Razor Pocket Rocket/MX500 battery options

£17 on ebay will buy you 2x 15v Lipo packs 4000mah

I tried these on a scooter -great,but I had a few issues getting a decent charger.

Now Ive got the charger sorted (does cost about £50) I would really recommend a couple of these batteries. In series will give you 30v,loads of amps for a 5km range,and only weigh 200grams!

I was looking at Lipo, but all the comments on the forum about cell balancing and fire put me off. They do sound good though.

The fire problem is solved on the Lithium batteries provided you buy good ones.

The cell balancing does not go away by changing to Lead Acid or NiMH batteries. Balancing your batteries is just as important with these chemistries as any other.

I raced RC cars for 16 years during the time NiCd were in use and we went a step further than balancing our batteries, we matched all the cell charge and discharge characteristics before we made the battery packs. This was done to eliminate the need to balance each cell in a pack. When you cycle NiCd about 7 times they settle into the charge, discharge pattern they will have for life unless you do not discharge them all the way with each use. Once they have stabilized you can measure the charge, discharge characteristics and match all the cells into packs. With the cells of a pack matched and running them to full discharge each time they stay balanced. I love NiCd and have some battery packs that are more than 25 years old that have had a hard life but still hold a normal charge and push well over 30 amps when call upon to do so. If you do not match all the batteries in a pack you will have to design some type of a cell balancing circuit.

So what am I saying, I am saying the chemistry of the battery does not matter. Balancing of the cells in a battery pack is the number one requirement for battery performance and life.
Example:
When I first started racing I did not match my battery cells. During a race the car would slow down and if you continued to drive after a race was completed the car would slow to a crawl before stopping all together. When I started matching cells to build my battery packs the car ran almost as fast at the end of a race as it did in the beginning. With matched cells there was no fall-off of performance as the pack discharged. When the pack was at 100% DoD the car would be running normal and then just stop without any warning. This was the sign of a well balanced pack.

Grandpa Chas S.

Yep Ive had good results with NiCd too- shame its so poisonous!

Anyway my electric skateboard has proved to be life threatening too. Had nasty crashes so its going into retirement! still Ive learnt something and that is how much I like the 'D' Cell battery format.

I dissasembled my lipo packs and rolled each 4v 4ahr cell into a D cell container (a plastic AA to D expander). Ok first time I tried this it burst into flames but subseqent gentle rollings were ok. I connected the + /-tabs to each end of the D cell holder

Anyway now I have 7 D cell lipos. And can use standard battery holders to link them all a) in series for use , and b) in a modified D cell charger them all in parallel upto 4.2v.

All worked well. One huge advantage is no leads required as my LipoCells just connect like normal D cells in a line.

Skateboard went really fast - Ive got the grazes to prove it.

Upshot is I would urge manufacturers to look at making D cell style Lipos. You could also use them in conventional equiptment putting blanks every other cell!