How low should you run SLA batteries until?

I run them into the ground somewhere around 10.5V/batt or even a little lower. It's better to not go below 10.75-11V, but SLA sucks so I don't care.

since you have a wattsup meter, your are better off measuring the AH taken from the pack rather than the voltage for determining state of charge.

just make sure the AH you pull from the pack between charges is 70-80% or less of the rated AH capacity at 1C.
The voltage you can pull SLA down too depends upon battery, rate of discharge and temperature.

Matt

lead acid batteries are happier & will cycle longer if they don't drop below 50% of capacity.. that's amp hours.. hard to do on a small scooter. I know i ran mine down to barely crawling several times. But it is preferred to keep the batteries full.. have a place to recharge on your rides.. do shorter runs.. get a bigger scooter!

I eventually overvolted, & that gives me ~ 7-8 miles of distance, but i usually keep it under 6. My batteries seem to be fresher & holding charge better, & i've been bank charging them, too.

Continually draining the batteries will definitely shorten their useful life.

Uh huh... yup.. unfortunately that's the way things are and that's why we're so excited by lithium-ion batteries. The power to weight and power to size ratio is much better. And they can usually be discharged more deeply without harm.

A 24v 20 ah Ping Lifepo4 battery should be well under $500.

Double post.

Sorry

As someone who doesn't have a watt meter or Cycle Analyst yet,what is a safe level
to drain my 48v battery packs too voltage wise.
I have an 11 km ride to work and am going to check and see what the pack is before I leave and when I get to work.I'm just wanting to make sure I don't drain them too low.
The meter on my Kaishan K500WS really doesn't help me.

Thanks

eRick

I don't have information on GreenSavers, but this looks typical of all the deep cycle lead acid battery tests I've seen. The X-Axis is percent depth of discharge, the Y-Axis is cycle life.

Here is what the website I got this graph from says:

Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film. The graph above shows how lifespan is affected by depth of discharge. The chart is for a Concorde Lifeline battery, but all lead-acid batteries will be similar in the shape of the curve, although the number of cycles will vary.

Source: Windsun.com

I found another link to some very interesting experiments people are doing on reviving Flooded Lead Acid Batteries with home made electrolyte with good results.

I'm more interested in building a zinc nickel battery. Is there some reason home made batteries are only made from lemon?

just ride the bike till the batterys are close to completely discharged. Then back off on the distance till you are in the happy zone. Pay attention to how the bike runs as the pack discharges and you will be able to tell by how the bike rides how you are doing. So if you can go 20 mph at the start, and most of the middle of the ride at 15, then when you can only go 10 it's past time you stopped. The middle part of the ride will have a small, but noticalble voltage sag, but when it really sags, its past time to stop. Very soon you will get a feel for it, and know what to do without needing to check voltage. I think 70- 80% discharge is good enough for battery life, unless you are into setting a record for it.