I have a 6 volt 4.5 SLA battery.

I have been charging it for 10 hrs. at 500 ma.

The battery powers (2) 1000 lumen lights for my bicycle.

When I powered up the lights, they are pretty dim.

Is there a load test I can do to see if the battery is dead ?

How many amps are the lights?
What is the battery voltage under load?

2 x 1000 lumen sounds a bit much for a 4.5Ah battery

Do you have an electrical multimeter? If so, test for voltage. If you don't have a multimeter, consider getting one. They are marvelously useful in all kinds of current events.

All joking aside, if this is not normal behavior for this battery after that amount of charge-time, the likelihood is that this parrot's dead.

Stuff, even rechargeable batteries, wears out. I've used rechargeable batteries extensively for certain devices; one of the signs that they are wearing out is that they no longer take a full charge.

Yes, one can use a load test and they still work. Cheapo meters are out there that use a resistive load. More modern systems can more fully provide more info. The issue is that no one really builds a meter for that small of a battery. Might use the cheapo one to see if the scale goes that far down and instead of many seconds just for a few. You'd have to interpolate that.

You can reduce the charge and see if you can charge it for 100 hours.


Basically if it did work correctly then we can assume that under your load the battery should not drop to 6 volts. The normal charge ought to be close to 7 on new battery. If fully charged only reads below 6 on multimeter then you aren't going to go very far. Similarly is that you test under normal load or create a load. If it fails to maintain voltage then it is no good.


Be careful. SLA's can still blow up. Wear all safety gear.

They are quite cheap to replace too.

My battery voltage got to 6.72 volts.

The battery is less than one year old.

If it went dead, I have to say that SLA batteries are a poor substitute for the traditional lead acid battery which last much longer.

Most of my car batteries lasted at least 3 years.

They operated under Texas summers which is very hard on batteries.

If me. Since I work on DC circuits on motorcycles. 1st check would be for corroded connection points and cleaning mating contacts. From there. I would disconnect one headlight next and take it apart and check for corrosion. Clean where needed with vinegar and tooth brush (maybe a spoon of baking soda).

Then disconnect the other headlight and hook the one I cleaned up next. Test. If bright and stays that way. Move on to cleaning the next headlight.

I live in Texas also. That is how I troubleshoot DC electrical hookups.
The battery from China may be a POS. It is possible especially if buying the cheapest.
I use GEL batteries on my motorcycles with lots of amps. Not as cheap as wet cell batteries.
Nice thing is you can mount them any way you want.

The lights are rated to 6V, not 12V perhaps?

SLA and traditional lead acid shouldn't have much difference in useful life. It depends on how the battery is used.
Also consider that most car batteries are significantly diminished in capacity in after 3-5 years. Nobody really cares because they still provide enough
peak current to start the engine. But I am sure you would find endurance to be down in a 3 year old battery compared to a brand new one.

SLA is considered a flooded lead battery. Very little difference.

Yes, you can't buy a cheapo battery and use it in Texas for too long.

6.7VDC isn't bad but now put a load on it. Could be poor connection inside.

http://www.free-energy-info.co.uk/Chapt6.html
about half way down there is a relay charger
this device can restore a sulfated battery
tip add a larger air coil in parallel with the relay coil

It turned out that a toggle switch was badly corroded and was letting little current through.

I live close to the ocean.

The step down circuit is still working fine.

I got rid of the switch entirely and made the project box waterproof. (I just disconnect one battery terminal as an Off switch.)

I'll bet that now the time between charges will go up somewhat.

Thanks for the update and solution.