Jump start from your leisure battery

[Clive and Sarah]

Now...I'm going to risk being a wally or teaching grandma to aspirate an egg but flattened the main battery today just leaving ignition on (only took 2 hours or so !which was a suprise!!) Someone had some jump leads and was about to get them to drive into a position for jumping from them when had the bright (or maybe not so bright) idea of jumping from the leisure battery. Only needed one lead to connect the two positives as, presumably, both batteries earthed through the chassis.

....and....weyhey up she fired and and away we went. So...only need to carry one jump lead around with us for such eventualities.

Please tell me this was a great idea and I'm not likely to have blown something.

[timhum]

Great idea I think. Well it worked didn't it! You will not have blown anything in my view.
I am guessing here but the glowplugs are probably the culprit for draining the battery in a couple of hours. They take a hefty current and will not be turned off until the engine has warmed up as I understand it.
That would do for your battery easily enough.
Tim

[francophile1947]

So...only need to carry one jump lead around with us for such eventualities[-o<

Unless you've been camping, and your leisure battery isn't fully charged!!!

[mikeonb4c]

Are leisure batteries happy having the high current drain that comes with starting an engine? I dont know but perhaps someone could offer reassurance?

Mike

[moonshine]

I regularly start one engine on my boat from the leisure batteries, as long as they aren't flat that is. If they are too low, a system of switches allows me to start the port engine from the starboard engine's battery. An "internal jump-start" in effect.

I have heard that leisure batteries aren't designed to take large current drains such as engine starting, but as I have been doing it for years without noticing any rapid deterioration of my leisure batteries, I shall continue to do so.

Clive and Sarah, I am surprised at how quickly your main battery was drained just by leaving the ignition on. Are you sure it is in good condition? The glow-plugs do take a large current, but I think they are on a timer as I would have thought that leaving them on for two hours would probably burn them out otherwise.

[Clive and Sarah]

Hi Moonshine. The aircon was still running I suppose but the condition of the main battery worried me as well. Seems to start really well all the time.....so far. Also worried that drawing large current from the leisure battery might upset it, but its not for long.

[moonshine]

If your Bongo starts as easily as mine, it will start ok on a slightly dodgy battery provided it hasn't been standing for a week or more. I would get your main battery checked, as it may be on its way out.

You are right about the heavy discharge of starting on a leisure battery not being for long just starting your Bongo's engine. My boat engines sometimes take ages to start, unlike my Bongo, as they are over 40 years old. It still doesn't seem to have affected the leisure batteries though. I certainly wouldn't worry about the occasional emergency jump-start from your Bongo's leisure battery.

[mikeonb4c]

There's been recent discussion about this on BF. Conclusion was (as moonshine has indicated) that if your battery is healthy you shoud be able to leave the ignition on for a very long time (one owner - was it Dandy - did that for 24hrs or so with no ill effect). Glow plus would have to switch off on a timer I think (or they'd burn out?). Aircon doesnt figure as it only works when engine is running. So the battery may be suspect (or as in my case, after I'd bought a new battery and went to take the old one out I found a terminal wasnt tightly connected - I still wonder if I bought a new battery for no good reason!).

Mike