TedMo

Perhaps someone out there remembers the M.E.N chargers. I have 3 of them and used them for years totally successfully for my Ni Cd's and still do. Unfortunetly these are out of business now as far as I can see. They operate in a totally diffetent manner than other chargers but I love them. Now I'm switching over to NiMh batteries and do not know if I can use the M.E.N's for them. Really don't want to ruin some new Ni Mh packs just to find out. Anyone have any knowledge about them?

guver

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A link or info might be helpful to describe this different manner. It may be ok to use ? I can't seem to locate any info on them.

TedMo

Thanks Guyer but I lost the booklet on it so all I remember is that they operated on some sort of pulse system. no need to set anything other than could only use voltage it was made for. Either 4.8V, 6V. or 9.6V.Just plugged in regardless of MA. Red light would come on if for RX. or TX. charge or both. Red light stayed on till got certain stage of charge then would blink and shortly after go out thereafter it could remain plugged in indefinitly with a trickle chg. Nothing fancy but worked great. I still use on my Ni Cd's.

guver

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I suppose (without finding any info on them) the best way is to try a nimh pack and see if it gets hot at the end. Many chargers do make a distinction between the two types of nickel batts. Many do not know or care and will treat them all the same. Generally it is the voltage drop at end of charge that is different with nimh batts using about half the value of a nicad. I'd guess that it is ok to use it and the pulse will not hurt either. That's my best guess.

Here's a thread about voltage drop (nicads use 10 mv and nimh use 5 usually ) http://www.rcuniverse.com/forum/m_83...tm.htm#8313483

TedMo

Thanks Guyer I'm a bit late reading your reply but anyway what you suggest is what I'm trying \. So far seems good.

EloyM

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Remember that the MEN charger appeared long before NiMH batteries did, so they would not have been considered in the design.
It should not destroy NiMH's, and there is a sure way to determine effectivenes. First charge your NiMH's as you normally do, and check (cycle? - an erroneous term in this application) their capacity. Then, starting with a partially discharged NiMH, hit it with the MEN, and check the capacity once again. If it is any less, of course, the charger is not compatible.
Heat should not be a problem, as the charge rate is not that high, but it would be a good idea to check it periodically.
To establish my expertise (Ahem!), I have owned MEN chargers, I have an schematic diagram, and I even know what M.E.N. stands for.............Luck, Eloy

Dusey52

The M.E.N. (Model Engineering of Norwalk) charger uses a simple zener diode / resistor network to trigger an SCR that controls the high rate charge circuit. As the pack voltage rises, the on state of the SCR is ramped down until it's off and then you're left with just the trickle charge. The high rate cut off is set to about 80% charge based on pack voltage. It's a simple, effective design but since the voltage detector circuit is hard wired, it can only be used with packs with the cell count that the charger was designed for.

Since the high rate to low rate transition is based on a fixed voltage it should be OK to use with NiMh. I think the M.E.N. high rate charge current is fairly modest by today's standards. Just keep an eye on the pack the first time and make sure it doesn't get to warm.