# [EVDL] Ok, time to put 50 fuses in the pack



## EVDL List (Jul 27, 2007)

I'm planning on dropping the pack in my 94 Geo Prizm next week (50 26ah 
batteries, 2 strings of 25, 300v pack) and I'm going to bite the bullet 
and install a pair of 30 pin connectors in the back of the pack and run 
a wire from each battery to the connector so I can

Monitor the pack using paktrakrs
Install a Lee Hart BMS thing
Charge individual batteries if needed (2a max say)
Do other things in the future without having to drop the pack.

However this will put 50 *live* wires at the end of the pack. And put a 
lot of wires inside the pack.

The question is how do I fuse these wires so if there is a short on the 
outside the fuses will *blow* instead of doing something like melting 
the insulation and causing a massive short-out?

I could go with 10k resistors, but the problem is I want to be able to 
install a Lee Hart BMS someday. Maybe. Or I could go with auto fuses, 
but then when I make a mistake and short some wires I could have a 300 
volt plasma torch in the pack.

So what's the best way to fuse these kinds of lines? Small 10 ohm 
resistors? Something else? I don't have the room for 50 KLKD type Buss 
fuses and those cost $20 each.

Chris

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## EVDL List (Jul 27, 2007)

Hello Chris,

That is one problem I have with fusing separate circuits from each battery. 
The fuse should be place as close to the battery post as possible if you are 
using a smaller wire than the battery link.

Now if your battery connection links are 2/0 wire, you could run a unfuse 
tap wire of not more than 30 percent reduction of the battery maximum ampere 
for a maximum of 10 feet. This would mean about a No AWG 2 copper 52 
stranded wire that is design for chassis work which has a designation of MTW 
that has a thicker very flexible insulation.

Then you can put a KLKD type fuse in another compartment away from the 
batteries. I would track mount the fuses in a terminal block fuse holder.

Now if the batteries happen to have a stud connection or could tap in a 
stud. Install a bolt on buss type fuse with the spade end of the fuse 
connected to this bolt. Connect a offset nylon stand off to the other end 
of the fuse which has a bolt hole for connecting the fuse and wire end 
together. The nylon offset stand off can be fasten to a lift mounting 
bracket on the battery if it has one or glue a mounted to the surface of the 
battery.

This type of fuse should be a totally enclose one, that when blown, shall 
not shatter or break like the glass fusses. Even some thin housing fuses of 
different material may also burn in two. It is best to use a heavy wall 
sand buss bolt in fuse that will contain the short and will not come apart.

I would not use any thing less than that type of fuse if I was installing 
them at my battery.

Roland




----- Original Message ----- 
From: "Christopher Zach" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, April 30, 2009 8:01 AM
Subject: [EVDL] Ok, time to put 50 fuses in the pack


> I'm planning on dropping the pack in my 94 Geo Prizm next week (50 26ah
> batteries, 2 strings of 25, 300v pack) and I'm going to bite the bullet
> and install a pair of 30 pin connectors in the back of the pack and run
> a wire from each battery to the connector so I can
>
> Monitor the pack using paktrakrs
> Install a Lee Hart BMS thing
> Charge individual batteries if needed (2a max say)
> Do other things in the future without having to drop the pack.
>
> However this will put 50 *live* wires at the end of the pack. And put a
> lot of wires inside the pack.
>
> The question is how do I fuse these wires so if there is a short on the
> outside the fuses will *blow* instead of doing something like melting
> the insulation and causing a massive short-out?
>
> I could go with 10k resistors, but the problem is I want to be able to
> install a Lee Hart BMS someday. Maybe. Or I could go with auto fuses,
> but then when I make a mistake and short some wires I could have a 300
> volt plasma torch in the pack.
>
> So what's the best way to fuse these kinds of lines? Small 10 ohm
> resistors? Something else? I don't have the room for 50 KLKD type Buss
> fuses and those cost $20 each.
>
> Chris
>
> _______________________________________________
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>
> 

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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> > 94 Geo Prizm... 50 26ah batteries, 2 strings of 25, 300v pack...
> > install a pair of 30 pin connectors in the back of the pack and
> > run a wire from each battery to the connector...
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > 2. Or, you can use several connectors and cables, such that no more
> > than 125v or 250v appears between pins in this connector. This
> > allows you to use cheaper 125vdc or 250vdc rated fuses. The ceramic
> ...


