Vision Peak Ultra

[swampfox201]

Hello everyone,

I have the Vision Peak Ultra charger

www.dynamiterc.com/Products/Default.aspx?ProdID=DYN4053

It is both AC and 12VDC. It works great charging my 8 cell 1500mah elites on the AC side. I can top off a pack thats been previously charged a few days ago in around 6 min at 1.5 amps. The voltage peaks at around 12.40 volts.

The problem I have is when I try charging in DC mode. I hook the cables up to the battery on my pickup and set the charge rate to 1.5 amps and it won't charge above around 11.60 volts and it won't peak even if I try charging at the maximum 5 amps. The battery doesn't even get warm.

Does anyone have any ideas? Is it because my pickup battery is only 12 volts. It says in the manual not to charge with engine running.

Thanks,
Todd

[cjg]

How old is your truck battery, is it turning out 13.5v like normal car batteries (even when rated at 12 volts)?

[swampfox201]

I'm not sure how old it is but my tester says it is putting out 12.1 volts. My experience with car batteries is that they will show a voltage of around 12 volts unless the engine is running then it will be somewhere in between 13 and 14 because the alternator is charging it.

I forgot to mention that the charger seemed to work great charging my stock 7 cell battery with the pickup battery.


Todd

[mrmugen]

I am not sure why but these chargers like 12.6v or higher. Mine does the same thing if my battery is below 12.6 the charger beeps all weird and goes wacko. A charged 12v should read 12.6-12.8v from what I understand. Try charging it up and trying it again. If it is in your truck then shut off your lights and any ohter power drain and let it run and try again. Kevin

[davemac2]

As to your issue Swampfox with charging the 8 cell pack with your car's battery: do the charger specs state that it is possible? I don't think it is without the car running to give 13.5 or 14v. Even then, it may have trouble peaking the charge. The Nimh cells can reach anywhere from 1.6 to 1.8v per cell when peaking. So for your 8 cell pack, that's 12.8 - 14.4V. So you pretty much need the car/truck running for peak detection to work. Otherwise, the charger's current source will simply stop supplying current and the pack will never peak. Depending upon the charger design, it may not even work reliably with 13.5v alternator voltage. Why? Because the charger may need a minimum 0.8V drop across its pass transistor to function. The charger manufacturer may not spec. the charger for alternator voltage because of noise issues with the peak detection, or they may be other reasons.

I know that the HZ 1026 charger that comes with the cub is probably capable of charging the 8 cell pack with the car running, but just barely. This charger puts out ~1A charge current when the pot is set full clockwise. I have examined the charging circuit and know that the charger is quite capable of supplying up to 2.5A charging current since the pass transistor in there is rated for 6A. The only limitation would be heat dissipation, but for higher cell packs like 7 or 8, that should be less of a problem. If you look inside that charger, there is a small pot in there that is factory adjusted for peak current. Turning that fully clockwise can usually get you to 1.5A output to decrease the charging time.

dave mc

[swampfox201]

Dave,

Thanks for the reply. Sounds like you have a lot of knowledge in this area. To answer your question - The manual just says it will charge a 8 cell pack. It doesn't say anything about not being able to charge an 8 cell on the DC side. In the manual it says DO NOT USE CHARGER WITH ENGINE RUNNING. It is even underlined.

I'm kinda bummed but it makes sense I guess. The only question I have is about a 12VDC power supply that plugs into 110V. You buy these to run a DC only charger inside - how can that be any better? I've never heard of anyone not being able to charge a 8 cell pack on a DC charger.

Todd

[davemac2]

swampfox201 said:

The only question I have is about a 12VDC power supply that plugs into 110V. You buy these to run a DC only charger inside - how can that be any better? I've never heard of anyone not being able to charge a 8 cell pack on a DC charger.

Todd

I can only assume that the 110 AC-to-DC supply puts out 14V and not 12V.

dave mc