12V to 24V please help

[greengrass]

because of history i seem to be stuck at 12V  on my battery bank but want to go grid tie

Ivans grid tie looks ok, ive heard of te soladin 120 and even used te gridfit 250 for a short while.

I need an electrical wizard out to tell me can i connect this gadget below

http://www.flatbatt.co.uk/Electrical/12v-24vcon/12v-24vcon.html

to my batteries and get 2.5A 24V and feed it to an inverter or will I get a big bang???
Thanks

[wyleu]

Should work ( at this point is prodded by little legal team in the head to issue some disclaimer) it might be interesting to see how it behaves as the 12V supply side starts to reduce to some lower threshold. It should turn itself off in a fairly friendly way but it would be good to know.

These devices are fairly similar to the PC power supply They are pretty efficient and do a pretty good job. However when they do fail they do so fairly spectacularly. Probably will fail faster than a fuse but at least if it fails with a short circuit you should have a couple of fuses inline to stop it destroying the equipment on either side of it.

[Antman]

I would assume (based on lack of spec and a statement on their website declaring otherwise) that you will only get a maximum 30W output.
Therefore when set to 12V o/p it will deliver up to 2.5A but at 24V output may well only produce 1.25A max....

Regards

Antman

[solaluvva]

There are much much better and safer ways of doing this.
Run a 24v battery charger from your 12 volt inverter into a small bank of 5Ah or bigger batteries (2 x 12v seriesed to 24v). This will be much safer in the long run, be hugely reliable, deliver maximum required power @ 24v, deal with fluctuations and interruptions in the 12v supply and respond dynamically to demands of the 24v side (eg, start-up current, etc).
Get a 24v battery charger (6Amax @24v eg£15), cost u less than that thing u were looking at.

[greengrass]

sounds like a plan

can you point me at a charger??

[solaluvva]

Was looking for charger as per, found this!

http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=1242771

12v to 24v @ max 6A £19.99

Hope this helps

[Paulh_Boats]

Was looking for charger as per, found this!

http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=1242771

12v to 24v @ max 6A £19.99

Hope this helps

That item is not a charger...its a power supply, similar to the one in greengrass's first post.

-Paul

[solaluvva]

Waddaya mean??
It's PERFECT for him!!!
Same price but much much better quality.
I did gooogle for the motor factor shop down the road from me, but they're not on the web.
 
My comments are still valid tho. GG's been pointed in a better direction than the one he was on.
I wish I had a magic wand and could sort his problem from here, but I haven't, so I just did my best.
His lot is improved, unless you could do better. You are welcome to try. Everybody is welcome. I offered no critisism of his comments, I just thought he was asking a bit much from the item he'd found. I found a better one that he could order direct while trying to help him. I still think he would be well advised to go look round shops himself, should he need to now that he has access to a far better unit at the same price.
I don't see what I've done wrong?
 
If he wants to, he'll contact me via PM and we'll arrange for him to send me money and I'll post him one like I have, once I've been to the shop to confirm the unit I bought last year is still available. But, if he felt it was too urgent, as the tone of his posts suggests, I presented him with another option.
Personally, I've just built a 48v charger out of an old inverter and 2x transformers.
1x 240:12 and 1x 240:36, connected both secondaries, and the output (primary T2) just touches 60v with no load. Perfect. (don't try this unless you REALLY know what you're doing)
But not everyone can play so confidently.
So I do what I can to help.
If I'd known it'd draw critisism, I'd have been more selfish with my knowledge.
Sorry.

[Antman]

Jon

Please don't take Paul's comment as a criticism. He was merely pointing out that the suggested power supply is just that - it is not intended or suitable for direct connection to batteries with a view to charging them.

In the least it will fail to charge the batteries properly since the voltage required needs to be 2.25 to 2.36 per cell (depending on whether you are float or bulk charging). 24V will only charge 12 cells (2x12V batteries in series) to 2V per cell - which although the nominal cell voltage, is not sufficient to fully charge them.
Worst case scenario is that the power supply will 'fry' and fail if connected across flat batteries - due to the batteries attempting to draw more current than the switch-mode inverter can deliver.

Sealed lead acid (and indeed vented wet LA batteries) need voltage regulation and current limiting when on continuous charge.

Regards

Antman

[Paulh_Boats]

Jon,

No criticism intended, its a great find and excellent for running a laptop off a solar 12V system as the output voltage can be tuned to 19V which is common for modern laptops.

One solar panel, one battery and that inverter would be a low cost entry into PV power for laptop users - simply switch over to the laptop power supply when the solar battery runs down. The lower powered panels don't need charge controllers.

Unfortunatly its not ideal for charging as Antman explained.

-Paul

[solaluvva]

Okay, cool.
So, my initial idea was correct, but I have to admit defeat on finding a suitable charger at the stated price on the web. Seally do one that comes in at about £30.
Or just build your own.
Computer UPS units make great inverter/charger units. Anyone else tried this?

[greengrass]

Now, Now Boys.

Thanks for all the great comments.

I always like good ideas from you guys on the Navitron Forum.

Please don't fall out over it.

Best Regards

Gary