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## EVDL List (Jul 27, 2007)

> On 1 May 2009 at 14:11, Christopher Zach wrote:
> 
> > > 5. Or, you could put circuitry inside the battery box, so you don't
> > > need to bring these high-current high-voltage wires out....
> ...


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## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> > I considered buying one of those clean, elegantly converted Prisms several
> > years ago. I decided against it mostly because of the battery layout. In
> > my view, the designers took the notion of "maintenance free" a little too
> ...


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## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> >> I considered buying one of those clean, elegantly converted Prisms several
> >> years ago. I decided against it mostly because of the battery layout. In
> >> my view, the designers took the notion of "maintenance free" a little too
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> > The question is how do I fuse these wires so if there is a short on the
> > outside the fuses will *blow* instead of doing something like melting
> > the insulation and causing a massive short-out?
> ...


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## EVDL List (Jul 27, 2007)

>> If only someone made a waterproof/suitable for under-car connector that
>> could handle 200+ amp draws.
>
> Railroad connectors, and MIL-spec circular connectors can do it.
> Expensive, though!

Might be easier to try and weatherproof an Anderson SB350. If you're only 
using it every 3-4 years then wrap the whole thing in EPDM. Or get a 
junction box, cut slightly oversize holes for the 2/0 cables (right below 
the lid) and line them with a good gasket material. Remove the lid and 
pull the cables out enough to undo the SB350.

Just spitballin' here.

-Adrian


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## EVDL List (Jul 27, 2007)

>> If only someone made a waterproof/suitable for under-car connector that
>> could handle 200+ amp draws.
>
> Railroad connectors, and MIL-spec circular connectors can do it.
> Expensive, though!
>

Just had another thought:

Cut the 2/0 cable, add lugs to both cut ends, and secure them together 
with a stainless steel bolt. Coat the whole thing with petroleum jelly or 
other anti-oxidant compound. Slide a length of 3/4" PVC over the 
connection to keep most of the road grime out. You could caulk the ends, 
or stuff them with something removeable like mastic putty.

Might be easier to just use an SB350 and seal the cable side with mastic. 
Make sure to clean/recoat the connector ends with something gooey every 
time you service the batteries. They can't get much worse than the cable 
connections to your motor.

-Adrian

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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > Except that the original USE setup had *no* battery regulators of any kind.
> 
> True. That was a serious mistake. I wonder how GM kept the batteries
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >
> >
> > On my Balancer, I put the relay boards in the battery boxes, so the fuses
> ...


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## EVDL List (Jul 27, 2007)

I came across some resettable fuses from Raychem that are rated for high
voltages. It looks to me that they would work well for battery voltage
sensing where the currents are low but you want to protect the wiring in the
event of a short. I plan to attach a lug directly to one lead and connect it
to the battery post clamp, then connect a wire to the other lead.

The part number I'm looking at is TRF600-150. Less than a buck each at
www.mouser.com. Here's a link to the datasheet.

http://www.circuitprotection.com/catalog/telecompolyswitchDS.pdf

My battery pack is 136V nominal, 180V max. Is there something I'm missing
that would make this a bad choice?

Thanks
Chris Simon
FocusEV
Minneapolis




> Lee Hart wrote:
> > 4. Or, you could use PTC devices, which act like fuses but reset
> > themselves when the fault goes away. They are generally only
> > available up to 150 volts, so again, you'd have to spread the
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> > Hm. Now that we think about this for a minute, I do have two strings,
> > and there's nothing preventing me from putting in two connectors. One
> > would have the lower 150 volts, the other would have the upper 150
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> Lee Hart wrote:
> >> Except that the original USE setup had *no* battery regulators of any kind.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Lee,
> How is the next batch of Balancer boards coming along, BTW ? The last I
> heard the engineer had put a gun to his own head and was threatening to end
> ongoing improvements ;>) .

