Battery Chargers

By Paul Williams.
Article posted 2nd March 2008.

In the mid to late 1990s, the FE world in Europe was divided into those racers who owned Simprop's NC Manager 2 charger and who won races, and everyone else. Ok, this is perhaps overstating events for the purpose of a dramatic opening line, but it's certainly true that the NC Manager 2 charger with its "burp" charging system gave you a very significant advantage over those racers who used a lesser charger. Why? Simple: the NC Manager 2 not only put more capacity into a cell pack, it also gave the pack a kick up the backside and made it perform. 7 amp charge current and burp-charging (a system where the charger briefly discharges the cell pack at intervals during charging to dislodge oxygen bubbles from the electrode plates inside the cell) took an underperforming cell pack by the scruff of the neck and gave it a stern talking to. The difference was remarkable.

The other striking thing about the NC Manager 2 was this: the manual was utterly, utterly useless. So useless in fact, that for a while I was probably the only FE boater in the UK who actually knew how to use one. So useless, that I ended up typing my own instructions for it, so I wouldn't have to keep showing everyone I'd recommended these things to how to use it.

Which One?

Chargers range in price from a few pounds to many hundreds, yet all do the same basic thing: charge batteries. So, when buying a charger what features should you look for?

With the widespread adoption of lithium-based cells, choice of charger is not quite so critical. Obviously, whatever you choose should above all be capable of safely charging lipos or A123s, and ideally it's better to get a charger with balancing built-in, instead of seperate charger and balancer, if for no other reason than convenience and not having to trail cables between balancer, charger and cell pack.

However, if you have an older charger which does not have a balancer built-in, then buying a balancer can allow you to keep using a perfectly good old charger - but only if it has a dedicated lipo or A123 program. Balancers range in price from less than £20 to well in excess of £100, depending on how fast you need to balance and how many cells you want to balance simultaneously. Schulze's "LipoProfiBal14" will balance up to 14 lipo cells in one go, and also balances very accurately and very quickly.

Schulze 10.36-8 The very best chargers in the world are made by Schulze in Germany. In common with all premium products, Schulze chargers tend to be more expensive than other brands. However, Schulze offer excellent customer backup and their latest chargers (the "nextGeneration" series) are upgradeable via USB. There is a review of Schulze's 10.36-8 here. Back down here on Earth, a more affordable range of chargers are the "Imax" B-Series. The B5, for example, currently costs under £40 from Allan at Astec, and will charge and balance up to 5 lipo cells.

There are literally dozens of lipo-capable chargers and charger/balancers available on the market, some from established and trusted names like Schulze, others from companies no one's ever heard of before. As ever, ebay offers a range of what appear cracking good deals on a multitude of really cheap chargers from the far east. Imax B5 If you're on ebay however, my advice would be to look out for a secondhand Schulze ISL6-330D and pair it with a mid-range balancer. Although not made anymore, the 330D is a classic charger that Schulze made for years, so there's plenty of them around and the backup from Schulze is second to none. Otherwise, buy a charger/balancer from a shop or supplier like Astec, then you've got someone to backup the product, which you might not get if buying on ebay from abroad.

Charging Lithium Polymer Cells

Some chargers claim to able to auto-detect the number of cells you connect in series. If you connect the cell pack to an integral balancer on every charge, which is recommended, or to a separate balancer that can communicate with the charge (for example, the Schulze LipoProfiBal8 or -14), then the balancer will know how many cells you have connected. However, do not trust your charger to always auto-detect the correct number of cells connected - check it every time and you won't lose any cell packs through overcharging.

Also, most lithium polymer cells should never be charged at more than 1C, or one times their capacity. For 5000 mah cells, the maximum charge rate is 5 amps, for 4000 mah, 4 amps etc., so check the charge rate when charging.

Conclusion

You do not need to spend a great deal of money on a lipo-capable charger. There are many, many chargers to choose from, just be careful to do some basic research before buying - for example, asking questions on a forum such as Astec Models or Rum Runner to get opinions from other fast electric boaters who can help you decide what suits your requirements and budget.

Whatever you buy, you must have the capability of balancing cells while charging, either by getting a charger with an integral balancer or buying a separate balancer.

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Last modified: 08th July 2010 @ 09:05