Brunton Solarroll

Is anyone using the Brunton Solarroll for charging batteries? I'm looking at the 4.5 watt version. Does this do the job fairly well? I'm mostly looking at recharging batteries while away from other power sources. Does it have sufficient output for a Ray O Vac 15-minute charger?

Thanks, all!

I don't have any experience with the exact combination that you're looking for but I can vouch for a Uni-Solar flex panel and an AccuManager 20 charger. Uni-Solar makes 5, 11, and 32 watt flexible solar panels. From what I saw on-line they may not be as flexible as the Bruntons - 8" roll vs 6" – and are a little heavier for the same output - but they are a lot less expensive. The AccuManager 20 is a full-featured charger that accepts a pretty wide DC voltage range which makes it a good choice for solar applications. For my setup I just wired up a two pole SAE (trailer hitch-like) connector to cigarette lighter socket then connected the SAE to the panel's built in connector, plugged the AccuManager car adapter into the socket – and that's it. Charge time with a 32 watt panel is one to two hours for AAs – same as plugged into the wall.

If the fifteen-minute charge time is critical, I'm sure that someone here should be able to calculate the current requirements needed to size the solar panel. You should also check the voltage ranges on both ends - unless you're going through an inverter but then you may have to bump up the panel.

I also read somewhere that it is not a good idea to leave the chargers running when the solar panel output drops – i.e. dark clouds or sunset.

I am using the Brunton Solarroll 4.5 with the Brunton BattJack charger. I can do 2 AAs a day in bright sun. There is some kind of undocumented behavior with low voltage though. The charger just blinks constantly, but does charge the batteries. As sunlight becomes more intense, the blinking gradually becomes constant, and the unit switches to normal function.

So, about this AccuManager 20 -- it works ok with low voltage from the panel? That sounds like it might be a better charger than the Brunton. Can it do one or two batts?

Scott

The AccuManager 20 documentation says that it accepts a range from 12V to 16V DC. I did a quick test about an hour before sunset with the UniSolar flex 32 panel and a couple AAs and it appeared to be working fine – normal blinking lights – which is the charge indicator for this charger – steady when done/trickle. I then began to fold/shadow the panel to reduce the output and eventually got two different flashing/charger error conditions – which I assume indicated that the voltage was too low. I put a meter on the leads while everything was connected and got about 6V in the fully exposed very late afternoon sun - normally reads in the mid teens in full sun. The voltage was around 5V when the first abnormal/undocumented flashing occurred, and around 4V when the next condition kicked in. So it appears this charger works down to around 6V but I did not test the charge rate in that condition – all I'm going on is the indicator lights on the charger. The panel is not the Brunton panel but there is a good chance that the cells are similar – although this model is capable of supporting higher current loads than the Solaroll 4.5 – which could be the limiting factor. Weather permitting I'll try to do some more testing in the next or day two and see if I can mimic the performance of a smaller panel.

The charger itself is very nice and can handle one to four AAAs, AAs, Cs, or Ds, and one or two 9V – NiCad, NiMh, and RAM cells – smart charge followed by a trickle charge. The unit, without the wall wart, is very light and easy to hook up to a solar panel. It may be a little bulky for camping but the versatility is certainly a plus. I bought it about a year before it was reviewed on this site – I was glad to see other people liked it as well.