875 Ahr battery equivalent?

kaipo_boy

I have a chance to buy a used 875 Ahr lift battery... when I questioned the rep, he said the rating they use is based on the 6 hour rate. Do any of you know what the rough equivalent rating would be for a 20 hour rate on this battery? since that's the rating we mostly see in the costco batteries that I have been buying... trying to compare apples to apples. Also, what would be the approximate minimum number of panels I would need for this size battery? I estimate 12 of the 285w panels I currently have, but I think the Midnite Classic can only handle about 90 amps, so a better fit would be 9 panels? is that enough for this size battery? Sounds a little light...

Vic

Hi kaipo..,

Guessing that the candidate 875 AH is 24V.

The Classic can output as much as 96 A on a 12 V system..

For 24 V systems, would expect that the MAX output current would be as much as 90 A, but would not want to run any CC at its absolute maximum current for extended time periods.
Here are some Classic Power Graphs:
http://www.midnitesolar.com/images/classicFrontPage/graphs.php

Here is a link to the Classic String Sizer:
http://www.midnitesolar.com/sizingTool/displaySizing.php

You can play with the string configurations to see what works best.

Regarding the 20-hour rate of any specific battery when only the 6-hour rate is known can be difficult. It might be best to ask the seller of the battery that you are interested in for the name of the battery manufacturer, and try contacting that manufacturer for their estimate of the 20-hr rate.

FWIW, Vic

reefbum

Who is the battery manufacture?
Spec's on BBI manufactured lift batteries 850Ah/6hr = 1062Ah/20hr

Photowhit

Here is the price list and batteries for GB industrial Batteries, They list both 6 hour and 20 hour rates! Looks like 850 at 6 hour would be about 1340Ah in a 24 volt battery. The BBI specs give seem pretty low, I couldn't find them on line.

The numbers / information on the side of the battery, have to do with the size, The 12-85-21 that I gave the Am rating for has 12 (cells) - 85Ah per positive plate - and 21 plates per cell (10 of which are positive)

The Midnite classic I believe delivers maximum amps in a 24 volt configuration, but figure around 90 max, a 1300 Ah battery would need 130 amps to charge at a 10% of capacity rate, likely a minimum for most lift batteries. to deliver 130 amps you would need 130Amps x 24 volts = 3120 watts delivered to the battery, Panels typically only produce 75% of there rated wattage, so figure 3120 x .75 = 4160 watts of panels minimum... and 2 Midnite classics.

reefbum

I purchased a brand new 24-85-25 48volt bank from GB Industrial
GB quoted and sold me these batteries to be 1020Ah@6hr / 1608Ah@20hr.

GB Industrial does not manufacture their own batteries, GB is strictly a reseller of BBI manufactured batteries.

When my battery bank arrived it was in fact manufactured, shipped and delivered by BBI with BBI data plates in which BBI listed the batteries as 1020Ah@6hr.
I was having issues with the batteries, my battery monitor was programmed for a 1600Ah@20hr battery bank and even though the battery monitor was showing a 30% DoD the battery voltage and SPG was telling a different tune.
I called the 800 number to BBI from the data plate to see what was going on and to make sure I received the correct batteries. After spending an hour or so on the phone with BBI support it was confirmed that i did in fact have the 24-85-25 48volt battery bank.
BBI support further told me that they rate this bank at 1020Ah@6hr / 1275Ah@20hr which is a far cry from the 1608Ah@20hr listed, quoted and sold by GB.
BBI emailed me a copy of the specs for my battery bank showing in fact that they (BBI the manufacture) rate it at 1020Ah@6hr / 1275Ah@20hr.
I called GB Industrial to talk to them about this issue and the fact that the performance of my batteries were not even close to 1608Ah@20hr but close to the 1275Ah rating from BBI. GB told me that they calculate their own specs for these batteries by using a Peukert Exponent of 1.6 (1608Ah) while the manufacture says their batteries have a tested Peukert Exponent close to 1.3 (1275Ah).
To try and double check both the GB info and BBI info I called HUP Solar to ask about their HUP Solar One traction batteries. HUP emailed me their battery spec's for their SO-6-85-25 48volt bank. Their spec's show the same as what BBI provided. The HUP battery spec is 1020Ah@6hr and 1270Ah@20hr with a tested Peukert Exponent close to 1.3

From my usage and monitoring of the battery bank I have I find it very close to the 1275Ah@20hr
GB Industrial as far as I'm concerned is full of crap and selling battery banks listed with a 20hr rating much higher than is the actual performance.

For the OP according also to the HUP battery data sheets they list their traction batteries of 850Ah@6r / 1055Ah@20hr
http://hupsolar.com/

Regards

inetdog

Fork lift batteries are designed with low internal impedance for two reasons:
1. Intermittent high current capabilities for heavy lifting.
2. Fast recharge between shifts.

A normal use cycle will be a close to 100% discharge over 8-16 hours followed by a prompt recharge. That is not the sort of load profile that you get when using it for Solar PV.

That low internal impedance is also generally associated with a lower Peukert exponent.

GB's extrapolation from C₆ to C₂₀ when the manufacturer actually provides contradictory data is, IMHO, criminal fraud.