Battery Ohm Meters

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Spaceangel
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Joined: 07/15/2009
Points: 490

Testing of Battery packs and modules.

OHM METERS FOR BATTERIES & CELLS

A lot of EVers want to find and need to find a quick and easy way of finding which ones of the cells and or modules are bad in their battery packs. HP makes a very expensive impedence tester for batteries; and like most people, it's not in my budget. I have been using for the past 5 or 10 years a Schumacher battery tester and it gets me very close into the ball park on which of traction batteries are going south. The only problem with it is it gives me the reading in CCA, of which there is a direct correlation to a Ohmic value. I have a small collection of 38 AH batteries that have been occasionally used for 12 & 24 volt applications, and they have not been charged as often as the ones in my XM 3000. One of my 12 volt batteries exploded and I had to replace it in order to have a 60 volt system and didn't want to put in a new (NIB) battery for it would quickly match the other weak or nearly-dead batteries that are in the scooter. I recently puchased an ugly-looking ohm meter on eBay for approx. $40.00 and was pleasantly surprised by its accuracy compared to HP meter.

When I recently tested my old supply of green batteries, they all had different ohmic values because I cycled them individually vs. being in a 60 volt application. I picked one with the same weight within an ounce of two and the same ohmic value as what was in my XM 3000 and installed it in my scooter. I marked it with an X as the latest replacement battery, charged the scooter pack until the green light came on, and rode the bike for 10 or 12 miles and recharged. I re-measured the individual 12 volt batteries and the impedence of all the batteries were almost all equal. I think that proves that charging and discharging a pack on a Pb-acid pack seems to self-balance the batteries. I have a 102 cells in my Vectrix with some 8 cell modules and 9 cell modules. I have of 9 cell modules I use for ham radio and computer applications. They are really my spares for my VX 1. I don't know if there is a BMS system in the Ni-MH battery pack. I do know if you install a Lithium pack, you need a BMS.

I went to Batteries Plus, and they wouldn't tell me too much about their battery testing procedures. I know from dealing with Interstate Battery that they have a sufficient amount of test equipment including ohm meters for batteries and load testers, and are a lot more knowledgable about batteries and their replacement. The price is so perfect for my budget that I'm going to get a couple more ohm meters from eBay to have and keep in my toolboxes. This eBay item is 60 bucks and I am going to get it and compare also.

One good thing about testing the impedance of cells, modules, and 12 volt battery packs is that you don't need to charge the cells in order to get a reading. Cycling the cells or modules might change the impedance a bit but it is basically the same discharged or charged a bit. If they vary a few milli-ohms and they are cycled in series they seem to self balance for Pb-acid pack. I am so impressed at this device. I can't figure out how I lived for so long without a Ohm meter for battery packs.
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http://www.ebay.com/itm/Internal-Battery-Resistance-Impedance-Meter-Tester-Voltmeter-/171036127989?pt=LH_DefaultDomain_0&hash=it...

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Johnny J
Johnny J's picture
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Joined: 07/08/2008
Points: 372
Re: Battery Ohm Meters

Thank you for this info, have ordered 2 myself.
It seems like the 40$ one is the same as the 60$ version, if you look further down at the product description they show pictures with the same look/colour as the cheaper one.

Spaceangel
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Joined: 07/15/2009
Points: 490
Re: Battery Ohm Meters

I just found another battery tester. It is the Cen-Tech Item number 66892. Along with my Schumacher SEC-100 and the made-in China SM8124 impedance meters, I just found and tested the Cen-Tech Battery tested impedance meter. The actual name is called Digital Automotive Battery Analyzer. It does 4 in one actual battery testing parameters. The Schumacher SEC-100 only tells of CCA of which can be converted into relative test results but having an ohmic value with actual voltage is far better. The first reading to come up on the meter is top line voltage then underneath it is 20.06 m Ohms. The next two lines are 325 CCA and underneath again is 133.0 CCA for my one test. I dialled in 325 CCA for estimated size of U-1 Gel Cell and proceeded to test unknown battery. My battery for testing purposes was a MK U-1 dated H3 and punched out code of August 2003. Yes, it is ten years old. I decided to test an old Hawker Energy 12 volt 26 AH, of relatively know capacity and entered 350 CCA and got 9 m Ohms 12.26 volts 355 test CCA and actual 315 CCA reading. Scale said 70 % on top and gave all same readings I got on individual meters. I ordered the Cen-Tech on Amazon but I am going to slide up to Salem and pick one up in the store this time in order to have two meters. I can't believe my Hawker SBS-30 is twenty year old either but I do know they use virgin lead, virgin Pb. It also is AGM and quality construction. My Marine Wal-Mart batteries read dead on my testers and decided to force a charger in the 27 series batteries and my Schumacher charger finally blinked bad, then bat,bad,bat and I shut if off and recycled to Interstate for 21 cent a pound. 350 pounds worth. So I got a few battery boxes for Ham use too. Schumacher makes some really accurate stuff but now Harbor Freight has something that tops Schumacher now.
Maybe the moderator, David can do further testing and writes up on these play toys for EV enthusiasts. So far the best battery for scooters and consistent limited range is CSB-12200, 14 m Ohms,12.6 nominal, and 60 to 70ish dollars, with 3 years average life. I have got 5 years on some batteries. Get a Harbor Freight battery tester- it is non destructive testing. If any one on V has an unusual battery reading please post. Like maybe a battery that lasted ten or more years, whether it be NiCad, NiMH, NiZn, LiFePO4
or any other type of battery pack.There is Lithium Mn also and of course of other batteries and fuel cells too. But having a pack last for a useful ten to more years is impressive enough. Keeping a pack charged is the key. Don't store a weak or dead pack, even Lithium ion types. Since my Vectrix is almost a door stop, I might just throw in a lead pack and strip Plastic off of the scoot and make a chopper out of it. Easy replacement of battery pack and go through lead like crazy. It seem like Lithium companies don't keep same style in production for very long. Maybe if I can I will post some common Impedances on V soon.

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