Deep Cycle Battery Question

You do not seem to be caring for the batteries very well.
Mixing an old sulfated battery with a new one is not helping either.
Any charger that takes 12+ hours is too small. You need 40+ amps.
The 12 Volt Side of Life

Alicia,

I guessing your battery sat all winter without any type of charge? The first time you bring it up, it will take a while. After that, somewhat quicker charging.

Get a good charger, one that you can leave in trickle charge mode all winter long --- much better for your battery.

You didn't say what kind of batteries. The above assume FLA or flooded lead acid. These will need distilled water from time to time. With the caps removed they should be filled to the bottom of the split ring, looks like a tube with a slot going about an inch into the battery. Fill to the bottom of this. AGM's, absorbed glass mats and Gel cells don't require adding water. Look up the battery manufacturers charging specs for your batteries and make sure the charger you use can meet those specs. Never mix old and new batteries; say 6 months to a year between manufacturing dates although no more then a month apart is better.

The printed rules we go by are when we run our batteries down to around 12.0VDC (Approximately the 50% charge state) we want to re-charge right away. Using our PD9260C 60A Smart Mode converter/charger we will see 14.4VDC hitting the battery bank of the three old Interstate SRM-24s 12V Batteries which was installed in 2008. I originally had four of these 12V batteries but lost one due to boiling out fluids before I changed to the PD-9260C Converter/charger unit. The DC current always jumps up to around 52-53 AMPS DC Current and then start tapering back after some 15-30 minutes after the charge cycle has started. After two hours of 14.4VDC the smart mode charger drops back to 13.8VDC. The DC current being demanded at this point is around 6 AMPS or so... This will continue for another hour at the 13.6VDC. This is when when the charger see a 90% charge state completed...

I can do some 12-14 of these 50%-90% charge cycles without doing harm to my three batteries. After this I need to charge my battery bank for a FULL Charge which takes over 12 hours for me...

If I just use the batteries for small wattage items over a few days my PD9260C will start up a re-charge cycle but it will only be for a few minutes to maybe up to an hour before the 14.4VDC drops back to 13.6VDC. If the batteries are not much discharged the 14.4VDC charge will drop back to 13.6VDC in just a few minutes...

Also my PD9260C will go into a 14.4VDC charge mode about every 21 hours for a 15 minutes charge cycle called the Equalize Mode.

My PD9260C Converter/charger for me pretty much follows this charge diagram in the owners manual...



I have this homemade meter panel setup showing the DC VOLTAGE for my two switched in Battery groups and a DC Current meter showing the total DC Current being drawn by the load as well as how many DC AMPs are being demanded by the batteries when I am in charge mode... The minus (-) symbol on the DC Current meter means I am drawing some 18AMPs DC Current from the load. Without the Minus (-) means the batteries are demand DC Current from the PD9260C converter/charger unit.



Knowing what is going on with your battery setup makes the OFF-GRID camping much more pleasant.. The only thing I wish I had added was a settable DC VOLTAGE ALARM like the TRIMETRIC unit has that would automatically start beeping when my batteries were down to the 12.0VDC region...

When we are in OFF-GRID mode camping the normal routine is to run my trailer off my 2KW Generator starting at 8AM each morning when allowed to run my generator and this always gets me back to a good 90% charge state in about a three hour generator run time... Good to go for the next day/night run off the batteries...

I have been getting by with just monitoring the DC VOLTAGE levels but to be absolute I would want to do a gravity check on the fluids. I also check the batteries fluids for proper water level all the time and will add distilled water when needed... Learned my lesson on this when I lost one battery due to boiled out fluids by over-charging for a long period at 13.6VDC.

Roy Ken

Get a decent multimeter and check for gravity. You can also equalize charge the battery with higher end chargers. Decent gravity should be around 1.20

If they need water, add it. Just make sure it's distilled.

As far as charge time, it's no surprise that the first time takes longer, but it sounds to me like you are putting back more than you are taking out, so yes, the charge time will be less.

The choice of chargers it another conversation.. Is it a 3-Stage charger?

How far are you discharging them? At what voltage do you start to recharge?