[RE-wrenches] Surrette Battery Question

[jay peltz]

HI Allan,

so right you are.

Thanks about the surrette link.
There batteries sure seem to be prone to odd things in the PV world.


peace,

jay
On Aug 3, 2008, at 5:12 PM, Allan Sindelar wrote:

> Jay,
> You're right about leaving off the post at the bottom - whoops.  
> It's at the bottom here.
>
> About voltage drop: I meant only that by running the array at a  
> higher voltage than the batteries, there could never be sufficient  
> hot-weather and undersized-wire voltage drop to prevent the array  
> from exceeding the EQ voltage of the batteries. This is most often  
> a potential problem with 12V systems. I mentioned it only to  
> eliminate it as a possible cause of this situation.
>
> The Surrette Tech Bulletin 614 is available for download at http:// 
> surrette.com/files/BU-RS-614.pdf. My understanding is that this  
> bulletin is the direct result of the complaints on this list about  
> two years ago about Surrette battery performance and life.
>
> Allan
>
> -----Original Message-----
> From: jay peltz [mailto:jay at asis.com]
> Sent: Sunday, August 03, 2008 1:41 PM
> To: Allan Sindelar
> Subject: Fwd: [RE-wrenches] Surrette Battery Question
>
> HI Allan,
>
> You mention about a Surrette tech bulletin, I can't seem to find  
> it? Can you tell me where it might be on their site?
>
> Also I"m curious about you saying that hot modules isn't going to  
> affect voltage drop.
> Sure it will.  If the wire is upsized for the lower voltages from  
> hot weather, then you've compensated for it, but there is still  
> added voltage drop.
>
> And about the adding new panels to old? I didn't see the link/post  
> at the bottom?
>  Thanks, jay
>
> OK, the story,
> This client had started off-grid in the early nineties with a tight  
> budget. He and his wife would add modules as they could afford  
> them, usually used. The built a homemade tracker with a Wattsun SA  
> controller and two linear actuators, using a DPDT momentary switch  
> to adjust elevation seasonally. Over time the tracker filled out  
> with eight Arco 16-2000s, nine Carrizo (Arco) M52L 5V Quad-Lams,  
> two BP 275s, and two old square whatsises with 2" cells from the  
> seventies.
>
> Eventually their income increased and their house and house loads  
> got bigger. They asked us to upgrade their array, which eventually  
> led to the 8 160W modules I added on a pole-top array. There were  
> several catches, though:
> 1. They wanted to keep as much as possible of the original  
> "democracy tracker" in operation;
> 2. The house had grown over the years, and the existing tracker had  
> to be moved 50' farther away;
> 3. The balance-of-system was still in the original basement, now  
> inaccessible from the outside, as the house had been expanded bit  
> by bit in all directions.
> 4. The #2 (or 2/0, I can't recall) USE copper array input wires had  
> been built over and couldn't be replaced; we had to use them.
>
> We dismantled the tracker and moved the pole (yep, lifted pole,  
> concrete and all and set it in a new, larger hole with more  
> concrete). We put a 3R j-box where the old pole had been and  
> trenched to the new locations. After playing with different  
> calculations, we changed the old tracked array as follows:
> 1. We added two BP 380s (the closest we could get then to the older  
> 275s) and wired them as one 48V string;
> 2. We dumped the whatsises, which had low output;
> 3. Now I'm trying to remember: I think I wired the four 16-2000s  
> (originally 2.2A at 12V) in parallel, then wired this set of four  
> in series with the nine Quad-Lams (think of M52Ls, originally used  
> in the Carrisa Plains utility central power plant in California  
> from 1984-1989 or so, as similar to 16-2000s but with the 3 rows of  
> cells wired in parallel, to make about 7A at 4 1/2V nominal. That's  
> why they're called Quad-Lams: it took four in series to charge a  
> 12V battery).
>
> So we ended up with a 17-module array wired at 48V nominal, tied in  
> with the new 48V array. What made it so special, other than that  
> it's the only 17-module array I ever built? When we were all done  
> and it was charging the 24V battery through the MX60, I alternately  
> turned each array off and let the MX60 find its MPPT voltage: the  
> two arrays were within one volt of each other. We got it right, and  
> I have always been especially pleased with that job.
>
> That's all.
>
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