I'm struggling along. I have the first of the new Control boards 
assembled and working. There were only a couple of cuts and patches. I'w 
writing the software now.

The most notable problem was that I needed to hand-pick the optocouplers 
for the serial port isolation. I plan to fix this on the production 
boards by changing to a 6N139, which is spec'd to work at low currents.
-- 
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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## EVDL List (Jul 27, 2007)

One final question for Lee (and the list)

So I'm going to go with 125 volt 3AG fuses, DC rated, 10k AIR. That 
should do it for 12 volt monitoring at the batteries with wires going in 
bundles not to exceed 125 volts to bulkheads in the back that will not 
allow >125v shorts.

However now I need fuse holders. The in-line fuse holders are rated for 
32 volts. Can I use those in this assembly since I will never pull more 
than 12 volts through the lines (unless of course I short in which case 
there will be up to 125 volts until the 125 volt DC rated fuse in the 
holder blows)

Also another thought: Since each battery lead has a fused line coming 
off it, if I were to short there would be two fuses in series between 
the battery + and -. Now I know that fuses in series do not increase the 
blow current but do fuses in series double the Amp Interrupt Rating 
(AIR) or the AIR voltage rating (I know there was a discussion on this 
WRT breakers, but this is fuses)?

Chris

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## EVDL List (Jul 27, 2007)

> Christopher Zach wrote:
> > So I'm going to go with 125 volt 3AG fuses, DC rated, 10k AIR.
> 
> For 125 volts *DC*, it will be a Bussman 3AB (not 3AG). Or Littelfuse
> ...


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## EVDL List (Jul 27, 2007)

Lee, list; what is your take on the fuseable link wire?????
Louis in central BC
----- Original Message ----- 
From: "Lee Hart" <[email protected]>
.>

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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > Christopher Zach wrote:
> >> So I'm going to go with 125 volt 3AG fuses, DC rated, 10k AIR.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Zach <[email protected]> wrote:
> 
> >> As an alternative, you may want to consider a fuse with wire leads that
> >> you crimp or solder into your circuit. Add a piece of heat shrink tubing
> ...


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## EVDL List (Jul 27, 2007)

>


> > Christopher Zach wrote:
> >> So I'm going to go with 125 volt 3AG fuses, DC rated, 10k AIR.
> >
> > For 125 volts *DC*, it will be a Bussman 3AB (not 3AG). Or Littelfuse
> ...


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## EVDL List (Jul 27, 2007)

>> As an alternative, you may want to consider a fuse with wire leads
>> that you crimp or solder into your circuit.



> Christopher Zach wrote:
> > Thank you. Specifically the LittleFuse 0324003... however both DigiKey
> > and Jameco have 6 week lead times on qty 60.
> 
> ...


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## EVDL List (Jul 27, 2007)

> Evan Tuer wrote:
> > Chris, I had a similar situation a few years ago - I couldn't get the
> > exact right wire ended fuse so I just soldered straight to it. If
> > you're careful it doesn't damage the fuse.
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> > When they put lead wires on such fuses, the wire is attached
> > to a separate metal cap. The cap is then spot welded onto the fuse.
> ...


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## EVDL List (Jul 27, 2007)

Just as a follow-up: I sat down with a crimper and wire cutters,
shortened the signal wires, and managed to fit 8 of the PakTrakr sensors
in the pack and get it lifted. So now I have:

50 zener regulators
8 Paktrakrs monitoring 48 batteries

All in a pack that had no space to begin with  The last two batteries
can be monitored by comparing the difference between the PT voltages and
the voltage reported by the Link-10 E-meter.

Pack is now up, trakrs are all talking. Next step is to get another
display unit so I can watch both packs while I drive.

I will say that these things are *very* impressive. Just what I was
looking for, and safe to boot.

Chris


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> >> When they put lead wires on such fuses, the wire is attached to a
> >> separate metal cap. The cap is then spot welded onto the fuse.
> >> Unfortunately, this adds to the length.
> ...


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