Hi,
I am trying to design a very small power generator (500w) in order to dump a bit of power in the pack
Hence I'd like to get info about the ideal charging voltage
it would be great if I could find back the pack data sheet lost somewhere in my 4 macs....
regards
jean mi
pack charging voltage
Sun, 10/31/2010 - 12:57
#1
pack charging voltage
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Support V is for Voltage
It will very much depend on the chemistry of your batteries. Assuming that they're SLA, here's a useful resource. Designing a charger is a non-trivial electronic exercise.
http://www.power-sonic.com/sealed_batteries.php
Mark
I'm guessing this is for a Vectrix?
at 500W (~4A) the max charge voltage I would set is 148v.
if its a real generator (so prime mover to alternator to rectifier bridge) then you should be ok hooking it up directly.
if theres power electronics inbetween, you will need an effective current limit.
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Hi Mark,
I am thinking of the vectrix nimh battery pack .
I did not want to publish too manny details about this project cause you know I hate guy's posting "I will do this and this and that" who do nothing but .... so as I may also be part of those who won't do what they would like to .... well maybe a couple of extra details would help to reply properly my question so :
I fact I am not trying to design a charger .
I just would like to dump 500w in the pack during my trips and short stops at destination where there is nothing to recharge in my f....n country .....
so over a 5 hours trip I could add 2000 w in the pack, far less then the capacity but far enough to extend my range up to 100 km just to provide me with the flexibility I need in the 10% on my trips where I am really close to the limit ...
I mean the pack will never be fully recharge under those conditions and the current would be max 3,5 amp ... (rather smooth for the pack)
one of my typical trips is going from Nice city (in the south of France) at the sea level to Grasse city 35 km away 800m above the sea level, arrived in Grasse my power gauge says I have used half of my power, going down to Nice is Okay cause down hill it takes less power but I usually arrive in Nice with one or 2 bars ...with no safety margin ...
the generator would only be started a few km after departure, and only in the cases where an extra range is necessary and charging point is available
this is why I though adding a bit of hybridization .
I did not invent anything, my mate has done this on his crap chinese lead scooter and has a 70 km range where 40km was a max before .
He uses a wankel RC model engine and a brushless motor/generator, rpm is 18.000 !!!!!! and on a 4 hours daily use (which i will never ever need) the life expectancy is 4 years,
the engine weights 2 kilos an consumes 0.12 lt/hour ....
he propose me to make me one ...
here is why I am asking the ideal charging voltage in those conditions... I tend to think that 145 v would be an interesting charging voltage.
posting this story is only aimed at let you know details to help with the choice of a charging voltage , for the rest I will do it and after publish photos,
regards
jean mi
vectrix for long i hope ...
Thanks a lot,
I was thinking of 145 volts,
regards
jean mi
vectrix for long i hope ...
The max voltage only really matters when you get to full charge.
for what you are using it for, it won't much matter as long as it is above 144v.
one thing to look for are 120vac nominal ~1kw inverter gensets.
they will weigh ~12kg.
their internal DC bus is nominal 170vdc (155vdc if 110vac nominal, thats actually a better match).
you won't need the inverter part.
you can direct connect the traction battery to that DC bus.
the battery will hold the dc bus voltage down.
the main effect this will have is the engine inside the gen set will turn slower, and reduces the gen set max power.
the voltage should still be high enough for the engine controls to work.
the governor may need to be dispensed with.
leaving the generator full throttle will be fine, as the motor rpm hill be regulated indirectly by your battery voltage.
back to your friends RC engine powersupply,
that will make a much lighter solution than mine.
choice of fuel may be more limited though, and efficiency will be lower.
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km