Low Power DC-DC for Link10 / LinkPro

4753 Views 17 Replies 6 Participants Last post by tomofreno, Oct 27, 2010

etischer

Discussion Starter · Oct 20, 2010

I found a nice little power supply for running my Link 10 battery monitor. An isolated power supply is needed if your pack is above 50 volts.

Input 120-370 VDC
Output 10.8 - 13.2 VDC @ 1.25A

It is really small, about 1" x 3" and dinrail mounted.
100M ohm, 500V isolation,
CE, UL, TUV, and a 3 year warranty.

Around $20.

http://www.jameco.com/Jameco/Products/ProdDS/2094952.pdf

1 - 18 of 18 Posts

resago

· #2 · Oct 20, 2010

thats in the range of a plug-in brick for a router 12v 1amp.
$3 at the thrift store.

etischer

Discussion Starter · #3 · Oct 20, 2010

resago said:
thats in the range of a plug-in brick for a router 12v 1amp.
$3 at the thrift store.

Well, for the extra 17 bucks, you can get a supply that is specifically rated for input voltage of 120-370 VDC, and has a working temp of 60 deg C.

Also, having a wall wart plugged into an extension cord doesn't look as clean as having screw terminals and dinrail mounting.

brainzel

· #4 · Oct 21, 2010

Do you need a power supply or a voltage devider / prescaler?

etischer

Discussion Starter · #5 · Oct 21, 2010 (Edited)

brainzel said:
Do you need a power supply or a ?

I need both. Without the isolating power supply you either:

- Have your 12v system grounded to your high voltage pack or
- Power your meter with a few cells from the high voltage pack and need to re-balance them occasionally.

I'd rather add a supply and not have either of those issues.

Note, the pictures in the voltage divider / prescaler link show two power supplies, one at 300v the other at 24v.

etischer

Discussion Starter · #6 · Oct 25, 2010

Got my shunt installed, got my isolated power supply, and got my pre-scalar built. Just need a link 10!

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Overlander23

· #7 · Oct 25, 2010

Any particular reason why a Link 10 instead of the LinkPro? Or a Victron? Or an E-Meter?

I thought the Link 10 had been discontinued. I've got a Link Pro in mine on a 10:1 prescaler with a 12v isolated DC-DC converter that seems to be working fine.

I've read (all heresay, mind you) that the Link-10 was more unreliable than the later Link Pro, and that TBS, who make the Xantrex stuff, used to make the Victron stuff until they contracted to supply Xantrex with all their monitors.

brainzel

· #8 · Oct 25, 2010

My knowledge:
The Xantrex Link 10 is no longer produced.
The TBS eXpert Pro is an exact copy of the Xantrex LinkPro but less expensive.

I got a Link10 at 125 volts in my conversion and if I could, I would "update" to the newer version TBS eXpert Pro (Xantrax LinkPro).
So if anyone wants to swap, let me know ;-)

Tesseract

· #9 · Oct 25, 2010

I have been called upon to make 10:1 prescalers for TBS expert pro's (or whatever they are called) for Rebirth Auto on several occasions. I really try to dissuade them from abusing me like this, but, well...

Anyway, my approach is to use a 1W isolated dc-dc converter module to power the gauge and a series string of 1% resistors to get to 436.5k - 200k, 200k and 36.5k - followed by a 0.1uF capacitor to filter out noise. I don't use a pot because that's a no-no in a high vibration environment, I don't like having to calibrate them, and most resistive materials have a voltage coefficient, so you really want to keep the voltage across them below 200V or so regardless of the actual dissipation. Also, those are standard values from the E96 series.

For the dc-dc converter I have used both the Cincon part number EC1TA12N and the Murata part number MER1S1212SC - both are 1W 12V to 12V isolated converters in SIP modules.

Cost is about $10 in parts. I might get around to making this an actual product, with a bit more protection than a rectifier in series with the dc-dc module, etc., but this is mainly so I don't ever have to hand-wire one again, which I view as a seriously bad use of my time

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etischer

Discussion Starter · #10 · Oct 25, 2010 (Edited)

Well, I bought a link 10 on ebay. Problem is it appears to be fried, it reads -511A all the time. The seller has already refunded me, but I may check to see if I can get it repaired first.

I already built the pre-scaler for the Link10, not sure if the LinkPro's would be the same. The Link10 is cheaper. The Link10 has a brighter display. The Link10 can read higher voltage (500v), if I'm balancing my pack I'll be upwards of 400v.

If I can't get the Link10 repaired, then I'll happily switch to the LinkPro, it was a tough choice from the start.

Overlander23 said:
Any particular reason why a Link 10 instead of the LinkPro? Or a Victron? Or an E-Meter?

I thought the Link 10 had been discontinued. I've got a Link Pro in mine on a 10:1 prescaler with a 12v isolated DC-DC converter that seems to be working fine.

