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Old 06-28-2009, 08:43 AM   #1
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Default NiMh pack

Could anyone tell me if there are any preparations prior to building NiMh battery pack? Do we need to balance them or something? Thanks.
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Old 06-28-2009, 09:35 AM   #2
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Balance it after building.

Usual care in assembly, so make sure you have a good, powerful iron, tin the cells, and a good jig makes the whole process a lot quicker.
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Old 06-28-2009, 11:10 AM   #3
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Default how to build race pack

i hope this will help http://www.rcuniverse.com/magazine/article_display.cfm?article_id=481
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Old 06-28-2009, 04:21 PM   #4
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One thing I have learnt, after a few frustrating builds, is to check each cell for zero-volt PRIOR to building. It's a pain to strip the pack again because the middle cell is dead!
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Old 06-28-2009, 04:33 PM   #5
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What's the advantage to building the pack? Are there any tricks to building one that would get you better power? I've see NiMH sticks with 75 dollar price tags, Lipo is but a few happy meals away from that.

Local stock class is non-Lipo, I happen to like Li-po very much, so anything I can do NiMH to get close or better (even if that includes building my own packs) is on my radar.

Yes - I am trying to read the article presented - danged type is all over the place on the web-page tho. Hard to read.
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Old 06-28-2009, 05:34 PM   #6
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A few things to building a good race pack.

1. Buy good cells.

2. Use good solder and a good iron. You don't want to use much solder, just enough to cover the surface of the bar and get a solid bond.

3. Buy good battery bars. They are cheap, and the battery is only as good as the weakest link.

4. Buy good wire and connectors. I use Deans plugs, and Deans 12 guage Wet Noodle or Ultra Wire.

5. Take your time building them and make a clean job. You get more street-cred at the track with a tidy looking pack. It also helps you win races, as when the other racers see the awesomeness of the pack, they are intimidated by the very thought of your racing prowess
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Old 06-28-2009, 07:59 PM   #7
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Quote:
Originally Posted by JR007 View Post
One thing I have learnt, after a few frustrating builds, is to check each cell for zero-volt PRIOR to building. It's a pain to strip the pack again because the middle cell is dead!
But I have heard that batteries should not be discharged down to 0 volt. With NiMh I have been told that it should only go as low as 0.9-1 volt per cell. What do you think?
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Old 06-28-2009, 08:10 PM   #8
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Quote:
Originally Posted by sosidge View Post
Balance it after building.

Usual care in assembly, so make sure you have a good, powerful iron, tin the cells, and a good jig makes the whole process a lot quicker.
I haven't seen NiMh balancer, but plenty of LiPo balancers out there. Can I use a charger and discharge them with a cut-off at certain volt? Does it work? Thanks.
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Old 06-28-2009, 08:16 PM   #9
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Balancer for Nimh packs is not tied to the charger at all and is a stand alone piece of equipment.
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Old 06-28-2009, 08:37 PM   #10
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Quote:
Originally Posted by xniperliams View Post
But I have heard that batteries should not be discharged down to 0 volt. With NiMh I have been told that it should only go as low as 0.9-1 volt per cell. What do you think?
I mean, sometimes when you buy batteries, they have "gone bad" and read out as zero volts on a volt meter. It isn't common, but does happen. If a cell is reading zero volts, it's a throw away.

I use the LRP Battery Conditioner for balancing my cells. It's an individual cell balancer, that has a cut-off you can set to your own desired voltage. I use 0.9v

You can also use something like a Muchmore Zero V, but it doesn't have an automatic cut-off, so you need to maunally disconect the cells as the lamps go out or it will completely discharge.
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Old 06-28-2009, 09:19 PM   #11
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Quote:
Originally Posted by JR007 View Post
I mean, sometimes when you buy batteries, they have "gone bad" and read out as zero volts on a volt meter. It isn't common, but does happen. If a cell is reading zero volts, it's a throw away.

I use the LRP Battery Conditioner for balancing my cells. It's an individual cell balancer, that has a cut-off you can set to your own desired voltage. I use 0.9v

You can also use something like a Muchmore Zero V, but it doesn't have an automatic cut-off, so you need to maunally disconect the cells as the lamps go out or it will completely discharge.
Ah, thanks! But any reasons why we have to use a dedicated balancer? I mean I have LRP Pulsar 2. Can I discharge cells individually down to 0.9v then build the pack?
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Old 06-29-2009, 12:52 AM   #12
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Quote:
Originally Posted by xniperliams View Post
Ah, thanks! But any reasons why we have to use a dedicated balancer? I mean I have LRP Pulsar 2. Can I discharge cells individually down to 0.9v then build the pack?
That will work - it's just very time consuming. You should be able to find a usable discharge tray for not too much money, especially now that people are selling off their NiMH gear. Make sure it is a tray with a cutoff, they tend to range from 0.5V to 0.9V, all of which are fine.

Oh, and a cell at 0V is not a bin-job. More often than not they can be coaxed into taking a charge, and will perform satisfactorily (although probably not as well as a cell that has never dropped to zero).
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Old 06-29-2009, 03:34 AM   #13
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Quote:
Originally Posted by JR007 View Post
A few things to building a good race pack.

1. Buy good cells.
So I found out the hard way. Some cells just dont like being soldered.
Also the cheaper cells plastic cover is far too thin.
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Old 06-29-2009, 06:27 AM   #14
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You are the best guys! Thanks for sharing your knowledge.
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Old 06-29-2009, 07:29 PM   #15
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I'll reiterate the 'good hot iron' with a broad tip.

The Negative side is usually the more stubborn of the two to solder.

Get good solder - I usually used radio shack high silver content.

Battery jig - Venom makes a nice one now: http://www.thercshack.com/ven1599bat...semblyjig.aspx

Deans used to have the best one in my opinion until that came out..
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