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Old 09-08-2002, 08:21 PM   #1
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Default Panasonic UMH cells

I just bought two packs of Pro Match UMH cells and I'm not sure if I'm using the right charger or if the cells just suck. I wanted to try something new for stock and heard these are lighter and better cells than Sanyo 2400s.

I use the Indi 16x3 v2.5 charger. The best peak voltage I can get from the UMHs is 9-9.5 volts. Put them in the car today and they had far less punch compared to some of my old 2400 packs. I'm not sure if I need to use a different charger or what. (I can't set delta peak on the Indi.) I've not had any charging or run problems with Sanyo 3000HVs using my charger.

Any input or advice out there? Thanks.
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Old 09-08-2002, 08:23 PM   #2
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You should charge the UMH much different than HV's - .03 delta peak and no higher than 6 amps. Also, lower peak voltage is generally a good thing, it means lower internal resistance
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Old 09-08-2002, 08:50 PM   #3
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Mine peak at around 9 volts also.
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Old 09-08-2002, 10:30 PM   #4
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Guys, correct me if I'm wrong. It has been my experience that a battery that peaks at a lower voltage (such as in the 9's) is a better battery than one that peaks at a higher voltage, say in the 10's or 11's.

When a battery gets older or is charged over many months or years it does not want to accept a charge as readily, that is, it starts to resist charging more and more throughout it's life span.

As it becomes more resistant to charging, something has to happen to be able to get the energy into the battery. That "something" is that the charger peaks at a higher and higher voltage to compensate.....trying to get that energy into the cells.

A battery that peaks at a higher number is not a better battery with more voltage to offer you. It is a battery that is starting to develope more internal resistance, and less performance.

Can't speak for Speedo, but I think this is the long version of what he said.

I did have a problem with my SMH's when I would run them half way down, then recharge them. They would be VERY flat. I started to discharge them prior to charging and they came back like gang busters....!!!! They are a good battery! By the way, I have bought batteries for ProMatch (Jeff Rowe) and have found them to be great batteries and a great guy to deal with.

Last edited by Graphitedust; 09-08-2002 at 10:37 PM.
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Old 09-09-2002, 12:23 AM   #5
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Peak voltage is meaningless. Average Discharge voltage is the real thing to look at.

That charger also has a relatively high threshold delta value, which is most likely overcharging the cells. I would pick up and adjustable delta peak charger.

It may take a few cycles to 'wake up' the cells as well.
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Old 09-09-2002, 05:31 AM   #6
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Coolrcdad,

Are you following the instructions that Jeff from Promatch sent with the batteries? If so, you should have no problem.

My peaks are in the low 9's
Peak delta set at .03 on the Turbo and 8-10mv on the Pulsar.

The cells should be warm to the touch.

I've found that after the cells have been run a few times they get better.

Hope this helps,
Mark
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Old 09-09-2002, 07:30 AM   #7
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Thanks for all of the responses. I've learned a few things. I may have to get a better charger in order to charge these packs properly.
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Old 09-09-2002, 07:40 AM   #8
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If you guys are still looking for the ultra metal batteries we do have a few remaining from Pro Match in stock. Check them out at KT Hobbies Batteries and Accessories Here is just an example.

335-349 1.130+ $40.99 Qty.
350+ 1.130+ $46.49 Qty.
335-349 1.140+ $48.99 Qty
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Old 09-09-2002, 09:01 AM   #9
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coolrcdad,

I think your charger might be the problem. I personally had a 16x3 myself, and it did it's job of charging the battery, but for the panasonic cells, the 16x3 does not offer adjustable delta mv needed for the panasonic. Since the charger charged your Sanyo with no problem, then I'm assuming the delta mv is set higher than 3, which is too high for the panasonics.

Try a charger (if that's an option) like 16x5 and up (16x7, 16x9) I personally use a 16x9 now and it has been charging my 3000s without a problem. Also, a buddy of mine that works at Novak suggest charging the panasonics at no higher than 5 amp, and to put them on a tray for about 1 min. before charging (this will equalize all the cell before charging).

One last thing, I personally find that the panasonics are great once a week racing packs, they tend to feel flat on back to back runs (same day, or consecutive days of running). The Sanyos seems to be okay with back to back, but the panasonics, especially the UMH are ideal for one week run.

Hope that helped

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Old 09-09-2002, 01:07 PM   #10
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Steve,

Thanks for your info. I just spoke with Jeff Roe at ProMatch and he offered some valuable advice and info. I may have overcharged one of my packs and that could have resulted in its bad performance. I do need to buy better chargers when my budget permits. My concern in the short term was being at a disadvantage for an upcoming event by using 2400 nicads while other stock racers used NiMHs. I don't want to fry expensive batteries so I'll stick to Nicads until I have the right chargers for NiMHs.
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