I believe those calculations use some general assumptions about the shape of the curve, but they are far better than nothing. If the manufacturer can supply you with a measured number, all the better.

Please report what you get, if you do. It will be interesting to see how far apart the numbers are.

[quote=Gorgonshead;16205]I will be installing a Victron BMV-600 battery monitor and have set about finding the Peukert Number for my US Battery 2200 batteries. I couldn't find it on USBattery's site, but found this site:

[URL]http://www.batterystuff.com/kb/tools/calculator-for-load-specific-run-ti...

Which has a calculator for Peukert. Just input 2 sets of Ah:

I put in 20 hours and 232 Ah [the 20 hour]
and 10 hours and 207 Ah [the 10 hour]

And it calculated the Peukert number to be 1.196. Is this method trustworthy? I sent an e-Mail to USBattery, and will see what they send me, but failing that, should I use this number?

Thanks in advance, electrical gurus![/quote]

I sent an email to US Battery about this in November 2012. I have the 2200's as well. Here's what they said:

<<<<<<<<<<<<<<<<
Hi Bud:

The Peukert exponent for US2200 XC is 1.23616

Sincerely

Nawaz Qureshi
VP of Engineering and Technology

[EMAIL="nqureshi@usbattery.com"]nqureshi@usbattery.com[/EMAIL]
T: 951-371-8090
Fax: 951-371-4671
>>>>>>>>>>>>>>

[QUOTE=Gorgonshead;16205]I will be installing a Victron BMV-600 battery monitor and have set about finding the Peukert Number for my US Battery 2200 batteries. I couldn't find it on USBattery's site, but found this site:

[url]http://www.batterystuff.com/kb/tools/calculator-for-load-specific-run-ti...

Which has a calculator for Peukert. Just input 2 sets of Ah:

I put in 20 hours and 232 Ah [the 20 hour]
and 10 hours and 207 Ah [the 10 hour]

And it calculated the Peukert number to be 1.196. Is this method trustworthy? I sent an e-Mail to USBattery, and will see what they send me, but failing that, should I use this number?

Thanks in advance, electrical gurus![/QUOTE]

These calculators are not always accurate. For example one comes up with 1.134 for a Trojan T145 and the real Peukert is 1.25....

I don't have the US2200 Peukert in front of me but US Battery should get back to you. Fred W. is usually who will respond..

FWIW These are the Trojan Peukert #'s....
[B]
6 Volt[/B]
T105 = 1.24 (I would expect the US2200 to be similar)
T-125 = 1.23
T-145 = 1.25
L-16H = 1.79

[B]12 Volt[/B]
SCS-150 = 1.29 (group 24)
SCS-200 = 1.22 (group 27)
SCS-225 = 1.24 (group 31)

I'm really surprised most manufacturers don't supply this number as this value is so important to modern charging and monitoring systems.
For instance my boat came with parallel'd Interstate 4D batteries and I can't find the values anywhere so had to go with the default of 1.15 that my monitor suggests for all 4D's. (which seems kind of low)

Speaking of 4D's, how would you calculate the Peukert of a gel cell 4D purchased in 2000??? They still seem to be working fine, but I'd think that the values displayed by my monitor would have to be off. I don't even remember the brand they were purchased so long ago.

I know nothing about calculations, but I know high pucker numbers when I see them:
[IMG]http://www.sail-world.com/photos_2012_3/Alt_us17sdemise0251.jpg[/IMG]

[QUOTE=plaineolde;16220]Speaking of 4D's, how would you calculate the Peukert of a gel cell 4D purchased in 2000??? They still seem to be working fine, but I'd think that the values displayed by my monitor would have to be off. I don't even remember the brand they were purchased so long ago.[/QUOTE]

They are most likely Deka/East Penn batteries. They make approx 90% of the gels sold in the US, most are just re-branded Deka such as the WM Sea Volt line.... They originally licensed the technology from Sonnenschein in Germany but have been building the Gels in PA since the 80's..

[QUOTE=Gorgonshead;16230]I did get a reply from US Battery, from a Mike Coad who quots a Peukert value of 1.235 which isn't too far off from the calculator number of 1.19.

PL[/QUOTE]

A 450Ah bank with a 5A load and a Peukert of 1.19 has an effective capacity at 5A of 598 Ah's..

A 450Ah bank with a 5A load and a Peukert of 1.24 has an effective capacity at 5A of 646 Ah's..

That is a difference of 48Ah's of effective capacity..

These counting errors add up. If you want the most accuracy from a battery monitor beginning with the correct Peukert number is critical. A 1.235 would get rounded to 1.24 in most monitors.

The data I have from US Battery is as follows. It came from the VP of Engineering..

[B]US Battery Peukert[/B]
[B]12 Volt[/B]
24DCXC = 1.23137
27DCXC = 1.27900
31DCXC = 1.23877
8D = 1.32416
US185 = 1.21796
US185HC = 1.23011

[B]6Volt[/B]
US 1800 = 1.23632
US 2000 = 1.22472
US 2200 = 1.23616
US 125 = 1.19078
US 145 = 1.16370
US L16HC = 1.26562