I've read (all heresay, mind you) that the Link-10 was more unreliable than the later Link Pro, and that TBS, who make the Xantrex stuff, used to make the Victron stuff until they contracted to supply Xantrex with all their monitors.

etischer

Discussion Starter · #11 · Oct 25, 2010

It looks like the TBS gauge is sold without the shunt, while Xantrex sells the Link Pro with the shunt included.

Xantrex LinkPro seems to be the cheaper option, $253 from Buy.com.
TBS eXpertPro is $250 + $25 from evolveelectrics

brainzel said:
My knowledge:
The Xantrex Link 10 is no longer produced.
The TBS eXpert Pro is an exact copy of the Xantrex LinkPro but less expensive.

I got a Link10 at 125 volts in my conversion and if I could, I would "update" to the newer version TBS eXpert Pro (Xantrax LinkPro).
So if anyone wants to swap, let me know ;-)

tomofreno

· #12 · Oct 25, 2010 (Edited)

The TBS ExpertPro usually comes with a 500A shunt. See for example:
http://www.evworks.com.au/index.php?product=INS-TBS-PRO
Looks like the shunt at evolve is only 200A. When I first contacted TBS in early 2009 they gave me Xantrex's name as their only U.S. distributor. At that time Xantrex didn't sell the voltage prescaler, so I bought from evworks who offered both the 5:1 prescaler from TBS and their own 10:1. I run the gauge off the main pack (all cells) with the 5:1 prescaler, since my pack is only a max of about 125VDC. The 12V accessory battery is isolated from the pack, and not connected to the gauge.

etischer

Discussion Starter · #13 · Oct 25, 2010

That's still $325 USD. I might as well buy the Xantrex for $250, and buy it locally in the USA.

tomofreno said:
The TBS ExpertPro usually comes with a 500A shunt. See for example:
http://www.evworks.com.au/index.php?product=INS-TBS-PRO
Looks like the shunt at evolve is only 200A. When I first contacted TBS in early 2009 they gave me Xantrex's name as their only U.S. distributor. At that time Xantrex didn't sell the voltage prescaler, so I bought from evworks who offered both the 5:1 prescaler from TBS and their own 10:1. I run the gauge off the main pack (all cells) with the 5:1 prescaler, since my pack is only a max of about 125VDC. The 12V accessory battery is isolated from the pack, and not connected to the gauge.

Overlander23

· #14 · Oct 25, 2010

Hmmm, you'll have to build a "bigger" prescaler for the Link Pro as it's limited to 35vdc. Fine for for my 240v needs, but won't obviously work on 10:1 for 400v. And the other problem is, it only has prescaler options for 5:1 and 10:1.

The Xantrex LinkPro comes with a 500A shunt.

Overlander23

· #15 · Oct 25, 2010

Hey, I'm using a Cincon 12v converter in mine, and I didn't have to ask you first!

Mines probably wired up wrong, though...

Tesseract said:
For the dc-dc converter I have used both the Cincon part number EC1TA12N and the Murata part number MER1S1212SC - both are 1W 12V to 12V isolated converters in SIP modules.

etischer

Discussion Starter · #16 · Oct 25, 2010

I'll just have a zener clip the prescalers output voltage at 35v. Its not a big deal if my pack is at 400v and the meter sees only 350v, it will be a rare occasion and I can live with the inaccuracy.

I placed my order, $249 shipped, no tax.

Overlander23 said:
Hmmm, you'll have to build a "bigger" prescaler for the Link Pro as it's limited to 35vdc. Fine for for my 240v needs, but won't obviously work on 10:1 for 400v. And the other problem is, it only has prescaler options for 5:1 and 10:1.

The Xantrex LinkPro comes with a 500A shunt.

etischer

Discussion Starter · #17 · Oct 27, 2010 (Edited)

I bought the LinkPro last night. 3 day shipping from NJ to CA took only 1 day, it was waiting on my doorstep when I got home tonight.

I got the meter installed and the accuracy is amazing. Out of 500A it displays down to 0.1A, and the reading is rock solid, that's 10 micro volts resolution. I'm really happy I got the LinkPro now.

The highest voltage I can set for "charger float voltage" is 330v, which is just out of reach of where I need to set it, 338v. I may have to add some resistance to my prescaler to get the synch function to work.

I also found a schematic showing the pre-scalar
http://www.tbs-electronics.nl/downloads/epro_passive_1-10_prescaler.pdf

tomofreno

· #18 · Oct 27, 2010

I also found a schematic showing the pre-scalar

Probably too obvious to most here to consider worth mentioning, but for the less-informed who might view this: The schematic shows the auxiliary battery negative terminal connected to the main pack negative, which means the main pack negative is then connected to chassis ground. This is not a good idea in general, as you are then exposed to electrical shock if your body connects between a cell or battery terminal on the main pack and ground, and the pack is typically high voltage and can supply a lot of current. With the pack isolated from chassis ground there is no return path for charge flow from your body back to the pack, no closed loop for charge flow, and no shock.

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