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Mixing Hytrons & Dionics Battery Chemistries


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#1 David Shawl SOC

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Posted 19 August 2008 - 06:13 PM

Hello all,

I would like to buy some new AB batteries soon and am wondering if it's OK to mix Hytrons and Dionics on the same sled. I have a LOT of Hytron 50s and I am considering buying some Dionics. I have read that you DON'T want to mix chemistries parallel (which I'm not sure if I can even do that on my sled, not totally sure). Otherwise I would get some new Hytron 50s. I would like to be able to handle the power-hog HD cameras and high speed film cameras and from what I've read, I need either Lith-Ion and/or NiCad to do this for reasonable runtimes. Thanks
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#2 Eric Fletcher S.O.C.

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Posted 19 August 2008 - 11:47 PM

Hello all,

I would like to buy some new AB batteries soon and am wondering if it's OK to mix Hytrons and Dionics on the same sled. I have a LOT of Hytron 50s and I am considering buying some Dionics. I have read that you DON'T want to mix chemistries parallel (which I'm not sure if I can even do that on my sled, not totally sure). Otherwise I would get some new Hytron 50s. I would like to be able to handle the power-hog HD cameras and high speed film cameras and from what I've read, I need either Lith-Ion and/or NiCad to do this for reasonable runtimes. Thanks



NO You cannot mix chemistries. Well you can if you have an XCS sled, but no other sled allows you to do it
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#3 Lawrence Karman

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Posted 19 August 2008 - 11:55 PM

Hello all,

I would like to buy some new AB batteries soon and am wondering if it's OK to mix Hytrons and Dionics on the same sled. I have a LOT of Hytron 50s and I am considering buying some Dionics. I have read that you DON'T want to mix chemistries parallel (which I'm not sure if I can even do that on my sled, not totally sure). Otherwise I would get some new Hytron 50s. I would like to be able to handle the power-hog HD cameras and high speed film cameras and from what I've read, I need either Lith-Ion and/or NiCad to do this for reasonable runtimes. Thanks



NO You cannot mix chemistries. Well you can if you have an XCS sled, but no other sled allows you to do it


I just ran a Sony 900 off one Dionic and one Proformer in parallel for much of the day with no problems. Why can't you mix, Eric?
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#4 Eric Fletcher S.O.C.

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Posted 20 August 2008 - 12:42 AM

Hello all,

I would like to buy some new AB batteries soon and am wondering if it's OK to mix Hytrons and Dionics on the same sled. I have a LOT of Hytron 50s and I am considering buying some Dionics. I have read that you DON'T want to mix chemistries parallel (which I'm not sure if I can even do that on my sled, not totally sure). Otherwise I would get some new Hytron 50s. I would like to be able to handle the power-hog HD cameras and high speed film cameras and from what I've read, I need either Lith-Ion and/or NiCad to do this for reasonable runtimes. Thanks



NO You cannot mix chemistries. Well you can if you have an XCS sled, but no other sled allows you to do it


I just ran a Sony 900 off one Dionic and one Proformer in parallel for much of the day with no problems. Why can't you mix, Eric?



Okay let me rephrase that, you can't mix chemistries if you want the batteries to live.

Due to the chemistries and internal construction each type has a very different discharge curve and internal resistance. and when you run different chems you will heat the battery with the higher resistance and heat is what kills the cells.
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#5 Alec Jarnagin SOC

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Posted 20 August 2008 - 09:52 AM

"Due to the chemistries and internal construction each type has a very different discharge curve and internal resistance. and when you run different chems you will heat the battery with the higher resistance and heat is what kills the cells."

I was under the impression this was only true if putting them in parallel (so yes, not a good idea) but it is okay when they are in series.
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#6 JimBartell

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Posted 20 August 2008 - 11:21 AM

It depends on what you mean by "mixing".

1. Paralleling batteries can be very dangerous and shorten cell lives. Unless they have exactly the same charge state the battery with the higher charge state will dump energy into the lower at a massive rate until they equalize. This high current surge can damage both batteries and shorten their lives. However, if the batteries are at the same charge state this is minimized. Paralleling batteries of different chemistries is much more problematic because the intrinsic cell voltages are different so even fully charged batteries will have different voltages and lead to problems.

2. Putting two batteries in series is perfectly fine as long as you don't overload either cell. A 2 amp load going through a battery is the same regardless of what other cells it is hooked to. As long as you keep the current within the range of the smaller cell everything should be fine. Amps are amps, baby.

