Deep Cycle 12V

postman · December 20, 2017, 07:40 PM

Just bought 2 Interstate SRM-27 off CL. Have fingers crossed as the seller said they were purchased new around June. I will check level, fill, and charge. I am old school and will check specific gravity. Wish me luck!

Rickf1985 · December 20, 2017, 08:23 PM

Good luck, they are still a marine dual purpose battery and not a true deep cycle. They do appear to have a fairly good reserve capacity but I have never gotten the advertised amount out of a dual purpose. My next batteries are going to be true deep cycle. No starting rating at all.

postman · December 20, 2017, 09:45 PM

Rick I have two maintenance free, however they have absolutely no markings & suspected (mexico). I took one to be tested and showed 850 amps. Now I have these SRM-27. I will configure them parallel and take the best of the (mexico) batteries that I suspect were from Deka as chassis.

Rickf1985 · December 21, 2017, 09:20 AM

Be careful running mismatched batteries in parallel, whichever one is lower will drag the other down and for some unknown reason it will go all the way down to dead in days. When if not hooked together they are fine. i?? i?? I have had that happen several times, I then take those batteries and put them in one of my military vehicles that are hooked in series and it does not affect them the same way since there is no physical connection between the two batteries. In series one is basically grounded to the other, strange way of putting it but it puts it in perspective that they are not really attached like they are in parallel where power is flowing back and forth between them.

postman · December 21, 2017, 01:05 PM

My bad. My plan is the two SRM-27's in parallel for the house or coach whichever is proper. The Maintenance Free batteries, the strongest of the two will go to chassis.

Your description is accurate just expressed differently. I was taught it is because VDC maximum amperes is always available in a circuit. I will have to look through my manuals for the fix. I remember it was common in solar banks.

At some point soon I want to inspect the two solar panels. Todo list keeps getting longer and the Honey-Do's demand priority.

postman · December 21, 2017, 05:17 PM

I found this diagram that supports you.

Note: terminal positions on opposite corners. Hm?

Rickf1985 · December 21, 2017, 08:00 PM

Right, that is a parallel connection. But if one of those batteries is a bit weak it will draw down the good battery. That is why parallel batteries should always be replaced with a matched pair. Terminal position on the battery makes no difference.

postman · December 21, 2017, 08:43 PM

my understanding is you draw (+) off one battery and (-) off the other. As in the diagram.

DaveVA78Chieftain · December 21, 2017, 10:15 PM

Rick's point is
Forget how the batteries connect to the rest of the system. If one battery is weaker than the other then the good battery will try to charge the weaker battery until both are discharged. Has nothing to do with how you connect the batteries to the rest of the system. HAs to do with different voltage potentials between the 2 batteries.

postman · December 21, 2017, 11:24 PM

DaveVA78Chieftain,

Both SRM-27s are charging in parallel. I've seen disagreement on charging rate. So the Amp hour is 160 ea so in parallel that is 320. I opted to tickle charge @2amp. Tomorrow I will check the specific gravity.

Froggy1936 · December 23, 2017, 02:54 PM

Please do be specific W% Frank

postman · December 23, 2017, 07:20 PM

Rickf1985 · December 23, 2017, 08:47 PM

Ok, So if the batteries are 320 amp total and we will say they are at 75% that means they are now at 240 amp so you need to replenish 80 amps. At a 2 amp hour rate that will take 40 hours to recharge that 25%. BUT, If you have a newer 3 or 4 stage charger it would be much faster since they will charge the first 30-40 amps rather quickly and then drop down to around a 15 amp rate and taper to a trickle and then a maintenance charge. But in defense of the good old fashioned chargers like that 2 amp charger, I have put so called dead batteries on one and left it for a week and the battery has come back to life and lasted a good long time. It is not one that you want to leave plugged in all winter though.

postman · December 23, 2017, 09:47 PM

Rickf1985,

Right now batts are charging 2amp in parallel. Because the charge is 2amp I will leave it tonight. Tomorrow I will charge them @2amp seperately.

postman · December 26, 2017, 12:04 AM

After 24hr. rest, both batteries showed 12.76v which specs @ 95%. Maybe not brand spanky newie, but an upgrade to my Ahr X 2.

postman · January 07, 2018, 11:21 PM

The Battery tray is in for lack of a better term Battery Bay. Here's a pic of that wiring.

Whats that wire do? i??

LJ-TJ · January 08, 2018, 08:11 AM

That's how my Battery Box started out and this is what I ended up with. Hm?

Rickf1985 · January 08, 2018, 10:21 AM

Quote from: postman on January 07, 2018, 11:21 PM
The Battery tray is in for lack of a better term Battery Bay. Here's a pic of that wiring.

Whats that wire do? i??

I see voltage loss at just about every terminal in there! Yea, mine looked that way too. I think that area is a problem with just about all older units and it is usually overlooked as long as the lights even come on.

LJ-TJ · January 08, 2018, 10:29 AM

:)rotflmao Yeah no kidding. I keep waiting for someone to come up with a indoor alternative Hm? .

postman · January 08, 2018, 06:43 PM

LJ-TJ,

That is a work of art compared to my copper spaghetti. Did you have a diagram or schematic to work from? I haven't found a single bit of useful info on my "House" circuits. it would save me days per circuit if you can help.

tmsnyder · January 09, 2018, 01:27 PM

It does make a difference, hook it up as the diagram shows in, on positive of one battery and negative terminal of the other. The reason is b/c the connections are never perfect, resistance is always >0 ohm. (especially looking at the photos of your cables ! ) So you'll have a voltage drop at each connection once current starts to flow. The dirtier the connection, the more the voltage drop for any given current. You can and should clean them, it will help but it will never be perfect. So if you connect the leads on one battery and parallel all the batteries after that off the first battery, the second battery will get less voltage than the first one, the third will get less then the second, and so on. Taken to infinity, the last battery will get a charge voltage approaching 0V.

If you wire as shown in your diagram, there may be voltage drop in the lines but at least both batteries are getting a similar charge, which is the goal. You want them to be treated the same as each other so that they charge and discharge as one battery.

Considering that these can be charged at 20, 50, 100 amps.... even a fraction of an ohm of resistance on the connections can result in significant charge voltage difference between the first and second battery if not wired as in the diagram. So I wire them as in the diagram you posted.

Just this camper's view.

Quote from: postman on December 21, 2017, 08:43 PM
my understanding is you draw (+) off one battery and (-) off the other. As in the diagram.

Winnebago Warrior 94 · January 09, 2018, 02:05 PM

My batteries in my rig was never hooked,up right ..it only had one battery in it so I need to use the diagram y'all have and hook up another battery up so I'm jave two batteries ..I also need to replace the terminal wires and beef up the battery holder as the older one is rusting through ..wouldnt be fun to loose my batteries when in driving down the road

postman · January 09, 2018, 02:21 PM

I do wish I could find a "House" diagram. LJ-TJ's pic is great, but I have 4 reset breakers. Then I wonder, "Would Winnebago really wrapped up a bundle of wires like that?" D:oH!

LJ-TJ · January 10, 2018, 05:48 AM

You would think it wouldn't make much scents for a company the size and caliber of Winnebago would approve that type of workmanship. But yep! I have five Winnebago's and all the battery compartments are the same. Hm?

postman · January 10, 2018, 01:20 PM

Quote from: LJ-TJ on January 10, 2018, 05:48 AM
You would think it wouldn't make much scents for a company the size and caliber of Winnebago would approve that type of workmanship. But yep! I have five Winnebago's and all the battery compartments are the same. Hm?

LJ-TJ did you track, trace, and reverse engineer? Or. did you have a MAP!

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