not find my the answer to my questions. Here's my questions:
1) After a regular camping trip of say 4-5 days with no "shore-power" hookups, the batterys are pretty well used. Therefore, what should I set the charger amp cylce for on the batteries when I return home? (15, 10 or 2 amps?)
2) Can I charge my two 12v batteries together with the "smart charger," while they are wired up in parallel on my garage (wood) floor? Or should I only charge up one battery at a time?
Oh...by the way,A friend of mine owned a battery plant for many years and there is NO truth to the story that setting a battery on concrete will kill it,I put them on a block of wood for years until he told me the truth!
2008 Keystone Cougar XLite 29RLS
2006 Super Duty V10 6 Speed 4.10S Tow Command Tow Pkg. 4X4
Your tow vehicle will start the charge on the ride home. I'd recommend you read the documentation on your charger. It may have a controller that manages the charge for you. If it does and your battery falls within it's design (which I'd expect) just hook up, plug in, set the high charge rate, and let it cycle. The lower rates are for small batteries. On the programmed high rate the charger will manage it's amps and volts to a finished charge.
My cheapy Vector does it plenty well enough for the battery in the trailer. These chargers do a lot better job that my converter which runs at one rate all the time.
Some of the motorhome and 5er folks will likely chime in because they have bigger battery systems and better rigs so they probably have far better chargers.
05 F150 FX4 Supercrew, 5.4, 3.73 LS, Jordan Ultima 2020 Brake Controller,
04 TrailCruiser 30QBSS, Battery Disconnect,
Dual Cam HP, Ultra Fab Power Tongue Jack, Bal Lockarm Stabilizers
First off, you NEED to get a good digital meter to check your batteries---along with that "smart charger." While I have NO experience with stand alone smart chargers, I know there are a bunch out there that work fine......(.I have PD 9100 series with their Charge Wizards in three Ts of mine, and one in the dungeon for doing all my other toy batteries.......flawless! Worth the $$$.)
Long stays and batteries dropping below 11.7 (approx. 50% charged), can kill your batteries easily in a season.....repeated 4-5 day stays as you describe will, too...no question----you need more battery, too.....
Use the 15A setting---CHECK YOUR ELECTROLYTE LEVEL AT EACH STEP(and don't let your batteries get hot and boil) ---keep it just above the plates.......Both paralleled charging is fine....after you disconnect the charger, as long as the no-load voltage holds at 13.6 +/- you're probably doing the best you can.......if they sit more than a couple days, give them a 15-30 minute shot of 15A....and again before you head out again.....
I gotta' stress....repeatedly "killing" the batteries as you describe, and then charging like this will kill them well before their time......get a smart charger---it'll cost you less than batteries........AND cut back on your 12V use as much as possible to prevent voltage dropping below 11.7....use your TV or even a small genset to recharge and get 'em back above 11.7 ASAP----preferably 13.6.....or go to a higher output set of 6V REAL batteries set up in series!(Even high quality 6V like the T-105s and T-125s need proper care and feeding of a smart charger to get the most life out of them!)
Your charger SHOULD have good reading on the charge cycles---if not, check out the Progressive Dynamics site.....www.progressivedyn.com...... look over their "Charge Wizard" charge cycle specs........you'll see what I mean and why.....good luck....
J
* This post was
edited 06/11/08 08:26pm by nny12972 *
Deep cycles batteries like to be charged at 10 amps or less, for a longer period to get to a full charge versus a higher amp setting for a shorter duration. Charging at higher rates is ok when you need to charge them up quickly especially with the smart charger. The charger is designed to supply the batteries with the current that they will accept. So if you are not in a hurry charge at a low setting.
Yes it is okay to charge them both at the same time in parallel. One thing you might consider is a BatteryMinder to supply a trickle charge to the batts over long periods of non use.
Rick
1998 HD Chevy Silverado 2500
- Super Charged Vortec 5.7
- Air Lift Suspension System
- Drawtite WD hitch with 1200# bars
- Drawtite DC sway control
- Honda EU3000IS
Set it on 15 and charge them in parallel. That is only 7.5 each and is both plenty fast and plenty slow.
Verify full charge with a hydrometer. Some smart chargers often cut off at 90/95% rather than 100%. They are primarily for a recharge to just get the vehicle started and let the alternator finish.
Battery Minder, Battery Tender and Xantrex Truecharge will provide a float charge continuously and make sure they get to tip top 100% charged. The smart chargers turn off power when done.
Nothing wrong with setting them on wood. Any acid residue will stain the concrete.
2001 F150 SuperCrew 5.4 Lariat Offroad 4x4 Tow Package 4.10 Truetrac
2006 Keystone Springdale 249FWBHLS
12K SuperGlide, KGE3000Ti 2.3kw rated 2.6kw max
Frank's voltage booster, Prosine 1800 powered by 4 GC2 batteries
Charging rates are highly dependent on battery type, condition, temperature, and state of charge. Without going in to too much technical detail, a battery can TYPICALLY be charged at a rate of C/10 to C/25. C stands for charge and the number is the amount of current that can be safely supplied to the battery. Flooded lead acid batteries should be C/10, while AGM (Absorbed Glass Mat) can be charged at much higher rates, like C/25, or higher.
This means that if you have a 100 amp hour battery, you should charge the batteries at 10 amps. Since you probably have 2 12-volt marine deep cycle batteries, that means you have around 200 amp hours of capacity. So you can safely charge them at a rate of 20 amps, or at the max setting of your charger.
Many charge at much higher rates and get away with it but for the longest life, C/10, while conservative, is a good and safe rate.
electricity in batterys is just like water. if two batteries are connected in parallel, the charge will flow from the stronger one to the weaker one. the only way to effectively charge two batteries even if they are a little bit mismatched is to charge them independently. What i have always done with my batteries is to have a charger that will handle several batteries, (generally three), then connect each one independly to the charger. And get a charger that will cut down to a float charge when the battery is fully charged to maintain it. Ive used this system for many years. it doesnt strain the battery, and all are always charged.
Another point, I know many people will tell you to use the batterys connected in parallel at the same time,but the water principle applys here stronger will flow to the weaker. better to buy a battery switch at a marine store and connect the batterys independly, then use one and when it gets low use the other.
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