3. Obviously, if you have one battery power your sled and one your camera with no power sharing the point is moot.

Jim "Mixmaster" Bartell
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#7 David Shawl SOC

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Posted 20 August 2008 - 01:16 PM

Thank you everyone for the helpful info. How do you put batteries in parallel versus series? On my sled, two batteries are used to provide 24 volt power. Are those two batteries in parallel or a series to provide that 24 volt power? A separate third battery receptacle is used to power 12 volts accessories. Can that battery be any chemistry because it is separate from the dual-battery 24 volt power? Thanks
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#8 JimBartell

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Posted 20 August 2008 - 01:34 PM

Thank you everyone for the helpful info. How do you put batteries in parallel versus series? On my sled, two batteries are used to provide 24 volt power. Are those two batteries in parallel or a series to provide that 24 volt power? A separate third battery receptacle is used to power 12 volts accessories. Can that battery be any chemistry because it is separate from the dual-battery 24 volt power? Thanks

Parallel means you connect + to + and - to - to keep the same voltage but increase run time. Series means you connect the - of one battery to the + of the other to increase the voltage, i.e. putting to 12V batteries in series to get 24V.

Yes, the third battery can be any chemistry since it is not mixing with the other two.

And whatever you do, NO NOT connect them perpendicularly or tangentially.

Jim "Mr. Geometry" Bartell
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#9 Michael Collier

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Posted 20 August 2008 - 06:43 PM

Tangentially.....I knew I should have paid attention in geometry class.

Not that I am an expert with various SC and battery combos, but I did study to be an electronic engeneer in a former life so let me post my humble idea as a question.

Could you, if you had different chemistries that you needed in parrallel, place a diode on each positive terminal between the batter and the power bus? So each battery's positive would connect to a diode and the diodes would be bussed together to provide power. Theoretically it should prevent reverse current if one battery should fall below the voltage of the other, while maintaning common ground and still sharing current output between the two. Yes, no? is this the 'magic' the XCS sled has? Because a couple of high amper diodes would only run a few bucks each, and add negligable weight. and further wouldn't this be a good idea to do even if you had the same chemistry batteries if they need to parallel, since even in the same batch run no battery will ever have the same voltage curve over time as another.
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#10 Jess Haas SOC

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Posted 20 August 2008 - 06:50 PM

Yes you can add diodes and run batteries in parallel all you want. The downside is that the diodes will lower the voltage as well as lose some power as heat both of which will decrease runtime. This may or may not be a problem for your particular needs and the degree of effect they have will be dependent on the particular diodes speced. If you manage to find some diodes with minimal voltage drop and loss let me know.

~Jess
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#11 Eric Fletcher S.O.C.

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Posted 21 August 2008 - 01:09 AM

is this the 'magic' the XCS sled has?



Nope the XCS sled has a power supply that isolates the three batteries at the input level.
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#12 Jerry Holway

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Posted 21 August 2008 - 07:52 AM

It depends on what you mean by "mixing".

1. Paralleling batteries can be very dangerous and shorten cell lives. Unless they have exactly the same charge state the battery with the higher charge state will dump energy into the lower at a massive rate until they equalize. This high current surge can damage both batteries and shorten their lives. However, if the batteries are at the same charge state this is minimized. Paralleling batteries of different chemistries is much more problematic because the intrinsic cell voltages are different so even fully charged batteries will have different voltages and lead to problems.

Jim "Mixmaster" Bartell


SOME batteries have no problem being paralleled, even if they are are not at the same voltage... as they have internal diode/reverse protection built in.... BUT, as Jim warns, MOST DO NOT, so you can have serious problems.

Read everything you can about your specific batteries, plus the white papers of Anton Bauer and IDX and Sanyo and anyone else, before you commit to a custom power solution.

Jerry
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#13 Iain Baird

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Posted 21 August 2008 - 05:18 PM

I have installed a diode called a schottky power rectifier in one of my PRO power jumper boxes to allow me to parallel two batteries with out having them cross charge each other.

Attached File  L221.pdf   34.16KB   68 downloads

Schottky power rectifier diodes work in varying degrees. This particular one is a very low loss version and larger than most diodes so doesn't get as hot as the smaller versions. It is still small enough to fit inside my PRO power jumper box. Panavision Canada is using the same Diodes to build battery belts (three 140's) for the Genesis Toaster when flying in two piece mode.
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#14 Jess Haas SOC

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Posted 21 August 2008 - 05:36 PM

Specs look good and mouser.com has them for only $3.99 a piece. Looks like one actually contains 2 diodes so It could protect two batteries. I might have to get a few of these to play with. The only thing I haven't been able to find are the physical dimensions. Any idea what they are?

~Jess
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#15 Iain Baird

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Posted 22 August 2008 - 03:45 AM

Yes each one can handle two batteries. They have a common cathode for the shared output of the two sources.

The diode is 16mm wide, 5mm deep and approx. 32 mm long with the pins, without the pins it's 20.5mm long


IAIN
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