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Battery amp-hours from watt/cell minutes?
By Jerry, Section Storage Posted on Wed Sep 02, 2009 at 01:54:24 AM MST
I have 40 of these.

I was recently given 40 of the batteries. They just came out of service.
It wasn't time to replace them yet but a new much larger power back up system was installed.
They all measure somewhere between 12.6v - 12.72v. I have the wheeled racks they go in also. Even the racks weigh 100 LBs each.
They were configured as 240 volts per rack. My RE system is 48 volt, so I'm relocating them in my shop.
Brand is DATA SAFE By ENERSYS INC. Mod # NPX-150R specs 12v, 150W/CEL 15 MIN.
They measure 7.75" wide X 6.75" tall X 6.5" deep and weigh 31 LBs each.
I picked these up in my E-Truck. 10 miles to town, pick up 1500 LBS of batteries and 10 miles home. Not a hitch. E-truck works great. Even thought about putting these in the E-truck but Nah, I need them in the RE system.
The question is, how many amp hours are these batteries? I did a load test after 1 hr charging on one to 13.6 volts. With my carbon pile 500 amp load tester I got 220 amps at 10 volts and 125 amps at 11 volts. I figure even if there good for 50 AH that should add 500 ah at 48 volts to my RE system?
Heres the pictures.

Jerry

Battery amp-hours from watt/cell minutes? | 14 comments (14 topical)

Re: Battery watt hour ? (3.00 / 0) (#2)
by commanda on Tue Sep 01, 2009 at 08:10:49 PM MST

Rule of thumb;
They're about the size & weight of my old SLA scooter batteries, which are either 40 or 50 AHr in that size package.

Amanda

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#3)
by zeusmorg on Tue Sep 01, 2009 at 09:44:03 PM MST

from the enersys site:
Specifications
Chemistry    Lead Acid
Voltage    12
Capacity    40,000 mAh / 40 Ah
Rating    480 Whr
Length    7.76 inch / 19.71 cm
Width    6.50 inch / 16.51 cm
Height    6.89 inch / 17.50 cm
Color    Gray
Weight    34.2 lb / 15,512.78 g

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#4)
by DanG on Tue Sep 01, 2009 at 09:44:21 PM MST

NPX-150R VO Flame Retardant VRLA, 12V, 150 WPC (15min. To 1.67VPC), 40AH (10hr rate), 7.76"L x 6.5"W x 6.89"H, 34.1 lbs., e/w threaded terminals

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#5)
by DanG on Tue Sep 01, 2009 at 10:10:08 PM MST

You have thoroughbred race-horse batteries there: They require grain not hay!

the OEM manual is about the best I've seen, good reading.

Voltage limited w/ limited ripple charging only if you want them to last!

http://www.enersysreservepower.com/documents/US-NP-AM-002_0606.pdf

Charging
* Standby use: Apply constant voltage charging at 2.275 volts per cell (or 2.25-2.30VPC).
* Cyclic use: Apply constant voltage charging at 2.40-2.50 VPC. Initial charging current should be set at less than 0.25CA.
* Top charge: Product in storage (ambient temperature 25°C/77°F) requires a top charge every six months. Apply constant voltage at 2.40 volts per cell, initial charging current should be set at less than 0.1CA for 15 to 20 hours.

Discharge
* Stop operation when voltage has reached the minimum permissible voltage. Recharge immediately.
* Do not operate at 6CA or more current continuously. (C Ampere; the C-rate of a battery measured in amperes)

[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#6)
by tecker on Wed Sep 02, 2009 at 07:45:22 AM MST

They can't take any under charge or over charge it seems to cause the lead buttons to separate inside .I think that is some sort of glass packed for the acid .I've tried to re acidify these and they don't absorb more acid so once they have been taken to a very low ph or put through an over charge where they get hot your going to have a bad cell . I would have to say pulse them lightly if they load test . I have pulsed them with 110 with some success under 100 uf (4 amps or so )

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#7)
by Jerry on Wed Sep 02, 2009 at 08:47:39 AM MST

Holy good info guys. Sounds like they are a bit delicate. If you diviate to much from charge or discharge you may kill them.

