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Wilco

Beginners question about battery capacity

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Wilco

It's a long time since I had any electrical education so I just want to run this past the better informed.

 

I am trying to fill out my heated kit options for winter, and just want to make sure the wiring and current draw is OK.

 

I currently have a Keis vest, Blaze trousers and socks and RST gloves. I can run the gloves and vest from their own batteries, but assuming I want to run them all from the bike, I think the total draw would be vest 3A, trousers 4A, gloves and socks 1A each giving a total of 9A. If I upgrade the vest to a full Keis jacket that would go up to about 13A.

 

I have the standard fused (15A) cable with y splitter which came with the vest wired directly to the battery, no relay or sub involved.

 

So my 3 questions are;

 

1. On the basis that this power will only ever be used when the engine is running can I assume that a switched relay is not required?

2. Is 13A OK to draw from the bike together with the normal lighting and heated grips?

3. Are there any other issues I am too thick to know about?

 

Thanks all.

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ste7ios

Don't think, be sure. Double check everything. Every detail is important to do the necessary math...

 

Do your list (if I guess correctly):

* Keis B101: 3.3A, 40W

* Keis T102: 3.25A, 39W

* Keis S102: 1.3A, 15W

* RST THERMOTECH HEATED CE WATERPROOF GLOVE: ???

 

You've more than 7.85A / 94W which is probably more than what our 420W generator can afford and your battery will get discharged especially when not riding with more than 2,500 - 3,000 RPM (the max. power output (420W) are produced when the RPMs are near to 5,000 RPM).

 

The relay can save you by a lot of troubles. I strongly suggest it.

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slowboy

Fully support Stelios, a switched relay saves an awful lot of hassles and it is not difficult to do and not expensive. I've done a few on my bikes and friends bikes. Not sure where you're based, but if you can make it down to the South West of Devon, I could do it for you🛠

It takes a couple of hours at most and needs; an inline fuse, a relay, a fuse box and some connectors and wires.

I did put the wiring diagram on another thread a while ago.

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Wilco

Thanks ste7ios,

 

Yes that's about right my kit is -

 

Keis X10 vest                     3.3A

Blaze trouser liner             3.2A

Blaze socks                        0.6A

Oxford grips                       3.8A

RST Thermotech gloves  2.0A ?

Total                                 12.9A

 

If I was to upgrade the vest to the Keis J501 jacket that would add another 3.5 Amps. So I guess it would be better to stick with the vest and run it and the gloves from my battery packs, leaving a maximum of 7.6 amps for the bike to handle. By keeping the grips on low just to add a bit to the gloves and the clothing controllers not drawing max power all the time hopefully the power drain on the battery would be acceptable.

 

It would certainly be interesting to hear what people think the available watts/amps are for the NC at normal running rpm.

 

Thanks for the offer Slowboy, that's very kind. I am  in the East Midlands so it would be a bit of a trek. I am still confused by the need for a relay. The heated clothes all come with a fused battery cable, so does the relay just add the ability to switch off any accessories with the ignition, or does it add extra protection. If it is just switching I am happy to do without as the clothing has to be disconnected when off the bike.

 

Thanks again.

 

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shiggsy

A relay is only required for the Heated Grips I'd say, saves leaving them on by accident.  Do you really need heated trousers and socks ?   Otherwise your probably best hooking it up to a smart charger each night.

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embee

One option I'd suggest considering is one of the voltage sensing switched supplies, these can switch things off when the voltage drops below a set value, some are adjustable. If you supplied your heated clothing via one of these it could avoid the possibility of flattening the battery.

Some are advertised as "split charge relays" such as here http://www.brocott.co.uk/split-charge-relays/

Intended for charging a second battery but you can use the switched output to power your devices, it'll only switch on when the voltage rises above a certain value and will switch off again when it drops below another set value, for example when you come to a standstill.

There are other versions where you can adjust the voltages, like this http://www.brocott.co.uk/kemo-m148a-adjustable-battery-guard-12volt-20-amp/

These usually have some current drain so need to be on an ignition switched supply.

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ste7ios

Every mAh is precious for such tiny batteries especially as they’re aging and having less chances to get fully charged.

 

It’s very easy to add a relay, it’s cheap, it may save the day, and may help the battery lifetime in the longterm...

 

Whatever you do, monitor your battery and use a maintainer when necessary.

 

Also the heating grips seems too be an hyperbole when having the gloves...

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Wilco

Thanks again.

 

The switched relay sounds good but Would probably need a trip to a bike shop.

 

The heated trouser liners are nice for old knees like mine, but are a luxury and save having to run the socks cable up the bike trousers. However I could probably do without them. The socks are a godsend on long cold rides, My fingers and toes go cold quickly at speed. The grips compliment the gloves nicely as they provide warmth to the palm whilst the gloves concentrate on the back of the hand. However I am sure I can turn them right down.

 

So from all the good advice I guess I will look into a meter to measure the battery, and in the mean time not use the grips and trousers at the same time. This will keep the draw below 5amps. 

 

 

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Deltabi

The NC has about 120 Watts available for accessories, that is around 10A. I would safely stay well below this value, especially if you ride in traffic (eg. low revs -> small current from alternator).

A relay is just a way to control big current devices, it does not change your amperes consumption. It would be useful if you want to switch on/off your high current devices from a switch, instead of connect/disconnect their cables.

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