Beresford Bushmaster DAC

[StanleyB]

Oh bum! Its sounding so good, bass is stonking

email me with the problem Neal and I shall email you back the solution. I need a record of the various problems and solutions offered.

[NRG]

Done...

[Martinh]

So, I did a test on my battery pack and found that after 4 hours of use, I needed to put 400mA back in to top it up again.

Therefore, my 3000mA pack should give me up to 30 hours and the 6800 mA pack will give 60+ hours.

I usually leave my BM on 24/7, so battery power will be reserved for special occasions only.

Cheers,

[NRG]

The problem of auto-detecting the source on my BM has been resolved by Stan, not that it was of great concern to me but its nice to know its fully functional again. Cheers Stan!

[sergiox]

Thanks for the warning. I shall no longer leave it on charge when I go out.

be aware with the li-po type , watch what could happen...

[jandl100]

[NRG]

You need to put this in perspective though.

The use of Lithium Ion packs without a BMS (battery management system) is fool hardy as they have the potential to be explosive as shown if they are the variety based on a Cobalt cathode. The later and current compound cathode types are far less likely to explode as shown in the video.

Lithium Polymer referes to the type of construction of these batteries IE Soft cell pouches not hard cased cells, as they are soft walled they can be punctured and damaged so should be encased in a secondary box.

As I mentioned above use without a BMS is foolish as issues with the cells occur when they are discharged too far and then on the subsequent charge cycle they can, if the older cobalt types, cause a fire.

All the horror stories came about in the early use of them by RC enthusiasts who didn't use a BMS and didn't use the correct charging schemes.

The modern compound types are far more robust and feature fusible links for short cct protection but still need a BMS and correct balance CC/CV charger to ensure a good cycle life...

[Martinh]

be aware with the li-po type , watch what could happen...

I wouldnt take too much notice of is video, the packs shown were seriously overcharged on purpose to cause an explosion. If you do the same to nimh cells they can also explode.

I am an RC enthusiast and can tell you that fires are a constant concern, even with the latest packs and the best chargers/low voltage cut off devices.

From my experience, most fires occur when there's a fault in the battery management systems, causing massive amounts of current to flow in circuit. I certainly would think twice about relying on a cheap Chinese made charger or low voltage cut off.

As I said before, it is not recommended to charge or even store lipo cells indoors.

Over discharge is not a safety problem, it simply reduces the life of the pack. In fact the accepted way to dispose of a lipo is to drain the pack and then leave it in a saline solution to reduce the Voltage to zero.

I suspect that the pack you all have may be a lithium ion type not lipo.

[NRG]

Over discharge is most certainly a concern, this is where the damage to the cathode occurs (dendrite formation) and repetitive over discharge causes internal shorting and huge problems on the subsequent charge cycle. Its does not just affect cell cycle life.

http://www.techbriefs.com/index.php?.../NPO19897.html

So many RC enthusiasts fail to understand this and wonder why their cells fail to give full life or fail unexpectedly.

The latest compound Lipo cells are better than their early Cobolt cousins and are far less likely to combust...but they may especially if abused as above. LVC monitoring helps but BMS is better and accurate cell balance charging using CC/CV is wise.

Lipo is the same chemistry as Lithium Ion is other than for the cell construction: Soft pouch or hard case.

[nortot]

Hi all. I have one of the chinese lipo batteries but the destructions are in chinese. Anybody, Stan??, know the correct method of charging??, The is an on/off switch on the unit, and a red and green light on the charger of which the green goes on only in one switch position. I know they can be a little tricky so any help gratefully received, Thanks,
Tom