Battery charging by mini gennie

Responder59 · Post by **Responder59** » Sun Feb 03, 2008 4:29 pm

I recently bought a Wolf 950 generator,new for £30. Beats me how they do it! It has a max output .72Kw 240 volts and a 12 volt battery charging output of 12v DC @ 8.3 amps and a charge capacity
of 40Aamp hour battery.

At the moment it is happily purring away putting 13.6 volts into a 110 amp
hour battery that I purposely ran down to 8 volts.

Question........... The handbook clearly states DC output charge capacity 40 amp hour. By charging a 110 ah battery am I doing anything that may damage the gennie or the battery?

Over to you Bongotechs.

regards,
Steve

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 4:39 pm

No. Your not doing it any harm. However why did you discharge the battery so low. If you discharge a "12" volt battery below about 11.5 volts you could be causing damage. A "12" volt battery when full will read about 12.8 volts and is about 50% at around 12.4 Volts. You should not let them get much lower than this. When they read 12 volts they are to all effect flat. If you have a 95 amp hour battery, you will only get about 85 amps into it and the last 25 amps are not going to be much good therefore when charged you only have about 50 amp hours worth of useable power.

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 4:48 pm

Note...all above figures %'ages are approx. I could give accurate ones but carn't find my bit of paper. Still your 110 amp hour battery really only has a "useable" capicity of around 75 amp hours.
Your genny is charging at 8.3 amps so it will take about 13 hours to fill it up. Be cheaper to plug it into the mains.

Responder59 · Post by **Responder59** » Sun Feb 03, 2008 5:10 pm

Oh S***! Thanks for the advice. The battery in question is an old one that I removed from the Bongo when I fitted the L/B. I left a 12 volt test lamp burning overnight just to do this test.

Multimeter read 8.6v before I hooked it up to the gennie.
I anticipate using the gennie to top up the L/B when wild camping or to give the starter battery a quick boost should it fail to start the vehicle.
This seems to happen very easily on my Bongo and I have read similar
posts along these lines.

The gennie has been running for 2 hours now so I will go check the voltage of the said battery.

Thanx again for the advice guys,

Steve

Responder59 · Post by **Responder59** » Sun Feb 03, 2008 5:16 pm

12.7 volts after 2 hours charging by gennie. How does this sound?

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 5:17 pm

You will not get a good reading untill the battery has stopped gassing and settled down. Leave it 2 or 3 hours and then read the voltage.

Responder59 · Post by **Responder59** » Sun Feb 03, 2008 5:34 pm

Cheers Haydn I will do this. While you are "on air" could I pick your brain further. I have tried to run a small 3 stage charger (3.8 amps)
from the 240 volt output of the gennie. I bought this from Liddles
£12.99 after reading a recommendation in the forum.

I thought that this wouls be ideal for the L/B as it would not overcharge but the gennie doesn't like it at all. The gennie output voltage starts to fluctuate wildly after a short time and then the safety cut out stops the engine. Any comments?

Steve

trevd01 · Post by **trevd01** » Sun Feb 03, 2008 5:36 pm

I think the Wolf 950 has been replaced by the 980. AFAIK the 950 doesn't meet the 2007 emission regulations -doesn't stop you using it if you've got one, though.

These little generators cost about £1/hr to run in fuel, so if on a campsite with hookup available, that will generally be a cheaper (and less annoying for your neighbours) option.

But if you are wild camping in particular, and don't want to drive for several days it would be ideal. I have no idea how much fuel a Bongo uses on tickover, which is obviously the alternative?

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 5:45 pm

Don't know why the genny dosn't like to run the charger. However charging a 100amp hour L/Batt with the 13.8 amps from the genny charging output will not overcharge it as long as you dont leave it running too long. If you let it drop to about 12,2 volts and then give it a couple of hours you will be putting around 20/25 amp hours back so no danger of over doing it.

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 6:00 pm

Point to bear in mind.... Your bongo has about a 80 amp alternator on board and charges the batteries at a much greater rate than 13 amps.
Your L/B may have a gizzmo in line that reduces this down but it will still be quite high.
Vehicle alternators are designed to "whack" high currant into the vehicle battery to replace the power used to cold start it. Thats why the belts squeal first thing in the morning (if they are a bit worn) when they are under max load. The alternater gets feedback from the battery and then reduces output as the amps are replaced.

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 6:05 pm

Thinking about running your charger from the genny. It could be the electric produced by the genny is a very crude waveform and the charger dosn't like it. They will run power tools etc but I wouldnt try a radio or TV as they like a pure sine wave and I doubt the genny produces this. Same rule applies to cheap inverters.

Responder59 · Post by **Responder59** » Sun Feb 03, 2008 6:58 pm

Thanks Haydn, food for thought there. My 15 inch LCD TV runs quite happily from "gennie 'lecric" using a surge protector. I can also run a 12 inch fluorescent tube flicker free simultaneously.

Steve

haydn callow · Post by **haydn callow** » Sun Feb 03, 2008 7:10 pm

They will run fine ..then out of the blue they will start smoking and pack in. Somthing to do with Thyristors instead of transformers which were in old time tv's..
Not a expert on this but blew up a couple of tellys on my boat useing cheap inverters and gennys

heatherpetch · Post by **heatherpetch** » Sun Feb 03, 2008 7:44 pm

HELLO STEVEN $\:D/$ $\:D/$ $\:D/$ $\:D/$ $\:D/$ $\:D/$ $\:D/$ $\:D/$