After 10 months of use my hope vision 4 battery in only lasting 1.5 hours on full. If hope wont warrant it, does anyone know if new cells can be added. The battery pack is sealed but im sure i could open it and make a new one.

Thanks

Our (1st edition Hope LED) had same battery problem (out of warranty). Write a nice letter and send it back to Hope – will usually sort it out FOC. Forget about sending an email – they rarely respond.

If you live somewhere near to Hope then have also found it works wonders getting my Mrs to take things in! (she is usually the one that wears stuff out anyway)

Cheers mick, this will be the 3rd time i have had to contact them about the light both times ok but just wondering who easy it is to make a new battery. thanks

I'm still unable to get an "educated" opinion on how best to discharge/charge the battery. Some say run it flat before recharging, others say always top up when you can. Some say run it flat from time to time, others say new batteries dont ever need to be run flat…Everyone seems to be an armchair expert but nobody actually backs up their opinions with any hard facts 😥

Hope have excellenst customer service – give them a call and they will sort you out. Re batteries, this is useful (off the Lumicycle website)

Do I need to charge my Li-Ion battery if I am using it for the first time?

Yes. It is necessary to give your Li-Ion battery a full charge before using it.

What is the life-span of my Li-Ion battery and how often can I recharge it?

You can expect the service life of your Li-Ion battery to be approx. 300 charge-discharge cycles. For most riders this equates to about 3 years use. The service life means up to the point when the battery has 80% of its original capacity and is then ready for replacement.

How long does it take to charge my Li-Ion battery?

This obviously depends upon the amount the battery has been discharged. Generally recharge of Li-Ion batteries takes 2-6 hours.

I use my Lumicycle light system for an hour every day. Is it better to charge it every day or wait 3-4 days and give it a full charge?

This is not such an important issue for Li-ion batteries. However, we recommend an occasional discharge/charge cycle as a good maintenance principle.

Discharging (running the light system)

Can I completely drain my Li-Ion battery before recharging it?

This is not necessary on a regular basis but is beneficial occasionally.

How big is the loss of capacity at low temperatures?

Li-Ion batteries operate between -20 and + 60 degrees centigrade. However, performance significantly decreases below freezing.

Storage

How do I store my battery during the off-season when it is not being used and what is the rate of self-discharge?

Li-Ion batteries should be stored in a cool place when not in use for extended periods. Their self-discharge rate is 10% per month. This is far lower than for NiMH batteries. Although it is not essential, we recommend occasionally charging you Li-Ion battery during the off season to counter the self-discharge effect.

Guidelines for prolonging Li-ion battery life

Unlike NiCad batteries or NiMH batteries, lithium-ion batteries should be charged early and often. However, if they are not used for a longer time, they should be brought to a charge level of around 40%. Never use thebattery care functions some cellular phones provide for nickel based batteries. (This will deep cycle the batteries.)
Li-ion batteries should be kept cool. Ideally they are stored in a refrigerator. Aging will take its toll much faster at high temperatures. Keeping them in very hot cars can kill lithium-ion batteries.
Avoid running the battery through "deep discharge" cycles — that is using it until it's fully depleted to 0 %.
Many authors suggest that freezing Li-ion batteries may be detrimental. However, most Li-ion battery electrolytes freeze at approximately -40 °C. Household freezers rarely reach below -20°C. Published experiments demonstrate that freezing (even below -40°C) is unharmfulif the battery is fully warmed to room temperature before use. More details are given in the book "Characteristics and Behavior of 1M LiPF6 1EC:1DMC Electrolyte at Low Temperatures" by L.M. Cristo, T. B. Atwater, U.S. Army Research, Fort Monmouth, NJ.
Buy Li-ion batteries only when needed, because the aging process begins as soon as the battery is manufactured.

Thanks but even this information contradicts itself:

"Avoid running the battery through deep discharge cycles — that is using it until it's fully depleted to 0 %."

"we recommend an occasional discharge/charge cycle as a good maintenance principle."

If you only have a finite number of recharge cycles then maybe it IS better not to top-up after every ride, but I've also been told to top up Li-ion at every oportunity to retain runtimes.

😥

I understand full discharge will destroy Li-ion cells so they usually have protection circuitry to prevent this, and there's:
a) no benefit to deep discharge
b) no penalty for frequent recharge

as for the 40% storage rule, I'd say it's almost impossible to know when you're at this stage, but if you just don't charge it after the last few light uses of the early 'summer' you should be about right – and the lights-free period (mid-May to late Aug) is not long enough for serious self discharge

Unless you know what you are doing jonk please dont go there.
I'm sure like others have said if you ring HopeTech up direct they can sort it out for you.

And yes the protection circuit should protect against under-discharge, Over-charge and also short circuit protection. One of the main reasons about leaving the battery approx 40-50% charged for long periods is because the protection circuit continues to drain the battery even when not in use. Although this is only a few milliamps this can build up over time and will continue to 0V if left for long periods. Also Li-ion cells dont like being left 100% for long periods either.

let us know hoe you get on anyway Jonk.

I thought Li-ion batteries "forget" their max charge point over time unless they're kept fully topped up.. 😥

I'm now thinking about inventing a frog powered light so I can easily top up while I'm out riding.