Author Topic: ST2 starter battery replacement  (Read 116 times)

ChrisW

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ST2 starter battery replacement
« on: November 23, 2021, 03:16:00 AM »
I need to replace the starter battery on my ST2 which is only used periodically. I've tried keeping it on a solar charger, but in the winter months when there's snow and it doesn't get used, the battery gets drained quick. Can I use a deep cycle battery or just a standard AGM? Is there an alternative to removing the battery when it is not being used for more than a month? Also, once the generator is started does it charge the battery back up?
Thanks!

mihit

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Re: ST2 starter battery replacement
« Reply #1 on: November 24, 2021, 07:25:13 AM »
A battery Isolation key/switch would be simpler than "removing the battery"

Solar panels output more in cold weather...are you sure your charger is able to handle that and not cooking the batteries?

Any battery technology (VRLA, SLA, AGM, Wet Cell, even LiPo) will be fine as long as it has the CCA rating required. NONE of them like being drained and left undervoltage.

I'm not sure of the wiring setup on your ST, but it really should charge the battery when running, and if it doesn't then you should be putting a generator/alternator/rectifier on the unit, so it does.

mikenash

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Re: ST2 starter battery replacement
« Reply #2 on: November 25, 2021, 05:09:05 AM »
A battery Isolation key/switch would be simpler than "removing the battery"

Solar panels output more in cold weather...are you sure your charger is able to handle that and not cooking the batteries?

Any battery technology (VRLA, SLA, AGM, Wet Cell, even LiPo) will be fine as long as it has the CCA rating required. NONE of them like being drained and left undervoltage.

I'm not sure of the wiring setup on your ST, but it really should charge the battery when running, and if it doesn't then you should be putting a generator/alternator/rectifier on the unit, so it does.

Just a comment:  In my work we have lots of remote sites with generators.  From time to time one of them will lose the 12VDC side of their output and no longer charge the various batteries associated with the installation.  What we have done is simply go down to the local auto parts store, buy a single-phase battery charger, and plug it into one of the single-phase outlets of the genset

Simple solution often the best :)

mihit

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Re: ST2 starter battery replacement
« Reply #3 on: November 25, 2021, 07:38:56 AM »
Fair comment.
But I'd rather fix the thing.
Although the losses may be low in converting rotation-ac-dc, especially with the new switchmode  chargers... it's still a loss,
...and I don't have the luxury of much "overhead"
...and the "local" store is a fair waysaway
...and it's one more "thing" to go wrong... I can re-wind an alternator and solder up a diode bridge if I have to. Beggared if I could fix the circuitry in a microchip controlled charger.

BruceM

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Re: ST2 starter battery replacement
« Reply #4 on: November 25, 2021, 08:04:54 PM »
AGM batteries have a lower self discharge rate so might help, but make sure there is no current drain on the battery via a sensitive DC clamp on ampmeter.  You shouldn't have to go AGM for a starter battery, but I use my retired home/shop 12V AGM 100AH battery for my Listeroid.  I retire them to the Listeroid, with solar charger at 5 years.  They may still have move capacity than needed for that application, since starting is via air motor.  They die at about 10 years or so.

These clamp on DC/AC amp meters are cheap and work fairly well and can measure very small DC currents: https://www.amazon.com/gp/product/B07P5QKQ5L/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

You can also check the charging current easily with it.

An old lead acid battery may have a high self discharge rate, and it sounds like that's your problem, but I'd want to be sure before killing a replacement battery.
Taking out the battery and keeping it on a trickle charger is best for lead acid battery life.  Solar panel and chargers work well as long as the panel is tilted to self clear of snow in a day or three, and the climate is suitable.  I use one on my Kubota tractor.  It's 7 year old battery loves it, since it's not used regularly.  If you aren't getting 5+ years from a starting battery, you're killing it...most often by sulphation (protracted undercharge).

A modern switch mode low current charger off the mains as Mikenash suggests is quite high efficiency and is certainly no more of a load on the engine than the stock alternator charging circuitry.  Fixing things is nice but it's a legitimate work around without penalty, especially if time and parts aren't available.

The cheapest $12 or less Chinesium on/off type solar charge controllers work well for your application; that's what I use for my Listeroid solar charger, with a roof mounted 40W PV panel.






ChrisW

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Re: ST2 starter battery replacement
« Reply #5 on: November 29, 2021, 09:00:31 PM »
Thanks for the replies. Since the genset is used to power my off grid cabin that I don't use too often, usually a week every month or two, the battery is really not getting much use. I had good results during the summer keeping the battery topped off with a 20 watt solar, (https://www.amazon.com/gp/product/B07Y5TKMZ4/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&th=1) but it didn't do it in the winter when left without running for a month or two. There could be a leak, which I will solve with a kill switch, but I  think the location of the solar panel is the main issue and I can't really get full sun at this time of year within 30 feet of the genset.....
I was just up at the cabin and took the panel of the electric side of the genset and discovered a 12 v charger built in! I guess this acts like an alternator? I installed a new Optima red top battery which I discovered came at only 12.38 volts. I switched the charger to high and ran for a couple hours per day. It did not bring the voltage up to 12.8 as it should be so might be the battery (which I've already replaced) or maybe the charger...
BTW the old battery was pretty small and only like 500 cca so I think it just drained itself in the winter trying to turn the engine over, which it did once, but then never again...after that the battery voltage dropped to below 10 and I couldn't revive it....supposedly Optima can be drained to almost nothing and revived.

BruceM

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Re: ST2 starter battery replacement
« Reply #6 on: November 30, 2021, 12:42:33 AM »
I"d fix the solar charger problem, myself.  Some direct burial 12-3 gives you 4 conductors for your run to a post where you can get some sun.  I would go at least 40W; panel output will less than advertised.  I say this because it will extend battery life greatly.

AGM batteries won't tolerate being run flat. Not even the Optima yellow top "deep cycle". If you get back 50% of the battery capacity you'll be lucky, just like wet lead batteries.