Arlec rechargeable camping lantern

[tytower]

I bought one of these and when I got it switched on the red charging led came on then went out fairly quickly and the green came on. I turned the lamp on overnight to see how long it would lastand it was out by morning.

I put it on charge again but the green led came on immediately. Pulled it down to have a look and the solder on the board was pretty bad . Removed a loose bit trapped under a screw and cleaned it up generally but when reassembled only the green came on even though the battery was flat.

So returned it and got another which looked good when plugged in , the red led came on but I found the green led does not appear to come on . Cleaned this shocker of a board up and removed some loose solder too but it still hasn't turned green yet .

So I've been looking at the rechargeable 6 Volt sealed lead acid batteries supplied and they are called "valved regulated rechargeable battery -constant voltage charge"

I firstly wondered what that meant and where I might see a typical circuit for the "valve". I assume the valve restricts charging current as I left one of them on for a few hours at 1 Amp charge and when I came back it had closed up and was not taking any current at all.

Its a LT640 XINSHUN Chinese 4.0 amp hour battery so I charged it at 400mA and I find it is gassing at about 7V and the notes on the side say "cyclic use 7.25-7.45V, standby use 6.8-6.9V"

So I have the battery charged to 7.3V odd and the red led is still not off so I think Ill take this one back also

Does anybody know anything about the battery or the lantern. It seems it might be a good useable product if I can get the battery charging /discharging as intended?

 

[Hero999]

Sorry but it sounds like a load of cheap Chinese junk to me.

A valve regulated battery is a lead acid battery like the kind used in a car but it's sealed and a valve is used to vent the hydrogen gas if the pressure is too high. Providing the battery is treated properly, the valve should never have to open. There's also often a mechanism which combines the hydrogen gas with oxygen to form water which is returned to the electrolyte, in the higher quality batteries.

Just find a 6V battery of a similat Ah range.

The battery should be charged to 7.25V then float charged at 6.9V. The battery should never be left connected to 7.25V for too long otherwise it will gas.

 

[tytower]

Sorry but it sounds like a load of cheap Chinese junk to me.
A valve regulated battery is a lead acid battery like the kind used in a car but it's sealed and a valve is used to vent the hydrogen gas if the pressure is too high. Providing the battery is treated properly, the valve should never have to open. There's also often a mechanism which combines the hydrogen gas with oxygen to form water which is returned to the electrolyte, in the higher quality batteries.

Ok well I think the with newer ones the valve refers to an electrical current flow device which seems to be scaled dependent on voltage . As the voltage gets to 7V odd the current drops to about 100mA and unless you increase the supply voltage to say 9V it will not allow any more current flow . It is marked "Constant Voltage".

This device is not evident so it must be built in somewhere. That's the circuit I'm interested in.
I've removed the lid to find rubber cups over each cell top and a single piece of cotton wool . A glued plastic piece sits over the rubber cups so they can't just pop off.

When fully charged I cannot get it to take any more than about 100mA . When flat it will take 3 Amps or more if I give it .

 

[Hero999]

The valve has nothing to do with electricity, it's a purely mechanical device required to prevent the battery from exploding.

The current probably drops as the voltage approaches the voltage of the charger, 7V. Increasing the voltage will increase the current flow because there's a higher potential difference between the battery and the charger, if the voltage exceeds 7.25V the battery will start to gas and will eventually dry up. This has nothing to do with the valve system and everything to do with Ohm's law.

 

[tytower]

OK You have had your say . Perhaps we can now let someone else have a go.

I'm now on my third lamp and its possibly faulty too . Very shoddy soldering on the board . This last I cleaned up the board before even switching it on.

Just to reiterate when charged at about 7.5 V constant voltage the battery initially takes a lot of current then as the voltage goes over 7 V it drops to 100mA. To get it to take more than that I must move the voltage up to about 9V before a change occurs ( no change until 9V . I can set my variable voltage / variable current supply at any constant voltage I like .

Now the fact that it is not a normal increase with voltage is the point of my original post.
Does anybody else know anything about these batteries?

 

[Chippie]

I have to agree with Hero999 on this....


SLA batteries are designed to be constant current/constant voltage charged to a terminal voltage of approx 6.9v in the case of your 6.0v battery...As the battery becomes charged and reaches its terminal charge voltage of 6.9v the current will decrease, raising the voltage does no good at all!! You will simply boil the battery dry!

Another characterisitic of SLAs, do not allow them to become fully discharged, they are not designed for this.......If you need a battery that can be discharged fully then go for Nicd/Nimh

Sorry this is probably not what you want to hear but you did ask the questions......

 

[tytower]

Thanks chippie I welcome your post

Fact remains however that there is something built in to resist current . Not just the battery's internal resistance that we all know about . This appears to be a new type of battery and while all ofthe factors mentioned so far are quite correct for SLR batteries there is a difference here

I seek a post from someone who has one of these or knows of them. Not general chat on SLR's
I have tested three of them so far .
I do not recommend the lantern it is junk but the battery is very good.

 

[HiTech]

I have a Ray-o-Vac twin tube lantern that is built rather well and feels solid. The lamps never flicker and provide ample light. Instead of using alkaline or NiCad batteries, I use Li-Ion rechargeables taken from laptop battery packs. I have a Li-Ion charger for it and the lantern operates much longer from these batteries while also providing longer shelf-life when fully charged. Perhaps you can visit a nearby computer repair shop and inquire if they have any Li-Ion packs available and just forego the SLA battery.

**broken link removed**

 

[Hero999]

Fact remains however that there is something built in to resist current . Not just the battery's internal resistance that we all know about .

Have you reverse engineered the charging circuit?

The chances are it's pretty simple?

This appears to be a new type of battery and while all ofthe factors mentioned so far are quite correct for SLR batteries there is a difference here

I thought it was an SLA battery?

What's an SLR battery?

There's nothing new about SLAs and value regulated batteries as as I described above.

I seek a post from someone who has one of these or knows of them. Not general chat on SLR's

I thought we were talking about SLAs?

No, I haven't owned one but if you posted more information i.e. photographs of the PCB or better still a reverse engineered schematic etc. I might be able to help anyway.

I have tested three of them so far .
I do not recommend the lantern it is junk but the battery is very good.

You said it's not charging properly?

How do you know that the battery is good and that the charger is poor? Could it be that the battery is poor or both the charger and battery are crap?

Are these new?

Where did you buy them from?

If they're new and it's not obvious you've opened them, I suggest you take them back for a refund rather than trying to repair them.

 

[HiTech]

OK You have had your say . Perhaps we can now let someone else have a go.

HERO, considering his above statement, he may have closed the door on you, leaving you outside and looking in!

Here's a link to the battery and it's published specs.
SLA Battery 6V4AH - Detailed info for SLA Battery 6V4AH,SLA Battery,SLA Battery 6V4AH,LT640 on Alibaba.com

Here's a WIKI link to VRLA batteries: VRLA battery - Wikipedia, the free encyclopedia

Regardless of all this, IMHO it appears that the lantern's charging circuit is the culprit either by improper design, shoddy workmanship, or faulty components.


To ty-tower:
You could try contacting Arlec Tech Support for further assistance or perhaps obtain a replacement circuitboard. Here is their contact info.:

Spare Parts Email: spareparts@arlec.com.au
Customer Service Email: custservice@arlec.com.au
Tech Support Email: techenquiries@arlec.com.au

Here's a link to a very simple yet effective charger circuit that you can build in no time and will not overcharge the battery, regardless if it's plugged in for days.
Sealed Lead-Acid Battery Charger Circuit

Hopefully, all this is of some help to you.