New Batteries and Solar Cells Finished

[andyman5002]

Hi all, thought I would post where I'm up to with everything, not posted for a while been bogged down with uni and not got anything done. Things are moving on now though. I just bought 4 92ah batteries off ebay:

Not really sure what to do with these until my panels are up? Do you think I should charge them all up and then store them until my panels are up and running? I don't want to ruin them. Also is it safe to charge them with a car battery charger as long as I monitor them? What sort of cut off voltage should it be? I think the float voltage is 13.68v? Not sure what I should charge it up to, 14.2v?

When I first got them there were at 12.66 volts. In the manual that says about 80%.

Also heres a few pics of my solar cells that are cleaned, soldered and ready to be mounted in the panel:

Sorry for all the questions but I don't have a clue about batteries. These are supposed to maintenance free.

Hopefully my panel will be finished soon and I can start charging these batteries and use them.

Thanks for the Advice

Andy

[AbyssUnderground]

I don't see why you can't use a car battery charger since they are a high capacity. They are SLA by the look of it so 14.2v is perfectly safe to get a good charge but don't leave it at 14.2 for more than a few hours until you start using them. Even though they are SLA they can still boil. 13.6-13.8v would be a good float voltage to keep them at indefinately until you come to use them.

What you could do is buy a low current regulated 13.8v ham radio power supply and use that to float them. It should do the job perfectly until you get round to using them and you can leave it connected indefinately. I used to use this setup as my "UPS" for my ham radio's on a 7Ah SLA. Charged it would use about 10mA.

Id do this but others may have better advice.

[Bruce S]

Andy;

  1st, nice job on those panels!!

With respect to the batts. The label on the side tells a tons of info:-)

It gives you the full amount of info needed.

Pretty nice!!

The top part shows that you can safely discharge and recharge at a C/10 which is the total 92Ahr / 10. With that and knowing the type of chemistry you can design the charger charge and float charge rates.

I would say looking at them that they are SLAs and that the second part is the float voltage you should be able to read once the batts are fully charged. Being 12 there are 6 cells (2.2volt per cell, okay a little more but....)

Use the C10 rating for the bulk charge and the float to keep them topped off.

You can use a car type 12volt charger but only have it set to no more than 6A unless you have one that is a multi-step charger that adjusts itself the State of charge. Better ones do this. Once it close to being full, turn off the charger and let the batts rest for ~30mins. Then check the voltage.

The time and rest is to let the batts cool and the surface charge to trickle down so to speak. this will give you a good idea of what their nominal charge will be, then put them on a charger that is set for 1A this will help finish the charge, but don't leave them on more than 8 hours!!! this is where a house timer comes in real handy!!

This will allow you to store them for a few months without much worry until you have those beautiful panels setup.

Cheers and have fun.

Bruce S

[Nando]

Andy:

You can leave them in float charge = 13.8 volts with any small charger or power supply that can be limited to 13.8 Volts, if you are not loading the batteries.

You can place them in parallel once they are charged then a single supply to 13.8 volts to keep them healthy all together.

For years, we have been doing such arrangement and never have had any problems with them.

Also, you can float charge each battery alone once a month ( for a week) with one charger rotating between them.

I do not see the brand name of the batteries to see what type of peak charging profile limits you need to have, since they are sealed.

Nando

[stop4stuff]

Batts are 'PowerSafe' brand... VRLA... some data here;

http://www.enersys-emea.com/pdf/EN-VFT-RS-007_0506.pdf

Looks like there's a nice range of batts there... & the weight is right for the EV I'm converting. EU markings too... so I'm in the right part of the world (for once)

Do you have a link to the ebay seller Andy?

paul

[andyman5002]

Thanks guys for all the help and advice, I think I need to get my self a regulated battery charger with 13.8V float charge on it from somewhere and leave them on charge for a day or 2. Any thoughts on a charge that can be sourced from the uk?

The seller Id was andreac7530, at the moment there are none listed but when the auction ended there were 10 left. I did see some at the warehouse, so might be worth emailing them?

Also its probably only worth it if you can pick them up, as they wanted 20 quid delivery for each battery.

Thanks Andy

[andyman5002]

Heres a link to the sellers shop:

http://stores.ebay.co.uk/andreac753026

[andyman5002]

OK I think I'm going to do what nando and abyss said to do, get a small power supply regulated at 13.8 volts. I was thinking of a 13.8v 3Amp CB radio supply of ebay? Or is the current too high? I will float them all for 2 days each and then parallel them up and leave them on float.

Andy

[AbyssUnderground]

A CB supply is fine. Current won't matter as when it hits float voltage the current will also drop. Like I said my 7Ah SLA used to float on about 10mA so 90Ah will float on around 80mA. You could probably parallel all the batteries and float them all at once. Not sure if anyone else would agree with this but Id do it myself as it would save the hassle of swapping.

[Nando]

How much is a quid , in  dollars ?.

Nando

[Nando]

Yes a 13.8 volts at any current above 500 milliamps will do.

Nando

[stevesteve]

Hi Nando,

A 'quid' is a pound the equivalent of saying a 'buck' for dollar. So it's whatever the rate is now 1.9xUS$?

[AbyssUnderground]

Roughly $2 to every £1.