T-Pain Is On A Boat: Re: [Electric Boats] Re: charging troubles solved (Not so much)

Tuesday, July 6, 2010

Re: [Electric Boats] Re: charging troubles solved (Not so much)

For what it is worth. I just found I had a bad battery. I use the 48v kipoint with agm batteries. I never felt very good about this set up. I wish I would have invested in a charger like the promariner with the individual 12v charging modules.

With my 134ah 48v bank I had significant power loss after consuming about 40aH. Upon measuring individual batteries I found the number 2 battery in the string to be down to 9.5V whereas the other three batteries in the string were all at about 12.4 to 12.5 volts. This could be a result of the punishing effects of series charging on the weak battery in the string.

Hans

I

--- On Tue, 7/6/10, aweekdaysailor <aweekdaysailor@yahoo.com> wrote:

From: aweekdaysailor <aweekdaysailor@yahoo.com>
Subject: [Electric Boats] Re: charging troubles solved
To: electricboats@yahoogroups.com
Date: Tuesday, July 6, 2010, 12:52 PM

David, I think there is a typo where you meant you adjusted the charger to 63.6V (=2.65/cell). And to summarize - I think you are saying that the Kipoint is just doing 2 step charging - first 2.45V/cell (59V) and then dropping to float.

This is useful information. I was also seeing some early battery failure with the Kipoint - luckily my WalMart strategy continues to pay off (trade in old batteries just before the warranty expires...)

Hans also has a Kipoint, but is using AGM batteries if I recall - so maybe he can comment on how that is working out.

I have switched back to ProMariner (20amp, distributed to 2 banks X 2). Individually charging the batteries seems a better strategy long-term given how the weak battery will always get punished trying to charge @48V

-Keith
--- In electricboats@yahoogroups.com, "davidchristiansen60" <dc@...> wrote:
>
> Found the problem why my 48V 120Ah open lead acid pack wasn't charged properly. Open LA semi traction batteries need 2,65V per cell for the last part of the charge. First step constant current up to 2,45V, then next step max 3,5A to the 2,65V, last step float charge at reduced voltage.
> So with the KIPOINT 48V20A charger stopping at 59V the batteries were never fully charged, and they sulphated! The KIPOINT charger is not a real automatic 3 point charger. After reaching the 59V it went directly into float mode. After shifting a zener diode (instructed by the factory) the top voltage could be adjusted to 53,6V BUT: depending of the float point adjusting potmeter it then either 1) went on charging with constant 53,6V at about 10Amps!!! without stopping, or 2) went directly into float charge mode.
> Analysing the circuitry it turned out the device is more a power supply than an automatic charger. Only regulating IC is an OpAmp. The other 2 IC's are switch mode controllers.
> The KIPOINT charger is maybe OK for SLA type batteries, where the voltage may suffice, but I found no real 2. charging step in the device.
>