PM4 Battery Problem

[aylos84]

I didn't use my E model with PM4 for about a year and now I am having a problem with the battery. When I connect the PM4 via usb it powers up fine but I get the message battery empty or not present. I left the battery overnight to charge but still the battery gets no charge and every time I connect via usb I get the message battery empty or not present.

Why isn't the battery recharging?

[Citroen]

Rechargable batteries do not survive well if you leave them to go flat.
You'll need to replace the rechargable battery pack or switch to using D-cells.

One home hobbyist I know opened a PM4 battery pack and replaced the two rechargable cells - needs some soldering skill.

[Carl Watts]

You can open up the rechargable pack but as above you do need soldering skills and the two AA Ni-MH battereis need to have solder tabs on them. The capcity of the ones I looked at were only 1200mAh so you can get them with twice this capacity now days. My advice would be to just buy a new pack or switch to D Alkalines or get D rechanrgable Ni-MH batteries as these should last the best part of a year before they need recharging anyway. You can also get plug packs with the USB cable on and just fit D alkalines in the monitor that will efectively only ever then be memory backup in the event of mains failure and so last for years. Also if you have a PC anywhere close by that maintains power to the USB sockets when shutdown you can just use this as well. Anyone using RowPro pretty much never has to worry about battereries with a PC connected to the monitor all the time. The PM4 rechargable battery still really needs plugging into the USB now an again to keep it fully charged.

[mikedepetris]

Do you have an image or a drawing of the inside of the pack? I guess there is a component in the connections of the batteries, may it fail? Which pin of the pack should be the positive (+) and which one negative(-)?

[c2scott]

The batteries should be marked or have a ring on them.
The "component" could be tested with a digital multi-meter. It should be less than 10 ohms. Or you could bypass it and see if that makes a difference. I doubt this part would fail. This is a self-resetting fuse and protects from short circuit or someone trying to rapid charge the batteries.
Is it possible your laptop or whatever you used to charge the batteries went to 'sleep' 10 minutes after starting to charge? Or did you use something like an iPhone charger?

[Carl Watts]

Do you have an image or a drawing of the inside of the pack? I guess there is a component in the connections of the batteries, may it fail? Which pin of the pack should be the positive (+) and which one negative(-)?

If you have a PM4 made after mid 2008, just change to quality Alkaline batteries. The current consumption of the monitor is so low on standby and its powered by the pickup when your rowing. Batteries in these last over a year. Replacement Ni-MH batteries in the pack need solder tabs, personally I think they are not worth playing with just buy a new pack from Concept 2 or switch to Alkaline.

You can check if you have a later version PM4 here.

http://www.concept2.com/service/monitors/pm4/firmware