I've just ordered a new Owon PDS5022S DSO from CPC (Farnell).
**broken link removed** This scope can take an external battery pack, so it doesn't have to be plugged in. This sounds like a good feature, although the battery costs £65. **broken link removed** The £65 battery is a 7.4v Lipo pack, with a capacity of 8000mah. I have found from sources on the internet that it is possible to make your own battery pack.
**broken link removed**
The webpage also states the battery charging voltage is 8.4v - this sounds right for a lipo pack, as it would charge the cells to 4.2v/cell - the fully charged voltage for lipo batteries. The scope's low voltage shutdown will also presumably be at a level which is safe for the cells.
A full charge takes ~12 hours, so the charge rate is very low.
I want to make a battery pack that will fit in the battery compartment, and will power the scope. The 8000mah battery will power the scope for about 5 hours - I would be happy with half of that - so a capacity of ~4000mah.
Options:
- Use six 4500mah NiMh cells in series.
Advantages:
Cheap
Robust
Disadvantages:
Heavy
Large
Won't fully charge at 8.4v
Low voltage cutoff may activate too soon
- Use a 7.4v R/C lithium pack
Advantages
Rectangular
Quite Cheap
High capacity
Light
Disadvantages
Fragile
Reguire cell balancing?
- Use individual lithium cells (**broken link removed**) - two parallel, two series.
Advantages
High capacity
Light
Built in overcharging and over discharging protection (4.2v charging, 2.75v discharging)
Disadvantages
Cost (not too bad...)
Bad use of space in the battery compartment
Balancing issue?
**broken link removed**
From this comparison, the individual lithium cells look ideal, although I'm not sure if I'd have to make my own balancing circuit for them? Or prehaps just connect an external balancer occasionally. Or prehaps the internal protection circuit would prevent it becomming an issue.
Any thoughts or comments?
Thanks,
Andrew
**broken link removed** This scope can take an external battery pack, so it doesn't have to be plugged in. This sounds like a good feature, although the battery costs £65. **broken link removed** The £65 battery is a 7.4v Lipo pack, with a capacity of 8000mah. I have found from sources on the internet that it is possible to make your own battery pack.
**broken link removed**
The webpage also states the battery charging voltage is 8.4v - this sounds right for a lipo pack, as it would charge the cells to 4.2v/cell - the fully charged voltage for lipo batteries. The scope's low voltage shutdown will also presumably be at a level which is safe for the cells.
A full charge takes ~12 hours, so the charge rate is very low.
I want to make a battery pack that will fit in the battery compartment, and will power the scope. The 8000mah battery will power the scope for about 5 hours - I would be happy with half of that - so a capacity of ~4000mah.
Options:
- Use six 4500mah NiMh cells in series.
Advantages:
Cheap
Robust
Disadvantages:
Heavy
Large
Won't fully charge at 8.4v
Low voltage cutoff may activate too soon
- Use a 7.4v R/C lithium pack
Advantages
Rectangular
Quite Cheap
High capacity
Light
Disadvantages
Fragile
Reguire cell balancing?
- Use individual lithium cells (**broken link removed**) - two parallel, two series.
Advantages
High capacity
Light
Built in overcharging and over discharging protection (4.2v charging, 2.75v discharging)
Disadvantages
Cost (not too bad...)
Bad use of space in the battery compartment
Balancing issue?
**broken link removed**
From this comparison, the individual lithium cells look ideal, although I'm not sure if I'd have to make my own balancing circuit for them? Or prehaps just connect an external balancer occasionally. Or prehaps the internal protection circuit would prevent it becomming an issue.
Any thoughts or comments?
Thanks,
Andrew
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