I've never been to kind or watchfull of batteries. One thing in my favor though, they were free.

I'll use them till they quit then recycle them. Might get one winter anyway?

Looks like then I'll be adding 400 amp hrs to the battery pack?

I had thoughts of floating them seperatly at the voltage they like and switch to them as the other bank gets low?

Thanks again guys.

Jerry

Airheads Page

[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#8)
by ghurd on Wed Sep 02, 2009 at 09:16:20 AM MST

Hey Jerry, that's 1600AH at the 10 hour rate. More at the 20 hour rate.
Seems like it may be worth setting up a separate system for them. Got a spare windmill??? LOL
I bet they last quite a few years if they are regulated to 13.7~13.9V and use is stopped at 12.15V.
G-
Ghurd.info
[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#9)
by Jerry on Wed Sep 02, 2009 at 07:11:40 PM MST

Hi G.

At one time I had 14 gennies flying at my store. The store is gone now. At one time I had 7 flying here at home, only have 2 flying now.

Should be finished up with the roof in a week or so. So maybe I can get some RE building under way?

I'm going to replace the home wind farm and get a few more gennies up. I should have a machine or 2 for this new pack. I'll also be here to keep an eye things.

I hope to be a littel less on grid this winter? Eventuly I'll get into dump loads and MPPT but for now just gota get things up and runing.

I also want to try some direct wind generator connected things without batteries.

I have a DC flouresent lite ballist. It operates some where around 90 to 180 vdc.
I thought this would a fun expiriment to connect directly to a high voltage genny?

Same thing with computer power supplies. They have a wide voltage input swing with a very regulated output.

Allways a bunch of crazy ideas goin on. Sometimes can't sleep?

Jerry

Airheads Page

[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#10)
by dnix71 on Wed Sep 02, 2009 at 07:41:04 PM MST

That's a sturdy bench you have. I see nearly 500 pounds of lead on one end.

40 batteries is 1400 pounds of scrap lead eventually. That must be worth something.

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#11)
by Jerry on Wed Sep 02, 2009 at 08:40:27 PM MST

Yes its a very strong bench. I built it years ago to hold 12 group 31s. Not sure how heavy they are?

However I beefed it up today. I added some stronger supports. These batteries weigh 35 LBs each. So handeling one at a time is doable.

I put half of them up on the shelf today. The shelf is 6 ft off the floor. There will be 2 layers of batteries. Gota wire the first group befor setting the second group atop the first group.

I'm dressing all the post with anti corosion stuff since I won't see those termanals again for a few years I hope.

Jerry

Airheads Page

[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#12)
by ghurd on Wed Sep 02, 2009 at 08:43:07 PM MST

Might want to leave some space in between them for circulation.
G-
Ghurd.info
[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#14)
by TomW on Wed Sep 02, 2009 at 10:18:03 PM MST

Maybe a couple laths between rows to keep them off each other too? Good air circulation is a plus, IMHO.

Tom

The Truth is the Truth, even if no one believes it; and a lie is a lie even if everyone believes it

[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#15)
by Jerry on Thu Sep 03, 2009 at 08:20:04 PM MST

Great idea Tom W. I found some wood perfect for the job. Hope to have it all together in a week or so.

Jerry

Airheads Page

[ Parent ]

Re: Battery amp-hours from watt/cell minutes? (3.00 / 0) (#16)
by chubbytrucker01 on Sun Oct 04, 2009 at 08:05:37 AM MST

If you were going to use these to say run an inverter, what size interconnects would you use? I bought some 4/0 wire and ends to run a xantrex 3000 watt inverter and had to argue with the tech at the battery supply house to get him to sell it to me. The manual in the Xantrex manual tells you to use 4/0 cable but his argument was the internal interconnects inside most batteries were only like 2/0. So I was wondering. Just because these batteries could supply a large amperage where does it say what to limit their paralleled current to and how big of interconnects they have? I am sorry its kinda off topic but I am still learning. Thanks for the help.
Doug

Battery amp-hours from watt/cell minutes? | 14 comments (14 topical)

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